Anil Mahapatro

Biodegradable nanoparticles are excellent vehicle for site directed in-vivo delivery of drugs and vaccines

Biodegradable nanoparticles (NPs) are gaining increased attention for their ability to serve as a viable carrier for site specific delivery of vaccines, genes, drugs and other biomolecules in the body. They offer enhanced biocompatibility, superior drug/vaccine encapsulation, and convenient release profiles for a number of drugs, vaccines and biomolecules to be used in a variety of applications in the field of medicine. In this manuscript, the methods of preparation of biodegradable NPs, different factors affecting optimal drug encapsulation, factors affecting drug release rates, various surface modifications of nanoparticles to enhance in-vivo circulation, distribution and multimodal functionalities along with the specific applications such as tumor targeting, oral delivery, and delivery of these particles to the central nervous system have been reviewed.

Bio-functional nano-coatings on metallic biomaterials

Metals and their alloys have been widely used in all aspects of science, engineering and medicine. Metals in biomedical devices are used due to their inertness and structural functions. They are generally preferred over polymers or ceramics and are especially desirable in applications where the implants are subjected to static, dynamic or cyclic loads that require a combination of strength and ductility. In biomedicine, the choice of a specific biomaterial is governed by many factors that include biocompatibility, corrosion resistance, controlled degradability, modulus of elasticity, fatigue strength and many other application specific criterions. Nanotechnology is driving newer demands and requirements for better performance of existing materials and presents an opportunity for surface modification of metals in response to demands on the surface of metals for their biomedical applications. Self-assembled monolayers (SAMs) are nanosized coatings that present a flexible method of carrying out surface modification of biomaterials to tailor its surface properties for specific end applications. These nanocoatings can serve primary functions such as surface coverage, etch protection and anti-corrosion along with a host of other secondary chemical functions such as drug delivery and biocompatibility. We present a brief introduction to surface modification of biomaterials and their alloys followed by a detailed description of organic nanocoatings based on self-assembled monolayers and their biomedical applications including patterning techniques and biological applications of patterned SAMs.

Microwave assisted lipase catalyzed solvent-free poly-ε-caprolactone synthesis

Abstract Microwave (MW) assisted enzymatic polymerizations is an area that is largely unexplored. In the current study, the effect of MW reaction parameters on poly-ε-caprolactone (PCL) properties has been investigated using a statistical design. A {3,5} modified mixture experimental design was used to identify the parameter values that gave the desired properties of PCL. The three process parameters that were tested are temperature, MW intensity, and the reaction time. Experimental results showed that in the range of values tested, temperature had the highest positive influence on the properties of PCL, whereas high MW irradiation is not desirable. A cubic regression model was developed and optimal process parameters were obtained using this model. Conducting the polymerization reaction under optimal conditions (90°C, 240 min, 50 W), PCL with M n of 20,624 and polydispersity index of 1.2 were obtained. The regression model was validated by carrying out validation experiments and by 3D visualization.

In vitro stability study of organophosphonic self assembled monolayers (SAMs) on cobalt chromium (Co-Cr) alloy

Surface modification of cobalt chromium (Co-Cr) alloy is being investigated as a possible solution to the biomedical challenges arising from its usage. Self assembled monolayers (SAMs) of organophosphonic octadecylphosphonic acid (ODPA) were formed on the oxide surface of Co-Cr alloy by chemisorption using the solution deposition technique. High quality and well-ordered SAMs were formed which were characterized using Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle measurements and ellipsometry. The resulting monolayers were then exposed to in vitro conditions using phosphate buffered saline (PBS) solution. The samples were analyzed for a period of 1, 3, 7 and 14 days. The resulting samples were characterized using XPS, AFM and Contact angle measurements. XPS atomic concentrations and detailed high energy elemental scans gave an insight into the trends of elemental concentrations over the duration of the study. SAMs were found to be strongly bound to the oxide surface after PBS exposure. AFM gave the topographic details of SAMs presence by island formation before and after SAM formation and also over the duration of the PBS exposure. Contact Angle Measurements confirmed the hydrophobicity of the surface after SAM formation and indicated a slight disorder of the SAM alkyl chain upon exposure to PBS. Thus, ODPA SAMs were successfully coated on Cobalt Chromium (Co-Cr) alloy surface and were found to be stable and strongly bound after PBS exposure.

Nanostructured self assembled monolayers on magnesium for improved biological performance

Abstract Magnesium (Mg) and its alloys are being extensively investigated for its use as a biodegradable metallic implant material. Surface modification strategies are critical for Mg to be able to address application-specific criterion for applications such as cardiovascular stent, orthopaedic bone screws/plates and as a metallic scaffold for bone tissue engineering. Self-assembled monolayers (SAMs) are nano-sized coatings that present a simple and flexible method of carrying out surface modification of biomaterials to tailor its surface properties for specific end applications without altering the bulk properties of the material. In this manuscript, we present a brief overview of Mg as a biodegradable metallic implant material followed by surface modification of Mg using SAMs.

Spectroscopic evaluations of interfacial oxidative stability of phosphonic nanocoatings on magnesium

Magnesium (Mg), and its alloys, is being investigated for its potential biomedical applications for its use as a biodegradable metal. However surface modification strategies are needed to modify the surface of the Mg alloy for its applicability in these applications. Self-assembled monolayers (SAMs) have been investigated as a coating strategy on magnesium for biomedical applications. In this report we evaluate the oxidative interfacial stability of phosphonic nanocoatings on magnesium using spectroscopic techniques. Self-assembled mono-/multilayers (SAMs) of octadecylphosphonic acid (ODPA) were formed on the native oxide layer of magnesium alloy using solution deposition technique. The SAMs modified Mg alloy and its oxidative stability were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). FTIR studies indicated mono-/bidentate bonding of the phosphonic SAMs to the Mg alloy surface. XPS confirmed SAM formation showing presence of “P” peaks while consequently showing decrease in peak intensity of Mg peaks. XPS analysis of the phosphonate peaks showed consistent presence of this peak over a period of 21 days. AFM images showed consistent coverage of the Mg alloy over a period of 21 days. The results collectively confirm that the monolayers are stable under the chosen oxidative study.

Surface Modification of Cobalt Chromium Alloy via Phosphonic Acid Organic Nanosized Thin Films

Phosphonic Acid Organic Nanosized Thin Films Rahul Bhure, Tarek M. Abdel-Fattah, Carl Bonner, Joseph C. Hall and Anil Mahapatro* Center for Materials Research, (CMR), Center for Biotechnology and Biomedical Sciences (CBBS), and Department of Chemistry, Norfolk State University, Norfolk, Virginia 23508 Applied Research Center and Department of Biology, Chemistry, and Environmental Science, Christopher Newport University, Newport News, Virginia 23606 *Email: amahapatro@nsu.edu

Fabrication of magnesium-based metallic scaffolds for bone tissue engineering

Abstract Repairing and regenerating defects of large bones caused by disease or trauma is a significant clinical challenge. Extensive research has been done on bone tissue regeneration incorporating biodegradable scaffolds mainly polymeric scaffolds which are used heavily due to their ease in manufacturing, biocompatibility and biodegradability. The use of biodegradable polymers for scaffolding has certain drawbacks for bone tissue regeneration such as mismatch in mechanical properties and issues relating to bone infection and osseointegration of the bioresorbable scaffold. Metallic foams have been explored as an alternative to polymers as a scaffolding material. Metallic porous structures have advantages such as high strength and ductility relative to polymeric scaffolds that could be favorable for hard tissue regeneration such as bone. In this manuscript, we review metallic scaffolds for bone tissue engineering including potential metals for tissue engineering scaffold applications. Current techniques of metallic scaffold production including production of magnesium scaffold are discussed.

Bioceramic Coatings on Magnesium Alloys

Magnesium (Mg)-based materials have attracted interest as for its use as a biodegradable metallic implant material. However, one of the main challenges in the use of magnesium and its alloys for biomedical applications is its poor corrosion resistance in physiological environments. Surface coatings to control biodegradation of magnesium offer the flexibility to be easily modified for specific applications and have significantly less investment. Hydroxyapatite-based bioceramic coatings on metallic implants have been favorably viewed because of its excellent bioactivity and biocompatibility and the fact that the composition of hydroxyapatite is similar to that of natural bone. In this manuscript, we discuss the context of magnesium as biodegradable metal, current challenges on use of magnesium-based materials for biomedical applications. Focusing specifically on orthopedic applications, we elaborate on calcium phosphate-based bioceramic coatings. Recent work on hydroxyapatite coatings on magnesium, fabrication process and the biological response of the coatings are highlighted.

An Electrospun Polyaniline Nanofiber as a Novel Platform for Real-Time COX-2 Biomarker Detection

The presence of Cyclooxygenase-2 (COX-2) biomarker has been associated with the development of certain types of cancer such as breast cancer. Moreover, reliable quantification of COX-2 as an enzyme responsible for pain and inflammation is vital. Here we demonstrate the feasibility of sensitive COX-2 detection via integration of nanoporous polyaniline fibers on the microfabricated platform to develop a label-free biosensor. Highly porous polyaniline nanofibers were fabricated in different diameters and integrated on the interdigitated microelectrodes to develop electrochemical platforms. Characterization results revealed that the smaller diameter improved the sensitivity of the biosensor due to enhancement in the specific surface area. The developed biosensor was able to detect analyte as low as 0.1pg/mL with a large dynamic linear range of 10fg/mL to 1μg/mL. The fabricated sensor showed remarkable sensitivity towards COX-2 antigen suggesting the significant contribution of this nanofiber based platform to the enhanced sensitivity in COX-2 analyte detection.Copyright