Gautam Mishra - Academia.edu (original) (raw)

Papers by Gautam Mishra

Research paper thumbnail of Efficient photocatalytic hydrogen evolution system by assembling earth abundant NixOy nanoclusters in cubic MCM-48 mesoporous materials

RSC Advances, 2016

A MCM-48 mesoporous support containing NiO and Ni2O3 nanoclusters exhibit high activity for photo... more A MCM-48 mesoporous support containing NiO and Ni2O3 nanoclusters exhibit high activity for photocatalytic hydrogen production in comparison to NiO.

Research paper thumbnail of Estimation of New Chemical Entities in Biological Fluids for Bioavailability and It S Pharmacokinetic Evaluation to Screen the Suitable Lead Candidate

Research paper thumbnail of Statement of Retraction: Dual approach utilizing self microemulsifying technique and novel P-gp inhibitor for effective delivery of taxanes

Journal of Microencapsulation, 2021

Ajeet K. Singh, Akash Chaurasiya, Anshumali Awasthi, Gautam Mishra, Dinesh Asati, Roop K. Khar, &... more Ajeet K. Singh, Akash Chaurasiya, Anshumali Awasthi, Gautam Mishra, Dinesh Asati, Roop K. Khar, & Rama Mukherjee (2009) Oral Bioavailability Enhancement of Exemestane from Self-Microemulsifying Drug Delivery System (SMEDDS), AAPS Parm SciTech, DOI: 10.1208/ s12249-009-9281-7 In addition, concerns were raised regarding the integrity of Figure 7, which contains panels that are identical, after color adjustments, to those in Figure 11 of the following manuscript:

Research paper thumbnail of Photocatalytic Hydrogen Evolution from Earth Abundant Nickel Oxide Clusters Dispersed on MCM-48 Mesoporous Materials

ECS Meeting Abstracts, 2015

NiO, as an earth abundant metal oxide that has been extensively studied as a co-catalyst for a va... more NiO, as an earth abundant metal oxide that has been extensively studied as a co-catalyst for a variety of photocatalytic reactions, including solar hydrogen generation. Mesoporous materials have been used as a support to disperse spatially isolated semiconductor clusters to minimize photoinduced charge-carrier recombination and enhance photocatalytic efficiency. Such well-dispersed semiconductor particles encapsulated in mesoporous matrices possess small sizes due to quantization effect and higher redox potentials compared with those in bulk. In this work, NiO semiconductors were dispersed onto MCM-48 mesoporous materials and their photocatalytic activities were explored. The physico-chemical properties of all the prepared samples have been investigated using a wide selection of techniques ranging from powder X–ray diffraction (XRD), BET surface area analysis, atomic absorption spectroscopy (AAS), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS), and ...

Research paper thumbnail of Thin Head and Single Use Microkeratomes Reduce Epithelial Defects During LASIK

Journal of Refractive Surgery, 2006

To evaluate the effect of microkeratome design and head dimension (flap thickness) on the rate of... more To evaluate the effect of microkeratome design and head dimension (flap thickness) on the rate of epithelial defects. A retrospective review of 4000 LASIK procedures performed between May 2000 and December 2003 was conducted. Intraoperative epithelial defects were identified in 326 cases. The microkeratome design (reusable vs disposable) and head dimensions (100, 130, and 150 micron) were recorded along with age, sex, central ultrasonic pachymetry, keratometry, preoperative refraction (sphere, cylinder, and axis), and Schirmer testing. The chi-square and Student t test were used in data analysis. A total of 326 (8.2%) procedures had an associated epithelial defect. With the reusable microkeratome, heads that produced thinner flaps were associated with a lower incidence of epithelial defects (P<.05 for all three groups, 100, 130 and 150 micron head). When compared to a reusable head of the same dimension and to the entire population of reusable heads, the disposable 130 head exhibited a significantly lower rate of epithelial defects (P<.0001). The results of this study support that both microkeratome design and head dimension (and resulting corneal flap thickness) play a role in the formation of epithelial defects. These are surgeon selectable factors, unrelated to technique or patient risk factors, which can be used to reduce the rate of epithelial defects and associated complications.

Research paper thumbnail of Evaluation of in vitro anti-psoriatic activity of a novel polyherbal formulation by multiparametric analysis

Anti-inflammatory & anti-allergy agents in medicinal chemistry, Jan 20, 2017

The beneficial role of traditional herbal medicines in the treatment of inflammatory skin disorde... more The beneficial role of traditional herbal medicines in the treatment of inflammatory skin disorders has been widely reported. Psoriasis is characterized by uncontrolled hyper-proliferation of keratinocytes, disturbed apoptosis, over-secretion of inflammatory cytokines and angiogenic factors. We have developed a novel aqueous polyherbal formulation (SIRB-001) consisting of 3 herbs; Rheum palmatum L., Rehmannia glutinosa Libosch and Lonicera Japonica in the ratio 1:1:3. SIRB-001 has demonstrated efficacious effects in psoriasis patients. Therefore, this study was aimed at scientifically evaluating the in vitro antipsoriatic activity of SIRB-001. Cell based and enzymatic assays were employed with multi-parametric analysis of key markers. SIRB-001 significantly inhibited (p<0.01) proliferation of keratinocytes (HaCaT cells) and resulted in induction of apoptotic markers (Phosphatidyl Serine externalization, mitochondrial potential depolarization, caspase-3, cell cycle (SubG0/G1), DNA...

Research paper thumbnail of Intraoperative aberrometry versus preoperative biometry for intraocular lens power selection in axial myopia

Journal of cataract and refractive surgery, 2017

To compare the accuracy of intraoperative wavefront aberrometry (ORA) and the Hill-radial basis f... more To compare the accuracy of intraoperative wavefront aberrometry (ORA) and the Hill-radial basis function (RBF) formula with other formulas based on preoperative biometry in predicting residual refractive error after cataract surgery in eyes with axial myopia. Private practice, Harrisburg, Pennsylvania, USA. Retrospective consecutive case series. Eyes with an axial length (AL) greater than 25.0 mm had cataract extraction with intraocular lens implantation. For each eye, the 1-center Wang-Koch AL-optimized Holladay 1 formula was used to select an IOL targeting emmetropia. Residual refractive error was predicted preoperatively using the SRK/T, Holladay 1 and 2, Barrett Universal II, and Hill-RBF formulas and intraoperatively using wavefront aberrometry. The postoperative refraction was compared with the preoperative and intraoperative predictions. The study comprised 37 patients (51 eyes). The mean numerical errors ± standard error associated with using the SRK/T, Holladay 1, AL-optimi...

Research paper thumbnail of Antidiabetic potential of polyherbal formulation DB14201: Preclinical development, safety and efficacy studies

Journal of Ethnopharmacology, 2017

Ethnopharmacological relevance: The poly-herbal formulation DB14201 is a new combination of ayurv... more Ethnopharmacological relevance: The poly-herbal formulation DB14201 is a new combination of ayurvedic ingredients for treatment of diabetes. The aim of present study was to investigate safety and in vivo efficacy of DB14201 extract. Further this work was aimed to develop, characterize and standardize DB14201 extract and develop it as a botanical drug. Materials and methods: The polyherbal extract was standardized using four chemical markers. The LC-MS/MS method was developed for identification and quantification of mangiferin, berberine, kaempferol and curcumin. The extract was standardized for heavy metal content, aflotoxins, and microbial tests. The mechanism of action of DB14201 extract was explored through glucose uptake by adipocytes, TNF-α production and free fatty acid release, in vitro, was studied using murine adipocytes (3T3-L1). The effect of extract on insulin release was evaluated using murine pancreatic beta cell (β TC-6). The safety and in vivo efficacy of extract was studied using suitable animal model. Hematology and blood biochemistry parameters were also assessed. Results: In vitro studies of DB14201 in murine adipocytes and murine pancreatic beta cells demonstrated the plausible mechanism of action of DB14201 could be through increase in glucose uptake and by stimulation of insulin release by RIN-5f cells. The microbial load, heavy metals were found to be within the AYUSH permissible limits and aflotoxins were absent. Preclinical efficacy studies in animal models proved the anti-diabetic potential of the extract. The preclinical acute dose toxicity study and 90-days repeated dose toxicity study of DB14201 extract in wistar rats by oral route indicated that the extract is safe up to 1000 mg/kg dose. Hematology and blood biochemistry parameters were within the normal range. Conclusions: The data presented herein demonstrated anti-diabetic potential of developed DB14201 extract and this study will serve as the benchmark for the further research on this polyherbal formulation.

Research paper thumbnail of Correction to Measuring Compositions in Organic Depth Profiling: Results from a VAMAS Interlaboratory Study

The journal of physical chemistry. B, Jan 15, 2015

Research paper thumbnail of Measuring Compositions in Organic Depth Profiling: Results from a VAMAS Interlaboratory Study

The journal of physical chemistry. B, Jan 23, 2015

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interla... more We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interlaboratory study on the measurement of composition in organic depth profiling. Layered samples with known binary compositions of Irganox 1010 and either Irganox 1098 or Fmoc-pentafluoro-L-phenylalanine in each layer were manufactured in a single batch and distributed to more than 20 participating laboratories. The samples were analyzed using argon cluster ion sputtering and either X-ray Photoelectron Spectroscopy (XPS) or Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) to generate depth profiles. Participants were asked to estimate the volume fractions in two of the layers and were provided with the compositions of all other layers. Participants using XPS provided volume fractions within 0.03 of the nominal values. Participants using ToF-SIMS either made no attempt, or used various methods that gave results ranging in error from 0.02 to over 0.10 in volume fraction, the latter re...

Research paper thumbnail of Applications of XPS in Biology and Biointerface Analysis

Surface Analysis and Techniques in Biology, 2014

Research paper thumbnail of Spontaneously reactive plasma polymer micropatterns

A combination of spontaneous reactive chemical domains bounded by non-fouling zones provides a me... more A combination of spontaneous reactive chemical domains bounded by non-fouling zones provides a means to covalently immobilize biomolecules in structured, spatially defined arrays. These arrays have application in a wide range of biotechnologies including tissue engineering, proteomics, and diagnostics. In this paper, we describe the fabrication of multi-chemistry micropatterns from plasma polymers. X-ray photoelectron spectroscopy (XPS), together with Time-of-Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS) and confocal imaging has been utilized to confirm the reactivity and integrity of micropatterns fabricated from amine-reactive maleic anhydride (ppMA) on non-fouling tetraglyme (ppTg). The covalent immobilization of antibodies via the formation of amide linkages with the anhydride groups occurs only in the ppMA domains, while antibody activity is confirmed via their ability to attract specific fluorescent antigens. These micropatterns therefore provide a convenient and effective platform for covalently immobilizing biomolecules in spatially defined areas without the need for multiple step wet chemical immobilization strategies.

Research paper thumbnail of Artificial intelligence

Proceedings of the International Conference and Workshop on Emerging Trends in Technology, 2010

Research paper thumbnail of Total Tannin Content and Antidiarrheal Activity of Tecomaria capensis Leaves Extract

The Natural Products Journal, 2013

ABSTRACT Purpose of the research: Ethnopharmacological survey indicated that leaves decoction of ... more ABSTRACT Purpose of the research: Ethnopharmacological survey indicated that leaves decoction of Tecomaria capensis (Thunb.) Spach (Bignoniaceae) was used in the treatment of diarrhea and intestinal inflammation. To confirm this activity, estimation of Total tannin content and evaluation of antidiarrheal potential of methanol Tecomaria capensis leaves extract (denominated TCLE) were performed. Major Findings: Acute toxicity study showed that no mortality and toxicity were found in animal until 14 days. TCLE showed that it contained high quantity of tannins. TCLE showed significant and dose-dependent inhibition of diarrheic defecations, intestinal transit and antienteropooling effect at doses 100, 200 and 500 mg/kg p.o. Conclusion: This study supports previous claims regarding its ethnopharmacological use in treatment of diarrhea

Research paper thumbnail of Organic Depth Profiling of a Binary System: the Compositional Effect on Secondary Ion Yield and a Model for Charge Transfer during Secondary Ion Emission

The Journal of Physical Chemistry B, 2009

In recent years, it has been demonstrated that cluster ion beams may be used to sputter some mate... more In recent years, it has been demonstrated that cluster ion beams may be used to sputter some materials, particularly organic materials, without the significant accumulation of damage. It is therefore possible to use cluster ion beam sputtering in conjunction with a surface analytical technique, such as SIMS, to obtain depth profiles and three-dimensional images of the distribution of organic species in the near-surface region. For SIMS organic depth profiling to be useful as an analytical tool, it is important that it is able to measure physically meaningful quantities, such as the local concentration of a species within a blend. In this paper, we investigate a model system of a miscible binary mixture of codeine and poly(lactide). We show that there is a strong surface enrichment of poly(lactide), which provides a reference signal and permits the direct comparison of different samples in terms of secondary ion yield behavior. We demonstrate that it is possible to relate secondary ion intensities to local concentrations for a binary system and that there is a direct correspondence between the yield enhancement of one component and the yield suppression of the other. The dependence of secondary ion yield on composition is described using a model of the kinetically limited transfer of charge between secondary ions and secondary neutrals. Application of the model to pure materials under the assumption that only highly fragmented secondary ions are initially produced and interact with unfragmented secondary neutrals leads to the prediction that high molecular mass quasi-molecular ions have intensities proportional to the square of the total secondary ion yield. This relationship has been independently observed in other work (Seah, M. P. Surf. Interface Anal. 2007, 39, 634.).

Research paper thumbnail of A ToF-SSIMS study of plasma polymer-based patterned metal affinity surfaces

Polymer, 2009

Polymers that exhibit an affinity to metal ions are important for separation science and sensor a... more Polymers that exhibit an affinity to metal ions are important for separation science and sensor applications. In this paper, we describe the creation of surface micropatterns with three plasma polymers, acrylic acid (ppAAc), allylamine (ppAAm) and tetraglyme (ppTG). Time-of-Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS) imaging has been used to visualise the chemical specificity and selectivity of the plasma polymers as substrates for immoblised metal affinity protein separation. This technique provides the necessary spatial resolution to chemically resolve the multiple components present on these surfaces. Enzyme-linked immunosorbent assay (ELISA) was also employed to confirm the biological specificity of these surfaces. The results clearly demonstrate that under the correct solvent conditions, ppAAc-modified surfaces coordinate gallium and are able to selectively attract phosphoproteins. Critically, it is possible to then remove the protein from the surface and regenerate the chemistry using a simple elevated pH washing step. These results indicate the potential of these surfaces for implementation in microfluidic devices for the rapid isolation or pre-concentration of phosphopeptides/proteins.

Research paper thumbnail of Plasma Polymer Coatings to Support Mesenchymal Stem Cell Adhesion, Growth and Differentiation on Variable Stiffness Silicone Elastomers

Plasma Processes and Polymers, 2009

The mechanical properties of the underlying substratum have previously been shown to affect a num... more The mechanical properties of the underlying substratum have previously been shown to affect a number of cellular processes including locomotion, proliferation and differentiation. Although polyacrylamide is the most studied variable-stiffness substrate, silicone elastomers offer a ...

Research paper thumbnail of Plasma Polymerization of Maleic Anhydride: Just What Are the Right Deposition Conditions?

Langmuir, 2010

Maleic anhydride plasma polymers enable amine containing biomolecules and polymers to be covalent... more Maleic anhydride plasma polymers enable amine containing biomolecules and polymers to be covalently coupled to a surface from an aqueous solution without any intermediate chemistry. The challenge in developing these functionally active plasma polymers lies in determining the optimal deposition conditions for producing a stable, highly active film. Unlike many previous studies that explore highly varied pulsed and continuous wave (CW) deposition conditions, this paper focuses on the comparison of films deposited under the same low nominal power conditions (1 W) and compares a range of CW, ms and µs pulsing parameters that can be used to produce this power condition. The use of attenuated total reflectance-Fourier transform infra red spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) has enabled the quantitative examination of the effects of processing parameters on the chemical functionality of the films. For the first time, the molecular specificity, surface sensitivity and high mass resolution of time-of-flight static secondary ion mass spectrometry (ToF-SSIMS) has been exploited to compare these films and multivariate analysis techniques used to explore the relationships between plasma processing parameters and surface chemistry. The results of the studies clearly demonstrate that a range of conditions can produce maleic anhydride films, with optimal functionality seen under µs pulsing regimes. Critically, the study demonstrates that the tight control and monitoring of the deposition parameters is critical if these films are to be manufactured with optimal functionality, stability and minimum processing time.

Research paper thumbnail of Physical vs Photolithographic Patterning of Plasma Polymers: An Investigation by ToF−SSIMS and Multivariate Analysis

Langmuir, 2010

Physical and photolithographic techniques are commonly used to create chemical patterns for a ran... more Physical and photolithographic techniques are commonly used to create chemical patterns for a range of technologies including cell culture studies, bioarrays and other biomedical applications. In this paper, we describe the fabrication of chemical micropatterns from commonly used plasma polymers. Atomic force microcopy (AFM) imaging, Time-of-Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS) imaging and multivariate analysis have been employed to visualize the chemical boundaries created by these patterning techniques and assess the spatial and chemical resolution of the patterns. ToF-SSIMS analysis demonstrated that well defined chemical and spatial boundaries were obtained from photolithographic patterning, while the resolution of physical patterning via a transmission electron microscopy (TEM) grid varied depending on the properties of the plasma system including the substrate material. In general, physical masking allowed diffusion of the plasma species below the mask and bleeding of the surface chemistries. Multivariate analysis techniques including Principal Component Analysis (PCA) and Region of Interest (ROI) assessment were used to investigate the ToF-SSIMS images of a range of different plasma polymer patterns. In the most challenging case, where two strongly reacting polymers, allylamine and acrylic acid were deposited, PCA confirmed the fabrication of micropatterns with defined spatial resolution. ROI analysis allowed for the identification of an interface between the two plasma polymers for patterns fabricated using the photolithographic technique which has been previously overlooked. This study clearly demonstrated the versatility of photolithographic patterning for the production of multichemistry plasma polymer arrays and highlighted the need for complimentary characterization and analytical techniques during the fabrication plasma polymer micropatterns.

Research paper thumbnail of Non-fouling microfluidic chip produced by radio frequency tetraglyme plasma deposition

Lab on a Chip, 2007

This Technical Note presents the direct surface modification of a glass/PTFE hybrid microfluidic ... more This Technical Note presents the direct surface modification of a glass/PTFE hybrid microfluidic chip, via radio frequency glow discharge plasma polymerisation of tetraethlylene glycol dimethylether (tetraglyme), to produce hydrophilic, non-fouling, PEO-like surfaces. We use several techniques including X-ray photoelectron spectroscopy (XPS), direct enzyme-linked immunosorbent assays (ELISA) and immunofluorescent imaging to investigate the channel coatings. Our results indicate the successful deposition of a PEO-like coating onto microchannel surfaces that has both solution and shelf stability (.3 months) and is capable of preventing fibrinogen adsorption to the microchannel surfaces. Plasma polymerisation Plasma polymerisation of the glass microfluidic chip and PTFE sheet was carried out in a home-built stainless steel

Research paper thumbnail of Efficient photocatalytic hydrogen evolution system by assembling earth abundant NixOy nanoclusters in cubic MCM-48 mesoporous materials

RSC Advances, 2016

A MCM-48 mesoporous support containing NiO and Ni2O3 nanoclusters exhibit high activity for photo... more A MCM-48 mesoporous support containing NiO and Ni2O3 nanoclusters exhibit high activity for photocatalytic hydrogen production in comparison to NiO.

Research paper thumbnail of Estimation of New Chemical Entities in Biological Fluids for Bioavailability and It S Pharmacokinetic Evaluation to Screen the Suitable Lead Candidate

Research paper thumbnail of Statement of Retraction: Dual approach utilizing self microemulsifying technique and novel P-gp inhibitor for effective delivery of taxanes

Journal of Microencapsulation, 2021

Ajeet K. Singh, Akash Chaurasiya, Anshumali Awasthi, Gautam Mishra, Dinesh Asati, Roop K. Khar, &... more Ajeet K. Singh, Akash Chaurasiya, Anshumali Awasthi, Gautam Mishra, Dinesh Asati, Roop K. Khar, & Rama Mukherjee (2009) Oral Bioavailability Enhancement of Exemestane from Self-Microemulsifying Drug Delivery System (SMEDDS), AAPS Parm SciTech, DOI: 10.1208/ s12249-009-9281-7 In addition, concerns were raised regarding the integrity of Figure 7, which contains panels that are identical, after color adjustments, to those in Figure 11 of the following manuscript:

Research paper thumbnail of Photocatalytic Hydrogen Evolution from Earth Abundant Nickel Oxide Clusters Dispersed on MCM-48 Mesoporous Materials

ECS Meeting Abstracts, 2015

NiO, as an earth abundant metal oxide that has been extensively studied as a co-catalyst for a va... more NiO, as an earth abundant metal oxide that has been extensively studied as a co-catalyst for a variety of photocatalytic reactions, including solar hydrogen generation. Mesoporous materials have been used as a support to disperse spatially isolated semiconductor clusters to minimize photoinduced charge-carrier recombination and enhance photocatalytic efficiency. Such well-dispersed semiconductor particles encapsulated in mesoporous matrices possess small sizes due to quantization effect and higher redox potentials compared with those in bulk. In this work, NiO semiconductors were dispersed onto MCM-48 mesoporous materials and their photocatalytic activities were explored. The physico-chemical properties of all the prepared samples have been investigated using a wide selection of techniques ranging from powder X–ray diffraction (XRD), BET surface area analysis, atomic absorption spectroscopy (AAS), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS), and ...

Research paper thumbnail of Thin Head and Single Use Microkeratomes Reduce Epithelial Defects During LASIK

Journal of Refractive Surgery, 2006

To evaluate the effect of microkeratome design and head dimension (flap thickness) on the rate of... more To evaluate the effect of microkeratome design and head dimension (flap thickness) on the rate of epithelial defects. A retrospective review of 4000 LASIK procedures performed between May 2000 and December 2003 was conducted. Intraoperative epithelial defects were identified in 326 cases. The microkeratome design (reusable vs disposable) and head dimensions (100, 130, and 150 micron) were recorded along with age, sex, central ultrasonic pachymetry, keratometry, preoperative refraction (sphere, cylinder, and axis), and Schirmer testing. The chi-square and Student t test were used in data analysis. A total of 326 (8.2%) procedures had an associated epithelial defect. With the reusable microkeratome, heads that produced thinner flaps were associated with a lower incidence of epithelial defects (P&amp;amp;amp;amp;amp;amp;amp;amp;lt;.05 for all three groups, 100, 130 and 150 micron head). When compared to a reusable head of the same dimension and to the entire population of reusable heads, the disposable 130 head exhibited a significantly lower rate of epithelial defects (P&amp;amp;amp;amp;amp;amp;amp;amp;lt;.0001). The results of this study support that both microkeratome design and head dimension (and resulting corneal flap thickness) play a role in the formation of epithelial defects. These are surgeon selectable factors, unrelated to technique or patient risk factors, which can be used to reduce the rate of epithelial defects and associated complications.

Research paper thumbnail of Evaluation of in vitro anti-psoriatic activity of a novel polyherbal formulation by multiparametric analysis

Anti-inflammatory & anti-allergy agents in medicinal chemistry, Jan 20, 2017

The beneficial role of traditional herbal medicines in the treatment of inflammatory skin disorde... more The beneficial role of traditional herbal medicines in the treatment of inflammatory skin disorders has been widely reported. Psoriasis is characterized by uncontrolled hyper-proliferation of keratinocytes, disturbed apoptosis, over-secretion of inflammatory cytokines and angiogenic factors. We have developed a novel aqueous polyherbal formulation (SIRB-001) consisting of 3 herbs; Rheum palmatum L., Rehmannia glutinosa Libosch and Lonicera Japonica in the ratio 1:1:3. SIRB-001 has demonstrated efficacious effects in psoriasis patients. Therefore, this study was aimed at scientifically evaluating the in vitro antipsoriatic activity of SIRB-001. Cell based and enzymatic assays were employed with multi-parametric analysis of key markers. SIRB-001 significantly inhibited (p<0.01) proliferation of keratinocytes (HaCaT cells) and resulted in induction of apoptotic markers (Phosphatidyl Serine externalization, mitochondrial potential depolarization, caspase-3, cell cycle (SubG0/G1), DNA...

Research paper thumbnail of Intraoperative aberrometry versus preoperative biometry for intraocular lens power selection in axial myopia

Journal of cataract and refractive surgery, 2017

To compare the accuracy of intraoperative wavefront aberrometry (ORA) and the Hill-radial basis f... more To compare the accuracy of intraoperative wavefront aberrometry (ORA) and the Hill-radial basis function (RBF) formula with other formulas based on preoperative biometry in predicting residual refractive error after cataract surgery in eyes with axial myopia. Private practice, Harrisburg, Pennsylvania, USA. Retrospective consecutive case series. Eyes with an axial length (AL) greater than 25.0 mm had cataract extraction with intraocular lens implantation. For each eye, the 1-center Wang-Koch AL-optimized Holladay 1 formula was used to select an IOL targeting emmetropia. Residual refractive error was predicted preoperatively using the SRK/T, Holladay 1 and 2, Barrett Universal II, and Hill-RBF formulas and intraoperatively using wavefront aberrometry. The postoperative refraction was compared with the preoperative and intraoperative predictions. The study comprised 37 patients (51 eyes). The mean numerical errors ± standard error associated with using the SRK/T, Holladay 1, AL-optimi...

Research paper thumbnail of Antidiabetic potential of polyherbal formulation DB14201: Preclinical development, safety and efficacy studies

Journal of Ethnopharmacology, 2017

Ethnopharmacological relevance: The poly-herbal formulation DB14201 is a new combination of ayurv... more Ethnopharmacological relevance: The poly-herbal formulation DB14201 is a new combination of ayurvedic ingredients for treatment of diabetes. The aim of present study was to investigate safety and in vivo efficacy of DB14201 extract. Further this work was aimed to develop, characterize and standardize DB14201 extract and develop it as a botanical drug. Materials and methods: The polyherbal extract was standardized using four chemical markers. The LC-MS/MS method was developed for identification and quantification of mangiferin, berberine, kaempferol and curcumin. The extract was standardized for heavy metal content, aflotoxins, and microbial tests. The mechanism of action of DB14201 extract was explored through glucose uptake by adipocytes, TNF-α production and free fatty acid release, in vitro, was studied using murine adipocytes (3T3-L1). The effect of extract on insulin release was evaluated using murine pancreatic beta cell (β TC-6). The safety and in vivo efficacy of extract was studied using suitable animal model. Hematology and blood biochemistry parameters were also assessed. Results: In vitro studies of DB14201 in murine adipocytes and murine pancreatic beta cells demonstrated the plausible mechanism of action of DB14201 could be through increase in glucose uptake and by stimulation of insulin release by RIN-5f cells. The microbial load, heavy metals were found to be within the AYUSH permissible limits and aflotoxins were absent. Preclinical efficacy studies in animal models proved the anti-diabetic potential of the extract. The preclinical acute dose toxicity study and 90-days repeated dose toxicity study of DB14201 extract in wistar rats by oral route indicated that the extract is safe up to 1000 mg/kg dose. Hematology and blood biochemistry parameters were within the normal range. Conclusions: The data presented herein demonstrated anti-diabetic potential of developed DB14201 extract and this study will serve as the benchmark for the further research on this polyherbal formulation.

Research paper thumbnail of Correction to Measuring Compositions in Organic Depth Profiling: Results from a VAMAS Interlaboratory Study

The journal of physical chemistry. B, Jan 15, 2015

Research paper thumbnail of Measuring Compositions in Organic Depth Profiling: Results from a VAMAS Interlaboratory Study

The journal of physical chemistry. B, Jan 23, 2015

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interla... more We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interlaboratory study on the measurement of composition in organic depth profiling. Layered samples with known binary compositions of Irganox 1010 and either Irganox 1098 or Fmoc-pentafluoro-L-phenylalanine in each layer were manufactured in a single batch and distributed to more than 20 participating laboratories. The samples were analyzed using argon cluster ion sputtering and either X-ray Photoelectron Spectroscopy (XPS) or Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) to generate depth profiles. Participants were asked to estimate the volume fractions in two of the layers and were provided with the compositions of all other layers. Participants using XPS provided volume fractions within 0.03 of the nominal values. Participants using ToF-SIMS either made no attempt, or used various methods that gave results ranging in error from 0.02 to over 0.10 in volume fraction, the latter re...

Research paper thumbnail of Applications of XPS in Biology and Biointerface Analysis

Surface Analysis and Techniques in Biology, 2014

Research paper thumbnail of Spontaneously reactive plasma polymer micropatterns

A combination of spontaneous reactive chemical domains bounded by non-fouling zones provides a me... more A combination of spontaneous reactive chemical domains bounded by non-fouling zones provides a means to covalently immobilize biomolecules in structured, spatially defined arrays. These arrays have application in a wide range of biotechnologies including tissue engineering, proteomics, and diagnostics. In this paper, we describe the fabrication of multi-chemistry micropatterns from plasma polymers. X-ray photoelectron spectroscopy (XPS), together with Time-of-Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS) and confocal imaging has been utilized to confirm the reactivity and integrity of micropatterns fabricated from amine-reactive maleic anhydride (ppMA) on non-fouling tetraglyme (ppTg). The covalent immobilization of antibodies via the formation of amide linkages with the anhydride groups occurs only in the ppMA domains, while antibody activity is confirmed via their ability to attract specific fluorescent antigens. These micropatterns therefore provide a convenient and effective platform for covalently immobilizing biomolecules in spatially defined areas without the need for multiple step wet chemical immobilization strategies.

Research paper thumbnail of Artificial intelligence

Proceedings of the International Conference and Workshop on Emerging Trends in Technology, 2010

Research paper thumbnail of Total Tannin Content and Antidiarrheal Activity of Tecomaria capensis Leaves Extract

The Natural Products Journal, 2013

ABSTRACT Purpose of the research: Ethnopharmacological survey indicated that leaves decoction of ... more ABSTRACT Purpose of the research: Ethnopharmacological survey indicated that leaves decoction of Tecomaria capensis (Thunb.) Spach (Bignoniaceae) was used in the treatment of diarrhea and intestinal inflammation. To confirm this activity, estimation of Total tannin content and evaluation of antidiarrheal potential of methanol Tecomaria capensis leaves extract (denominated TCLE) were performed. Major Findings: Acute toxicity study showed that no mortality and toxicity were found in animal until 14 days. TCLE showed that it contained high quantity of tannins. TCLE showed significant and dose-dependent inhibition of diarrheic defecations, intestinal transit and antienteropooling effect at doses 100, 200 and 500 mg/kg p.o. Conclusion: This study supports previous claims regarding its ethnopharmacological use in treatment of diarrhea

Research paper thumbnail of Organic Depth Profiling of a Binary System: the Compositional Effect on Secondary Ion Yield and a Model for Charge Transfer during Secondary Ion Emission

The Journal of Physical Chemistry B, 2009

In recent years, it has been demonstrated that cluster ion beams may be used to sputter some mate... more In recent years, it has been demonstrated that cluster ion beams may be used to sputter some materials, particularly organic materials, without the significant accumulation of damage. It is therefore possible to use cluster ion beam sputtering in conjunction with a surface analytical technique, such as SIMS, to obtain depth profiles and three-dimensional images of the distribution of organic species in the near-surface region. For SIMS organic depth profiling to be useful as an analytical tool, it is important that it is able to measure physically meaningful quantities, such as the local concentration of a species within a blend. In this paper, we investigate a model system of a miscible binary mixture of codeine and poly(lactide). We show that there is a strong surface enrichment of poly(lactide), which provides a reference signal and permits the direct comparison of different samples in terms of secondary ion yield behavior. We demonstrate that it is possible to relate secondary ion intensities to local concentrations for a binary system and that there is a direct correspondence between the yield enhancement of one component and the yield suppression of the other. The dependence of secondary ion yield on composition is described using a model of the kinetically limited transfer of charge between secondary ions and secondary neutrals. Application of the model to pure materials under the assumption that only highly fragmented secondary ions are initially produced and interact with unfragmented secondary neutrals leads to the prediction that high molecular mass quasi-molecular ions have intensities proportional to the square of the total secondary ion yield. This relationship has been independently observed in other work (Seah, M. P. Surf. Interface Anal. 2007, 39, 634.).

Research paper thumbnail of A ToF-SSIMS study of plasma polymer-based patterned metal affinity surfaces

Polymer, 2009

Polymers that exhibit an affinity to metal ions are important for separation science and sensor a... more Polymers that exhibit an affinity to metal ions are important for separation science and sensor applications. In this paper, we describe the creation of surface micropatterns with three plasma polymers, acrylic acid (ppAAc), allylamine (ppAAm) and tetraglyme (ppTG). Time-of-Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS) imaging has been used to visualise the chemical specificity and selectivity of the plasma polymers as substrates for immoblised metal affinity protein separation. This technique provides the necessary spatial resolution to chemically resolve the multiple components present on these surfaces. Enzyme-linked immunosorbent assay (ELISA) was also employed to confirm the biological specificity of these surfaces. The results clearly demonstrate that under the correct solvent conditions, ppAAc-modified surfaces coordinate gallium and are able to selectively attract phosphoproteins. Critically, it is possible to then remove the protein from the surface and regenerate the chemistry using a simple elevated pH washing step. These results indicate the potential of these surfaces for implementation in microfluidic devices for the rapid isolation or pre-concentration of phosphopeptides/proteins.

Research paper thumbnail of Plasma Polymer Coatings to Support Mesenchymal Stem Cell Adhesion, Growth and Differentiation on Variable Stiffness Silicone Elastomers

Plasma Processes and Polymers, 2009

The mechanical properties of the underlying substratum have previously been shown to affect a num... more The mechanical properties of the underlying substratum have previously been shown to affect a number of cellular processes including locomotion, proliferation and differentiation. Although polyacrylamide is the most studied variable-stiffness substrate, silicone elastomers offer a ...

Research paper thumbnail of Plasma Polymerization of Maleic Anhydride: Just What Are the Right Deposition Conditions?

Langmuir, 2010

Maleic anhydride plasma polymers enable amine containing biomolecules and polymers to be covalent... more Maleic anhydride plasma polymers enable amine containing biomolecules and polymers to be covalently coupled to a surface from an aqueous solution without any intermediate chemistry. The challenge in developing these functionally active plasma polymers lies in determining the optimal deposition conditions for producing a stable, highly active film. Unlike many previous studies that explore highly varied pulsed and continuous wave (CW) deposition conditions, this paper focuses on the comparison of films deposited under the same low nominal power conditions (1 W) and compares a range of CW, ms and µs pulsing parameters that can be used to produce this power condition. The use of attenuated total reflectance-Fourier transform infra red spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) has enabled the quantitative examination of the effects of processing parameters on the chemical functionality of the films. For the first time, the molecular specificity, surface sensitivity and high mass resolution of time-of-flight static secondary ion mass spectrometry (ToF-SSIMS) has been exploited to compare these films and multivariate analysis techniques used to explore the relationships between plasma processing parameters and surface chemistry. The results of the studies clearly demonstrate that a range of conditions can produce maleic anhydride films, with optimal functionality seen under µs pulsing regimes. Critically, the study demonstrates that the tight control and monitoring of the deposition parameters is critical if these films are to be manufactured with optimal functionality, stability and minimum processing time.

Research paper thumbnail of Physical vs Photolithographic Patterning of Plasma Polymers: An Investigation by ToF−SSIMS and Multivariate Analysis

Langmuir, 2010

Physical and photolithographic techniques are commonly used to create chemical patterns for a ran... more Physical and photolithographic techniques are commonly used to create chemical patterns for a range of technologies including cell culture studies, bioarrays and other biomedical applications. In this paper, we describe the fabrication of chemical micropatterns from commonly used plasma polymers. Atomic force microcopy (AFM) imaging, Time-of-Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS) imaging and multivariate analysis have been employed to visualize the chemical boundaries created by these patterning techniques and assess the spatial and chemical resolution of the patterns. ToF-SSIMS analysis demonstrated that well defined chemical and spatial boundaries were obtained from photolithographic patterning, while the resolution of physical patterning via a transmission electron microscopy (TEM) grid varied depending on the properties of the plasma system including the substrate material. In general, physical masking allowed diffusion of the plasma species below the mask and bleeding of the surface chemistries. Multivariate analysis techniques including Principal Component Analysis (PCA) and Region of Interest (ROI) assessment were used to investigate the ToF-SSIMS images of a range of different plasma polymer patterns. In the most challenging case, where two strongly reacting polymers, allylamine and acrylic acid were deposited, PCA confirmed the fabrication of micropatterns with defined spatial resolution. ROI analysis allowed for the identification of an interface between the two plasma polymers for patterns fabricated using the photolithographic technique which has been previously overlooked. This study clearly demonstrated the versatility of photolithographic patterning for the production of multichemistry plasma polymer arrays and highlighted the need for complimentary characterization and analytical techniques during the fabrication plasma polymer micropatterns.

Research paper thumbnail of Non-fouling microfluidic chip produced by radio frequency tetraglyme plasma deposition

Lab on a Chip, 2007

This Technical Note presents the direct surface modification of a glass/PTFE hybrid microfluidic ... more This Technical Note presents the direct surface modification of a glass/PTFE hybrid microfluidic chip, via radio frequency glow discharge plasma polymerisation of tetraethlylene glycol dimethylether (tetraglyme), to produce hydrophilic, non-fouling, PEO-like surfaces. We use several techniques including X-ray photoelectron spectroscopy (XPS), direct enzyme-linked immunosorbent assays (ELISA) and immunofluorescent imaging to investigate the channel coatings. Our results indicate the successful deposition of a PEO-like coating onto microchannel surfaces that has both solution and shelf stability (.3 months) and is capable of preventing fibrinogen adsorption to the microchannel surfaces. Plasma polymerisation Plasma polymerisation of the glass microfluidic chip and PTFE sheet was carried out in a home-built stainless steel