Study on free and entangled binary metal nanocatalysts for removal of 2,4,6-trichlorophenol in aqueous phase: a comparative study

The present study highlights the comparative catalytic removal of 2,4,6-trichlorophenol (TCP) in the aqueous phase by binary nanoparticles in free as well as entangled forms. In brief, binary nanoparticles comprising Fe-Ni are prepared, characterized, and subsequently entangled in reduced graphene oxide (rGO) for better performances. Optimization studies on the mass of free and rGO-entangled binary nanoparticles with respect to TCP concentration and other environmental factors were carried out. Results suggested that free binary nanoparticles at 40 mg ml^-1took 300 min to dechlorinate 600 ppm of TCP, whereas rGO-entangled Fe-Ni particles at the same mass took only 190 min to dechlorinate when the pH was maintained at near neutral. In addition, experiments on the reuse of the catalyst with respect to removal efficiency were carried out, and the results implied that, compared to free form, rGO-entangled nanoparticles exemplify more than 98% of removal efficacy even after 5 times of exposure to 600 ppm TCP concentration. The reduction in percentage removal was observed after the sixth exposure. A sequential dechlorination pattern was assessed and confirmed using high-performance liquid chromatography. Further, the phenol-enriched aqueous phase is exposed toBacillus licheniformisSL10, which degrades the phenol effectively within 24 h. In conclusion, the prepared binary nanoparticles, both in free as well as in rGO-entangled forms, effectively dechlorinate 2,4,6-TCP contaminations in the aqueous phase, but with differences in removal duration. Entanglement also makes it easier to reuse the catalyst. Furthermore, microbial phenol degradation allows the aqueous phase to be free of 2, 4, and 6-TCP contamination and allows for the reuse of treated water.

Preparation, characterization and cell response studies on bioconjugated 3D protein hydrogels with wide-range stiffness: An approach on cell therapy and cell storage

The present study emphasizes the preparation and characterization of bioconjugated keratin-gelatin (KG) 3D hydrogels with wide-range stiffness to study cell response for cell therapy and cell storage applications. In brief, human hair keratin and bovine gelatin at different ratios bioconjugated using EDC/NHS provide five hydrogels (KG-1, KG-2.5, KG -5, KG-7.5 and KG-9) with modulus ranging from 0.9 ± 0.1 to 10.9 ± 0.4 kPa. Based on swelling, stability, porosity, and degradation parameters KG-5 and KG-9 are employed to assess the human dermal fibroblast (HDF) cell response, cell delivery and cell storage respectively. Characterization studies revealed the concentration of keratin determines the modulus/stiffness of the hydrogels, whereas gelatin concentration plays a vital role in porosity, swelling percentage, and degradation properties. HDF cell behaviour in the chosen hydrogels assessed based on cell adhesion, cell proliferation, PCNA expression, MTT assay, and DNA quantification. We observed the best cell behaviour in KG-5 hydrogels than in the KG-9 matrix. In cell storage and cell delivery studies, the KG-9 matrix displayed promising results. Thus, the present study concludes bioconjugated keratin-gelatin 3D hydrogel with modulus below 3.0 kPa facilitates the proliferation of HDFs, whereas matrix above 10 kPa modulus supports cell storage and cell recovery. The observations of the present study suggest the suitability of bioconjugated fibrous protein 3D hydrogel for cell therapy and cell storage.

Elucidation of 2, 4-Dichlorophenol degradation by Bacillus licheniformis strain SL10

2,4-Dichlorophenol (2,4-DCP) is a priority pollutant according to US Environmental Protection Agency. Its use in various chemical industries and its presence in the effluent necessitate effective removal studies. The present study focuses on degradation of 2,4-DCP by phenol adapted bacteria Bacillus licheniformis strain SL10 (MTCC 25059) at a relatively faster rate. The organism exhibited tolerance to 150 ppm of 2,4-DCP and showed a linear relationship between the growth and substrate concentration (µ_max 0.022/h) and the inhibitory concentration was 55.74 mg/L. The degradation efficiency of the organism was 74% under optimum conditions but increased to 97% when the growth medium containing nil sodium chloride. The degradation of 2,4-DCP was effected by the action of extracellular cocktail enzyme containing Catechol 2, 3 dioxygenase (C23DO), phenol hydroxylase and Catechol, 1,2 dioxygenase (C12DO). In vitro enzymatic degradation studies exhibit 98% degradation of 50 ppm of 2,4-DCP within 2 h. Analyses of degradation products infer that the chosen organism followed a meta-cleavage pathway while degrading 2,4-DCP. In conclusion, the bacteria Bacillus licheniformis strain SL10 finds potential application in the remediation of 2,4-DCP.

In vitro antibacterial activity of plumbagin isolated from Plumbago zeylanica L. against methicillin-resistant Staphylococcus aureus

Plumbagin (5-hydroxy-2-methyl-1,4-napthoquinone) is a bicyclic naphthoquinone, found in three major plant families viz. Plumbaginaceae, Ebenceae and Droseraceae. The phytochemical is reported to exhibit various pharmacological properties. In this study, plumbagin isolated from Plumbago zeylanica L. was investigated for its in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA). Against 100 MRSA isolates that included multi-drug-resistant phenotypes, plumbagin showed consistent activity with a narrow minimum inhibitory concentration (MIC) range of 4-8 μg ml^-1 . The time-kill study revealed 99% kill of a reference MRSA strain, 8 h after exposure to plumbagin. In the combination MIC study using the reference MRSA strain, plumbagin showed synergistic effect with ciprofloxacin and piperacillin while additive or indifference effect with other commonly used antibiotics. The transmission electron micrograph of the reference MRSA strain treated with plumbagin confirmed cell wall and cytoplasmic changes. Our results demonstrated potent anti-MRSA activity of plumbagin which was not impacted by multi-drug resistance. This is a first ever study that evaluated in vitro anti-MRSA activity of plumbagin employing large number of MRSA isolates. The findings of this study support the need for the further investigation on this phytochemical agent for therapeutic application. SIGNIFICANCE AND IMPACT OF THE STUDY: This study revealed phytochemical plumbagin's potent and consistent in vitro antibacterial activity against clinically problematic methicillin-resistant Staphylococcus aureus (MRSA) including multi-drug-resistant (MDR) phenotypes. The study results support further research to assess the clinical scope of plumbagin.

Dysregulation of miR-146a by periodontal pathogens: A risk for acute coronary syndrome

BACKGROUND

Periodontitis is a polymicrobial, chronic inflammatory disease leading to loss of tooth-supporting structures. The bacteremia, endotoxemia, and systemic low-grade inflammation associate periodontitis with systemic illnesses such as diabetes mellitus and coronary artery disease. Periodontal pathogens have been detected from atheromatous plaque by amplification of the genetic material by using specific oligonucleotide primers in polymerase chain reaction. Though the association between periodontitis and cardiovascular diseases has been ascertained by systematic reviews and meta-analyses, its pathophysiology is not lucid. MicroRNAs are currently implicated in the regulation of many cellular processes including inflammation and may play a vital role in our understanding of this disease association. In this case-control study, we explored the role of the inflammatory microRNA, miR-146a, in acute coronary syndrome (ACS) subjects with and without chronic periodontitis (CP) and its regulation of the innate immune host response to periodontal pathogens.

METHODS

Three groups each comprising 66 patients each, namely group 1 (ACS patients without CP), group 2 (ACS patients with CP) and group 3 (CP only) formed the study population. Subgingival plaque samples and serum samples were subjected to quantitative Polymerase Chain Reaction (qPCR) for detection of Porphyromonas gingivalis, a keystone pathogen and to assess the levels of circulating miR-146a and associated proinflammatory cytokines.

RESULTS

miR-146a associated significantly in group 2 subjects with an odds ratio 1.434, 95% confidence interval 1.013-2.030, P < 0.042, and a predictive percentage of 83.3% and group 1 with a predictive percentage of 76.0.% The associated cytokines interleukin-6 (IL-6), tumor necrosis factor-α, and IL-1β also showed an upregulation with statistical significance (P < 0.05).

CONCLUSION

microRNA-146a is a key molecule associating periodontitis with acute coronary syndrome.

Marine fungal DHICA as a UVB protectant: Assessment under in vitro and in vivo conditions

The present study explores UVB protective role of a melanin precursor namely DHICA (5,6- Dihydroxyindole-2-carboxylic acid) expressed by the marine imperfect fungus Aspergillus nidulans. In brief, A. nidulans grown in a modified growth medium for the period of 5 days at 25 °C under shaking conditions and the extracellular medium free from fungal biomass used for the extraction of DHICA. The extracted DHICA further exposed to partial purification and subjected to UVB protection studies using HaCaT cells and Balb/c mice independently. DHICA obtained in the present study found soluble in water. Experiments on HaCaT cell compatibility revealed nil cell death up to 500 μM concentration of DHICA. UVB protection studies under in vitro conditions emphasizes DHICA significantly protect HaCaT cells from UVB exposure by quenching the generated ROS, reducing cell apoptosis, maintain the cellular integrity and sequentially down regulating the LPO (Lipid peroxidation) and up-regulating the antioxidant enzyme (SOD (Superoxide Dismutase), Catalase, GPx (Glutathione peroxidase)) respectively. Further, experiments on cell cycle arrest analysis, gelatin zymography, and western blot analysis on COX-2 and TNF-alpha, IHC (Immunohistochemistry) on apoptotic markers (Bax, Bcl2) substantiate the protective role of DHICA. Furthermore, in vivo studies on BALB/c mice carried out and compared with the sunscreen cream with sun protective factor (SPF) of 20. Analysis of skin sections of experimental samples revealed that an appreciable reduction in the epidermal thickness of the skin samples of mice pre-exposed to DHICA followed by UVB exposure compared to UVB exposure alone. RT-PCR results on various inflammatory apoptotic markers also suggested that DHICA has UVB protective potential. The observations made in the present study explore the possible application of DHICA alone as a sun-protective agent for skin care.

Surface active gold nanoparticles biosynthesis by new approach for bionanocatalytic activity

In the present day, nanotechnology is one of the most promising leading scientific and potentials areas in modern key technology development toward to the humankind. The synthesis of noble metal nanoparticles (NPs) is an expanding research area due to the possible applications for the development of bio-medical applications. Eco-friendly approach for the biosynthesis of gold nanoparticles (AuNPs) using the aqueous extract from Ruellia tuberosa and Phyllanthus acidus (leaf and twig) for the first time. Surface active AuNPs were characterized by UV-Vis spectroscopy, FTIR (Fourier transform infrared) spectroscopy, DSC (differential scanning colorimetry), DLS (dynamic light scattering) and environmental SEM (scanning electron microscope) analysis at room temperature (RT). Enhanced surface plasmon resonance (SPR) absorbance UV visible optical spectra were detected in the range of 552, 548, 558 and 536 nm. SEM and DLS (transmission mode) analysis confirmed the morphology of the nanoparticles to be spherical with the average size in the range of 88.37, 94.31, 82.23 and 81.36 nm. Further they have enhanced the enzyme activity on α-amylase, cellulase, and xylanase. The results suggest that the phyto-fabricated AuNPs from R. tuberosa and P. acidus is simple, less expensive, eco-friendly, green synthesis and also can be exploited for the potential future industrial and bio-medical applications.

Preparation, characterization and reusability efficacy of amine-functionalized graphene oxide-polyphenol oxidase complex for removal of phenol from aqueous phase

The present study explores the preparation, characterization and reusability efficacy of an amine-functionalized graphene oxide and polyphenol oxidase complex for the removal of phenol from aqueous phase. In brief, graphene oxide (GO) is synthesized according to modified Hummer's method using graphite powder and functionalized with amine using the Bucherer's method (GO-NH₂). Partially purified polyphenol oxidase (PP-PPO) enzyme extracted from Solanum tuberosum is used for the preparation of the complex. The resultant GO-NH₂-(PP-PPO) complex is used for the phenol degradation studies. The samples of GO, GO-NH₂, and GO-NH₂-(PP-PPO) complex are characterized using various instrumental techniques. Spectral UV data and FTIR and XRD diffraction patterns confirm the amine functionalization on GO. Raman spectrum, SEM micrograph and thermogravimetric (TG) analyses authenticate the linked enzyme on GO-NH₂. GO-NH₂-(PP-PPO) complex demonstrates >90% enzyme stability at all the studied temperatures (4 °C, −20 °C, RT and 37 °C). Phenol degradation studies show >99% removal of 1000 ppm of phenol within 5 hours from the start of the experiment at the optimized pH of 5.0 and temperature of 30 °C, as inferred from HPLC analysis. Catechol and hydroquinone compounds are identified as intermediates during the removal of phenol. Furthermore, studies on the reuse of GO-NH₂-(PP-PPO) complex suggest that the complex can be used effectively for the removal of phenol up to maximum 7 cycles. In conclusion, the observations made in the present study show that the complex containing amine-functionalized graphene oxide and phenoloxidase is effective for the removal of phenol with appreciable reusability.

Schematic representation of the present study describing amine functionalization followed by enzyme immobilization and degradation of phenol.

Pre-treatment of extracellular water soluble pigmented secondary metabolites of marine imperfect fungus protects HDF cells from UVB induced oxidative stress

The melanin precursor of fungal origin was found to be an excellent UVB inhibiting agent as experimented in HDF cells and in small animals.

Efficacy of free and encapsulated Bacillus lichenformis strain SL10 on degradation of phenol: A comparative study of degradation kinetics

The present study exemplifies phenol degradation efficacy of the free and encapsulated bacterial isolate, explored the degradation kinetics and storage stability in detail. In brief, isolation, identification and phenol degradation potential of the bacterial made from wastewater treated sludge samples. The organism identified as B. licheniformis demonstrates phenol degradation at a concentration more than 1500 ppm. Optimization of environmental parameters reduces the time taken for degradation considerably. The organism has further been encapsulated using whey protein and the efficacy of encapsulated species suggested that encapsulation protects the cells from high concentration of phenol and at the same time expedite the degradation of the chosen pollutant at appreciable level. The encapsulated species effectively degrade 3000 ppm concentration of phenol within 96 h of incubation. Both pH and temperature stability observed in the encapsulated species suggests the effectiveness of the encapsulation. The encapsulated cells displayed storage stability for a four week period at 4 C and reusability up to three exposures. Degradation effected through intracellular catechol 2,3 dioxygenase. In conclusion, encapsulation of B. licheniformis (i) protects the cells from direct exposure to toxic pollutants; (ii) facilitates the field scale application and (iii) eliminate the practical difficulties in handling wet biomass in field application and assures the best possible way of remediating the phenol contaminated soil.

Redox responsive albumin autogenic nanoparticles for the delivery of cancer drugs

The present study explores preparation and characterization of redox sensitive albumin autogenic nanoparticles (ANPs) for drug delivery applications. Human serum albumin nanoparticles are prepared by desolvation method. The particles are stabilized through self-crosslinking and no external stabilizers are involved in the preparation. ANPs are then subjected to Camptothecin (CPT) drug loading. Experiments on in vitro and in vivo release profile, cytotoxic and cytocompatability, hemocompatability, blood clearance, tracking and bio imaging are studied in detail. The redox sensitive and drug release properties of ANPs studied in the presence of glutathione. Results on the physical, chemical and instrumental characterization warrant the property of the nanoparticles. ANPs obtained in the present study is biocompatible, biodegradable, effectively entangle the chosen drug, release the drug in the controlled manner, sensitive to reducing environment, nil toxicity and appreciable uptake by cells. In the current scenario on the requirement of a drug carrier with redox sensitive property to encounter cancer cells, the results of the present study on albumin nanoparticles with redox sensitivity is smart and pave the way in the cancer therapeutics.

Induced oxidative stress management in wounds through phenolic acids engineered fibrous protein: An in vitro assessment using polymorphonuclear (PMN) cells

The present study explores the preparation, characterization and the role of phenolic acid tethered fibrous protein in the management of induced oxidative stress studied under in vitro conditions. In brief, the biomaterial is prepared by engineering the fibrous protein with dihydroxy and trihydroxy phenolic acid moieties and subjected to characterization to ensure the tethering. The resultant biomaterial studied for its efficacy as a free radical scavenger using polymorphonuclear (PMN) cells with induced oxidative stress and also as an agent for cell migration using fibroblasts cells. Results revealed that induced oxidative stress in PMN cells after exposure to UVB radiation managed well with the prepared biomaterial by reducing the levels of superoxide anion, oxygen and hydroxyl radicals. Further, the protein and the phenolic acid interaction supports the cell migration as evidenced from the scratch assay. In conclusion, though phenolic acids are well known for their antimicrobial and antioxidant potential, indenting these acids directly to the wounds is not sensible, but tethering to protein explored the scavenging activity as expected. The present study infers that phenolic acid engineered protein has a significant role in managing the imbalance in the redox state prevailing in wounds and supports the healing at appreciable level.

In vitro profiling of antimethicillin-resistant Staphylococcus aureus activity of thymoquinone against selected type and clinical strains

This study explores antimethicillin-resistant Staphylococcus aureus (MRSA) activity of a bioactive phytochemical constituent, thymoquinone obtained from the medicinal herb, Nigella sativa Linn. Based on initial assessment on crude extract of seeds of Nigella sativa Linn, the pure active constituent was employed in the study. A total of 99 MRSA strains which comprised of 40 types and 59 clinical strains were selected for the study. Minimum inhibitory concentration (MIC), bactericidal activity, postantibiotic effect (PAE) and propensity to select resistant mutants were determined using standard protocols. Results revealed that thymoquinone exhibited MIC in the range of 8-16 μg ml(-1) and MIC90 of 16 μg ml(-1) against MRSA strains. It was bactericidal to MRSA by demonstrating >3 log kill. It showed a longer PAE of 3·2 ± 0·2 h. Upon exposure to high-density inoculum of MRSA, it did not select resistant mutants. Transmission electron microscopy of thymoquinone-treated MRSA showed no lysis but damage to cell wall and cell membrane which corroborated well with the salt tolerance and bacteriolysis assays. In conclusion, MIC90 , bactericidal property, longer PAE, absence of resistant mutant selection and damages in cell membrane and cell wall imply a promising anti-MRSA activity of thymoquinone.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first detailed report on anti-MRSA activity of thymoquinone. The assessment was made with both type and clinical strains. Thymoquinone may be a potential lead compound which can be further optimized to discover novel anti-MRSA agents.

Synthesis and characterization of chitosan-TiO2:Cu nanocomposite and their enhanced antimicrobial activity with visible light

In the present investigation, novel strategy for the preparation of hybrid nanocomposite containing organic polymer (Chitosan) and inorganic (TiO₂:Cu) nanoparticles (NPs) has been developed and demonstrated its biomedical application. The sol-gel and ultra-sonication method assisted for the preparation of uniformly distributed Chitosan-TiO₂:Cu (CS-CT) nanocomposite. The structural properties of prepared CS-CT nanocomposite were studied by XRD and FTIR techniques. The XPS was used to estimate elemental composition of the nanocomposite. Thermal properties were studied using TGA. TEM and SEM analysis showed the non-spherical nature of NPs with the average mean diameter 16nm. The optical properties were analyzed with UV-vis diffuse reflectance spectroscopy to confirm optical absorption in the visible region of light. Where CS-CT showed 200% enhanced light mediated photocatalytic antimicrobial activity against microorganism (Escherichia coli and Staphylococcus aureus) as compared with control. The antimicrobial activity of CS-CT nanocomposite in presence of light is found to be enhanced than that of its components, this is due to synergistic effect of organic and inorganic material complimenting each other's activity. The OH radicals release studied by PL spectroscopy on the surface of nanocomposite was used to examine antibacterial activity. Cytotoxicity assessment of CS-CT on human fibroblast cells was performed by MTT assay.

Synthesis of a carboxymethylated guar gum grafted polyethyleneimine copolymer as an efficient gene delivery vehicle

In the present study, a carboxymethylated guar gum-grafted-polyethyleneimine copolymer (CMGG-g-PEI) was synthesized and characterized by FT-IR, ¹H NMR, XRD and zeta potential analyses.

pH and redox sensitive albumin hydrogel: A self-derived biomaterial

Serum albumin can be transformed to a stimuli (pH and redox) responsive hydrogel using the reduction process followed by oxidative refolding. The preparation of albumin hydrogel involves a range of concentrations (75, 150, 300, 450, 600 and 750 μM) and pH (2.0-10.0) values and the gelation begins at a concentration of 150 μM and 4.5-8.0 pH value. The hydrogel shows maximum swelling at alkali pH (pH > 9.0). The increase in albumin concentration increases hydrogel stability, rheological property, compressive strength, proteolytic resistance and rate of in vivo biodegradation. Based on the observed physical and biological properties of albumin hydrogel, 450 μM was determined to be an optimum concentration for further experiments. In addition, the hemo- and cytocompatibility analyses revealed the biocompatibility nature of albumin hydrogel. The experiments on in vitro drug (Tetracycline) delivery were carried out under non reducing and reducing conditions that resulted in the sustained and fast release of the drug, respectively. The methodology used in the preparation of albumin hydrogel may lead to the development of autogenic tissue constructs. In addition, the methodology can have various applications in tissue engineering and drug delivery.

Curcumin loaded nano graphene oxide reinforced fish scale collagen – a 3D scaffold biomaterial for wound healing applications

We prepare a highly stabilized nano graphene oxide functionalized with type I collagen to make a 3D scaffold as a novel platform for better tissue engineering research..

Characterization and evaluation of curcumin loaded guar gum/polyhydroxyalkanoates blend films for wound healing applications

Schematic representation of the blockage of UV rays and controlled release of curcumin on a wound.

In vitro and in vivo assessments of a 3-(3,4-dihydroxyphenyl)-2-propenoic acid bioconjugated gelatin-based injectable hydrogel for biomedical applications

Imparting functional properties on a biomaterial for high end applications is always a challenging task. In the present study, an attempt was made to construct an injectable hydrogel through bioconjugation of dihydroxy phenolic acids to a gelatin backbone. Bioconjugating caffeic acid with gelatin followed by oxidation with mild oxidation agents provided a hydrogel with all the requisite properties (biocompatibility, controlled biodegradability, and antioxidant, antimicrobial and wound healing ability). Bioconjugation was performed using EDC/NHS and the resultant gel named as caffeic acid bioconjugated gel (CBG gel). The physicochemical, rheological, swelling, in vitro (biocompatibility, biodegradability, antimicrobial properties, antioxidant properties and drug release properties) and in vivo (biocompatibility, biodegradability and wound healing properties) studies on the CBG gel were carried out using standard protocols. The bioconjugation was confirmed by ¹H NMR and UV-Vis analysis. Rheological analysis of the CBG gel revealed that the storage modulus was greater than the loss modulus at all the frequencies and suggested the elastic nature of the gel. About 50% weight gain within 12 hours during swelling studies and 50% weight loss within 12 hours during evaporation suggested the suitability of the CBG gel as a drug carrier. The drug release studies implied that there was an initial burst and later the release was sustained. The CBG gel promotes cell migration and demonstrates radical scavenging behavior. When subcutaneously injected into the animal, as in situ CBG gel, the gel was highly biocompatible and did not cause any necrosis. The crosstalk with adjacent tissue cells was smooth and the gel completely degraded within 24 days. The wound healing efficacy on full-thickness wounds suggested that the CBG gel accelerated healing and imparted high strength on the healed skin at an appreciable level. With all these additional functional properties, the CBG gel could be useful for biomedical applications.

Enhanced production of Aspergillus tamarii lipase for recovery of fat from tannery fleshings

The influence of various oil cakes has been investigated for high level production of lipase using Aspergillus tamarii MTCC 5152. By solid state fermentation in wheat bran containing 2.5% w/w gingili oil cake at 70% v/w moisture content the fungus produced a maximal yield of lipase (758 ± 3.61 u/g) after 5 days of incubation using 2% v/w inoculum containing 10⁶ spores/mL. Wheat bran and gingili oil cake with supplementation of gingili oil (1.0% w/w), glucose (0.5% w/w) and peptone (0.5% w/w) gives an increased enzyme production of 793 ± 6.56 u/g. The enzyme shows maximum activity at pH 7.0, temperature 50 °C and was stable between the pH 5.0–8.0 and temperature up to 60 °C. Crude lipase (3%) applied to tannery fleshing shows 92% fat solubility. The results demonstrate that fat obtained from tannery fleshing, a by-product of the leather industry has a high potential for biodiesel production and the proteinaceous residue obtained can be used as animal feed.

Engineering of chitosan and collagen macromolecules using sebacic acid for clinical applications

Transformation of natural polymers to three-dimensional (3D) scaffolds for biomedical applications faces a number of challenges, viz., solubility, stability (mechanical and thermal), strength, biocompatibility, and biodegradability. Hence, intensive research on suitable agents to provide the requisite properties has been initiated at the global level. In the present study, an attempt was made to engineer chitosan and collagen macromolecules using sebacic acid, and further evaluation of the mechanical stability and biocompatible property of the engineered scaffold material was done. A 3D scaffold material was prepared using chitosan at 1.0% (w/v) and sebacic acid at 0.2% (w/v); similarly, collagen at 0.5% (w/v) and sebacic acid at 0.2% (w/v) were prepared individually by freeze-drying technique. Analysis revealed that the engineered scaffolds displayed an appreciable mechanical strength and, in addition, were found to be biocompatible to NIH 3T3 fibroblast cells. Studies on the chemistry behind the interaction and the characteristics of the cross-linked scaffold materials suggested that non-covalent interactions play a major role in deciding the property of the said polymer materials. The prepared scaffold was suitable for tissue engineering application as a wound dressing material.

Preparation and characterization of malonic acid cross-linked chitosan and collagen 3D scaffolds: an approach on non-covalent interactions

The present study emphasizes the influence of non-covalent interactions on the mechanical and thermal properties of the scaffolds of chitosan/collagen origin. Malonic acid (MA), a bifuncitonal diacid was chosen to offer non-covalent cross-linking. Three dimensional scaffolds was prepared using chitosan at 1.0% (w/v) and MA at 0.2% (w/v), similarly collagen 0.5% (w/v) and MA 0.2% (w/v) and characterized. Results on FT-IR, TGA, DSC, SEM and mechanical properties (tensile strength, stiffness, Young's modulus, etc.) assessment demonstrated the existence of non-covalent interaction between MA and chitosan/collagen, which offered flexibility and high strength to the scaffolds suitable for tissue engineering research. Studies using NIH 3T3 fibroblast cells suggested biocompatibility nature of the scaffolds. Docking simulation study further supports the intermolecular hydrogen bonding interactions between MA and chitosan/collagen.

Bioinformatics in crosslinking chemistry of collagen with selective cross linkers

Background

Identifying the molecular interactions using bioinformatics tools before venturing into wet lab studies saves the energy and time considerably. The present study summarizes, molecular interactions and binding energy calculations made for major structural protein, collagen of Type I and Type III with the chosen cross-linkers, namely, coenzyme Q₁₀, dopaquinone, embelin, embelin complex-1 & 2, idebenone, 5-O-methyl embelin, potassium embelate and vilangin.

Results

Molecular descriptive analyses suggest, dopaquinone, embelin, idebenone, 5-O-methyl embelin, and potassium embelate display nil violations. And results of docking analyses revealed, best affinity for Type I (- 4.74 kcal/mol) and type III (-4.94 kcal/mol) collagen was with dopaquinone.

Conclusions

Among the selected cross-linkers, dopaquinone, embelin, potassium embelate and 5-O-methyl embelin were the suitable cross-linkers for both Type I and Type III collagen and stabilizes the collagen at the expected level.

Bonding interactions and stability assessment of biopolymer material prepared using type III collagen of avian intestine and anionic polysaccharides

The present study demonstrate bonding interactions between anionic polysaccharides, alginic acid (AA) and type III collagen extracted from avian intestine used for the preparation of thermally stable and biodegradable biopolymer material. Further the study describes, optimum conditions (pH, temperature and NaCl concentration) required for the formation of fibrils in type III collagen, assessment on degree of cross-linking, nature of bonding patterns, biocompatibility and biodegradability of the cross-linked biomaterial. Results revealed, the resultant biopolymer material exhibit high thermal stability with 5-6 fold increase in tensile strength compared to the plain AA and collagen materials. The degree of cross-linking was calculated as 75%. No cytotoxicity was observed for the cross-linked biopolymer material when tested with skin fibroblast cells and the material was biodegradable when treated with enzyme collagenase. With reference to bonding pattern analysis we found, AA cross-linked with type III collagen via (i) formation of covalent amide linkage between -COOH group of AA and ε-NH₂ group of type-III collagen as well as (ii) intermolecular multiple hydrogen bonding between alginic acid -OH group with various amino acid functional group of type-III collagen. Comparisons were made with other cross-linking agents also. For better understanding of bonding pattern, bioinformatics analysis was carried out and discussed in detail. The results of the study emphasize, AA acts as a suitable natural cross-linker for the preparation of wound dressing biopolymer material using collagen. The tensile strength and the thermal stability further added value to the resultant biopolymer.

Preparation and characterization of a thermostable and biodegradable biopolymers using natural cross-linker

The present study describes preparation and characterization of a thermally stable and biodegradable biopolymer using collagen and a natural polymer, alginic acid (AA). Required concentration of alginic acid and collagen was optimized and the resulting biopolymer was characterized for, degree of cross-linking, mechanical strength, thermal stability, biocompatibility (toxicity) and biodegradability. Results reveal, the degree of cross-linking of alginic acid (at 1.5% concentration) with collagen was calculated as 75%, whereas it was 83% with standard cross-linking agent, glutaraldehyde (at 1.5% concentration). The AA cross-linked biopolymer was stable up to 245°C and Exhibits 5-6-fold increase in mechanical (tensile) strength compared to plain collagen (native) materials. However, glutaraldehyde cross-linked material exhibits comparatively less thermal stability and brittle in nature (low tensile strength). With regard to cell toxicity, no cytotoxicity was observed for AA cross-linked material when tested with mesenchymal cells and found degradable when treated with collagenase enzyme. The nature of bonding pattern and the reason for thermal stability of AA cross-linked collagen biopolymer was discussed in detail with the help of bioinformatics. A supplementary file on efficacy of AACC as a wound dressing material is demonstrated in detail with animal model studies.