Biocompatible Research Papers - Academia.edu (original) (raw)

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- Fluorescence, Confocal Microscopy, Polymers, Magnetic Resonance Spectroscopy

Biocompatible poly(vinyl alcohol)/poly (vinylpyrrolidone) iodine/poly(ethylene glycol) fibers containing (hydroxypropyl)methyl cellulose (HPMC) and aloe vera were successfully prepared by electrospinning their aqueous solution. Aloe vera which is known to be effective in the treatment of various wounds was added to the polymer solution. HPMC was added to the system as the water retention agent. The hybrid fiber mats were subjected to detailed analysis using a differential scanning calorimeter, a scanning electron microscope (SEM), and a Fourier transform infrared spectrometer. Images obtained from the SEM showed that the polymer fibers were linear, homogenous, and contained no beading. The fiber diameters ranged between 100 and 900 nm. It was seen that the electrospun mats obtained could potentially be used as a material for dressing wounds. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Biocompatibility or tissue compatibility describes the ability of a material to perform with an appropriate host response when applied as intended. Poly-methylmethacrylate (PMMA) based resins are most widely used resins in dentistry, especially in fabrication of dentures and orthodontic appliances. They are considered cytotoxic on account of leaching of various potential toxic substances, most common being residual monomer. Various in vitro and in vivo experiments and cell based studies conducted on acrylic based resins or their leached components have shown them to have cytotoxic effects. They can cause mucosal irritation and tissue sensitization. These studies are not only important to evaluate the long term clinical effect of these materials, but also help in further development of alternate resins. This article reviews information from scientific full articles, reviews, or abstracts published in dental literature, associated with biocompatibility of PMMA resins and it is leached out components. Published materials were searched in dental literature using general and specialist databases, like the PubMED database. V C 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B:

- by Emma Hollick
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- Dentistry, Biomedical Engineering, Leaching, Pubmed

Biopolymer composites for tensile testing were fabricated according to the American Society for Testing Materials, ASTM D638-10, using poly lactic acid (PLA) as the matrix material and varying volume percentage of heat treated and untreated luffa fiber as the reinforcement material. To achieve the composite materials with the highest tensile strength, optimization of the use of hot press machine for fabrication of composite specimens was given high importance. While optimizing the use of hot press machine, various parameters were considered. These parameters included processing temperature, processing time and cooling time. Combinations of varying magnitudes of these parameters were used to find the optimum processing method. The optimized method was then used to produce PLA – luffa composites. The fiber – matrix interface adhesion was studied using scanning electron microscope (SEM). The results show that composites made with heat treated fibers have higher tensile strength and better interfacial adhesion when compared with the tensile strength of composites made with untreated fiber. Heat treated fibers showed a remarkable improvement in the tensile strength of the biocomposites, which may be used for a variety of applications in the orthopedic field.

- by Akshay Kakar and +1
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- Materials Engineering, Biomaterials Engineering, Materials Science, Composite Materials and Structures

Skin aging is an unavoidable aspect of human life. Premature skin aging can result from poor care, environmental pollutants, and ultraviolet radiation exposure. Wrinkles, lines, spots, uneven skin tone, and pigmentation are often indicators of skin aging. One cannot avoid aging but cosmetics and pharmaceutical approaches can minimize and delay the damage. Topical applications of biocompatible and biodegradable vehicles have been explored for delivering anti-aging compounds. Lecithin organogel (LO) is an effective vehicle for topical delivery of many bioactive agents used in aging treatment. Lecithin is cell component isolated from soya beans or eggs and purified to show excellent gelation in non-polar solvents when combined with water. LO can form a heat-stable, resistant to microbial growth, visco-elastic, optically transparent, and non-birefringent micellar system. It serves as an organic medium to enhance dermal permeation of poorly permeable drugs by effectively partitioning into the skin. Its ability to dissolve in hydrophilic as well as in lipophilic drugs makes it a dynamic vehicle, which can be explored as a carrier for anti-aging agents.

- by Santosh Singh Bhadoriya
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- Biochemistry, Biocompatible, Topical, Skin Aging

Poly(glycerol sebacate) (PGS) is a biodegradable polymer increasingly used in a variety of biomedical applications. This polyester is prepared by polycondensation of glycerol and sebacic acid. PGS exhibits biocompatibility and biodegradability, both highly relevant properties in biomedical applications. PGS also involves cost effective production with the possibility of up scaling to industrial production. In addition, the mechanical properties and degradation kinetics of PGS can be tailored to match the requirements of intended applications by controlling curing time, curing temperature, reactants concentration and the degree of acrylation in acrylated PGS. Because of the flexible and elastomeric nature of PGS, its biomedical applications have mainly targeted soft tissue replacement and the engineering of soft tissues, such as cardiac muscle, blood, nerve, cartilage and retina. However, applications of PGS are being expanded to include drug delivery, tissue adhesive and hard tissue (i.e., bone) regeneration. The design and fabrication of PGS based devices for applications that mimic native physiological conditions are also being pursued. Novel designs range from accordion-like honeycomb structures for cardiac patches, gecko-like surfaces for tissue adhesives to PGS (nano) fibers for extra cellular matrix (ECM) like constructs; new design avenues are being investigated to meet the ever growing demand for replacement tissues and organs. In less than a decade PGS has become a material of great scrutiny and interest by the biomedical research community. In this review we consolidate the valuable existing knowledge in the fields of synthesis, properties and biomedical applications of PGS and PGS-related biomaterials and devices.

- by Alexandra Grigore
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- Engineering, Tissue Engineering, CHEMICAL SCIENCES, Biocompatible

Introduction: The aim of the present study was to evaluate the biocompatibility of two modified formulations of Portland cement (PC) mixed with either titanium oxide or both titanium oxide and calcium chloride. Methods and Materials: Polyethylene tubes were filled with modified PCs or Angelus MTA as the control; the tubes were then implanted in 28 Wistar rats subcutaneously. One tube was left empty as a negative control in each rat. Histologic samples were taken after 7, 15, 30 and 60 days. Sections were assessed histologically for inflammatory responses and presence of fibrous capsule and granulation tissue formation. Data were analyzed using the Fisher’s exact and Kruskal-Wallis tests. Result: PC mixed with titanium oxide showed the highest mean scores of inflammation compared with others. There was no statistically significant difference in the mean inflammatory grades between all groups in each of the understudy time intervals. Conclusion: The results showed favorable biocompatibility of these modified PC mixed with calcium chloride and titanium oxide.

- by Hossein Labbaf and +1
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- Biocompatibility, Endodontology, In Vivo, Biocompatible

Recently, as metal-, polymer-, and carbon-based biocompatible nanomaterials have been increasingly incorporated into biosensing applications, with various nanostructures having been used to increase the efficacy and sensitivity of most of the detecting devices, including field effect transistor (FET)-based devices. These nanomaterial-based methods also became the ideal for the amalgamation of biomolecules, especially for the fabrication of ultrasensitive, low-cost, and robust FET-based biosensors; these are categorically very successful at binding the target specified entities in the confined gated micro-region for high functionality. Furthermore, the contemplation of nanomaterial-based FET biosensors to various applications encompasses the desire for detection of many targets with high selectivity, and specificity. We assess how such devices have empowered the achievement of elevated biosensor performance in terms of high sensitivity, selectivity and low detection limits. We review the recent literature here to illustrate the diversity of FET-based biosensors, based on various kinds of nanomaterials in different applications and sum up that graphene or its assisted composite based FET devices are comparatively more efficient and sensitive with highest signal to noise ratio. Lastly, the future prospects and limitations of the field are also discussed.

- by Dr. K. P. Singh
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- Chemistry, Graphene, Nanotechnology, Nanoscience
- by Marcos Dias
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- Materials Engineering, Chemical Engineering, Biocompatible, Copolymerization

Titanium and its alloys can be used in various biomedical application. It is a biocompatible element, has a lower young's modulus, has great osseo-integration properties and can last for a long period of time that makes it better than its other metal counterparts. Further being non-ferromagnetic, titanium implants can safely be examined under Magnetic Resonance Imaging. It can also be used for production of surgical instruments, crutches, wheelchairs and products which require high strength and low weight. One of its alloys Ti-6Al-4V has long been preferred for medical applications. However, in case of permanent implant applications, the alloy may have a possible toxic effect due to the release of vanadium and aluminum. For this very reason, aluminium and vanadium free alloys are being introduced for implant applications.

- by Abhishek Gupta
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- Engineering, Materials Science, Biocompatible

Citric acid-polyethylene glycol-citric acid (CPEGC) triblock dendrimers as biocompatible compounds containing G 1 , G 2 and G 3 were applied as the drug-delivery systems. Some of the small size molecules and drugs are trapped with the above-synthesized dendrimers. The guest molecules, which are hydrophobic when trapped into the suitable sites of dendrimers, are becoming soluble in aqueous solution. The quantity of trapped molecules and drugs such as 5-amino salicylic acid (5-ASA), pyridine, mefenamic acid, and diclofenac was measured. The drug/dendrimer complexes remained in room temperature for about 10 months and after this long time they were stable and the drugs were not released. Also, the controlled release of the above-mentioned molecules and drugs in vitro conditions was investigated. The structure definition and controlled release of the molecules and drugs were carried out using different spectroscopy methods. r

- by Hassan Namazi
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- Biomaterials, Drug delivery, Drug Delivery System, Polymers

A novel tissue adhesive composed of urethane prepolymer and chitosan gel was synthesized. The presence and quantity of NCO groups were determined using FT-IR spectroscopy and titration method, respectively. The adhesion force of the compound was 14.6 N. Chitosan gel in this tissue adhesive was used to increase its biocompatibility. The porous structure, due to the presence of chitosan biopolymer, was illustrated using SEM, and its surface energy was 33.65 mN/m obtained by contact angle measurement. Cytotoxicity of the adhesive was measured using Caco-2, T47D, HT29, and NIH-3T3 cell lines, which exhibited the non-cytotoxic nature of the adhesive.

- by Zahra Shariatinia
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- Analytical Chemistry, Organic Chemistry, Cell line, Polymer

In situ implants containing Progesterone (PRG) were prepared by using biodegradable Poly (DLlactide-co-glycolide) polymer. Dimethyl sulfoxide (DMSO) was used as an aprotic solvent in this implant formulation. This system was prepared by dissolving a water insoluble and biodegradable polymer (PLGA) in a biocompatible organic solvent (DMSO) and then the drug progesterone was added to the polymer solution to produce the drug solution. When the PLGA-PRG solution (0.5 ml) was injected subcutaneously into rat (weight 130g), the solvent dissipated into the surrounding tissue leading phase separation and subsequent coagulation of the polymer & drug to form an implant in situ. The implants were removed from the rat after one hour and stored in freezing condition. The digital photographs of the in-situ formed implants obtained after 1hour shows the evidence of the formation of the implants. Two formulations of implants were made. One contained 10% of progesterone and the other 20%. In vitro dissolution studies of progesterone was performed at static condition in ethanol-water mixture (30:70) at 37°C for 30 days. The implants of 20% progesterone loading showed about 65% release and the implants of 10% loading showed 56% release within 30 days. The release mechanism from these implants resembles closely to Higuchian pattern and first order. The release rate was found faster from the implants with higher drug loading of 20% progesterone, compared to implants of 10% drug loading.

- by Reza-ul Jalil
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- Kinetics, Biodegradable, First-Order Logic, Biodegradable Polymer

We have developed a novel, reproducible, and facile methodology for the construction of artificial lipid envelopes for adenoviruses (Ad) by self-assembly of lipid molecules around the viral capsid. No alteration of the viral genome or conjugation surface chemistry at the virus capsid was necessary, therefore difficulties in production and purification associated with generating most surface-modified viruses can be eliminated. Different lipid bilayer compositions produced artificially enveloped Ad with physicochemical and biological characteristics determined by the type of lipid used. Physicochemical characteristics such as vector size, degree of aggregation, stability, and surface charge of the artificially enveloped Ad were correlated to their biological (gene transfer) function. In monolayer cell cultures, binding to the coxsackie and adenovirus receptor (CAR) was blocked using a zwitterionic envelope, whereas enhanced binding to the cell membrane was achieved using a cationic envelope. Envelopment of Ad by both zwitterionic and cationic lipid bilayers led to almost complete ablation of gene expression in cell monolayers, due to blockage of virion endosomal escape. Alternatively, artificial Ad envelopes built from lipid bilayers at the fluid phase in physiological conditions led to enhanced penetration of the vectors inside a three-dimensional tumor spheroid cell culture model and delayed gene expression in the tumor spheroid compared to nonenveloped adenovirus. These results indicate that construction of artificial envelopes for nonenveloped viruses by lipid bilayer wrapping of the viral capsids constitutes a general strategy to rationally engineer viruses at the nanoscale with control over their biological properties.

- by Ravindra Nath Singh
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- Biomedical Engineering, Self Assembly, Nanotechnology, Multidisciplinary

Biocompatible and biodegradable polyurethanes (PUs) based on castor oil and polypropylene glycols (PPGs) were prepared using various carbohydrate crosslinkers: monosaccharide (glucose), disaccharide (sucrose) and polysaccharides (starch and cellulose). The mechanical and thermal properties were investigated and interpreted on the basis of SEM study. The advantage of incorporating various carbohydrates is to have tunable mechanical properties and biodegradability due to variety in their structure. The glass transition temperature and sorption behavior were dominated by the type of polyol than by the type of crosslinker. All the PUs were observed to be biodegradable as well as non-cytotoxic as revealed by MTT assay in normal lung cell line L132. The study supports the suitability of carbohydrates as important components of biocompatible PUs for development of biomedical devices.

- by Jayen Mehta
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- Organic Chemistry, Polymers, Cell line, Glucose
- by Chieu D Tran
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- Biomedical Engineering, Chitosan, Macrophages, Cellulose

Many polyurethane elastomers display excellent mechanical properties and adequate biocompatibility. However, many medicalgrade polyurethanes are prepared from aromatic diisocyanates and can degrade in vivo to carcinogenic aromatic diamines, although the question of whether the concentrations of these harmful degradation products attain physiologically relevant levels is currently unresolved and strongly debated. It is therefore desirable to synthesize new medical-grade polyurethanes from less toxic aliphatic diisocyanates. In this paper, biocompatible segmented polyurethane elastomers were synthesized from aliphatic diisocyanates (1,4-diisocyanatobutane (BDI) and lysine methyl ester diisocyanate (LDI)), novel diurea diol chain extenders based on tyrosine and tyramine, and a model poly(ethylene glycol) (PEG) diol soft segment. The objectives were to design a hard segment similar in structure to that of MDI-based polyurethanes and also investigate the effects of systematic changes in structure on mechanical and biological properties. The non-branched, symmetric polyurethane prepared from BDI and a tyramine-based chain extender had the highest modulus at 37°C. Introduction of symmetric short-chain branches (SCBs) incorporated in the tyrosine-based chain extender lowered the modulus by an order of magnitude. Polyurethanes prepared from LDI were soft polymers that had a still lower modulus due to the asymmetric SCBs that hindered hard segment packing. Polyurethanes prepared from tyramine and tyrosine chain extenders thermally degraded at temperatures ranging from 110 to 150°C, which are lower than that reported previously for phenyl urethanes. All four polyurethanes supported the attachment, proliferation, and high viability of MG-63 human osteoblast-like cells in vitro. Therefore, the non-cytotoxic chemistry of these polyurethanes make them good candidates for further development as biomedical implants.

- by Scott Guelcher
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- Tissue Engineering, Multidisciplinary, Osteosarcoma, Urea

Strombus gigas (conch) shells and Tridacna gigas (Giant clam) shells have dense, tailored structures that impart excellent mechanical properties to these shells. In this investigation, conch and clam seashells were converted to hydroxyapatite (HAP) by a hydrothermal method at different temperatures and for different conversion durations. Dense HAP structures were created from these shells throughout the majority of the samples at the relative low temperature of 200°C.Theaveragefracturestresswasfoundtobe200°C. The average fracture stress was found to be 200°C.Theaveragefracturestresswasfoundtobe137-218 MPa for partially converted conch shell samples and $70-150 MPa for original and converted clamshell samples, which is close to the mechanical strength of compact human bone. This indicates that the converted shell samples can be used as implants in load-bearing cases. In vivo tests of converted shell samples were performed in rat femoral defects for 6 weeks. The microtomography images at 6 weeks show that the implants did not move, and untreated control defects remain empty with no evidence of a spontaneous fusion. Histological study reveals that there is newly formed bone growing up to and around the implants. There is no evidence of a fibrosis tissue ring around the implants, also indicating that there is no loosening of the implants. In contrast, the untreated controls remain empty with some evidence of a fibrosis ring around the defect hole. These results indicate good biocompatibility and bioactivity of the converted shell implants.

- by Kenneth Vecchio
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- Electron Microscopy, Hydroxyapatite, Multidisciplinary, Gastropoda

The use of biomaterials has revolutionized the biomedical field and has received substantial attention in the last two decades. Among the various types of biomaterials, phosphate glasses have generated great interest on account of their remarkable bioactivity and favourable physical properties for various biomedical applications relating to both hard and soft tissue regeneration. This review paper focuses mainly on the development of titanium-containing phosphate-based glasses and presents an overview of the structural and physical properties. The effect of titanium incorporation on the glassy network is to introduce favourable properties. The biocompatibility of these glasses is described along with recent developments in processing methodologies, and the potential of Ti-containing phosphate-based glasses as a bone substitute material is explored.

- by Robert Newport
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- Glass, Titanium, Multidisciplinary, Ceramics

This paper proposes a novel technique for fabricating micro patterns of glutaraldehyde(GA)-crosslinked gelatin. It provides another means to crosslink gelatin other than using the photo-sensitizing agents, and the micro patterns of GA-crosslinked gelatin can still be made successfully by accessing the conventional photolithography. The much less toxic and more biocompatible approaches of strenshening the gelatin microstructures can be developed according to the idea herein. The over-crosslinking or the edge-diffusion phenomena, and the correlated processing issues are also depicted in this paper.

- by LUNGJIEH YANG
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- Microstructure, MEMS, Molecular Biophysics, Thin Films
- by Frederik R Wurm
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- Engineering, Cytotoxicity, CHEMICAL SCIENCES, Biocompatible
- by Sarah Heilshorn
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- Adsorption, Biocompatible, Neural

- by Vehid Salih
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- Glass, Titanium, Multidisciplinary, Ceramics

Iron−platinum alloy nanoparticles (FePt NPs) are extremely promising candidates for the next generation of contrast agents for magnetic resonance (MR) diagnostic imaging and MR-guided interventions, including hyperthermic ablation of solid cancers. FePt has high Curie temperature, saturation magnetic moment, magneto-crystalline anisotropy, and chemical stability. We describe the synthesis and characterization of a family of biocompatible FePt NPs suitable for biomedical applications, showing and discussing that FePt NPs can exhibit low cytotoxicity. The importance of engineering the interface of strongly magnetic NPs using a coating allowing free aqueous permeation is demonstrated to be an essential parameter in the design of new generations of diagnostic and therapeutic MRI contrast agents. We report effective cell internalization of FePt NPs and demonstrate that they can be used for cellular imaging and in vivo MRI applications. This opens the way for several future applications of FePt NPs, including regenerative medicine and stem cell therapy in addition to enhanced MR diagnostic imaging.

- by Andreas Melzer
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- Chemistry, Biomedical Engineering, Medical Imaging, Biomaterials

This paper accounts for novel, low-cost, eco-friendly route for rapid biosynthesis of copper nanoparticles. Cysteine proteases present in the latex of Calotropis procera L. were used to fabricate copper nanoparticles from copper acetate. Copper nanoparticles were initially characterized by transmission electron microscopy (TEM) and X-ray diffraction technique (XRD). Transmission electron microscopy (TEM) was used to estimate the size and shape of nanoparticles. The average size of copper nanoparticles was found to be 15 ± 1.7 nm. Energy dispersive analysis of X-rays (EDAX) showed distinct peaks of copper. Fourier transform infrared spectroscopy (FTIR) was performed to confirm capping behavior of the latex proteins that contributed to long term stability of copper nanoparticles (6 months) in aqueous medium. Copper nanoparticles synthesized by above method were monodisperse type. Cytotoxicity studies of latex stabilized copper nanoparticles were carried out on HeLa, A549 and BHK21 cell lines by MTT dye conversion assay. HeLa, A549 and BHK21 cells showed excellent viability even at 120 M concentration of copper nanoparticles. This shows that copper nanoparticles synthesized by above method hold excellent biocompatibility.

- by Manish Hudlikar
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- Chemical Engineering, Biomedical Engineering, Water, Metal Nanoparticles

Gene therapy has garnered much interest due to the potential for curing multiple inherited and/or increases in the acquired diseases. As a result, there has been intense activity from multiple research groups for developing effective delivery methods and carriers, which is a critical step in advancing gene delivery technologies. In order for the carriers to effectively deliver the genetic payloads, multiple extracellular and intracellular barriers need to be overcome. Although overcoming these challenges to improve the effectiveness is critical, the development of safe gene delivery agents is even more vital to assure its use in clinical applications. The development of safe and effective strategies has therefore been a major challenge impeding gene therapy progress. In this regard, calcium phosphate (CaP) based nano-particles has been considered as one of the candidate non-viral gene delivery vehicles, but has been plagued by inconsistent and low transfection efficiencies limiting its progress. There has been major research effort to improve the consistency and effectiveness of CaP based vectors. Currently, it is therefore thought that by controlling the various synthesis factors such as Ca/P ratio, mode of mixing, and type of calcium phosphate phase, such variability and inefficiency could be modulated. This review attempts to provide a comprehensive analysis of the current research activity in the development of CaP based ceramic and polymer-ceramic hybrid systems for non-viral gene delivery. Preliminary transfection results of hydroxyapatite (HA or NanoCaPs), amorphous calcium phosphate (ACP) and brushite phases are also compared to assess the effect of various CaP phases, and correspondingly, changes in the dissolution characteristic of the pDNA-CaP complex on the gene transfection efficiency.

- by Prashant Kumta and +1
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- Engineering, Physical sciences, Nano Particles, CHEMICAL SCIENCES

In the current study, a series of polylactic acid and polylactic-co-glycolic acid were prepared in an easy, simple, safe and economically feasible way with yield% greater than 90%. Studying the effect of a catalyst on polymerization process was performed. Riboflavin (RF) was chosen as a model drug and microencapsu-lated in different (drug: polymer) ratios to modify its performance via o/w emulsion solvent evaporation technique and characterized in terms of the morphology and entrapment efficiency (E.E.) and evaluated via in vitro RF release studies. It has been found that, the release rate consists a burst release at the first 12 h, followed by a gradual release over 3 days. The cumulative riboflavin release from these microcap-sules formulations at the end of 3 days was 70% and 80% for PDLA and PDLAGA respectively. The kinetics of release profiles were zero order. The highest (E.E.) of RF obtained among all formulations was 85%.

- by Ahmed Abd El-Hay
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- Drug Delivery Systems, Biodegradable Polymers, Biocompatible

Homogenous amphiphilic crosslinked polymer films comprising of poly(ethylene oxide) and polysiloxane were synthesized utilizing thiol-ene "click" photochemistry. A systematic variation in polymer composition was Carried out to obtain high quality films with varied amount of siloxane and poly(ethylene oxide). These films showed improved gas separation performance with high gas permeabilities with good CO 2 /N 2 selectivity. Furthermore, the resulting films were also tested for its biocompatibility, as a carrier media which allow human adult mesenchymal stem cells to retain their capacity for osteoblastic differentiation after transplantation. The obtained crosslinked films were characterized using differential scanning calorimetry, dynamic mechanical analysis, thermog-ravimetric analysis, FTIR, Raman-IR, and small angle X-ray scattering. The synthesis ease and commercial availability of the starting materials suggests that these new crosslinked polymer networks could find applications in wide range of applications.

- by surendar venna
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- Materials Engineering, Membranes, Photochemistry, Films

The analysis of plasma proteins adsorbed onto a polyurethane (PU) biomaterial was performed using matrix-assisted laser desorption/ionization time-of-#ight mass spectrometry (MALDI-TOFMS). This article marks the "rst study on MALDI-TOFMS analysis of multiple proteins adsorbed from plasma, in vitro, onto the surface of a biomaterial to easily enable their characterization. Plasma standards from three di!erent hosts were placed in contact with non-porous PU, a model biomaterial. Following the use of washing protocols developed in our laboratory, the biomaterial was analyzed, directly, with MALDI-TOFMS. Proteins with molecular weights (M ) ranging from ca. 6.5 to 150 kDa were observed in the mass spectra and characterized upon comparison with proteins of known M . The proteins observed were tentatively identi"ed as those known to adsorb onto PU, both in vitro and in vivo. In an attempt to model in vivo sorption, the PU biomaterial was exposed to freshly collected canine plasma, in vitro, for di!erent lengths of time. Corresponding MALDI-TOFMS spectra displayed increasing protein signal for a number of di!erent proteins with increasing times of exposure to plasma. This method provided qualitative and semi-quantitative analysis of the proteins adsorbed onto the biomaterial surface.

One barrier to the application of current tri-octylphosphine oxide (TOPO) based quantum dots (QDs) for biomedical imaging is that the TOPO on TOPO-QDs can be replaced by the proteins in living system, which may cause the degradation of QDs and/or deactivation of protein. In order to develop biocompatible optical imaging agents, a novel triblock copolymer, designed as a multidentate ligand,

- by P. Wang
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- Engineering, Nanoparticle, Optical Imaging, Block Copolymer

The goal of this study was to develop a new route to prepare thermally responsive polymer nanogels. Poly (N-vinylcaprolactam) nanogels were prepared via inverse miniemulsion polymerization (W/O) at 70 C using n-hexadecane as a nonpolar continuous phase, potassium persulfate as an initiator, and N,N 0 -methylenebisacrylamide as a crosslinker. Sorbitan monooleate (Span 80) was used as surfactant and its influence on the polymerization kinetics and on the colloidal characteristics of the nanogels were principally investigated. It was observed that the addition of a strong ''lipophobe'' is required to stabilize the resulting miniemulsion. The nanogels were characterized in terms of morphology, size, zeta potential, and thermoproperties using transmission electron microscopy and dynamic light scattering. It was observed that all the nanogels obtained collapsed when the lower critical solution temperature (LCST) was raised. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3932-3941, 2010

- by Abdelhamid Elaissari
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- Materials Engineering, Emulsion polymerization, Polymer, Biodegradable

The controlled synthesis and characterization of a range of stimuli responsive cationic terpolymers containing varying amounts of N-isopropylacrylamide (NIPAM), 3-(methylacryloylamino)propyl trimethylammonium chloride (MAPTAC), and poly(ethylene glycol)monomethyl methacrylate (PEGMA) is presented. The terpolymers were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. Compositions of the terpolymers determined using 1H NMR were in close agreement to the theoretical values determined from the monomer feed ratios. GPC-MALLS was used to analyze the molecular weight characteristics of the polymers, which were found to have low polydispersities (Mw/Mn 1.1–1.4). The phase transitions were studied as a function of PEGMA and NIPAM content using temperature controlled 1H NMR and turbidity measurements (UV-Vis). The relationship between thermal stability and the comonomer ratio of the polymers was measured using thermogravimetric analysis (TGA). Protein interaction studies were performed to determine the suitability of the polymers for biological applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4021–4029, 2008

- by Vaibhav Jadhav
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- Materials Engineering, Polymer, Protein Interaction, Thermal Stability

We report the evaluation of dual-gelling poly (N-isopropylacrylamide)-based polymer systems as embolic agents for intracranial aneurysms. These hydrogels undergo gelation physically via temperature-responsiveness of poly (NIPAAm) and chemically through a Michael-addition reaction between thiol and vinyl functional groups on the copolymers. Cytotoxicity studies were performed for biocompatibility of the hydrogels. In vitro glass models were utilized to assess injectability and embolization using the gelling systems and an in vivo swine model was used as proof-of-concept for catheter delivery, injection, and occlusion properties of the hydrogels. Rheology creep tests were conducted for determination of viscoelastic behavior, and degradation of the hydrogels was also investigated. Live/dead and proliferation assays indicated good biocompatibility of the hydrogels. In vitro and in vivo assessment demonstrated that the hydrogels were easily delivered via catheters into the aneurysms. Slight recanalization was observed in vivo, with some adhesion of the gels to the balloon catheter seen in vitro. The materials show creep deformation occurring with time; however, the hydrogels did not degrade over the course of 1.5 year. With the possibility to engineer hydrogels bottom-up for particular applications, these studies show properties that need to be optimized for dual-gelling polymer systems to serve as liquid-to-solid embolic agents for aneurysm treatment. V C 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 00A: 000-000, 2013.

- by Brent Vernon
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- Engineering, Rheology, Polymers, Hydrogels

- by Marwa Tallawi
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- Engineering, Tissue Engineering, CHEMICAL SCIENCES, Biocompatible

Iron-platinum alloy nanoparticles (FePt NPs) are extremely promising candidates for the next generation of contrast agents for magnetic resonance (MR) diagnostic imaging and MR-guided interventions, including hyperthermic ablation of solid cancers. FePt has high Curie temperature, saturation magnetic moment, magneto-crystalline anisotropy, and chemical stability. We describe the synthesis and characterization of a family of biocompatible FePt NPs suitable for biomedical applications, showing and discussing that FePt NPs can exhibit low cytotoxicity. The importance of engineering the interface of strongly magnetic NPs using a coating allowing free aqueous permeation is demonstrated to be an essential parameter in the design of new generations of diagnostic and therapeutic MRI contrast agents. We report effective cell internalization of FePt NPs and demonstrate that they can be used for cellular imaging and in vivo MRI applications. This opens the way for several future applications of FePt NPs, including regenerative medicine and stem cell therapy in addition to enhanced MR diagnostic imaging.

- by Pascal Andre
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- Biomedical Engineering, Medical Imaging, Synthesis of nanoparticles, Biomaterials

- by Andreas Melzer
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- Chemistry, Biomedical Engineering, Medical Imaging, Biomaterials
- by Huanyu Cheng
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- Engineering, Materials Science, Advanced Materials, Medicine

Limbal tissues can be cultured on various types of scaffolds to create a sheet of limbal-corneal epithelium for research as well as clinical transplantation. An optically clear, biocompatible, biomimetic scaffold would be an ideal replacement graft for transplanting limbal stem cells. In this study, we evaluated the physical and culture characteristics of the recombinant human cross-linked collagen scaffold (RHC-III scaffold) and compared it with denuded human amniotic membrane (HAM). Optical/mechanical properties and microbial susceptibility were measured for the scaffolds. With the approval of the institutional review board, 2 mm fresh human limbal tissues were cultured on 2.5 × 2.5 cm 2 scaffolds in a medium containing autologous serum in a feeder cell-free submerged system. The cultured cell systems were characterized by morphology and immunohistochemistry for putative stem cells and differentiated cell markers. The refractive index (RI) and tensile strength of the RHC-III scaffold were comparable to human cornea, with delayed in vitro degradation compared to HAM. RHC-III scaffolds were 10-fold less susceptible to microbial growth. Cultures were initiated on day 1, expanded to form a monolayer by day 3 and covered the entire growth surface in 10 days. Stratified epithelium on the scaffolds was visualized by transmission electron microscopy. The cultured cells showed p63 and ABCG2 positivity in the basal layer and were immunoreactive for cytokeratin K3 and K12 in the suprabasal layers. RHC-III scaffold supports and retains the growth and stemness of limbal stem cells, in addition to resembling human cornea; thus, it could be a good replacement scaffold for growing cells for clinical transplantation.

- by Geeta Vemuganti
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- Technology, Biomedical Engineering, Tissue Engineering, Stem Cells

- by Jonathan Knowles
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- Glass, Titanium, Multidisciplinary, Ceramics

BACKGROUND: Until recently, hyperbranched polymers were thought to be ill-defined materials that were not useful as building blocks for well-defined complex polymer architectures. It is a current challenge to develop strategies that offer... more

- by Frederik R Wurm
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- Materials Engineering, Chemical Engineering, Analytical Chemistry, Kinetics

- by Mayur Dhaygude
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- Chemical Engineering, Biomedical Engineering, Water, Metal Nanoparticles

The controlled synthesis and characterization of a range of stimuli responsive cationic terpolymers containing varying amounts of N-isopropylacrylamide (NIPAM), 3-(methylacryloylamino)propyl trimethylammonium chloride (MAPTAC), and poly(ethylene glycol)monomethyl methacrylate (PEGMA) is presented. The terpolymers were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. Compositions of the terpolymers determined using 1 H NMR were in close agreement to the theoretical values determined from the monomer feed ratios. GPC-MALLS was used to analyze the molecular weight characteristics of the polymers, which were found to have low polydispersities (M w /M n 1.1-1.4). The phase transitions were studied as a function of PEGMA and NIPAM content using temperature controlled 1 H NMR and turbidity measurements (UV-Vis). The relationship between thermal stability and the comonomer ratio of the polymers was measured using thermogravimetric analysis (TGA). Protein interaction studies were performed to determine the suitability of the polymers for biological applications. V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4021-4029, 2008

- by Vaibhav Jadhav
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- Materials Engineering, Polymer, Protein Interaction, Thermal Stability

The gecko, and specifically the feet, has attracted significant attention in recent times with the focus centred around their remarkable adhesional properties. Little attention however has been dedicated to the other remaining regions of the lizard body. In this paper we present preliminary investigations into a number of notable interfacial properties of the gecko skin focusing on solid and aqueous interactions. We show that the skin of the box-patterned gecko (Lucasium sp.) consists of dome shaped scales arranged in a hexagonal patterning. The scales comprise of spinules (hairs), from several hundred nanometres to several microns in length, with a sub-micron spacing and a small radius of curvature typically from 10-20 nm. This micro and nano structure of the skin exhibited ultralow adhesion with contaminating particles. The topography also provides a superhydrophobic, anti-wetting barrier which can self clean by the action of low velocity rolling or impacting droplets of various s...

- by Bronwen Cribb
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- Multidisciplinary, Adhesion, Lizards, Wettability

A novel polyelectrolyte nanocapsule system composed of biopolymers, chitosan and heparin has been fabricated by the layer-by-layer technique on silica nanoparticles followed by dissolution of the silica core. The nanocapsules were of the size range 200 ± 20 nm and loaded with the positively charged anticancer drug doxorubicin with an efficiency of 89%. The loading of the drug into the capsule happens by virtue of the pH-responsive property of the capsule wall, which is determined by the pKa of the polyelectrolytes. As the pH is varied, about 64% of the drug is released in acidic pH while 77% is released in neutral pH. The biocompatibility, efficiency of drug loading, and enhanced bioavailability of the capsule system was confirmed by MTT assay and in vivo biodistribution studies.

- by divya prakash
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- Toxicology, Drug delivery, Nanotechnology, Layer-By-Layer