Pradip Kumar Dutta

External stimuli response on a novel chitosan hydrogel crosslinked with formaldehyde

Keeping in mind the significance of hydrogels as an external stimuli sensitive super absorbing material, some transparent covalent hydrogels of chitosan were prepared by crosslinking with varying amounts of formaldehyde solution used as crosslinking agent. The characteristics of hydrogels were investigated by Fourier transform infrared (FT-IR) spectroscopy and swelling experiments. The effect of crosslinking agent on water absorbency has been investigated. The hydrogels exhibited a relatively higher swelling ratio in the range of 2066–3306% and equilibrium water content (EWC) in the range of 95-38–97 06% at pH 7 and 35°C temperature. The influence of external stimuli such as pH, temperature, and ionic strength of the swelling media on equilibrium swelling properties has been observed. Hydrogels showed a typical pH and temperature responsive behaviour such as low pH and high temperature has maximum swelling while high pH and low temperature show minimum swelling. An increase in the ionic strength of swelling media caused a continuous decrease in the swelling of hydrogels at both acidic and basic pH.

Chitosan Aerogels Exhibiting High Surface Area for Biomedical Application: Preparation, Characterization, and Antibacterial Study

The objective of the present work is to improve the surface area of aerogel via supercritical carbon dioxide (sc · CO2) treatment and thus to obtain the chitosan derivative. The resulting mesoporous material exhibits the typical characteristics of aerogels such as high porosity and high surface area. The aerogels were characterized using FTIR, SEM, TEM, and thermal analysis. The specific surface areas and porosities of aerogels were determined using N2 adsorption. The antibacterial assays were done using E. coli. The prepared chitosan aerogels show important properties such as biocompatibility, non-toxicity, and antibacterial activity, making them suitable for biomedical applications.

Preparation, Antibacterial and Physicochemical Behavior of Chitosan/Ofloxacin Complexes

A novel chitosan derivative with ofloxacin (OFX) has been successfully prepared. The IR and 1H-NMR results revealed that the chitosan/ofloxacin (CH-OFX) complex exhibited an electrostatic interaction. The crystalline and surface morphology were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The antimicrobial activity of the complexes against various micro-organisms viz. Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus was tested. It was established that their antibacterial activity is up to four times greater than that of free quinolone drug and chitosan, probably due to the conjunction of favorable pharmacokinetics, excellent bacterial susceptibility and good stability towards metabolic degradation.

Chitosan silk-based three-dimensional scaffolds containing gentamicin-encapsulated calcium alginate beads for drug administration and blood compatibility

In the present study gentamicin was encapsulated within calcium alginate beads and incorporated into porous chitosan, gelatin, double-hybrid silk fibroin, chitosan/gelatin and double-hybrid silk fibroin/chitosan scaffolds. Physiochemical, morphological and biological properties of fabricated amenable model systems were evaluated, revealing hemocompatible nature of double-hybrid silk fibroin/chitosan and double-hybrid silk fibroin scaffolds of hemolysis %<5 and porosity >85%. Fourier transform infrared results confirmed the blend formation and scanning electron microscope images showed good interconnectivity. Double-hybrid silk fibroin/chitosan-blended scaffold shows higher compressive strength and compressive modulus than other fabricated scaffolds. A comparative drug release profile of fabricated scaffolds revealed that double-hybrid silk fibroin/chitosan scaffold is a pertinent model system because of its prolonged drug release, optimal hemocompatability and high compressive modulus.

Mechanically robust biocomposite films of chitosan grafted carbon nanotubes via the [2 + 1] cycloaddition of nitrenes

Chitosan functionalized multiwalled carbon nanotubes (CS-MWCNTs) are prepared using the [2 + 1] cycloaddition of nitrenes to the π electron system of carbon nanotubes followed by an amidation reaction with chitosan. The analysis of transmission electron microscopy (TEM) micrographs suggests the presence of more than 14 nm of chitosan grafted onto the MWCNTs, and the covalent linkage of chitosan with the MWCNTs is confirmed from FTIR and Raman spectra, XPS and energy dispersive X-ray spectroscopy (EDS) elemental mapping. The grafting density calculated using thermogravimetric analysis was 1.8 chitosan chains per 1000 MWCNT carbons. The effectiveness of the biofunctionalized CS-MWCNTs as a reinforcing filler (3 wt%) in a chitosan polymer matrix was verified by the dramatic enhancement of the mechanical properties (the tensile strength of the composite is significantly increased to 81.3 MPa from 36.5 MPa for pure chitosan, the highest modulus was up to 4.4 GPa for the composite with 3 wt% CS-MWCNTs) with a high elongation-at-break. The interfacial bonding between the CS-MWCNTs and the chitosan matrix plays a crucial role in the enhancement of the physical performance of the MWCNT-based composites.

Colorimetric and ON–OFF–ON fluorescent chemosensor for the sequential detection of Cu(II) and cysteine and its application in imaging of living cells

An easy-to-prepare colorimetric and ON–OFF–ON fluorescent naphthol derivative 1 has been synthesized and characterized for sequential detection of Cu2+ and cysteine. Chemosensor 1 detects Cu2+ selectively in DMSO/H2O (3 : 7 v/v) by changing its UV-visible spectrum and color (colorless to yellow), leading to the formation of 1-Cu(II) complex. The resultant 1-Cu(II) complex recognizes cysteine (Cys) and the solution turns colorless with regeneration of the absorption band of 1. The detection limit of 1 for Cu2+ ion is found to be 0.27 μM, which is much lower than that recommended by WHO for drinking water (30 μM). Cu2+ ion exhibits quenching of the fluorescence intensity of 1, which is restored upon the addition of cysteine. Chemosensor 1 is used as an imaging reagent for detection of the cellular uptake of Cu2+ ion in A549 cell line (human lung carcinoma cell).

Chitin, Chitosan, and Silk Fibroin Electrospun Nanofibrous Scaffolds: A Prospective Approach for Regenerative Medicine

Intensive studies have been done to a wide range of natural and synthetic polymeric scaffolds which have been done for the use of implantable and temporal devices in tissue engineering. Biodegradable and biocompatible scaffolds having a highly open porous structure with compatible mechanical strength are needed to provide an optimal microenvironment for cell proliferation, migration, differentiation, and guidance for cellular in growth at host tissue. One of the most abundantly available biopolymer chitins and its deacetylated derivatives is chitosan which is non-toxic and biodegradable. It has potential biomedical applications such as tissue engineering scaffolds, wound dressings, separation membranes, antibacterial coatings, stent coatings, and biosensors. Recent literature shows the use of chitin and chitosan in electrospinning to produce scaffolds with improved cytocompatibility, which could mimic the native extra-cellular matrix (ECM). Similarly, silk from the Bombyx mori silkworm, a protein-based natural fiber, having superior machinability, biocompatibility, biodegradation, and bioresorbability, has evolved as an important candidate for biomedical porous material. This chapter focuses on recent advancements made in chitin, chitosan, and silk fibroin-based electrospun nanofibrous scaffolds, emphasizing on tissue engineering for regenerative medicine.

Studies on thermo-optic property of chitosan–alizarin yellow GG complex: a direction for devices for biomedical applications

The optical parameters including the refractive index (n) and thermo-optic coefficient, TOC (dn/dT), the dielectric constant (ε) and its variation with temperature, and the thermal volume expansion coefficient (β) and its variation with temperature of chitosan–alizarin yellow GG (CS–AY GG) complex were examined. The dn/dT and ε-values for the polymer derivative were in the range −2.5 × 10−4 to 1.2 × 10−4°C−1 and 2.2 to 2.3, respectively. The dn/dT values were larger than that of inorganic glasses such as zinc silicate glass (5.5 × 10−6°C−1) and borosilicate glass (4.1 × 10−6°C−1) and were larger than that of organic polymers such as polystyrene (−1.23 × 10−4°C−1) and PMMA (−1.20 × 10−4°C−1). The ε-values are lower than optically estimated ε-values of conventional polymer (3.00), aliphatic polyimide (2.5) and semi-aromatic polyamide (2.83). The obtained results of chitosan derivative are expected to be useful for optical switching and optical waveguide areas for devices of biomedical applications.

D-Glucosamine and N-Acetyl D-Glucosamine: Their Potential Use as Regenerative Medicine

Glucosamine (GlcN), an amino sugar, is a compound derived from substitution of a hydroxyl group of a glucose molecule with an amino group. GlcN and its acetylated derivative, N-acetylglucosamine (GlcNAc), have been widely used in food, cosmetics, and pharmaceutical industries and are currently produced by acid hydrolysis of chitin (a linear polymer of GlcNAc) extracted from crab and shrimp shells. In this review, distribution and production of GlcN and GlcNAc, their chemistry and determination in the complex samples will be treated first. This review will describe the procedure to identify a high-quality glucosamine product for Glucosamine/chondroitin Arthritis Intervention Trial (GAIT) and to clarify confusing product information and nomenclature. GlcN is a precursor of the glycosaminoglycans and proteoglycans that make up articular cartilage. Glucosamine sulfate and glucosamine hydrochloride have used for the treatment of osteoarthritis for more than 30 years, with no major known side effects. The notion that augmenting the intake of the precursor molecule, glucosamine, may directly stimulate articular proteoglycan synthesis to modulate osteoarthritis has provided the rationale for its widespread use. Theoretically, exogenous glucosamine may augment glycosaminoglycan synthesis in cartilage. There is a simultaneous theoretical concern that it might also induce insulin resistance in insulin-sensitive tissues. While the efficacy of glucosamine was published in the definitive medical journals, there were views against it. This concern will be also discussed. While glucosamine was not effective without combination with chondroitin sulfate in the some trial, glucosamine alone was effective in the other trial. Some concerns about these trials will be discussed together with the mechanism of action of glucosamine and chondroitin for antiarthritic potential. Finally, the review will focus on the biomedical and other application of the glucosamine and chitosan oligosaccharide. Such biomedical applications include wound healing, bone regeneration, antibacterial effect, and oral hygiene. It also discusses the role of chitosan oligosaccharide as a drug carrier for molecular therapies, such as the drug and the gene delivery systems and the role in imaging for tumor and cancer detection.

In-vitro toxicity induced by quartz nanoparticles: Role of ER stress

In recent years with the advancement of nanotoxicology, the scientific communities drastically increased the investigation of the potential toxicity of nanominerals which are present in all atmospheres as well as are used in a variety of applications. In this study, we reported how Quartz Nanoparticles (QNPs) depending on concentration induces different signature ER stress markers in A549 cells. QNPs induced concentration-dependent decrease in cell viability and this concentration dependent toxicity intensifies production of reactive oxygen species leading to oxidative stress and inflammation. Furthermore, the levels of marker proteins of apoptosis (Cytochrome C, Caspase 3, Caspase-12) were found to be significantly up-regulated confirming apoptosis. To check the involvement of ER stress, the activation of ER stress signaling pathway was observed by up-regulated protein levels of ER stress marker proteins including PERK, eIF2α, DDIT3, ATF4 and GRP78 in a concentration-dependent manner. In summary, preliminary assessment of QNPs induced toxicity by monitoring the ER stress signaling pathway gives novel assumptions toward empathizing the effects of QNPs at the cellular level. The adverse effects associated with the exposure to QNPs can be avoided by sensibly using these minerals within the safe dose.