Silver-containing polysaccharide-based tricomponent antibacterial fibres for wound care applications.

OBJECTIVE: Polysaccharide-based biomaterials are extensively used in wound care healing due to their unique liquid absorption, gelling properties and biocompatibility properties. They play an important role in controlling infections of highly exuding hard-to-heal wounds. The main objective of this study was to develop silver-containing polysaccharide-based tricomponent antibacterial fibres for use in these complex wounds. METHOD: The fibres were developed by coating silver-containing alginate and psyllium fibres with hydrolysed chitosan. Dope solution containing alginate, psyllium and silver carbonate was extruded into a coagulation bath containing calcium chloride and hydrolysed chitosan. The developed fibres were tested for liquid absorption, swelling and antibacterial properties against a control fibre (of alginate and psyllium). RESULTS: The developed fibres showed comparatively better liquid absorption, gelling and antibacterial properties than the control fibres. CONCLUSION: The study concluded that developed fibres could be a preferred choice for application on hard-to-heal wounds with high levels of exudate, to support infection control and faster healing.

Recent developments in bioreactor scale production of bacterial polyhydroxyalkanoates.

Polyhydroxyalkanoates (PHAs) are biological plastics that are sustainable alternative to synthetic ones. Numerous microorganisms have been identified as PHAs producers. They store PHAs as cellular inclusions to use as an energy source backup. They can be produced in shake flasks and in bioreactors under defined fermentation and physiological culture conditions using suitable nutrients. Their production at bioreactor scale depends on various factors such as carbon source, nutrients supply, temperature, dissolved oxygen level, pH, and production modes. Once produced, PHAs find diverse applications in multiple fields of science and technology particularly in the medical sector. The present review covers some recent developments in sustainable bioreactor scale production of PHAs and identifies some areas in which future research in this field might be focused.

Metal nanoparticle assisted polymerase chain reaction for strain typing of Salmonella Typhi.

Salmonella enterica serotype Typhi (S. Typhi) is the causative agent of typhoid fever and remains a major health threat in most of the developing countries. The prompt diagnosis of typhoid directly from the patient's blood requires high level of sensitivity and specificity. Some of us were the first to report PCR based diagnosis of typhoid. This approach has since then been reported by many scientists using different genomic targets. Since the number of bacteria circulating in the blood of a patient can be as low as 0.3 cfu ml(-1), there is always a room for improvement in diagnostic PCR. In the present study, the role of different types of nanoparticles was investigated to improve the existing PCR based methods for diagnosis and strain typing of S. Typhi (targeting Variable Number of Tandem Repeats [VNTR]) by using optimized PCR systems. Three different types of nanoparticles were used i.e., citrate stabilized gold nanoparticles, rhamnolipid stabilized gold and silver nanoparticles, and magnetic iron oxide nanoparticles. The non-specific amplification was significantly reduced in VNTR typing when gold and silver nanoparticles were used in an appropriate concentration. More importantly, the addition of nanoparticles decreased the non-specificity to a significant level in the case of multiplex PCR thus further validating the reliability of PCR for the diagnosis of typhoid.

Chitosan microencapsulation of various essential oils to enhance the functional properties of cotton fabric.

The present study dealt with emulsive fabrication of chitosan microcapsules encapsulating essential oils in the present of bio/surfactant. The size distribution, morphology and stability of microcapsules were examined by using advanced surface characterisation techniques. At cetyl trimethyl ammonium bromide (CTAB) concentration of 330 mg/L, the smallest average size of microcapsules was observed as12.8 µm; whereas with biosurfactant at 50 mg/L, the microcapsules of smallest average size of 7.5 µm were observed. The fabricated microcapsules were applied on a desized, bleached and mercerised cotton fabric by using pad-dry-cure method by using a modified dihydroxy ethylene urea as a cross-linking agent. The cross-linking was confirmed by using scanning electron microscopy and Fourier transform infrared spectroscopy techniques. The antibacterial activity of finished fabric was evaluated using the turbidity estimation method. The stiffness and wrinkle recovery properties of the treated fabric were also investigated by using the standard methods. In general, antibacterial activity of treated fabric increased with the increase in chitosan and essential oil concentrations, whereas stiffness increased with increase in concentration of chitosan but decreased with increase in essential oil concentration.

Corn straw lignin - A sustainable bioinspired finish for superhydrophobic and UV-protective cellulose fabric.

Hydrophobic textiles have been considered extensively for self-cleaning, phase-separating, and biomedical curing applications. We focused on preparing an eco-friendly lignin-based bio-finish to develop superhydrophobic cellulose fabric under mild conditions. The mass spectroscopic analysis expressed that the lignin comprised the major constituents of p-coumaryl alcohol, ferulic acid, coniferyl alcohol, and sinapyl alcohol. The surface morphological analysis indicated the formation of a regular lignin coating on the cellulose fabric. The bio-finished cellulose fabric prepared (at 2 %, w/v, lignin) expressed the maximum water contact angle (WCA) of 157.2° and remained in the hydrophobic range (119°) after ten standard washes. The treated fabric expressed the WCA values of 135.0 and 133.0° after exposure to pH 2 and 12 aqueous media, respectively. The infrared spectroscopic analysis indicated the functional chemistry of the precursors involved and possible alteration in their chemical interactions during processing. The lignin-treated cellulose was observed to be less crystalline as compared to the untreated one. Such fabric expressed acceptable comfort, sensorial properties, and thermal stability up to 333 °C. The treated fabrics could block up to 92.24 % UV-A and 98.62 % UV-B radiations. Consequently, the lignin-based finish sourced from wasted corn straw was found cost-effective and efficient for producing superhydrophobic cellulose fabric.

Synthesis of aminolyzed gelatin-mediated chitosan as pH-responsive drug-carrying porous scaffolds.

Bio-based drug delivery devices have gained enormous interest in the biomedical field due to their biocompatible attributes. Extensive research is being conducted on chitosan-based devices for drug delivery applications. Chitosan being hydrophobic under neutral conditions makes it difficult to interact with a polar drug of curcumin. We tended to make it polar through sol-gel synthesis and modification via PEGylation, alkaline hydrolysis, and aminolysis. Such alterations could make the chitosan-based scaffolds porous, hydrophilic, amino-functionalized, and pH-responsive. The ninhydrin assay confirmed that a successful aminolysis occurred, and the chemical interaction among the precursors was explained under infrared spectroscopy. The scanning morphology of the optimum aminolyzed membrane appeared to be porous with an average pore size of 320 ± 20 nm. The aminolyzed chitosan membrane was found thermally stable up to 310 °C, hydrophilic with a water contact angle of 23.4°, moderate flowablity, and porous (97 ± 5 %, w/w) against ethanol. The curcumin-loaded chitosan membrane expressed the UV-protection behavior of 99 %. The curcumin-loading and release phenomena were found pH-responsive. The curcumin release results were evaluated through specific kinetic models. This study could be the first report on the amphiphilic, porous, and swellable drug-loaded gelatin/chitosan membrane with pH-responsive loading and release of curcumin for potential drug delivery applications.

Development of aminolyzed polylactic acid-based porous films for pH-responsive sustained drug delivery devices.

Biomaterial-based drug-carrying systems have scored enormous focus in the biomedical sector. Poly(lactic acid) (PLA) is a versatile material in this context. A porous and hydrophilic PLA surface can do this job better. We aimed to synthesize pH-responsive PLA-based porous films for uptaking and releasing amikacin sulfate in the aqueous media. The native PLA lacks functional/polar sites for the said purpose. So, we tended to aminolyze it for tailored physicochemical and surface properties. The amino (-NH2) group density on the treated films was examined using the ninhydrin assay. Electron microscopic analyses indicated the retention of porous morphology after aminolysis. Surface wettability and FTIR results expressed that the resultant films became hydrophilic after aminolysis. The thermal analysis expressed reasonable thermal stability of the aminolyzed films. The prepared films expressed pH-responsive behaviour for loading and releasing amikacin sulfate drug at pH 5.5 and 7.4, respectively. The drug release data best-fitted the first-order kinetic model based on Akaike information and model selection criteria. The prepared PLA-based aminolyzed films qualified as potential candidates for pH-responsive drug delivery applications. This study could be the first report on pH-responsive amikacin sulfate uptake and release on the swellable aminolyzed PLA-based porous films for effective drug delivery application.

Citrate silver nanoparticles impregnated cellulose as a photocatalytic filter in the degradation of organic dye in the aqueous media.

Photocatalysis is a clean and efficient process pursued under light irradiation with a suitable photocatalyst to degrade a contaminant. We report citrate functionalization of silver nanoparticles (SNPs) for effective immobilization on cellulosic fabric. The porous cellulosic matrix could be explored as microfiltration membranes for the photocatalytic degradation of organic dyes in the aqueous media. Where valid, the citrate functionalized SNPs and the treated cellulose fabrics were considered for optical, structural, surface chemical, thermal, textile, flowability, photocatalytic, and antibacterial attributes. The SNPs expressed the bandgap energy of 2.56 and 2.43 eV and Urbach energy of 3.38 and 5.21 eV before and after functionalization with the citrate moieties, respectively. The liquid chromatographic and FTIR analyses indicated that the crystal violet (CV) organic dye has been successfully photodegraded to environmentally safer and nontoxic species on passing the contaminated water through the SNPs-treated cellulosic filter. The spectroscopic data also supported the said outcomes. The results demonstrated that the citrate-SNPs-treated cellulose could be efficiently employed as antibacterial photocatalytic membranes for degrading organic dyes in the aqueous media for multiple cycles.

Development of lactic acid based chain extender and soybean oil-derived polyurethanes for ecofriendly sustained drug delivery systems.

In the present study, a range of sustainable, biocompatible and biodegradable polyurethanes (PU-1 to PU-4) were synthesized using different combinations of biobased polyol (obtained through the epoxidation of soybean oil, followed by ring opening with ethanol) and polyethylene glycol (PEG) and isophorone diisocyanate. The sustainable chain extender used in this study was synthesized by the esterification of lactic acid with ethylene glycol (EG). The synthesized PU samples were characterized through scanning electron microscopy (SEM), Fourier transformed infrared (FTIR) and nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopy. Wetting ability and thermal degradation analysis (TGA) of the samples were also studied. Subsequently, these PUs were examined as potential drug delivery systems using Gabapentin as a model drug, which was loaded in the polymer matrix using the solvent evaporation method. The drug release studies were carried out in 0.06 N HCl as a release medium according to the method outlined in the United States Pharmacopeia. The maximum drug release was observed for sample PU-P1, which was found to be 53.0 % after 6 h. Moreover, a comparison of different PU samples revealed a trend wherein the values of drug release were decreased with an increase in the PEG content.

Fabrication of gelatin-incorporated nanoporous chitosan-based membranes for potential water desalination applications.

Membrane technology has extensively been used in diverse phenomena such as separation, purification and controlled transportation. Herein, gelatin-incorporated porous chitosan membranes have been prepared using the sol-gel approach for potential water desalination applications. The porogens of poly(ethylene glycol) and Triton X-100 were employed for the mentioned purpose. The prepared porous membranes have been characterized for surface chemical, structural, thermal, mechanical and functional attributes using appropriate analytical approaches. Electron microscopy expressed porous surface morphologies of the resultant films with an average pore size of 14.5 nm. The infrared analysis demonstrated a successful crosslinking of the precursors in the resulting membranes via maleic anhydride. Differential scanning calorimetry analysis disclosed acceptable thermal stability of the test membranes, workable above ambient temperatures. The membrane expressed a water contact of 68.59°, which indicated moderate hydrophilicity, thus allowing controlled transport of the aqueous media. The resultant gelatin/chitosan porous membrane exhibited a porosity of 98 % against kerosene oil. In contrast, the flowability of 7.14 (ethanol), 5.00 (distilled water) and 0.53 (ethylene glycol) mL/min has been recorded against the mentioned liquids. The membrane efficiently purified the local canal water to permissible limits. Such membranes have been qualified for potential applications in water purification systems.

Effect of cold plasma treatment on polylactic acid and polylactic acid/poly (ethylene glycol) films developed as a drug delivery system for streptomycin sulfate.

Polylactic acid (PLA) being a renewable polyester have extensively researched in the biomedical field due to its non-toxicity, high biocompatibility, and easy processing properties. However, low functionalization ability and hydrophobicity limit its applications and hence demands physical and chemical modifications to overcome these limitations. Cold plasma treatment (CPT) is frequently used to improve the hydrophilic properties of PLA-based biomaterials. This provides an advantage to obtain a controlled drug release profile in drug delivery systems. The rapid drug release profile may be advantageous in some applications such as wound application. The main objective of this study is to determine the effects of CPT on PLA or PLA@polyethylene glycol (PLA@PEG) porous films fabricated by solution casting method for use as a drug delivery system with a rapid release profile. The physical, chemical, morphological and drug release properties of PLA and PLA@PEG films, such as surface topography, thickness, porosity, water contact angle (WCA), chemical structure, and streptomycin sulfate release properties, after CPT were systematically investigated. XRD, XPS and FTIR results showed that oxygen-containing functional groups were formed on the film surface with CPT without changing the bulk properties. Along with the changes in the surface morphology such as surface roughness and porosity, the new functional groups provide the films hydrophilic properties by reducing the water contact angle. The improved surface properties enabled the selected model drug, streptomycin sulfate, to exhibit a faster release profile with drug-released mechanism fitted by first order kinetic model. Considering all the results, the prepared films showed an enormous potential for future drug delivery applications, especially in wound application where rapid drug release profile is an advantage.

Citric Acid Cross-Linking of Chitosan Encapsulated Spearmint Oil for Antibacterial Cellulosic Fabric.

This study presents the encapsulation of spearmint oil (SMO) in chitosan microstructures prepared through the emulsion formation method. The SMO although is medicinally significant yet finds limited applications in medical and functional textiles because of its less stability and high volatility under ambient conditions. Nevertheless, its encapsulation in chitosan may enhance its stability and applicability for the said purpose. The SMO encapsulating chitosan microstructures were characterized using different analytical techniques and applied on cotton fabric through a green crosslinking of citric acid. The treated fabric revealed successful adhesion of microcapsules onto its surface confirmed via SEM and FTIR analyses. There observed a slight decrease in tensile strength of treated fabric; that, however, improved crease recovery behavior, and good antibacterial activity in response to broad-spectrum bacterial strains by reducing their 99% population; whereas, the stiffness of such fabric exhibited somehow increasing trend. Hence value-added multifunctional textiles produced, herein, may provide both surface and antibacterial activity for potential medical and healthcare applications without compromising their comfort properties.

Zinc sulfide mediation of poly(hydroxybutyrate)/poly(lactic acid) nanocomposite film for potential UV protection applications.

The present study dealt with the fabrication of zinc sulfide (ZnS) nanoparticles (NPs), prepared using the chemical precipitation method, mediated poly(hydroxybutyrate) (PHB)/poly(lactic acid) (PLA) composite films employing the solution casting approach. The films were characterized based on structural, surface, chemo-physical, thermal, electrical, antibacterial, UV protection and degradation profiles. The results demonstrated the successful formation of nanobiocomposite films with good intercalation of the constituents. The surface morphology results expressed the placement of ZnS NPs in the polymeric blend as supported by elemental analysis. The XRD analysis exhibited the crystalline behavior of the nanobiocomposite films. The surface wettability analysis indicated that with the inclusion of ZnS NPs, the water contact angle of the resultant film was observed to be 119.57°. The prepared nanobiocomposite film exhibited thermal stability up to 214 °C and tensile strength of 25.0 ± 2.4 MPa as compared to that of native PHB (as 15.0 ± 1.5 MPa) and PLA (as 20.0 ± 2 MPa) films. The nanobiocomposite films expressed good antibacterial properties as compared to the control. The prepared films expressed the degradability trends in the natural environment. The ZnS NPs inclusion in the PLA/PHB blend could enhance the AC conductivity of the resultant nanobiocomposite film with acceptable UV protection properties applicable for UV protective packings.

Biosurfactants in the sustainable eradication of SARS COV-2 from the environmental surfaces.

The COVID-19 outbreak has brought the world, at least, to one consensus that cleanliness is unavoidable under all circumstances. Hands are the main body part to interact with the environment and thus are prone to receive, initiate and propagate the chain of infection. Hand hygiene has, therefore, been most emphasized by experts to interrupt the spread of infection. Various harsh chemicals like synthetic surfactants and alcoholic preparations have been in practice to eradicate and disinfect the germs. This choice may be unsafe and cause a subsequent chain of adversities. Thereby, biosurfactants have been proposed as sustainable, non-toxic and safe surface cleaners cum disinfectants under a wide range of physiological and environmental conditions. The amphiphilic micellar behavior of biosurfactants makes them promising candidates as hygienic surface cleaners and therapeutic carriers. We overview the possibilities of using biosurfactants in different ways against microbial pathogens, in general, and the SARS COV-2, in specific.

Cupric oxide nanoparticles incorporated poly(hydroxybutyrate) nanocomposite for potential biosensing application.

We report the synthesis of a novel electrochemical biosensor comprising of cupric oxide (CuO) nanoparticles (NPs) mediated poly(hydroxybutyrate) (PHB) composite film with polyvinyl alcohol (PVA) as a binder/template support using the solution casting method for the detection of a biomolecule i.e., ascorbic acid (AA). The specimens were characterized for surface, chemical, mechanical, optical, and electrochemical attributes. The results expressed regular mediation of CuO NPs in the PHB/PVA matrix towards nanobiocomposite formation with enhanced crystallinity, inter-molecular interactions, mechanical, and electrochemical attributes, and decreased hydrophilicity and bandgap, thus being useful in potential optoelectronic devices. The synthesized biocomposite film exhibited a tensile strength of 86.24 ± 4.10 N which might be due to reinforcement/uniform dispersion of the CuO nanofiller in the PHB-based matrix. The PHB/CuO composite, then, deposited on a glassy carbon electrode surface exhibited good electrocatalytic activity towards the AA in the aqueous media even at low analyte concentrations. Such modified electrode surfaces with metal/biopolymer complex could find possible applications in the detection of other bioactive molecules.

Preparation, properties, and applications of gelatin-based hydrogels (GHs) in the environmental, technological, and biomedical sectors.

Gelatin's versatile functionalization offers prospects of facile and effective crosslinking as well as combining with other materials (e.g., metal nanoparticles, carbonaceous, minerals, and polymeric materials exhibiting desired functional properties) to form hybrid materials of improved thermo-mechanical, physio-chemical and biological characteristics. Gelatin-based hydrogels (GHs) and (nano)composite hydrogels possess unique functional features that make them appropriate for a wide range of environmental, technical, and biomedical applications. The properties of GHs could be balanced by optimizing the hydrogel design. The current review explores the various crosslinking techniques of GHs, their properties, composite types, and ultimately their end-use applications. GH's ability to absorb a large volume of water within the gel network via hydrogen bonding is frequently used for water retention (e.g., agricultural additives), and absorbency towards targeted chemicals from the environment (e.g., as wound dressings for absorbing exudates and in water treatment for absorbing pollutants). GH's controllable porosity makes its way to be used to restrict access to chemicals entrapped within the gel phase (e.g., cell encapsulation), regulate the release of encapsulated cargoes within the GH (e.g., drug delivery, agrochemicals release). GH's soft mechanics closely resembling biological tissues, make its use in tissue engineering to deliver suitable mechanical signals to neighboring cells. This review discussed the GHs as potential materials for the creation of biosensors, drug delivery systems, antimicrobials, modified electrodes, water adsorbents, fertilizers and packaging systems, among many others. The future research outlooks are also highlighted.

Arsenic removal approaches: A focus on chitosan biosorption to conserve the water sources.

Globally, millions of people have no access to clean drinking water and are either striving for that or oppressed to intake polluted water. Arsenic is considered one of the most hazardous contaminants in water bodies that reaches there due to various natural and anthropogenic activities. Modified chitosan has gained much attention from researchers due to its potential for arsenic removal. This review focuses on the need and potential of chitosan-based biosorbents for arsenic removal from water systems. Chitosan is a low-cost, abundant, biodegradable biopolymer that possesses unique structural aspects and functional sites for the adsorption of contaminants like arsenic species from contaminated water. The chitosan-based biosorbents had also been modified using various techniques to enhance their arsenic removal efficiencies. This article reviews various forms of chitosan and parameters involved in chitosan modification which eventually affect the arsenic removal efficiency of the resultant sorbents. The literature revealed that the modified chitosan-based sorbents could express higher adsorption efficiency compared to those prepared from native chitosan. The sustainability of the chitosan-based sorbents has also been considered in terms of reusability. Finally, some recommendations have been underlined for further improvements in this domain.

Recent developments in polysaccharide-based electrospun nanofibers for environmental applications.

Electrospinning has become an inevitable approach to produce nanofibrous structures for diverse environmental applications. Polysaccharides, due to their variety of types, biobased origins, and eco-friendly, and renewable nature are wonderful materials for the said purpose. The present review discusses the electrospinning process, the parameters involved in the formation of electrospun nanofibers in general, and the polysaccharides in specific. The selection of materials to be electrospun depends on the processing conditions and properties deemed desirable for specific applications. Thereby, the conditions to electrospun polysaccharides-based nanofibers have been focused on for possible environmental applications including air filtration, water treatment, antimicrobial treatment, environmental sensing, and so forth. The polysaccharide-based electrospun membranes, for instance, due to their active adsorption sites could find significant potential for contaminants removal from the aqueous systems. The study also gives some recommendations to overcome any shortcomings faced during the electrospinning and environmental applications of polysaccharide-based matrices.

Surface properties and sub-surface aggregate assimilation of rhamnolipid surfactants in different aqueous systems.

Tensioactive properties of rhamnolipids produced by a Pseudomonas aeruginosa strain were investigated in the presence or absence of Sr(2+) or Pb(2+). Surface and interfacial properties, and aggregate forming properties and morphologies were studied by various techniques including scanning electron microscopy. When the pH of a rhamnolipid aqueous solution (40 mg/l) was increased from 5 to 8, irregular vesicles gradually took the shape of oligo-vesicles, then regular vesicles and finally smaller spherical vesicles. Addition of metal ions controlled the aggregates' morphology and stability, and influenced the surface and interfacial behavior of rhamnolipid solutions.

Recent progress in development and chemical modification of poly(hydroxybutyrate)-based blends for potential medical applications.

Poly(hydroxybutyrate) (PHB) has been considered as a promising biopolymer produced in certain microbes under specific fermentative and physiological conditions. Being less functional, hydrophobic and brittle, the processability of PHB is difficult which limits its widespread applications. However, its blends with suitable biopolymers, for instance biopolyesters, may impart in them desirable structural functionalities and properties, such as surface reactivity, amphiphilicity, controlled degradation and mechanical strength; thus making them inevitable candidates for biomedical applications. Herein, various chemical modification approaches have been discussed and analyzed including hydroxylation, aminolysis, block copolymerization (via either grafting or blending) with suitable biopolymers. The mentioned approaches may tune the mechanical and other desirable properties of resultant blends for value added biomedical applications particularly in drug delivery, tissue engineering and so on. Furthermore, some key areas have been highlighted where the future research may be focused.