Search

Inhibition of collagen fibrillation by small molecules is of growing interest to develop therapeutics for the illnesses related to excess deposition of collagen. In this context, we have studied the inhibitory effect of N-Vanillylnonanamide (NVA), a natural product from capsicum oleoresin and an analog of capsaicin (a known inhibitor of collagen fibrillation), on collagen self-assembly that leads to fibrillation in vitro. Commercially, capsaicin was found to be expensive than NVA. Therefore, it would be an advantage economically if NVA could display a similar/better inhibitory activity compared to capsaicin. The conventional turbidity measurements indicate that NVA completely inhibits collagen fibrillation at body temperature (37 °C) and its inhibition were concentration-dependent. The inhibition efficiency was observed to reduce at room temperature (25 °C). NVA protects the triple helical structure of collagen while it increases the thermal stability of collagen compared to collagen alone. Fluorescence results suggest that NVA binds in both telopeptide and triple helical regions of collagen and thereby prevents collagen self-assembly. The present results thus indicate that NVA is a potential inhibitor and, economically, it could be a better choice as a therapeutic agent compared to capsaicin in evolving treatment for disorders associated with excessive collagen deposition.

Hair waste is one of the solid substances rejected by the leather industry. This waste finds its way into the surroundings causing serious environmental pollution. This hair waste may be utilized for effective extraction of keratin, thereby generating value-added products with numerous applications. Thus we focusing on utilizing red sheep’s hair waste for extracting keratin by the application of different chemical treatments such as sodium hydroxide, sodium sulfide, mercaptoethanol, cysteine, sodium metabisulfite with urea (SMB), and SMB with SDS (SMBS). CD spectrum and FTIR results of the keratin samples indicated a predominance of the helical conformation along with β sheets. SDS-PAGE confirmed the molecular weight of the keratin samples to be in the range of 40–60 kDa. DSC and TGA analysis exhibited the extracted keratin to have a higher denaturation temperature (>200 °C) and thermal stability. The keratin samples obtained using varied chemical treatments were compared in terms of yield, protein content, and cost-effectiveness, and the sample obtained using SMBS was preferred for in vitro studies. It is indicated that keratin extracted using SMBS effectively involved for fibroblast cell growth. Thus, we suggest that these keratin could produce biomaterials that can serve as a valuable material for biomedical applications.

Zinc Oxide (ZnO) nanoparticles are used in the field of nanomedicine. ZnO is non-toxic and compatible with biological system. The major problem of wound is infections. The infections delays wound healing. Usage of Nanomaterials like ZnO nanoparticles for wound healing is promising. ZnO nanoparticles are synthesised by wet chemical method. It is annealed at 300, 500, 700, and 900 °C for 3 h. ZnO nanoparticle morphology and size distribution are analysed by XRD, FTIR and TEM. The influences of particle size on fibroblast cell growth (NIH3T3) and on antimicrobial activity are analysed. The growth of fibroblast cell is higher with ZnO nanoparticles of larger particle size. Further the MTT analysis, fluorescence calcein AM cell staining and F-actin analysis confirms the growth of fibroblast cells with improved biocompatibility behaviour. The antimicrobial activity is higher for ZnO nanoparticles of lower particle size. Confocal microscope analysis and Zone of inhibition analysis confirms the antimicrobial activity of ZnO nanoparticles.

Biomimetic nanofibrous scaffolds targeting multiple dysfunctional processes provide a multi-pronged strategy to restore functions and regenerate the damaged tissue. This study investigates a strategy of combining a regenerative component, Type I collagen Peptide (CP), along with a nitric oxide donor, S-Nitrosoglutathione (GSNO), in the form of nanofibrous scaffold to address the non-healing diabetic ulcer. Silk Fibroin-Polyvinyl alcohol (SF-PVA) nanofibrous scaffold is used as a carrier for delivering functional moieties. The developed nanofibrous electrospun mats (SF-PVA, CP-SF-PVA, and CP-GSNO-SF-PVA) showed continuous, bead-less and randomly oriented fibers with highly porous morphology. The in vitro biocompatibility was assessed by MTT assay, DAPI-Rhodamine 123 and FITC-Phalloidin imaging studies. CP-GSNO-SF-PVA nanofibrous scaffold showed a high degree of cell attachment, spreading of F-actin with viable cell morphology and appreciable inter-cellular connection. Thus the study showed that the proliferation of fibroblast cells are mainly facilitated by the presence of collagen peptide in the nanofibrous matrix. Griess assay demonstrated immediate release of NO for a day from the developed multifunctional scaffold. These results demonstrate the in vitro efficacy of CP-GSNO and indicate the opportunity of CP-GSNO-SF-PVA nanofibrous scaffold for the treatment of ischemic non-healing ulcers.

The detection of collagen fibrils and fibrillation is crucial for tissue regeneration, biomedical applications of collagen, and for studying the interaction of small molecules with the collagen fibrils in the development of therapeutics for collagen-based diseases. At present, collagen fibrillation is probed by high-value microscopic techniques, which limits real-time monitoring of collagen fibril growth and measurement only in dry form. In this context, a quick sensing method is necessary for detecting these fibrils, especially monitoring fibril growth in solution. Herein, we show that vibrational circular dichroism (VCD), a growing spectroscopic technique, can probe collagen fibrils in aqueous solutions by generating an enhanced amide I VCD signal (intensity) compared to monomer. Unlike regular protein VCD measurements, VCD of collagen fibrils require a very low concentration (5 mg/mL) of collagen and can be probed in a very short time (∼10 min). Moreover, VCD responds to the diameter and height of collagen fibrils as evidenced by an increased VCD intensity (close to 103) with pH and NaCl, making VCD a sensitive tool for monitoring the growth of the fibril diameter and height. VCD was also found to be suitable for detecting the time-dependent increase in fibril diameter under fibrillation conditions. Because no other probe is presently available for rapid detection of collagen fibrils in solution form, the ability of VCD to rapidly probe collagen fibrillation in solution and in real-time opens a new way of studying collagen fibrillation in different fields and applications.

Development of biomaterials for tissue engineering applications is of great interest to meet the demand of different clinical requirements. The wound heal dressing biomaterials should necessarily contain well-defined therapeutic components and desirable physical, chemical and biological properties to support optimal delivery of therapeutics at the site of the wound. In this study, we developed collagen-silica wound heal scaffold incorporated with the extract of Cynodon dactylon, characterized and evaluated for its wound heal potential in vitro and in vivo against collagen (Col) and Collagen-silica (CS) scaffolds that served as controls. The prepared Collagen-Silica-Cynodon extract (CSCE) scaffold exhibits porous morphology with preferable biophysical, chemical, mechanical and mass transfer properties besides its controlled biodegradation at the wound site. Stability of CSCE was found to be better than that of native collagen due to intermolecular interactions between collagen and constituents of C. dactylon as confirmed by FTIR analysis. Notably, in vitro biocompatibility assay using DAPI and Rhodamine 123 staining demonstrated that the proliferation of NIH3T3 fibroblast cells was better for CSCE when compared to the Col and CS scaffolds. In vivo wound healing experiments with full-thickness excision wounds in wistar rat model demonstrated that the wounds treated with CSCE showed accelerated healing with enhanced collagen deposition when compared to wounds treated with Col and CS scaffolds, and these studies substantiated the efficacy of CSCE scaffold for treating wounds.

Collagen is a unique protein abundantly present in the connective tissues of mammals and widely used for biomaterial preparation. In this study, we synthesized and characterized collagen-fucoidan blend films for tissue regenerative properties. Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) were used for thermal analysis of the blend films, and the films exhibited higher thermal stability and denaturation temperature (Td) than those of native collagen due to intramolecular hydrogen bonding interaction between collagen and fucoidan, which was analyzed by FTIR spectroscopy. Morphological evaluation of these films using Scanning Electron Microscopy (SEM) showed smaller pore size than the control. Moreover, fucoidan protects collagen against enzymatic degradation and thereby increases the structural stability of collagen. Further, the in vitro studies of the synthesized films showed that they effectively facilitated the proliferation and migration of fibroblast cells without exhibiting toxicity. These study results suggested that the collagen-fucoidan blend films are a favorable substrate for growth of fibroblast cells, and may have great potential for tissue engineering applications.

Intensifying researches in leather sector are focusing on eco-benign tanning chemicals with less environmental impact processing route. The present study aims to design an eco-acceptable shoe upper leather process that could potentially eliminate use of chrome from the leather industry. Possible conversion of Cr3+ to Cr6+ in suitable oxidant environment during leather manufacture is always a threat to the ecosystem. Water load for leather processing is very high, also becoming a precious resource that needs to be reduced for industrial applications. Further without water usage for a process, generation of wastewater could be averted. With this context, a combination tanning using wattle and aluminium has been developed in a pickle-less and waterless medium. The experimental leather possesses a shrinkage temperature of 84 °C with a fully loaded compact fibre structure indicating that tannin penetration is not affected in waterless medium. Experimental leathers exhibit better physical strength and comparable organoleptic characteristics. The process enjoys environmental benefits as it shows significant pollution load reduction in Biological Oxygen Demand (BOD), chemical oxygen demand (COD), Total Dissolved Solids (TDS) by 88, 89, and 97%, respectively. Hence, a viable option is made available to manufacture eco-acceptable leather without water usage and chrome salts in tanning.

Solid waste from all walks have registered their environmental impact by breathing out large amount of greenhouse gases. In this work, not only a waste to wealth strategy for effective utilization of trimmings (Solid waste) from tanning industry to recover gelatin is depicted, but also to use the extracted bio-polymer to develop a product alternative to non-biodegradable plastics. Ability of gelatin to form films is capitalized in the preparation of a composite film system comprising equal percentage ratios of gelatin (Gel) and poly vinyl alcohol (PVA) through solvent casting method. This Gel/PVA composite film is envisaged for producing sustainable packaging film materials. As the existing packaging film materials sourced from petroleum based products cause degradation and disposal concerns, the proposed value addition on the gelatin extracted from waste can be a greener alternative. Through progressive optimizations Gel/PVA film system was incorporated with percentages of glycerol (Gly) and glutaraldehyde (GA) to have performance similar to the low density polyethylene (LDPE) film taken as control. Mechanical, analytical, thermal sealability and printability tests on the developed composite film Gel/PVA/Gly/GA gave optimum results for packaging applications.

We report a novel method that exploits the differential solubility properties of native and denatured proteins to distinguish between them. We chose to study this using collagen because its unique native triple helical structure is critical for the desired properties of collagen-based biomaterials. We found that native and denatured collagen separate out from solution in alcohols(methanol, ethanol, n-propanol and isopropanol), but as different phases. Native collagen undergoes tight gel-like separation(macrophase) from the solution in alcohols(90%,v/v), whereas denatured collagen separates as particles(microphase), which turn milky-like turbid. It was found that the pH of the medium had to be alkaline for turbidity formation, which necessitated the use of buffered alcohols. In solutions having mixtures of native and denatured collagen, the method has sensitivity to visually confirm the presence of native collagen even as low as 10%. It was also confirmed that the formation of turbidity was a direct function of the concentration of denatured collagen. A thermal denaturation experiment, wherein stages of denaturation were studied both by the proposed method and circular dichroism, showed that information obtained from both methods of analysis was comparable. This highlights the potential of the proposed method to become an instant fool proof test for collagen.

Bioactive compounds are extracted from mekmeko and characterized for antioxidant, phytochemical, and antibacterial activities. The phytochemical studies of the extracts revealed the presence of condensed tannins, flavonoid, and phenolic compounds. Radical scavenging activity of the extract demonstrates that the ethanol extract has more significant antioxidant activity than the aqueous extract. Ethanolic extract of mekmeko is more effective against gram-positive bacteria compared to gram-negative. A Box–Behnken-design was used to study the response pattern and to determine the optimum combination of variables for maximization of extraction yield. Experiments were carried out to evaluate the four independent variable effects (particle size, temperature, time, and solid–solvent-ratio) on the maximum extraction yield of bioactive compounds. Second order polynomial mathematical model was developed with a high coefficient of determination ( R 2 = 0.99) from the experimental data. A maximum of 18.85% total extraction yield was achieved at the optimal conditions of particle size of 350 mesh, extraction temperature at 41 °C, solid–solvent-ratio of 0.07, and extraction time of 24 h. The extracted constituents are predominantly phenolics (39%) and condensed tannins (21%). Under theses optimal conditions, the experimental values agreed well with the predicted values and indicated the suitability of the developed models.

Raw hides and skins are preserved before processing them into leather, to protect the skin protein from microbial attack. The salting method of preservation using about 50% w/w common salt is the most popularly practiced preservation method worldwide. This conventional system results in high saline wastewater leading to a huge amount of pollution load in terms of total dissolved solids and chlorides which is discharged into the effluent during the soaking process in leather manufacture. In order to overcome these wastes problem at their source, researchers have been involved in search of alternative preservation methods using salt-less or less-salt options. In the present study, the herbal Rumex abyssinicus (mekmeko) roots, which were shade dried at room temperature and powdered was investigated for its effectiveness in the preservation of goat skins. The efficacy of this new preservation method was assessed at different curing period for a month. In the assessment, the following parameters viz., moisture content, extractable nitrogen content, soluble hydroxyproline, hydrothermal stability, bacterial count, and visual evaluation of skins (hair slip and putrefaction odor) were assessed. The mekmeko preservation experiments were compared with parameters obtained using the conventional curing method. After 30 days of preservation, the experimental and control skins were processed into upper leather and their quality was evaluated by analyzing the physical characteristics, organoleptic properties and fiber structure using scanning electron microscope. The results showed that the curing system using 10% mekmeko powder with 15% common salt is efficient in preserving the raw goat skins. The quality of the experimental crust leathers produced from the optimized preservation system is comparable with the control leathers. The generation of the pollution load during leather processing was determined by analyzing biochemical oxygen demand, chemical oxygen demand, total dissolved solids, and chlorides from soaking liquor. Most importantly, 55% total dissolved solids and 70% chloride reduction in the soaking liquor was achieved by using the plant-based method of preservation. The less-salt preservation system based on mekmeko is a cleaner alternative for the conventional salt-based preservation method.

Ulcerative colitis, particularly the chronic persistent form is characterized by the presence of active inflammation and extensive areas of ulceration in the colonic mucosa. The existing treatment protocol aims at only reducing intestinal inflammation, rather than targeting mucosal ulceration. In this study, type I collagen and its daughter peptides called collagen hydrolysate, highly popular reconstructive materials for tissue engineering applications, are hypothesized as healing matrices to target the recuperation of internal mucosal ulceration. The clinical assessments on day 10 of dextran sodium sulfate induced colitis in mice model revealed that both the collagen (1.56±0.29) and collagen hydrolysate treatments (1.33±0.33) showed a significant reduction in the rectal bleeding compared to the reference mesalamine treatment (2.50±0.33) and untreated negative control (2.40±0.40). VEGF, a potent angiogenic growth factor, over expressed during UC was down-regulated by collagen hydrolysate (1.06±0.25) and collagen (1.76±0.45) to a greater extent than by mesalamine (2.59±0.51) and untreated control (4.17±0.15). The down-regulation of proinflammatory cytokines such as TNF-α, IL-1β, and IL-6 also follows the same pattern. Histological observations were in accordance with the clinical indicators. Both collagen and collagen hydrolysate treatments showed significant reduction in mucosal damage score and facilitated faster regeneration of damaged mucosa.

Human life expectancy has been steadily increasing at a rapid rate, but this increasing life span also brings about increases in diseases, dementia, and disability. A global burden of disease 2010 study revealed that hip and knee osteoarthritis ranked the 11th highest in terms of years lived with disability. Wear and tear can greatly influence the quality of life during ageing. In particular, wear and tear of the articular cartilage have adverse effects on joints and result in osteoarthritis. The articular cartilage uses longevity of type II collagen as the foundation around which turnover of proteoglycans and the homeostatic activity of chondrocytes play central roles thereby maintaining the function of articular cartilage in the ageing. The longevity of type II collagen involves a complex interaction of the scaffolding needs of the cartilage and its biochemical, structural and mechanical characteristics. The covalent cross-linking of heterotypic polymers of collagens type II, type IX and type XI hold together cartilage, allowing it to withstand ageing stresses. Discerning the biological clues in the armamentarium for preserving cartilage appears to be collagen cross-linking. Therapeutic methods to crosslink in in-vivo are non-existent. However intra-articular injections of polyphenols in vivo stabilize the cartilage and make it resistant to degradation, opening a new therapeutic possibility for prevention and intervention of cartilage degradation in osteoarthritis of aging.

Discharge of huge quantities of raw skin/hide trimming wastes by leather industries has raised serious concerns on account of their environmental impacts. It is imperative to develop a simple method for the utilization of this waste to provide a practically feasible and economically viable solution. The trimmings contain high amount of fibrous protein, which are actually a valuable bioresource. The study presents the extraction of collagen, a product of high value, from raw trimmings. Experiments were carried out using propionic acid and acetic acid for the solubilisation of collagen from skin matrix. Of these acid extraction methods, propionic acid method showed higher yield of collagen (∼93%) compared to the acetic acid extraction (∼85%). The extracted collagen was further characterised by physicochemical techniques such as SDS-PAGE, circular dichroism and infrared spectroscopy. It was concluded that the collagen extracted from trimming waste using both acids were of type I and also found to have similar physicochemical properties. Therefore, the raw skin/hides trimming waste can be a cheap source of collagen, which has many high end applications like tissue engineering, biomaterials, cosmetics and pharmaceutical industry.

Leather is extensively used in the production of various lifestyle accessories such as shoes, bags, garments, upholstery, and various other products. The leather waste generated from the manufacturing units of leather and after the intended usage of the leather products leads to the accumulation of solid leather wastes. The studies on making the leather amenable for easy disposal is a priority research. A unique process prepared for the development of the tanning system and leather, which would be manageable for easy disposal (degradation under certain environmental conditions) after the intended usage of the product is an important need. In this present work, Gramineae Saccharum officinarum L. (Sugarcane Bagasse), a byproduct of the sugarcane industry is used as a tanning agent after converting the cellulose and hemicellulose content into dialdehyde polysaccharides from hydrolyzed bagasse (DAPB) by oxidation process. Leather from goatskins after conventional pre-tanning process (Soaking to Deliming), tanned by developed dialdehyde polysaccharides. The developed leather provided resistance to collagenase degradation, which reflects the tanning efficiency of dialdehyde polysaccharides. Additionally, tanned leather also provided reasonable mechanical strength. The leathers made from dialdehyde polysaccharides were observed to have properties comparable to conventional chrome tanned leathers. From hydrolyzed bagasse solution fungal strains are isolated and tested for the degradation of the crust dialdehyde polysaccharides tanned leather, where delimed pelt (untanned), chrome tanned, and vegetable tanned crust leathers were set as control. In comparison to delimed (untanned) pelt, the newly developed tanning system showed significant resistance to degradation. However, compared to chrome and vegetable tanned leathers, the dialdehyde polysaccharides tanned leather showed better biodegradation. The developed bagasse tanning system paves the way for a cradle to cradle approach in creating a circular economy and sustainable development in leather manufacture.

Leather industry is forced to adopt green manufacturing options due to consumer awareness and statutory environmental stipulation norms. Conventional leather manufacture involves various physico-chemical treatment processes, leading to the generation of wastewater with high pollution load. Several alternative leather chemicals and in-process control measures have been developed to overcome the environmental issues. Till date, no such significant measures have been found out. Sustainable leather manufacture necessitates complete redefinition of the conventional leather making processes. Replacement of water with alternative sustainable carrier medium could be one of the possible redefined approaches. In this perspective, an attempt has been made to summarize the current status of different alternative carrier medium and its pros and cons with respect to leather manufacture. Solvent selection tool, usage of supercritical fluid and switchable solvents in different unit processes of leather manufacture are the green chemistry approaches to be employed in order to overcome the drawbacks associated with alternative carrier medium based leather manufacture. This review focuses on such possible green chemistry approaches, challenges and critical factors for usage of alternate sustainable carrier medium in leather industry.

Matrix metalloproteinases (MMPs) have been investigated as a potential target for treating invasive breast cancers. The chemotherapy for breast cancer is often prescribed as a combination of drugs. The present study investigates a novel strategy of combining a MMP inhibitor, Epigallocatechin gallate (EGCG), along with an anticancer drug, Paclitaxel (PTX), in the form of a liposomal co-delivery system. The developed PTX/EGCG co-loaded liposomes showed an entrapment of 77.11 � 2.30% and 59.11 � 3.51% for PTX and EGCG, respectively. The in vitro efficacy of the liposomes was assessed by their ability to promote apoptosis and curtail cell invasion. On all parameters, namely cytotoxicity and caspase-3 activity that are indicators of apoptosis, and MMP-2 and - 9 inhibition and invasion assays that are indicators of cell invasion, the PTX/EGCG co-loaded liposomes showed better results than each of the individual drug loaded liposomes. These findings demonstrate the synergistic outcome of PTX/EGCG combination and indicate the suitability of PTX/EGCG co-loaded liposomes for the treatment of invasive breast cancer. � 2014 Elsevier B.V.

Keratin has gained much attention in the recent past as a biomaterial for wound healing owing to its biocompatibility, biodegradability, intrinsic biological activity and presence of cellular binding motifs. In this paper, a novel biomimetic scaffold containing keratin, chitosan and gelatin was prepared by freeze drying method. The prepared keratin composite scaffold had good structural integrity. Fourier Transform Infrared (FTIR) spectroscopy showed the retention of the native structure of individual biopolymers (keratin, chitosan, and gelatin) used in the scaffold. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) results revealed a high thermal denaturation temperature of the scaffold (200-250°C). The keratin composite scaffold exhibited tensile strength (96 kPa), compression strength (8.5 kPa) and water uptake capacity (>1700%) comparable to that of a collagen scaffold, which was used as control. The morphology of the keratin composite scaffold observed using a Scanning Electron Microscope (SEM) exhibited good porosity and interconnectivity of pores. MTT assay using NIH 3T3 fibroblast cells demonstrated that the cell viability of the keratin composite scaffold was good. These observations suggest that the keratin-chitosan-gelatin composite scaffold is a promising alternative biomaterial for tissue engineering applications.

In this paper, we report the synthesis of gold nanoparticles (AuNPs) using the aqueous neem (Azadirachta indica) fruit extract as a reducing agent and capped by two different capping agents (monomeric surfactant: hexadecyltrimethylammonium chloride (CTAC) and dimeric counterion coupled gemini surfactant (COCOGS): 1, 6-Bis (N,N-hexadecyl dimethylammonium) adipate (16-6-16)). The synthesized AuNPs have been characterized by different modern techniques such as, UV–Visible spectroscopy, HR-TEM, DLS, XRD, FTIR, and XPS analyses, etc. The FTIR measurements were used to evaluate the adsorption of CTAC and COCOGS on the AuNPs surface. A significant shift in the stretching vibrations of CTAC and COCOGS head functional groups suggested their orientation towards the AuNPs surface and was further supported by the high-resolution XPS spectra of CTAC and COCOGS on the AuNPs surface. The main objective of the work is to investigate how to achieve the stability and activity of COCOGS-AuNPs for developing novel anticancer agents against triple negative breast cancer cells (TNBC). Hence, we have synthesized CTAC-AuNPs and COCOGS-AuNPs and evaluated theirs in vitro cytotoxicity against TNBC cell line (MDA-MB-231) as well as in normal NIH3T3 cells. The synthesized COCOGS-AuNPs displayed the excellent cytotoxicity against selected TNBC cell lines without affecting normal cells. In addition to the analysis of cellular apoptosis with mitochondrial membrane potential ( Δ ψ m ) loss demonstrated an increased apoptotic cell death after 24 h at their dose-dependent concentrations. Thus we conclude that the synthesized AuNPs may directly inhibit the TNBC cell growth and induced the tumor cell autophagy which consequently increasing cellular apoptosis.

Leather processing involves various unit processes in which deliming is an essential unit process carried out conventionally using ammonium salts. This results in the generation of a huge amount of ammoniacal nitrogen and a considerable amount of total dissolved solids in tannery wastewater. In the current work, an effort has been made to design a deliming process using dry ice (solid carbon dioxide). It was observed that 2% (w/w) dry ice is adequate for the complete deliming of limed pelts of goat skins in 45 min; whereas the conventional process using 2% ammonium chloride requires 60 min. Morphological analysis using scanning electron microscopy shows no surface deposition or grain damage on delimed pelts processed using dry ice. Experimental leathers exhibit organoleptic and mechanical strength properties comparable to that of control leathers. The alternative method developed using dry ice reduces the generation of ammoniacal nitrogen, total dissolved solids, total Kjeldahl nitrogen and chloride from the deliming process by 98, 88, 95 and 94% respectively compared to the control process. This method also helps in reduction of chemical oxygen demand and biochemical oxygen demand in wastewater. Moreover, the methodology of using dry ice for deliming is very simple for practical applications. The option of using dry ice for deliming would be effective for cleaner leather manufacture.

Missense mutations, which replace one Gly with a larger residue in the repeating sequence of the type I collagen triple helix, lead to the hereditary bone disorder osteogenesis imperfecta (OI). Previous studies suggest that these mutations may interfere with triple-helix folding. NMR was used to investigate triple-helix formation in a series of model peptides where the residue replacing Gly, as well as the local sequence environment, was varied. NMR measurement of translational diffusion coefficients allowed the identification of partially folded species. When Gly was replaced by Ala, the Ala residue was incorporated into a fully folded triple helix, whereas replacement of Gly by Ser or Arg resulted in the presence of some partially folded species, suggesting a folding barrier. Increasing the triple-helix stability of the sequence N-terminal to a Gly-to-Ser replacement allowed complete triple-helix folding, whereas with the substitution of Arg, with its large side chain, the peptide achieved full folding only after flexible residues were introduced N-terminal to the mutation site. These studies shed light on the factors important for accommodation of Gly mutations within the triple helix and may relate to the varying severity of OI.

Concern about pollution related problems in the global scenario are persuading all the processing industries to adopt cleaner manufacturing practices. Thus, the leather industry is also under pressure to look for effective alternative tanning materials for chromium. Natural products like vegetable tannins are regaining importance. However, there are limitations in the use of vegetable tanning materials because of its high organic load in the effluent, which are difficult to degrade leading to high chemical oxygen demand (COD). Moreover, conventional vegetable tanning process requires partial pickling that involves the use of sodium chloride, to suppress osmotic swelling. This results in very high amount of total dissolved solid (TDS) content in wastewaters. In this investigation, an attempt has been made to design an eco-friendly vegetable tanning process combining pickle-free tanning and application of proteolytic enzymes to improve the exhaustion of vegetable tannins. Such an approach has resulted in more than 95% tannin exhaustion in the case of the experimental process, an increase of 10% compared with the conventional vegetable tanning process. The tanned leathers showed slight improvement in hydrothermal stability. Physical and tactile evaluation of experimental leathers has been better than conventionally tanned leathers. Surface colour values illustrated negligible variation in colour and shade between control and experimental leathers. The resultant leather showed opened up, split compact fibre structure that has been well coated, indicating that the enzyme assisted tanning process did not bring about any major change or destruction on the fibre structure of the leathers. The optimized system has been field tested in a commercial tannery. The results showed that the enzyme assisted tanning process is efficient in terms of improved quality of leather and also led to reduction in total solids (TS), chlorides and COD loads. The enzyme assisted tanning system presented appears to be a viable option for combating pollution arising from the conventional vegetable tanning system.

Collagenase enzymes are nontoxic and eco-friendly biocatalysts. Dyeing is an important process in the leather industry, which employs many synthetic colorants. Many good dyes suffer from incomplete exhaustion and this causes concern, as the biotreatability of the unexhausted dyes in effluent is normally difficult. Hence in the present study, an attempt has been made to improve the exhaustion of dyes by using bacterial collagenase enzymes as biocatalysts. The effect of process parameters of enzymatic treatment such as pH, temperature and duration on the exhaustion of the dye, levelness of dyeing, shade brightness, dye penetration and color intensity have been studied and the conditions are optimized. Uptake of dye as high as 99% has been observed by the treatment of collagenase. The change in shades due to enzymatic treatment has been quantified by reflectance measurements and compared with the visual assessment data. Scanning electron microscopy analysis showed a well opened-up fibre matrix for the collagenase treated leather. The strength properties are not significantly altered and the bulk properties like softness have been found to be improved by the use of collagenase.

Inhibitory effect of green tea polyphenols viz., catechin and epigallocatechin gallate (EGCG) on the action of collagenase against collagen has been probed in this study. Catechin and EGCG treated collagen exhibited 56 and 95% resistance, respectively, against collagenolytic hydrolysis by collagenase. Whereas direct interaction of catechin and EGCG with collagenase exhibited 70 and 88% inhibition, respectively, to collagenolytic activity of collagenase against collagen and the inhibition was found to be concentration dependent. The kinetics of inhibition of collagenase by catechin and EGCG has been deduced from the extent of hydrolysis of (2-furanacryloyl-L-leucyl-glycyl-L-prolyl-L-alanine), FALGPA. Both catechin and EGCG exhibited competitive mode of inhibition against collagenase. The change in the secondary structure of collagenase on treatment with catechin and EGCG has been monitored using circular dichroism spectropolarimeter. CD spectral studies showed significant changes in the secondary structure of collagenase on treatment with higher concentration of catechin and EGCG. Higher inhibition of EGCG compared to catechin has been attributed to the ability of EGCG to exhibit better hydrogen bonding and hydrophobic interaction with collagenase.

Collagen, a unique connective tissue protein finds extensive application as biocompatible biomaterial in wound healing, as drug carriers, cosmetics, etc. A work has been undertaken to study the stabilization of type I collagen using the plant polyphenol catechin. Catechin treated collagen fibres showed a shrinkage temperature around 70 degrees C implying that catechin is able to impart thermal stability to collagen. Catechin treated collagen fibres has been found to be stable even after treatment with high concentration of the secondary structural destabilizer, urea. Circular dichroism studies revealed that there is no major alteration in the structure of collagen on treatment with catechin. The study has demonstrated the involvement of hydrogen bonding and hydrophobic interactions as the major forces involved in the stabilization of collagen by the plant polyphenol, catechin.

In the present investigation, an attempt has been made to study the interaction of dipeptides with gallic acid, using Becke3 parameter Lee Yang Parr (B3LYP) method employing 3-21G*, 6-31G* and 6-31+G* basis sets. The interaction energies of the dipeptide–gallic acid complexes are in the range of −5 to −18 kcal/mol depending on the mode of intermolecular complexation. Calculated molecular electrostatic potential (MESP) for the various intermolecular complexes revealed the electrostatic nature of the interaction. Qualitative estimations based on chemical hardness and chemical potential demonstrated fractional electron transfer from dipeptide to gallic acid.

Molecular modelling approaches have been used to understand the interaction of collagen-like peptides with gallic acid, which mimic vegetable tanning processes involved in protein stabilization. Several interaction sites have been identified and the binding energies of the complexes have been calculated. The calculated binding energies for various geometries are in the range 6–13 kcal/mol. It is found that some complexes exhibit hydrogen bonding, and electrostatic interaction plays a dominant role in the stabilization of the peptide by gallic acid. The π-OH type of interaction is also observed in the peptide stabilization. Molecular dynamics (MD) simulation for 600 ps revealed the possibility of hydrogen bonding between the collagen-like peptide and gallic acid.