Discovery of Natural Bisbenzylisoquinoline Analogs from the Library of Thai Traditional Plants as SARS-CoV-2 3CLPro Inhibitors: In Silico Molecular Docking, Molecular Dynamics, and In Vitro Enzymatic Activity.

The emergence of SARS-CoV-2 in December 2019 has become a global issue due to the continuous upsurge in patients and the lack of drug efficacy for treatment. SARS-CoV-2 3CLPro is one of the most intriguing biomolecular targets among scientists worldwide for developing antiviral drugs due to its relevance in viral replication and transcription. Herein, we utilized computer-assisted drug screening to investigate 326 natural products from Thai traditional plants using structure-based virtual screening against SARS-CoV-2 3CLPro. Following the virtual screening, the top 15 compounds based on binding energy and their interactions with key amino acid Cys145 were obtained. Subsequently, they were further evaluated for protein-ligand complex stability via molecular dynamics simulation and binding free energy calculation using molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) approaches. Following drug-likeness and ADME/Tox assessments, seven bisbenzylisoquinolines were obtained, including neferine (3), liensinine (4), isoliensinine (5), dinklacorine (8), tiliacorinine (13), 2'-nortiliacorinine (14), and yanangcorinine (15). These compounds computationally showed a higher binding affinity than native N3 and GC-373 inhibitors and attained stable interactions on the active site of 3CLpro during 100 ns in molecular dynamics (MD) simulation. Moreover, the in vitro enzymatic assay showed that most bisbenzylisoquinolines could experimentally inhibit SARS-CoV-2 3CLPro. To our delight, isoliensinine (5) isolated from Nelumbo nucifera demonstrated the highest inhibition of protease activity with the IC50 value of 29.93 µM with low toxicity on Vero cells. Our findings suggested that bisbenzylisoquinoline scaffolds could be potentially used as an in vivo model for the development of effective anti-SARS-CoV-2 drugs.

The earth-star basidiomycetous mushroom Astraeus odoratus produces polyhydroxyalkanoates during cultivation on malt extract.

Polyhydroxyalkanoates (PHAs) including poly-3-hydroxybutyrate (P3HB) as secondary metabolisms were in vitro produced by the edible basidiomycetous mushroom Astraeus odoratus during its growth on malt agar extract. Various carbon and nitrogen sources containing cellulose, glucose, glycerol, rice straw powder, soybean meal and peptone were investigated for the growth of basidiomycetous mushrooms. During cultivation, the A. odoratus culture exudated the considerably extracellular fluid up to approx. 2.3 ml on 2% malt extract agar plate within 7 days. The chemical compounds of the exudated fluid were further investigated by Fourier-transform infrared spectroscopy (FTIR) and gas chromatography/mass spectrometry (GC/MS); and its morphology of the lyophilized sample was observed by scanning electron microscope (SEM). FTIR results showed the characteristic bands of OH at 3445 cm-1, CH/CH2/symmetric CH3 (stretch) at 2923 and 2852 cm-1, C=O at 1730 cm-1, asymmetric CH3 (bend) at 1454 and 1414 cm-1, C-O of COO- at 1396 cm-1 and C-O-C at 1223, 1160, 1116, 1058 and 1019 cm-1 which were similar to the absorptive characteristics of P3HB. Methyl ester derivatives of GC/MS results identified 7 compounds including: 3-hydroxybutanoic (monomer of PHB), aminobenzoic, salicylic, hexadecenoic, octadecadienoic, octadecenoic and octadecanoic acids. SEM images revealed a fibriform and porous materials. Hence, the occurrence of PHAs was first described in a basidiomycetous mushroom A. odoratus. Thus, PHAs could be found not only in bacteria and but also in basidiomycetous mushroom, which can be promising target for bioplastics and green environmental studies.

Surface-Modified Polypyrrole-Coated PLCL and PLGA Nerve Guide Conduits Fabricated by 3D Printing and Electrospinning.

The efficiency of nerve guide conduits (NGCs) in repairing peripheral nerve injury is not high enough yet to be a substitute for autografts and is still insufficient for clinical use. To improve this efficiency, 3D electrospun scaffolds (3D/E) of poly(l-lactide-co-ε-caprolactone) (PLCL) and poly(l-lactide-co-glycolide) (PLGA) were designed and fabricated by the combination of 3D printing and electrospinning techniques, resulting in an ideal porous architecture for NGCs. Polypyrrole (PPy) was deposited on PLCL and PLGA scaffolds to enhance biocompatibility for nerve recovery. The designed pore architecture of these "PLCL-3D/E" and "PLGA-3D/E" scaffolds exhibited a combination of nano- and microscale structures. The mean pore size of PLCL-3D/E and PLGA-3D/E scaffolds were 289 ± 79 and 287 ± 95 nm, respectively, which meets the required pore size for NGCs. Furthermore, the addition of PPy on the surfaces of both PLCL-3D/E (PLCL-3D/E/PPy) and PLGA-3D/E (PLGA-3D/E/PPy) led to an increase in their hydrophilicity, conductivity, and noncytotoxicity compared to noncoated PPy scaffolds. Both PLCL-3D/E/PPy and PLGA-3D/E/PPy showed conductivity maintained at 12.40 ± 0.12 and 10.50 ± 0.08 Scm-1 for up to 15 and 9 weeks, respectively, which are adequate for the electroconduction of neuron cells. Notably, the PLGA-3D/E/PPy scaffold showed superior cytocompatibility when compared with PLCL-3D/E/PPy, as evident via the viability assay, proliferation, and attachment of L929 and SC cells. Furthermore, analysis of cell health through membrane leakage and apoptotic indices showed that the 3D/E/PPy scaffolds displayed significant decreases in membrane leakage and reductions in necrotic tissue. Our finding suggests that these 3D/E/PPy scaffolds have a favorable design architecture and biocompatibility with potential for use in peripheral nerve regeneration applications.

Scalable and Room-Temperature Ring-Opening Polymerization of ε-Caprolactone Catalyzed by Active Lithium Tetramethylene-Tethered Bis[N-(N'-butylimidazol-2-ylidene)] N-Heterocyclic Carbene as a Lewis Acid Organocatalyst.

The Lewis acid organocatalytic system of lithium tetramethylene-tethered bis[N-(N'-butylimidazol-2-ylidene)] N-heterocyclic carbene (1,4-bisNHC) including lithium benzyloxide and benzyl alcohol has been successfully utilized in the ring-opening polymerization (ROP) of ε-caprolactone (CL) for the first time. The catalytic performance of this organic catalyst in the synthesis of high-molecular-weight polymers was investigated via bulk polymerization using different combinations of tetramethylene-tethered bis[N-(N'-butylimidazolium)] hexafluorophosphate (1,4-bis[Bim][PF6]), benzyl alcohol (BnOH), and n-butyl lithium (nBuLi) ([1,4-bis[Bim][PF6]]/[BnOH]/[nBuLi]) with the molar ratios of 0:2:2, 1:1:3, 1:2:3, and 1:2:4. The results showed that the molar ratio of 1:2:3 efficiently and rapidly initiated the bulk ROP of CL at room temperature with a high molar ratio of CL to 1,4-bis[Bim][PF6] of 3000/1 and produced the highest number of average-molecular-weight (Mn) poly(ε-caprolactone) (103,057 g mol-1) with the dispersity (D̵) and %conversion of 1.73 and 98% in a short period of time (152 s). From comparative studies, the relative polymerization rates of the bulk ROP of CL with different [1,4-bis[Bim][PF6]]/[BnOH]/[nBuLi] molar ratios was determined in the following order: 1:2:4 > 1:1:3 > 1:2:3 > 0:2:2. For mechanistic investigation, the bulk ROP mechanism of CL with our organic catalyst was proposed through the intramolecular bis-lithium-carbene interaction pathway for 1,4-bisNHC1,1,3, 1,4-bisNHC1,2,3, and 1,4-bisNHC1,2,4 systems.

Synthesis of Poly(ε-caprolactone) Diacrylate for Micelle-Cross-Linked Sodium AMPS Hydrogel for Use as Controlled Drug Delivery Wound Dressing.

This study focuses on the synthesis of poly(ε-caprolactone) diacrylate (PCLDA) for the fabrication of micelle-cross-linked sodium AMPS wound dressing hydrogels. The novel synthetic approach of PCLDA is functionalizing a PCL diol with acrylic acid. The influences of varying the PCL diol/AA molar ratio and temperature on the suitable conditions for the synthesis of PCLDA are discussed. The hydrogel was synthesized through micellar copolymerization of sodium 2-acrylamido-2-methylpropane sulfonate (Na-AMPS) as a basic monomer and PCLDA as a hydrophobic association monomer. In this study, an attempt was made to develop new hydrogel wound dressings meant for the release of antibacterial drugs (ciprofloxacin and silver sulfadiazine). The chemical structures, morphology, porosity, and water interaction of the hydrogels were characterized. The hydrogels' swelling ratio and water vapor transmission rate (WVTR) showed a high swelling capacity (4688-10753%) and good WVTR (approximately 2000 g·m-2·day-1), which can be controlled through variation of the PCLDA concentration. The mechanical property results confirmed that PCLDA improved the mechanical properties of the hydrogel; the stress increased from 37 to 68 kPa, and the strain increased from 198 to 360% with increasing PCLDA (0-30% wt of Na-AMPS). These hydrogels presented no cytotoxicity based on over 70% cell viability responses (L929 fibroblasts) using an in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Additionally, the drug release mechanism, kinetic models, and antibacterial activity were determined. The results demonstrated that antibiotics were released from the hydrogel with a Fickian diffusion mechanism and antibacterial activity against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus). Based on the results obtained, and bearing in mind that further progress still needs to be made, the fabricated hydrogels show considerable potential for meeting the stringent property requirements of hydrogel wound dressings.

High Substitution Synthesis of Carboxymethyl Chitosan for Properties Improvement of Carboxymethyl Chitosan Films Depending on Particle Sizes.

This study investigated the effect of chitosan particle sizes on the properties of carboxymethyl chitosan (CMCh) powders and films. Chitosan powders with different particle sizes (75, 125, 250, 450 and 850 µm) were used to synthesize the CMCh powders. The yield, degree of substitution (DS), and water solubility of the CMCh powders were then determined. The CMCh films prepared with CMCh based on chitosan with different particle sizes were fabricated by a solution casting technique. The water solubility, mechanical properties, and water vapor transmission rate (WVTR) of the CMCh films were measured. As the chitosan particle size decreased, the yield, DS, and water solubility of the synthesized CMCh powders increased. The increase in water solubility was due to an increase in the polarity of the CMCh powder, from a higher conversion of chitosan into CMCh. In addition, the higher conversion of chitosan was also related to a higher surface area in the substitution reaction provided by chitosan powder with a smaller particle size. As the particle size of chitosan decreased, the tensile strength, elongation at break, and WVTR of the CMCh films increased. This study demonstrated that a greater improvement in water solubility of the CMCh powders and films can be achieved by using chitosan powder with a smaller size.

Effective enhancement of polylactic acid-degrading enzyme production by Amycolatopsis sp. strain SCM_MK2-4 using statistical and one-factor-at-a-time approaches.

This study aims to find the optimal medium and conditions for polylactic acid (PLA)-degrading enzyme production by Amycolatopsis sp. SCM_MK2-4. Screening of the most effective components in the enzyme production medium by Plackett-Burman design revealed that the silk cocoon and PLA film were the most significant variables enhancing the PLA-degrading enzyme production. After an response surface methodology, a maximum amount of PLA-degrading enzyme activity at 0.74 U mL-1 was predicted and successfully validated at 95% after 0.39% (w/v) silk cocoon and 1.62% (w/v) PLA film were applied to the basal medium. The optimal initial pH value, temperature, and inoculum size were evaluated by a method considering one-factor-at-a-time. The values were recorded at an initial pH in the range of 7.5-9.0, a temperature of 30-32°C, and an inoculum size of 4-10%. The highest activity of approximately 0.95 U mL-1 was achieved after 4 days of cultivation using the optimized medium and under optimized conditions in a shake flask. Upscaling to the use of a 3-L stirred tank fermenter was found to be successful with a PLA-degrading activity of 5.53 U mL-1; which represents a 51-fold increase in the activity compared with that obtained from the nonoptimized medium and conditions in the shake flask.

Isolation and screening of biopolymer-degrading microorganisms from northern Thailand.

Forty agricultural soils were collected from Chiang Mai and Lampang provinces in northern Thailand. Bacteria, actinomycetes and fungi were isolated and screened for their ability to degrade polylactic acid (PLA), polycaprolactone (PCL) and poly(butylene succinate) (PBS) by the agar diffusion method. Sixty-seven actinomycetes, seven bacteria and five fungal isolates were obtained. The majority of actinomycetes were Streptomyces based on morphological characteristic, chemotaxonomy and 16S rRNA gene data. Seventy-nine microorganisms were isolated from 40 soil samples. Twenty-six isolates showed PLA-degradation (32.9 %), 44 isolates showed PBS-degradation (55.7 %) and 58 isolates showed PCL-degradation (73.4 %). Interestingly, 16 isolates (20.2 %) could degrade all three types of bioplastics used in this study. The Amycolatopsis sp. strain SCM_MK2-4 showed the highest enzyme activity for both PLA and PCL, 0.046 and 0.023 U/mL, respectively. Moreover, this strain produced protease, esterase and lipase on agar plates. Approximately, 36.7 % of the PLA film was degraded by Amycolatopsis sp. SCM_MK2-4 after 7 days of cultivation at 30 °C in culture broth.

Production of Nanocellulose from Sugarcane Bagasse and Development of Nanocellulose Conjugated with Polylysine for Fumonisin B1 Toxicity Absorption.

The present study aimed to extract nanocellulose (NC) from sugarcane bagasse agricultural waste through a chemical method (sulfuric acid hydrolysis and ultrasonication). Subsequently, the nanocellulose product was conjugated with polylysine (NC-PL) and assessed for its efficacy in reducing the toxicity of Fumonisin B1 (FB1), a mycotoxin produced by fungi commonly found in corn, wheat, and other grains. Experimental results confirmed the successful conjugation of NC and PL, as evidenced by FTIR peaks at 1635 and 1625 cm-1 indicating amide I and amide II vibrations in polylysine (PL). SEM analysis revealed a larger size due to PL coating, consistent with DLS results showing the increased size and positive charge (38.0 mV) on the NC-PL surface. Moreover, the effect of FB1 adsorption by NC and NC-PL was evaluated at various concentrations (0-200,000 µg/mL). NC-PL demonstrated the ability to adsorb FB1 at concentrations of 2000, 20,000, and 200,000 µg/mL, with adsorption efficiencies of 94.4-100%. Human hepatocellular carcinoma (HepG2) cells were utilized to assess NC and NC-PL cytotoxic effects. This result is a preliminary step towards standardizing results for future studies on their application as novel FB1 binders in food, food packaging, and functional feeds.

A MAX phase (Ti3AlC2) as a performance enhancer for poly(lactic acid) electrospun membranes in steam generation and solar desalination.

Clean water and sanitation issues motivate researchers to develop water evaporators for freshwater generation. The composite membrane evaporator was electrospun herein based on poly(lactic acid) (PLA) and Ti3AlC2 MAX phase as a property enhancer. As a precursor for the MXenes synthesis, the MAX phase has never been explored with PLA for water evaporator potential. Alternative use of the MAX phase can reduce the production cost arising from chemical synthesis. This work explored the potential of the MAX phase as an additive to enhance PLA membrane performance for steam generation and desalination applications. Under the infrared irradiation (∼1.0 kW/m2), the mechanically-improved PLA/MAX phase membrane showed an enhanced water evaporation rate of 1.70 kg/m2 h (93.93 % efficiency), with an approximately 52 % rate increment relative to the PLA membrane. Based on the artificial seawater (3.5 % w/w), the membrane exhibited an evaporation rate of 1.60 kg/m2 h (87.57 % efficiency). The membrane showed self-floating ability at the air-water interface, excellent thermal stability over the entire operating temperatures, and reusability after repeated cycles. Moreover, the generated freshwater contained exceptionally low cations concentrations, as low as those in potable water. The developed composite membrane also had proved its potential for solar desalination in the water generation field.

Modification of a Carboxymethyl Cellulose/Poly(vinyl alcohol) Hydrogel Film with Citric Acid and Glutaraldehyde Crosslink Agents to Enhance the Anti-Inflammatory Effectiveness of Triamcinolone Acetonide in Wound Healing.

Anti-inflammatory wound healing involves targeted drug delivery to the wound site using hydrogel materials to prolong drug effectiveness. In this work, hydrogel films were fabricated using carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) crosslinked with citric acid (CA) and glutaraldehyde (GA) at different concentrations. The crosslinker densities were optimized with various CA (2-10% w/v) and GA (1-5% v/v) concentrations. The optimized crosslink densities in the hydrogel exhibited additional functional group peaks in the FT-IR spectra at 1740 cm-1 for the C=O stretching of the ester linkage in CA and at 1060 cm-1 for the C-O-C stretching of the ether group in GA. Significantly, the internal porous structures of hydrogel composite films improved density, swelling capacities, solubility percentage reduction, and decreased water retention capacities with optimized crosslinker densities. Therefore, these hydrogel composite films were utilized as drug carriers for controlled drug release within 24 h during medical treatment. Moreover, the hydrogel films demonstrated increased triamcinolone acetonide (TAA) absorption with higher crosslinker density, resulting in delayed drug release and improved TAA efficiency in anti-inflammatory activity. As a result, the modified hydrogel showed the capability of being an alternative material with enhanced anti-inflammatory efficiency with hydrogel films.

Low cytotoxicity, antibacterial property, and curcumin delivery performance of toughness-enhanced electrospun composite membranes based on poly(lactic acid) and MAX phase (Ti3AlC2).

MXenes, synthesized from their precursor MAX phases, have been extensively researched as additives to enhance the drug delivery performance of polymer matrices, whereas there is a limited number of previous reports on the use of MAX phases themselves for such applications. The use of MAX phases can exclude the complicated synthesis procedure and lessen resultant production and environmental costs required to convert MAX phases to MXenes. Herein, electrospun membranes of poly(lactic acid) (PLA) and a MAX phase (Ti3AlC2) have been fabricated for curcumin delivery. The composite membrane exhibits significantly higher toughness (8.82 MJ m-3) than the plasticized PLA membrane (0.63 MJ m-3) with low cytotoxicity, supporting proliferation of mouse fibroblast L929 cells. The curcumin-loaded composite membrane exhibits high water vapor transmission (∼7350 g m-2 day-1), porosity (∼85 %), water wettability, and antibacterial properties against E. coli and S. aureus. Seven-day curcumin release is enhanced from 45 % (PLA) to 67 % (composite) due to curcumin diffusion from the polymer fibers and MAX phase surface that contributes to overall increased curcumin adsorption and release sites. This work demonstrates the potential of the MAX phase to enhance both properties and curcumin delivery, promising for other eco-friendly systems for sustainable drug delivery applications.

Physical Characteristics and Biocompatibility of 3D-Printed Polylactic-Co-Glycolic Acid Membranes Used for Guided Bone Regeneration.

Bioresorbable polymeric membranes for guided bone regeneration (GBR) were fabricated using the three-dimensional printing technique. Membranes made of polylactic-co-glycolic acid (PLGA), which consist of lactic acid (LA) and glycolic acid in ratios of 10:90 (group A) and 70:30 (group B), were compared. Their physical characteristics including architecture, surface wettability, mechanical properties, and degradability were compared in vitro, and their biocompatibilities were compared in vitro and in vivo. The results demonstrated that the membranes of group B had mechanical strength and could support the proliferation of fibroblasts and osteoblasts significantly better than those of group A (p < 0.05). The degradation rate in Group B was significantly lower than that in Group A, but they significantly produced less acidic environment (p < 0.05). In vivo, the membranes of group B were compared with the commercially available collagen membranes (group C). The amount of newly formed bone of rat's calvarial defects covered with the membranes of group C was stable after week 2, whereas that of group B increased over time. At week 8, the new bone volumes in group B were greater than those in group C (p > 0.05). In conclusion, the physical and biological properties of the PLGA membrane (LA:GA, 70:30) were suitable for GBR.

Preparation and Characterization of Cellulose Nanocrystals from Bamboos and Their Application in Cassava Starch-Based Film.

Cellulose from different species of bamboo (Thyrsostachys siamesi Gamble, Dendrocalamus sericeus Munro (DSM), Bambusa logispatha, and Bambusa sp.) was converted to cellulose nanocrystals (CNCs) by a chemical-mechanical method. First, bamboo fibers were pre-treated (removal of lignin and hemicellulose) to obtain cellulose. Next, the cellulose was hydrolyzed with sulfuric acid using ultrasonication to obtain CNCs. The diameters of CNCs are in the range of 11-375 nm. The CNCs from DSM showed the highest yield and crystallinity, which was chosen in the film fabrication. The plasticized cassava starch-based films with various amounts (0-0.6 g) of CNCs (from DSM) were prepared and characterized. As the number of CNCs in cassava starch-based films increased, water solubility and the water vapor permeability of CNCs decreased. In addition, the atomic force microscope of the nanocomposite films showed that CNC particles were dispersed uniformly on the surface of cassava starch-based film at 0.2 and 0.4 g content. However, the number of CNCs at 0.6 g resulted in more CNC agglomeration in cassava starch-based films. The 0.4 g CNC in cassava starch-based film was found to have the highest tensile strength (4.2 MPa). Cassava starch-incorporated CNCs from bamboo film can be applied as a biodegradable packaging material.

Mechanical properties and water resistance improvement of thermoplastic modified starch, carboxymethyl cellulose, and zinc oxide nanometal particles by reactive blending.

Novel biodegradable thermoplastic starch (TPS) with high mechanical properties and water resistance was developed using reactive blending technique. Effect of zinc oxide (ZnO) addition to TPS properties and reaction was investigated. Thermoplastic modified starch (TPMS) was prepared by melt-mixing modified starch with glycerol 70/30%wt/wt. Carboxy methyl cellulose (CMC) 5%wt was incorporated with modified starch, glycerol, and zinc oxide (ZnO) 0-5 %wt. Fourier-transform infrared (FTIR) spectroscopy analysis confirmed the formation of the carboxyl anion (OZn) between the -COO- of CMC and the free Zn+ ion of ZnO. The tensile strength of the TPMS/CMC/ZnO blend increased 7 time with ZnO 5 % (14 MPa) addition compared to TPMS (2 MPa). The color (∆E) of TPMS/CMC/ZnO differed notably at high ZnO concentrations (1-5 %wt). The TPMS/CMC blend displayed a smooth fracture surface due to the miscibility of the materials. Small particles of ZnO dispersed finely in the TPMS matrix and increased the interfacial tension and water contact angle of the blends. The miscibility of TPS with CMC and the occurrence of ionic interactions of -COO- of CMC and -OH of starch with the Zn+ ion as physical crosslinking were indicated to improve the mechanical properties and water resistance of the blends.

Enhanced mechanical properties and biocompatibility of bacterial cellulose composite films with inclusion of 2D MoS2 and helical carbon nanotubes for use as antimicrobial drug carriers.

Bacterial cellulose (BC) is a biomaterial being investigated for a range of applications. Herein, BC films derived from nata de coco pieces are reinforced by two-dimensional molybdenum disulfide (MoS2) and helical carbon nanotubes (HCNTs) to enhance their tensile mechanical properties, and the biocompatibility of the BC composite films is demonstrated. A simple preparation is presented using a kitchen blender to disperse and blend the BC fibers and additives in a common fabrication medium, followed by vacuum filtration. The mechanical properties of the BC/MoS2/HCNTs composite films are enhanced due to the synergistic effect of MoS2 and HCNTs embedded in the BC films. The MoS2/HCNTs binary additive (1 phr) is capable of increasing the strength and Young's modulus by 148 % and 333 %, respectively, relative to the BC films. The cell cytotoxicity of the BC/MoS2/HCNTs films was assessed using an MTT assay. The composite films are biocompatible with a cell viability of L929 fibroblast cells >70 %, coupled with observations of direct cell attachment on the films. The composite films also exhibited good performance in absorbing and releasing gentamicin antibiotics to inhibit the growth of Escherichia coli and Staphylococcus aureus. The BC/MoS2/HCNTs films are thus potential BC-based candidates as biocompatible robust antibiotic carriers.

Reactive Blending of Modified Thermoplastic Starch Chlorhexidine Gluconate and Poly(butylene succinate) Blending with Epoxy Compatibilizer.

Biodegradable starch-based polymers were developed by melt-blending modified thermoplastic starch (MTPS) with poly(butylene succinate) (PBS) blended with epoxy resin (Er). A modified thermoplastic starch blend with chlorhexidine gluconate (MTPSCh) was prepared by melt-blending cassava starch with glycerol and chlorhexidine gluconate (CHG) 1.0% wt. The Er was melt-blended with PBS (PBSE) at concentrations of 0.50%, 1.0%, 2.5%, and 5.0% (wt%/wt%). The mechanical properties, water resistance, and morphology of the MTPSCh/PBSE blends were investigated. The MTPSCh/PBSE2.5% blend showed an improvement in tensile strength (8.1 MPa) and elongation at break (86%) compared to the TPSCh/PBS blend (2.6 MPa and 53%, respectively). In addition, water contact angle measurements indicated an increase in the hydrophobicity of the MTPSCh/PBSE blends. Thermogravimetric analysis showed an improvement in thermal stability when PBS was added to the MTPSCh blends. Fourier transform infrared spectroscopy data confirmed a new reaction between the amino groups of CHG in MTPSCh and the epoxy groups of Er in PBSE, which improved the interfacial adhesion of the MTPSCh/PBSE blends. This reaction improved the mechanical properties, water resistance, morphology, and thermal stability of the TPSCh/PBSE blends.

Argon Plasma Jet-Treated Poly (Vinyl Alcohol)/Chitosan and PEG 400 Plus Mangifera indica Leaf Extract for Electrospun Nanofiber Membranes: In Vitro Study.

The wound-healing process can be disrupted at any stage due to various internal and external factors. The inflammatory stage of the process plays a vital role in determining the outcome of the wound. Prolonged inflammation due to bacterial infection can lead to tissue damage, slow healing, and complications. Wound dressings made using materials such as poly (vinyl alcohol) (PVA), chitosan (CS), and poly (ethylene glycol) (PEG) with Mangifera extract (ME) added can help reduce infection and inflammation, creating a conducive environment for faster healing. However, creating the electrospun membrane is challenging due to balancing various forces such as rheological behavior, conductivity, and surface tension. To improve the electrospinnability of the polymer solution, an atmospheric pressure plasma jet can induce chemistry in the solution and increase the polarity of the solvent. Thus, this research aims to investigate the effect of plasma treatment on PVA, CS, and PEG polymer solutions and fabricate ME wound dressing via electrospinning. The results indicated that increasing plasma treatment time increased the viscosity of the polymer solution, from 269 mPa∙to 331 mPa∙s after 60 min, and led to an increase in conductivity from 298 mS/cm to 330 mS/cm and an increase in nanofiber diameter from 90 ± 40 nm to 109 ± 49 nm. Incorporating 1% mangiferin extract into an electrospun nanofiber membrane has been found to increase the inhibition rates of Escherichia coli and Staphylococcus aureus by 29.2% and 61.2%, respectively. Additionally, the fiber diameter decreases when compared with the electrospun nanofiber membrane without ME. Our findings demonstrate that electrospun nanofiber membrane with ME has anti-infective properties and can promote faster wound healing.

Antimicrobial thermoplastic starch reactive blend with chlorhexidine gluconate and epoxy resin.

An antimicrobial thermoplastic starch (TPS) was developed by melt-mixing TPS with chlorhexidine gluconate (CHG) and epoxy resin (Er). The tensile strength and hardness of the TPSCh blend increased with the addition of Er (TPSCh/Er), especially at 5 wt% Er (TPSCh/Er5) (19.5 MPa and 95 %, respectively). The water contact angle of TPSCh/Er was higher than those of TPS and TPSCh because of the improved interfacial tension. Fourier transform infrared and nuclear magnetic resonance analyses confirmed the reaction between the epoxy groups of Er, hydroxyl groups of starch, and amino groups of CHG. TPSCh/Er5 exhibited a significantly lower CHG release than TPSCh owing to the rearrangement of TPSCh chains via Er crosslinking. TPSCh/Er0.5 and TPSCh/Er1 showed inhibition zones against both tested bacteria (Staphylococcus aureus and Bacillus cereus), whereas TPSCh/Er2.5, TPSCh/Er5, and TPSCh/Er10 showed inhibition zones only against S. aureus. Moreover, TPSCh and TPSCh/Er0.5-2.5 exhibited inhibition zones with Saccharomyces cerevisiae.

In Situ Compatibilized Blends of PLA/PCL/CAB Melt-Blown Films with High Elongation: Investigation of Miscibility, Morphology, Crystallinity and Modelling.

Ternary-blended, melt-blown films of polylactide (PLA), polycaprolactone (PCL) and cellulose acetate butyrate (CAB) were prepared from preliminary miscibility data using a rapid screening method and optical ternary phase diagram (presented as clear, translucent, and opaque regions) as a guide for the composition selection. The compositions that provided optically clear regions were selected for melt blending. The ternary (PLA/PCL/CAB) blends were first melt-extruded and then melt-blown to form films and characterized for their tensile properties, tensile fractured-surface morphology, miscibility, crystallinity, molecular weight and chemical structure. The results showed that the tensile elongation at the break (%elongation) of the ternary-blended, melt-blown films (85/5/10, 75/10/15, 60/15/25 of PLA/PCL/CAB) was substantially higher (>350%) than pure PLA (ca. 20%). The range of compositions in which a significant increase in %elongation was observed at 55−85% w/w PLA, 5−20% w/w PCL and 10−25% w/w CAB. Films with high %elongation all showed good interfacial interactions between the dispersed phase (PCL and CAB) and matrix (PLA) in FE-SEM and showed improvements in miscibility (higher intermolecular interaction and mixing) and a decrease in the glass transition temperature, when compared to the low %elongation films. The decrease in Mw and Mn and the formation of the new NMR peaks (1H NMR at 3.68−3.73 ppm and 13C NMR at 58.54 ppm) were observed in only the high %elongation films. These are expected to be in situ compatibilizers that are generated during the melt processing, mostly by chain scission. In addition, mathematical modelling was used to study the optimal ratio and cost-effectiveness of blends with optimised mechanical properties. These ternary-blended, melt-blown films have the potential for use in both packaging and medical devices with excellent mechanical performance as well as inherent economic and environmental capabilities.