Dr. Meryam Sardar - Academia.edu (original) (raw)

Papers by Dr. Meryam Sardar

Scientific Reports

The present work describes the in vitro synthesis and characterization of Zinc oxide nanoparticle... more The present work describes the in vitro synthesis and characterization of Zinc oxide nanoparticles (ZnO NPs) using an enzyme alpha amylase, the synthesized nanoparticles were used to study their beneficial effect in the growth and development of Brassica juncea. Transmission Electron Microscope (TEM) image reveals the average size of ZnO NPs was 11 nm and X-ray powder diffraction (XRD) suggests nanoparticles were crystalline in nature. In-silico study confirmed lysine, glutamine and tyrosine present in alpha amylase enzyme, plays a crucial role in the reduction of Zinc acetate dihydrate to ZnO NPs. The biochemical parameters and oxidative enzymes of Brassica juncea were compared with ZnO NPs treated plants. The effect of ZnO NPs on the cellular expression of metal tolerant protein (BjMTP) and cation efflux transporter gene (BjCET2) was also studied. The results indicate that nanoparticles can be used as a replacement for traditional harmful chemical fertilizers.

Bioseparation, 1998

Calcium-alginate beads were found to bind a variety of enzymes in a nonspecific fashion. However,... more Calcium-alginate beads were found to bind a variety of enzymes in a nonspecific fashion. However, alpha amylases from porcine pancreas, Bacillus subtilis (BAN 240L) and wheat germ bound at a significant level and B. subtilis and wheat germ amylases could be eluted with 1M maltose. The wheat germ alpha amylase could be purified 45 fold with 70% recovery. The SDS-PAGE pattern showed significant purification by this single step strategy.

Enzyme and Microbial Technology, 2000

Enzyme and Microbial Technology, 2003

It has been shown that a commercially available pectinase, Pectinex T M, hydrolyzes chitin fairly... more It has been shown that a commercially available pectinase, Pectinex T M, hydrolyzes chitin fairly efficiently with a K m of l.lmgml^1 of chitin and V max equal to 6.5nmolmin~1 mg^1. The pH optimum range (5.0-6.0) and temperature optimum range (55-65 °C) for this unusual activity are more in agreement with the corresponding known values for chitinases rather than the values observed in case of its pectinase activity. The half lives (of chitinolytic activity) of 81 and 76 min at 55 and 65 °C indicate that the chitinolytic activity survives much better that the pectinase activity of the molecule. The occurrence of a carboxyl group in both pectinases and chitinases suggests that similar active site designs may be responsible for this unusual and useful activity of Pectinex T M.

Enzyme and Microbial Technology, 1997

Enzyme and Microbial Technology, 2005

Tomato pectinase was immobilized on agarose linked Concanavalin A by successive layering of the l... more Tomato pectinase was immobilized on agarose linked Concanavalin A by successive layering of the lectin and the enzyme. After four layers of the enzyme, the optimum effectiveness factor of 0.73 was obtained. The immobilized enzyme showed slightly higher V max /K m (0.4) as compared to free enzyme (0.3). The immobilized enzyme showed enhanced thermal stability at 50 • C, enhanced storage stability at 4 • C and enhanced stability during exposure to 4 M urea. Higher conversion of polygalacturonic acid at 50 • C by the immobilized enzyme as compared to the free enzyme was observed. The immobilized enzyme could be reused three times without any loss in activity.

Enzyme and Microbial Technology, 2000

The non-covalent immobilization of a commercial preparation of xylanase from A. niger was carried... more The non-covalent immobilization of a commercial preparation of xylanase from A. niger was carried out on a reversibly soluble-insoluble enteric polymer Eudragit TM L-100. The immobilization of the xylanase activity by adsorption was simultaneously accompanied by removal of cellulase activity since the latter did not bind to the polymer. Thus, the soluble enzyme derivative may be useful for treatment of paper pulp bleaching in paper industry. The immobilized xylanase retained 60% of its activity toward xylan as the substrate. No change was observed in the pH optimum (5.5) of the enzyme upon immobilization. Only marginal increase in the K m of the free enzyme (3.6 mg ml Ϫ1 to 5.0 mg ml Ϫ1 ) upon immobilization on the soluble polymer reflected that the enzyme-substrate binding continues to be efficient in spite of the macromolecular nature of the substrate. Fluorescence spectroscopy and UV difference spectroscopy were used to probe the change(s) in the enzyme structure upon immobilization. This change in structure was correlated with the "effectiveness factor" of the enzyme activity. CD spectra also showed that the enzyme undergoes drastic changes in the structure.

Biotechnology Progress, 2003

The commercial preparation of pectinase (Pectinex Ultra SP-L) was conjugated to alginate by nonco... more The commercial preparation of pectinase (Pectinex Ultra SP-L) was conjugated to alginate by noncovalent interactions by employing 1% alginate during the conjugation protocol. The optimum "immobilization efficiency" was 0.76. The pH optimum and the thermal stability of the enzyme remained unchanged upon conjugation with alginate. The soluble bioconjugate showed a 3-fold increase in V(max)/K(m) as compared to the free enzyme when the smart biocatalyst was used for chitosan hydrolysis. Time course hydrolysis of chitosan thus showed higher conversion of chitosan into reducing oligosaccharides/sugars. The smart bioconjugate could be reused five times without any detectable loss of chitosanase activity.

Biochemical Engineering Journal, 2003

Pectinex™ Ultra SP-L was immobilized non-covalently on alginate. The smart (reversibly soluble–in... more Pectinex™ Ultra SP-L was immobilized non-covalently on alginate. The smart (reversibly soluble–insoluble) bioconjugate showed 56% activity as compared to the equivalent free enzyme for hydrolysis of chitin. The bioconjugate showed a broader pH optimum while the ...

Biocatalysis and Biotransformation, 2007

Immobilization of enzymes is carried out for stabilization and obtaining reusable forms (Katchals... more Immobilization of enzymes is carried out for stabilization and obtaining reusable forms (Katchalski 1993, Tischer & Kasche 1999). Linking enzymes to smart or reversibly soluble–insoluble polymers results in smart bioconjugates (Fuji & Taniguchi 1991; Sharma et al. 2003). These work ...

The nano-TiO2 was synthesized using Lactobacillus sp. and characterized by XRD and TEM.The X-ray ... more The nano-TiO2 was synthesized using Lactobacillus sp. and characterized by XRD and TEM.The X-ray diffraction showed that TiO2 nanoparticles were crystalline in nature. TEM images revealed that these particles are irregular in shape with an average particle size of 50–100 nm. The biosynthesized nanoparticles were used for the immobilization and refolding of thermally inactivated alpha amylase enzyme. The enzyme after adsorption on TiO2 nanoparticles retained 71% of enzyme activity. The immobilized enzyme was found to be thermally more stable as compared to the free enzyme. When the enzyme was heated to 60°C for 60 min the free enzyme loses all of its activity whereas the adsorbed enzyme retained 82% of its activity.The adsorbed/immobilized could be reused five times without any loss in enzyme activity.The operational stability data also shows that after immobilization the stability of the alpha amylase increases.To study the nanoparticles-protein interaction, alpha amylase enzyme was...

Indian journal of biochemistry & biophysics, 2014

Immobilization of cellulase from Aspergillus niger on TiO2 nanoparticles was studied by two diffe... more Immobilization of cellulase from Aspergillus niger on TiO2 nanoparticles was studied by two different approaches--physical adsorption and covalent coupling. A. niger was selected, as it is generally non-pathogenic, is found in nature in the broad range of habitats and produces cellulase extracellulary. For covalent method, TiO2 nanoparticles were modified with aminopropyltriethoxysilane (APTS). The adsorbed and covalently immobilized enzymes showed 76% and 93% activity, respectively, as compared to the free enzyme. The catalytic efficiency V(max)/K(m) increased from 0.4 to 4.0 after covalent attachment, whereas in adsorption method, it increased slightly from 0.4 to 1.2. The covalently-immobilized and adsorbed cellulase lost only 25% and 50% of their activity, respectively after 60 min of incubation at 75 degrees C. The reusability and operational stability data also showed that covalent coupling increased the stability of the enzyme. The presence of enzyme on TiO2 nanoparticles was...

Enzyme and Microbial Technology, 2000

The non-covalent immobilization of a commercial preparation of xylanase from A. niger was carried... more The non-covalent immobilization of a commercial preparation of xylanase from A. niger was carried out on a reversibly soluble-insoluble enteric polymer EudragitTM L-100. The immobilization of the xylanase activity by adsorption was simultaneously accompanied by removal of cellulase activity since the latter did not bind to the polymer. Thus, the soluble enzyme derivative may be useful for treatment of paper

In the present study iron oxide nanoparticles are synthesized extracellularly using baker’s yeast... more In the present study iron oxide nanoparticles are synthesized extracellularly using baker’s yeast under ambient conditions. Iron oxide nanoparticles obtained were characterized by means of transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), scanning tunneling microscopy (STM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). TEM and STM studies show that the particle size is in the range of 2-10 nm. Vibrating sample magnetometer measurement shows superparamagnetic behavior of nanoparticles. The biosynthesized nanoparticles were found to possess peroxidase enzyme like activity. The temperature optima, pH and kinetic parameters of the nanoparticles were investigated and compared with horseradish peroxidase (HRP). The kinetic parameters indicates that the synthesized nanoparticles can be efficiently used as an artificial peroxidase. The peroxidase like activity of the nanoparticles can be exploited for the detection of H2O2 and glucose.

Advanced Science Letters, 2014

The rapid production and application of nanoparticles (NPs) have resulted in substantial release ... more The rapid production and application of nanoparticles (NPs) have resulted in substantial release of nanosized particles into the environment. Nanoparticles (NPs) is being used in several products including food and agriculture sectors, is gaining importance in recent years. The antimicrobial properties of silver have made it as major ingredient in several agricultural products. Silver nanoparticle (AgNPs) is one of the most widely used NP in biological research due to their antimicrobial properties and do not produce any adverse effects on plants.

Science of Advanced Materials, 2012

In this paper, we report the synthesis of silver nanoparticles using the pure enzyme alpha-amylas... more In this paper, we report the synthesis of silver nanoparticles using the pure enzyme alpha-amylase. The silver ions were reduced in the presence of alpha-amylase, leading to the formation of stable silver nanoparticles. The nanoparticles were characterized by UV-Visible absorption and Transmission electron microscopy (TEM). UV-Visible studies show the absorption band at 422 nm due to surface plasmon resonance. TEM studies show the monodisperse nanoparticles 22-44 nm diameter with triangular and hexagonal shape. These studies will help in designing a rational enzymatic strategy for the synthesis of nanomaterials of different chemical composition, shapes and sizes.

Science of Advanced Materials, 2012

Nanotechnology as a field of knowledge is burgeoning day by day, making an impact in all spheres ... more Nanotechnology as a field of knowledge is burgeoning day by day, making an impact in all spheres of human life. Biological methods of synthesis have paved way for the "greener synthesis" of nanoparticles. The "green synthesis" has proven to be a better method due to their slower kinetics, better manipulation, control over crystal growth and stabilization. Recent advancement in the field includes enzymatic method of synthesis suggesting the enzymes to be responsible for the nanoparticle formation. The biomedical applications of silver nanoparticle (AgNPs) can be effective by the use of biologically synthesized nanoparticles which minimize the factors like cost of synthesis and toxicity of product. These are further found to be exceptionally stable when compared with the nanoparticles prepared through other methods. In the present study, silver nanoparticles were biologically synthesized using pure enzyme -amylase and the other one by using soluble proteins of neem leaf extracts. The nanoparticles were characterized by UV-Visible absorption, Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). In addition to the normal cell line , the cytotoxicity of the prepared nanoparticles was evaluated on human cervical cancer cells (SiHa) as well. The results indicated that the IC 50 of neem extracted AgNPs and -amylase were at marginally variable concentrations that is; lower concentration of ≤ 4.25 g/ml for the former and ≤ 32.5 g/ml for the latter. In addition, our results also demonstrated that in vitro cytotoxicity assessment of the AgNPs has significant correlation with the total protein concentration in treated cells. These findings confirm the cytotoxic properties of AgNPs, and suggest that they may be cost-effective and an alternative measure in the field of cancer therapeutics.

Advanced Science, Engineering and Medicine, 2013

Peroxidase isolated from Bitter gourd was covalently immobilized on TiO 2 nanoparticles (< 25 nm)... more Peroxidase isolated from Bitter gourd was covalently immobilized on TiO 2 nanoparticles (< 25 nm) after activation with aminopropyl triethoxy silane. The resulted bioactive nanoconjugates were used to remove phenols and dyes from aqueous solutions. The nanobioconjugate showed 83% activity as compared to the equivalent free bitter gourd peroxidase enzyme. The conjugate have a higher V max /K m (166.7) as compared to the free enzyme (100). It also showed enhanced thermal stability at 60 C compared to its soluble counterpart. The nanobioconjugate demonstrated high removal of phenols and dyes from aqueous solutions, even at a temperature of 60 C. The preparation could be reused four times without any loss in enzyme activity. The presence of enzyme on TiO 2 nanoparticles was confirmed by FTIR (Fourier transform infrared spectroscopy).

Advanced Science, Engineering and Medicine, 2015

ABSTRACT Titanium dioxide (TiO2 nanoparticles (&amp;lt;25 nm) were found to effectively assis... more ABSTRACT Titanium dioxide (TiO2 nanoparticles (&amp;lt;25 nm) were found to effectively assist refolding of thermally inactivated trypsin and alpha amylase enzymes. The native enzymes (alpha amylase and trypsin) were adsorbed on TiO2 nanoparticles separately, by incubating the native enzymes and the TiO2 nanoparticles for 2.0 hours at 25 C. The enzymes after adsorption on TiO2 nanoparticles retained 86% of enzyme activity in case of trypsin and 95% activity in the case of alpha amylase enzyme. Both the enzymes after adsorption on TiO2 nanoparticles were found to be thermally more stable as compared to the free enzymes. When the enzymes were incubated at 60 C for 60 min the free enzyme loses all of its activity whereas the adsorbed enzymes retained 80% of its activity in the case of trypsin and 94% activity in the case of alpha amylase. To study the nanoparticles-protein interaction, trypsin and alpha amylase enzymes were inactivated by heating at 60 C for 1.0 hour. Thermally inactivated enzymes were adsorbed on TiO2 nanoparticles in a similar manner as the native enzymes, and the activity in the adsorbed enzymes were determined after regular intervals of time. The thermally inactivated trypsin enzyme regains 90% of its activity after 2.0 hours of incubation on TiO2 nanoparticles and thermally inactivated alpha amylase regains nearly 100% activity after 1.5 hour. Thermally inactivated trypsin and alpha amylase enzymes were substantially refolded towards their native conformation after adsorption on TiO2 nanoparticles as evidenced by FTIR spectroscopy.

Advanced Science Letters, 2014

Nanotechnology is gaining momentum due to its diverse application in various fields of science. I... more Nanotechnology is gaining momentum due to its diverse application in various fields of science. In this paper, the antibacterial properties of green synthesized TiO 2 nanoparticles were studied for both Gram-positive and Gramnegative bacteria. The nanoparticles were synthesized using extracellular secretions of Lactobacillus sp. These studies demonstrate that the biologically synthesized TiO 2 nanoparticles have a wide range of antibacterial activities toward microorganisms. The MIC value for the TiO 2 nanoparticles was found to be 62.5 µg/ml for both S. aureus and E. coli. The Inhibition was further confirmed using Disc diffusion assay. It is evident from the zone of inhibition that TiO 2 nanoparticles possess potent bactericidal activity. Further, growth curve study of S. aureus and E. coli in the presence and absence of TiO 2 nanoparticles has been done. Proton pumping ATPase activity of S. aureus and E. coli were examined and found to be enhanced significantly with treated nanoparticles as compared to the control. Glucose used as positive control and found to enhance the proton efflux activity with respect to control. Transmission electron microscopy analysis of bacterial strain treated with TiO 2 nanoparticles shows alterations in morphology of cell wall, damage and lysis of plasma membrane. Also the nanoparticles show less haemolytic activity compared to the antibiotic ampicillin. This study indicates that the green synthesized nanoparticles can be used as effective antibacterial agents.

Scientific Reports

The present work describes the in vitro synthesis and characterization of Zinc oxide nanoparticle... more The present work describes the in vitro synthesis and characterization of Zinc oxide nanoparticles (ZnO NPs) using an enzyme alpha amylase, the synthesized nanoparticles were used to study their beneficial effect in the growth and development of Brassica juncea. Transmission Electron Microscope (TEM) image reveals the average size of ZnO NPs was 11 nm and X-ray powder diffraction (XRD) suggests nanoparticles were crystalline in nature. In-silico study confirmed lysine, glutamine and tyrosine present in alpha amylase enzyme, plays a crucial role in the reduction of Zinc acetate dihydrate to ZnO NPs. The biochemical parameters and oxidative enzymes of Brassica juncea were compared with ZnO NPs treated plants. The effect of ZnO NPs on the cellular expression of metal tolerant protein (BjMTP) and cation efflux transporter gene (BjCET2) was also studied. The results indicate that nanoparticles can be used as a replacement for traditional harmful chemical fertilizers.

Bioseparation, 1998

Calcium-alginate beads were found to bind a variety of enzymes in a nonspecific fashion. However,... more Calcium-alginate beads were found to bind a variety of enzymes in a nonspecific fashion. However, alpha amylases from porcine pancreas, Bacillus subtilis (BAN 240L) and wheat germ bound at a significant level and B. subtilis and wheat germ amylases could be eluted with 1M maltose. The wheat germ alpha amylase could be purified 45 fold with 70% recovery. The SDS-PAGE pattern showed significant purification by this single step strategy.

Enzyme and Microbial Technology, 2000

Enzyme and Microbial Technology, 2003

It has been shown that a commercially available pectinase, Pectinex T M, hydrolyzes chitin fairly... more It has been shown that a commercially available pectinase, Pectinex T M, hydrolyzes chitin fairly efficiently with a K m of l.lmgml^1 of chitin and V max equal to 6.5nmolmin~1 mg^1. The pH optimum range (5.0-6.0) and temperature optimum range (55-65 °C) for this unusual activity are more in agreement with the corresponding known values for chitinases rather than the values observed in case of its pectinase activity. The half lives (of chitinolytic activity) of 81 and 76 min at 55 and 65 °C indicate that the chitinolytic activity survives much better that the pectinase activity of the molecule. The occurrence of a carboxyl group in both pectinases and chitinases suggests that similar active site designs may be responsible for this unusual and useful activity of Pectinex T M.

Enzyme and Microbial Technology, 1997

Enzyme and Microbial Technology, 2005

Tomato pectinase was immobilized on agarose linked Concanavalin A by successive layering of the l... more Tomato pectinase was immobilized on agarose linked Concanavalin A by successive layering of the lectin and the enzyme. After four layers of the enzyme, the optimum effectiveness factor of 0.73 was obtained. The immobilized enzyme showed slightly higher V max /K m (0.4) as compared to free enzyme (0.3). The immobilized enzyme showed enhanced thermal stability at 50 • C, enhanced storage stability at 4 • C and enhanced stability during exposure to 4 M urea. Higher conversion of polygalacturonic acid at 50 • C by the immobilized enzyme as compared to the free enzyme was observed. The immobilized enzyme could be reused three times without any loss in activity.

Enzyme and Microbial Technology, 2000

The non-covalent immobilization of a commercial preparation of xylanase from A. niger was carried... more The non-covalent immobilization of a commercial preparation of xylanase from A. niger was carried out on a reversibly soluble-insoluble enteric polymer Eudragit TM L-100. The immobilization of the xylanase activity by adsorption was simultaneously accompanied by removal of cellulase activity since the latter did not bind to the polymer. Thus, the soluble enzyme derivative may be useful for treatment of paper pulp bleaching in paper industry. The immobilized xylanase retained 60% of its activity toward xylan as the substrate. No change was observed in the pH optimum (5.5) of the enzyme upon immobilization. Only marginal increase in the K m of the free enzyme (3.6 mg ml Ϫ1 to 5.0 mg ml Ϫ1 ) upon immobilization on the soluble polymer reflected that the enzyme-substrate binding continues to be efficient in spite of the macromolecular nature of the substrate. Fluorescence spectroscopy and UV difference spectroscopy were used to probe the change(s) in the enzyme structure upon immobilization. This change in structure was correlated with the "effectiveness factor" of the enzyme activity. CD spectra also showed that the enzyme undergoes drastic changes in the structure.

Biotechnology Progress, 2003

The commercial preparation of pectinase (Pectinex Ultra SP-L) was conjugated to alginate by nonco... more The commercial preparation of pectinase (Pectinex Ultra SP-L) was conjugated to alginate by noncovalent interactions by employing 1% alginate during the conjugation protocol. The optimum &amp;amp;amp;amp;amp;amp;amp;amp;quot;immobilization efficiency&amp;amp;amp;amp;amp;amp;amp;amp;quot; was 0.76. The pH optimum and the thermal stability of the enzyme remained unchanged upon conjugation with alginate. The soluble bioconjugate showed a 3-fold increase in V(max)/K(m) as compared to the free enzyme when the smart biocatalyst was used for chitosan hydrolysis. Time course hydrolysis of chitosan thus showed higher conversion of chitosan into reducing oligosaccharides/sugars. The smart bioconjugate could be reused five times without any detectable loss of chitosanase activity.

Biochemical Engineering Journal, 2003

Pectinex™ Ultra SP-L was immobilized non-covalently on alginate. The smart (reversibly soluble–in... more Pectinex™ Ultra SP-L was immobilized non-covalently on alginate. The smart (reversibly soluble–insoluble) bioconjugate showed 56% activity as compared to the equivalent free enzyme for hydrolysis of chitin. The bioconjugate showed a broader pH optimum while the ...

Biocatalysis and Biotransformation, 2007

Immobilization of enzymes is carried out for stabilization and obtaining reusable forms (Katchals... more Immobilization of enzymes is carried out for stabilization and obtaining reusable forms (Katchalski 1993, Tischer & Kasche 1999). Linking enzymes to smart or reversibly soluble–insoluble polymers results in smart bioconjugates (Fuji & Taniguchi 1991; Sharma et al. 2003). These work ...

The nano-TiO2 was synthesized using Lactobacillus sp. and characterized by XRD and TEM.The X-ray ... more The nano-TiO2 was synthesized using Lactobacillus sp. and characterized by XRD and TEM.The X-ray diffraction showed that TiO2 nanoparticles were crystalline in nature. TEM images revealed that these particles are irregular in shape with an average particle size of 50–100 nm. The biosynthesized nanoparticles were used for the immobilization and refolding of thermally inactivated alpha amylase enzyme. The enzyme after adsorption on TiO2 nanoparticles retained 71% of enzyme activity. The immobilized enzyme was found to be thermally more stable as compared to the free enzyme. When the enzyme was heated to 60°C for 60 min the free enzyme loses all of its activity whereas the adsorbed enzyme retained 82% of its activity.The adsorbed/immobilized could be reused five times without any loss in enzyme activity.The operational stability data also shows that after immobilization the stability of the alpha amylase increases.To study the nanoparticles-protein interaction, alpha amylase enzyme was...

Indian journal of biochemistry & biophysics, 2014

Immobilization of cellulase from Aspergillus niger on TiO2 nanoparticles was studied by two diffe... more Immobilization of cellulase from Aspergillus niger on TiO2 nanoparticles was studied by two different approaches--physical adsorption and covalent coupling. A. niger was selected, as it is generally non-pathogenic, is found in nature in the broad range of habitats and produces cellulase extracellulary. For covalent method, TiO2 nanoparticles were modified with aminopropyltriethoxysilane (APTS). The adsorbed and covalently immobilized enzymes showed 76% and 93% activity, respectively, as compared to the free enzyme. The catalytic efficiency V(max)/K(m) increased from 0.4 to 4.0 after covalent attachment, whereas in adsorption method, it increased slightly from 0.4 to 1.2. The covalently-immobilized and adsorbed cellulase lost only 25% and 50% of their activity, respectively after 60 min of incubation at 75 degrees C. The reusability and operational stability data also showed that covalent coupling increased the stability of the enzyme. The presence of enzyme on TiO2 nanoparticles was...

Enzyme and Microbial Technology, 2000

The non-covalent immobilization of a commercial preparation of xylanase from A. niger was carried... more The non-covalent immobilization of a commercial preparation of xylanase from A. niger was carried out on a reversibly soluble-insoluble enteric polymer EudragitTM L-100. The immobilization of the xylanase activity by adsorption was simultaneously accompanied by removal of cellulase activity since the latter did not bind to the polymer. Thus, the soluble enzyme derivative may be useful for treatment of paper

In the present study iron oxide nanoparticles are synthesized extracellularly using baker’s yeast... more In the present study iron oxide nanoparticles are synthesized extracellularly using baker’s yeast under ambient conditions. Iron oxide nanoparticles obtained were characterized by means of transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), scanning tunneling microscopy (STM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). TEM and STM studies show that the particle size is in the range of 2-10 nm. Vibrating sample magnetometer measurement shows superparamagnetic behavior of nanoparticles. The biosynthesized nanoparticles were found to possess peroxidase enzyme like activity. The temperature optima, pH and kinetic parameters of the nanoparticles were investigated and compared with horseradish peroxidase (HRP). The kinetic parameters indicates that the synthesized nanoparticles can be efficiently used as an artificial peroxidase. The peroxidase like activity of the nanoparticles can be exploited for the detection of H2O2 and glucose.

Advanced Science Letters, 2014

The rapid production and application of nanoparticles (NPs) have resulted in substantial release ... more The rapid production and application of nanoparticles (NPs) have resulted in substantial release of nanosized particles into the environment. Nanoparticles (NPs) is being used in several products including food and agriculture sectors, is gaining importance in recent years. The antimicrobial properties of silver have made it as major ingredient in several agricultural products. Silver nanoparticle (AgNPs) is one of the most widely used NP in biological research due to their antimicrobial properties and do not produce any adverse effects on plants.

Science of Advanced Materials, 2012

In this paper, we report the synthesis of silver nanoparticles using the pure enzyme alpha-amylas... more In this paper, we report the synthesis of silver nanoparticles using the pure enzyme alpha-amylase. The silver ions were reduced in the presence of alpha-amylase, leading to the formation of stable silver nanoparticles. The nanoparticles were characterized by UV-Visible absorption and Transmission electron microscopy (TEM). UV-Visible studies show the absorption band at 422 nm due to surface plasmon resonance. TEM studies show the monodisperse nanoparticles 22-44 nm diameter with triangular and hexagonal shape. These studies will help in designing a rational enzymatic strategy for the synthesis of nanomaterials of different chemical composition, shapes and sizes.

Science of Advanced Materials, 2012

Nanotechnology as a field of knowledge is burgeoning day by day, making an impact in all spheres ... more Nanotechnology as a field of knowledge is burgeoning day by day, making an impact in all spheres of human life. Biological methods of synthesis have paved way for the "greener synthesis" of nanoparticles. The "green synthesis" has proven to be a better method due to their slower kinetics, better manipulation, control over crystal growth and stabilization. Recent advancement in the field includes enzymatic method of synthesis suggesting the enzymes to be responsible for the nanoparticle formation. The biomedical applications of silver nanoparticle (AgNPs) can be effective by the use of biologically synthesized nanoparticles which minimize the factors like cost of synthesis and toxicity of product. These are further found to be exceptionally stable when compared with the nanoparticles prepared through other methods. In the present study, silver nanoparticles were biologically synthesized using pure enzyme -amylase and the other one by using soluble proteins of neem leaf extracts. The nanoparticles were characterized by UV-Visible absorption, Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). In addition to the normal cell line , the cytotoxicity of the prepared nanoparticles was evaluated on human cervical cancer cells (SiHa) as well. The results indicated that the IC 50 of neem extracted AgNPs and -amylase were at marginally variable concentrations that is; lower concentration of ≤ 4.25 g/ml for the former and ≤ 32.5 g/ml for the latter. In addition, our results also demonstrated that in vitro cytotoxicity assessment of the AgNPs has significant correlation with the total protein concentration in treated cells. These findings confirm the cytotoxic properties of AgNPs, and suggest that they may be cost-effective and an alternative measure in the field of cancer therapeutics.

Advanced Science, Engineering and Medicine, 2013

Peroxidase isolated from Bitter gourd was covalently immobilized on TiO 2 nanoparticles (< 25 nm)... more Peroxidase isolated from Bitter gourd was covalently immobilized on TiO 2 nanoparticles (< 25 nm) after activation with aminopropyl triethoxy silane. The resulted bioactive nanoconjugates were used to remove phenols and dyes from aqueous solutions. The nanobioconjugate showed 83% activity as compared to the equivalent free bitter gourd peroxidase enzyme. The conjugate have a higher V max /K m (166.7) as compared to the free enzyme (100). It also showed enhanced thermal stability at 60 C compared to its soluble counterpart. The nanobioconjugate demonstrated high removal of phenols and dyes from aqueous solutions, even at a temperature of 60 C. The preparation could be reused four times without any loss in enzyme activity. The presence of enzyme on TiO 2 nanoparticles was confirmed by FTIR (Fourier transform infrared spectroscopy).

Advanced Science, Engineering and Medicine, 2015

ABSTRACT Titanium dioxide (TiO2 nanoparticles (&amp;lt;25 nm) were found to effectively assis... more ABSTRACT Titanium dioxide (TiO2 nanoparticles (&amp;lt;25 nm) were found to effectively assist refolding of thermally inactivated trypsin and alpha amylase enzymes. The native enzymes (alpha amylase and trypsin) were adsorbed on TiO2 nanoparticles separately, by incubating the native enzymes and the TiO2 nanoparticles for 2.0 hours at 25 C. The enzymes after adsorption on TiO2 nanoparticles retained 86% of enzyme activity in case of trypsin and 95% activity in the case of alpha amylase enzyme. Both the enzymes after adsorption on TiO2 nanoparticles were found to be thermally more stable as compared to the free enzymes. When the enzymes were incubated at 60 C for 60 min the free enzyme loses all of its activity whereas the adsorbed enzymes retained 80% of its activity in the case of trypsin and 94% activity in the case of alpha amylase. To study the nanoparticles-protein interaction, trypsin and alpha amylase enzymes were inactivated by heating at 60 C for 1.0 hour. Thermally inactivated enzymes were adsorbed on TiO2 nanoparticles in a similar manner as the native enzymes, and the activity in the adsorbed enzymes were determined after regular intervals of time. The thermally inactivated trypsin enzyme regains 90% of its activity after 2.0 hours of incubation on TiO2 nanoparticles and thermally inactivated alpha amylase regains nearly 100% activity after 1.5 hour. Thermally inactivated trypsin and alpha amylase enzymes were substantially refolded towards their native conformation after adsorption on TiO2 nanoparticles as evidenced by FTIR spectroscopy.

Advanced Science Letters, 2014

Nanotechnology is gaining momentum due to its diverse application in various fields of science. I... more Nanotechnology is gaining momentum due to its diverse application in various fields of science. In this paper, the antibacterial properties of green synthesized TiO 2 nanoparticles were studied for both Gram-positive and Gramnegative bacteria. The nanoparticles were synthesized using extracellular secretions of Lactobacillus sp. These studies demonstrate that the biologically synthesized TiO 2 nanoparticles have a wide range of antibacterial activities toward microorganisms. The MIC value for the TiO 2 nanoparticles was found to be 62.5 µg/ml for both S. aureus and E. coli. The Inhibition was further confirmed using Disc diffusion assay. It is evident from the zone of inhibition that TiO 2 nanoparticles possess potent bactericidal activity. Further, growth curve study of S. aureus and E. coli in the presence and absence of TiO 2 nanoparticles has been done. Proton pumping ATPase activity of S. aureus and E. coli were examined and found to be enhanced significantly with treated nanoparticles as compared to the control. Glucose used as positive control and found to enhance the proton efflux activity with respect to control. Transmission electron microscopy analysis of bacterial strain treated with TiO 2 nanoparticles shows alterations in morphology of cell wall, damage and lysis of plasma membrane. Also the nanoparticles show less haemolytic activity compared to the antibiotic ampicillin. This study indicates that the green synthesized nanoparticles can be used as effective antibacterial agents.