Rachita Lakra

Plumbagin caged silver nanoparticle stabilized collagen scaffold for wound dressing

The present work describes the development of a novel wound dressing material based on nano-biotechnological intervention by caging plumbagin on silver nanoparticle (PCSN) as a multi-site cross-linking agent of collagen scaffolds with potent anti-microbial and wound healing activity. Cross-linking of collagen with PCSN enhanced the physical, thermal, and mechanical properties along with the kinetics of micro structural fibril assembly of the collagen molecule. FTIR and CD analysis revealed that cross-linking of collagen using PCSN did not induce any structural changes in the collagen molecule. Further, cross-linking of collagen with PCSN resulted in uniform alignment of collagen fibrils to form orderly aligned porous structured scaffolds with potent anti-bacterial activity that in turn enhanced its ability to promote cell proliferation and wound healing. The cross-linking ability, and biochemical and therapeutic properties of plumbagin caged silver nanoparticles were attributed to the cumulative effect of plumbagin and silver nanoparticles because individual molecules had minimal effect on these parameters.

Design and development of papain–urea loaded PVA nanofibers for wound debridement

Devitalized tissues present in a wound bed serve as a reservoir for bacterial growth and contain elevated levels of inflammatory mediators that promote chronic inflammation and impair cellular migration necessary for wound repair. Effective wound cleansing and debridement are essential for granulation and re-epithelization. Among various debridement methods, enzymatic debridement is a highly selective method that uses naturally occurring proteolytic enzymes. Papain combined with urea has been widely used to remove necrotic/devitalized tissues. Our approach is to encapsulate papain and urea in PVA nanofibers to bring out sustained release to enable breakdown of fibrinous material in necrotic tissue and enhance wound healing. Physico-chemical characterization of nanofibers depicted the enzyme interaction with the polymer and also confirmed that the enzyme was evenly distributed in the nanofibers in an amorphous state. Fluorescence spectroscopy confirmed that the structural integrity of the enzyme was maintained after encapsulation. The results of antibacterial activity along with cell compatibility assays confirm the structural and functional integrity of the enzyme preparation along with the biocompatibility of the electrospun nanofiber and thereby provide more suitability as a dressing for wound debridement.

Dinuclear phenoxo-bridged "end-off" complexes containing a piperazine that shows chemical nuclease and cytotoxic activities

Three dinuclear cobalt(II), nickel(II), and copper(II) complexes (1–3) of a phenol-based ‘end-off’ compartmental ligand, 2,6-bis[1-(N-ethyl)piperazineiminomethyl]-4-methylphenol (HL), have been synthesized and characterized by spectral analysis. The molecular structure of one of these complexes, 2,6-bis[1-(N-ethyl)piperazineiminomethyl]-4-methylphenolato-diaqua-μ-hydroxo-μ-nitrato-dicobalt(II) nitrate, [Co2(H2L)(μ-OH)(μ-NO3)(H2O)2](NO3)3] (1), was determined by single crystal X-ray crystallography. The complex exhibits a distorted octahedral geometry around cobalt with a Co–Co distance of 2.9882(8) Å. Electrochemical studies of 1–3 reveal that the redox processes are due to ligand reactions. The EPR spectrum of 3 showed a broad signal at g = 2.11 indicating magnetic interaction between the two copper ions. The μeff values for 1 and 3 are 4.94 and 1.93 BM, respectively, which indicate a spin–spin interaction between the metal ions. Complex 3 caused a cleavage of circular plasmid pBR322 DNA into nicked circular and linear forms in the presence of a co-reactant. Human epidermoid carcinoma cells, A431, were employed for in vitro cytotoxicity studies of the synthesized complexes. The IC50 value of 3 is lower than that of the other two complexes. The copper complex (3) exhibited better chemical nuclease and cytotoxic activity than the other two complexes. Graphical Abstract

Fabrication of Hybrid Collagen Aerogels Reinforced with Wheat Grass Bioactives as Instructive Scaffolds for Collagen Turnover and Angiogenesis for Wound Healing Applications

The present study illustrates the progress of the wheat grass bioactive-reinforced collagen-based aerogel system as an instructive scaffold for collagen turnover and angiogenesis for wound healing applications. The reinforcement of wheat grass bioactives in collagen resulted in the design and development of aerogels with enhanced physicochemical and biomechanical properties due to the intermolecular interaction between the active growth factors of wheat grass and collagen fibril. Differential scanning calorimetry analysis revealed an enhanced denaturation temperature when compared to those of native collagen aerogels. Fourier transform infrared spectroscopy analysis confirmed that the reinforcement of bioactives in the wheat grass did not affect the structural integrity of the collagen molecule. Additionally, the reinforced biomaterial with a systematic absorptive morphology resulted in a three-dimensional (3D) sponge-like aerogel exhibiting a potent highly oriented 3D structural assembly that showed increased water retention ability and substance permeability that would enable the passage of nutrients and gaseous components for cellular growth. Furthermore, the cumulative effect of the growth factors in wheat grass and the collagen molecule augments the angiogenic ability and collagen production of the aerogel by restoration of the damaged tissue thereby making it a potential 3D wound dressing scaffold. The results were confirmed by in vivo wound healing assays. This study shows the possibility for progress of a biocompatible, biodegradable, and nonadhesive nutraceutical-reinforced collagen aerogel as an instructive scaffold with good antimicrobial properties for collagen turnover and angiogenic response for wound healing applications.

Keloid collagen–cell interactions: structural and functional perspective

Keloids are a benign dermal proliferative disorder characterised by dense fibrotic tissue developing due to abnormal wound healing. Clinically, keloids extend beyond the margin of the original wound, do not undergo spontaneous regression and also recur after excision. The biochemical and cellular composition of keloids largely differ from that of normal dermis and mature scars plaguing physicians and patients for several decades. Keloids are rich in densely packed fibrillar collagen paralleled by up regulation of fibrogenic cytokines and growth factors. Adhesion of cells to the extracellular matrix (ECM) is a fundamental process during the formation and maintenance of animal tissue and therefore, aberrant cell–ECM interactions result in a number of diseases. There are numerous reports on the signalling mechanisms responsible for excessive production of collagen in keloids. However, the structure–function correlation of collagen fibres in keloids is not understood properly. This paper is the first report towards the understanding of the influence of keloid collagen on the behaviour of fibroblasts with reference to cell adhesion, spreading and growth that translates the adhesion mediated signalling response in keloid pathogenesis. Cells grown on normal collagen were well spread, adhered and proliferated while those on keloid collagen exhibited weak cell–matrix interactions and hence exhibited a lower degree of proliferation. The differences observed in the cell behaviour could be attributed to the altered structural and thermal properties of the keloid collagen.

Nano-caged shikimate as a multi-site cross-linker of collagen for biomedical applications

The present study evaluated the application of a nano-biotechnological intervention of nutraceutical shikimate for the development of a potential multi-site cross-linker with enhanced cross linking, anti-microbial and cell proliferative activities. The cross-linking and therapeutic properties of the nutraceutical shikimate were simultaneously utilized by caging them onto silver nanoparticles. The caging of shikimate on silver nanoparticles resulted in the cumulative expression of the physico-chemical properties of both silver nanoparticles and shikimate. We observed that in shikimic acid caged silver nanoparticle (SCS nanoparticle) cross-linked collagen, the viscosity and self-assembly process of collagen, along with its mechanical and thermal properties, were significantly improved when compared with native collagen. The three dimensional conformation of collagen was also retained after cross-linking with SCS nanoparticles. Cell viability with SCS nanoparticle cross-linked collagen was found to be enhanced, in comparison to collagen films cross-linked with shikimic acid and native collagen. SCS nanoparticle-stabilized collagen possessed both cell proliferative and anti-microbial properties, which would make SCS nanoparticles a superior cross-linker of collagen. The results suggested a new strategy for cross-linking collagen and provide scope for alternative biocompatible interventions in the development of biomaterials.

Fabrication of homobifunctional crosslinker stabilized collagen for biomedical application

Collagen biopolymer has found widespread application in the field of tissue engineering owing to its excellent tissue compatibility and negligible immunogenicity. Mechanical strength and enzymatic degradation of the collagen necessitates the physical and chemical strength enhancement. One such attempt deals with the understanding of crosslinking behaviour of EGS (ethylene glycol-bis (succinic acid N-hydroxysuccinimide ester)) with collagen to improve the physico-chemical properties. The incorporation of a crosslinker during fibril formation enhanced the thermal and mechanical stability of collagen. EGS crosslinked collagen films exhibited higher denaturation temperature (T d) and the residue left after thermogravimetric analysis was about 16 ± 5.2%. Mechanical properties determined by uniaxial tensile tests showed a threefold increase in tensile strength and Youngs modulus at higher concentration (100 μM). Water uptake capacity reduced up to a moderate extent upon crosslinking which is essential for the transport of nutrients to the cells. Cell viability was found to be 100% upon treatment with 100 μM EGS whereas only 30% viability could be observed with glutaraldehyde. Rheological studies of crosslinked collagen showed an increase in shear stress and shear viscosity at 37 °C. Crosslinking with EGS resulted in the formation of a uniform fibrillar network. Trinitrobenzene sulfonate (TNBS) assay confirmed that EGS crosslinked collagen by forming a covalent interaction with ε-amino acids of collagen. The homobifunctional crosslinker used in this study enhanced the effectiveness of collagen as a biomaterial for biomedical application.

Curcumin cross-linked collagen aerogels with controlled anti-proteolytic and pro-angiogenic efficacy

This paper elucidates the development of a curcumin cross-linked collagen aerogel system with controlled anti-proteolytic activity and pro-angiogenic efficacy. The results of this study showed that in situ cross-linking of curcumin with collagen leads to the development of aerogels with enhanced physical and mechanical properties. The integrity of collagen after cross-linking with curcumin was studied via FTIR spectroscopy. The results confirmed that the cross-linking with curcumin did not induce any structural changes in the collagen. The curcumin cross-linked collagen aerogels exhibited potent anti-proteolytic and anti-microbial activity. Scanning electron and atomic force microscopic analysis of curcumin cross-linked collagen aerogels showed a 3D microstructure that enhanced the adhesion and proliferation of cells. The highly organized geometry of collagen-curcumin aerogels enhanced the permeability and water-retaining ability required for the diffusion of nutrients that aid cellular growth. The pro-angiogenic properties of collagen-curcumin aerogels were ascribed to the cumulative effect of the nutraceutical and the collagen molecule, which augmented the restoration of damaged tissue. Further, these aerogels exhibited controlled anti-proteolytic activity, which makes them suitable 3D scaffolds for biomedical applications. This study provides scope for the development of biocompatible and bioresorbable collagen aerogel systems that use a nutraceutical as a cross-linker for biomedical applications.

Fabrication of core–shell nanofibers for controlled delivery of bromelain and salvianolic acid B for skin regeneration in wound therapeutics

The physiological and pathological complexity of the wound healing process makes it more challenging to design an ideal tissue regeneration scaffold. Precise scaffolding with high drug loading efficiency, efficient intracellular efficacy for therapeutic delivery, minimal nonspecific cellular and blood protein binding, and maximum biocompatibility forms the basis for an ideal delivery system. This paper describes a combinational multiphasic delivery system, where biomolecules are delivered through the fabrication of coaxial electrospinning of different biocompatible polymers. The ratio and specificity of polymers for specific biofunction are optimized and the delivery system is completely characterized with reference to the mechanical property and structural integrity of bromelain (debridement enzyme) and salvianolic acid B (pro-angiogenesis and re-epithelialization). The in vitro release profile illustrated the sustained release of debriding protease and bioactive component in a timely fashion. The fabricated scaffold showed angiogenic potential through in vitro migration of endothelial cells and increased new capillaries from the existing blood vessel in response to an in ovo chicken chorioallantoic membrane assay. In addition, in vivo studies confirm the efficacy of the fabricated scaffold. Our results therefore open up a new avenue for designing a bioactive combinational multiphasic delivery system to enhance wound healing.

Strategic design of cardiac mimetic core-shell nanofibrous scaffold impregnated with Salvianolic acid B and Magnesium l-ascorbic acid 2 phosphate for myoblast differentiation

The major loss of myocardial tissue extracellular matrix after infarction is a serious complication that leads to heart failure. Regeneration and integration of damaged cardiac tissue is challenging since the functional restoration of the injured myocardium is an incredible task. The injured micro environment of myocardium fails to regenerate spontaneously. The emergence of nano-biomaterials would be a promising approach to regenerate such a damaged cardiomyocytes tissue. Here, we have fabricated a dual bioactive embedded nanofibrous cardiac patch via coaxial electrospinning technique, to mimic the topographical and chemical cues of the natural cardiac tissue. The proportion and the concentration of the polymers were optimized for tailored delivery of bioactives from a spatio-temporally designed scaffold. The functionalization of polymeric core shell nanofibrous scaffold with dual bioactives enhanced the physico-chemical and bio-mechanical properties of the scaffolds that has resulted in a 3-dimensional topography mimicking the natural cardiac like extracellular matrix. The sustained delivery of bioactive signals, improved cell adhesion, proliferation, migration and differentiation could be attributed to its highly interconnected nanofibrous matrix with good extended morphology. Further, the expression of cardiac specific markers were found to increase on investigation of mRNA by real time PCR studies and proteins by immunofluorescence and western blotting techniques, confirming cell - biomaterial interactions. Flow cytometry analysis authenticated a potent mitochondrial membrane potential of cells treated with nanocomposite. In addition, in ovo studies in chicken chorioallantoic membrane assay confirm the efficacy of the developed scaffold in inducing angiogenesis required for maintaining its viability after transplantation onto the infarcted zone. These promising results demonstrate the potential of the composite nanofibrous scaffold as an effective biomaterial substrate for cardiac regeneration providing cues for development of novel cardiac therapeutics.