Valorization of Agricultural Waste as a Chemiresistor H2S-Gas Sensor: A Composite of Biodegradable-Electroactive Polyurethane-Urea and Activated-Carbon Composite Derived from Coconut-Shell Waste.

In this study, a high-performance H2S sensor that operates at RT was successfully fabricated using biodegradable electroactive polymer-polyurethane-urea (PUU) and PUU-activated-carbon (AC) composites as sensitive material. The PUU was synthesized through the copolymerization of biodegradable polycaprolactone diol and an electroactive amine-capped aniline trimer. AC, with a large surface area of 1620 m2/g and a pore diameter of 2 nm, was derived from coconut-shell waste. The composites, labeled PUU-AC1 and PUU-AC3, were prepared using a physical mixing method. The H2S-gas-sensing performance of PUU-AC0, PUU-AC1, and PUU-AC3 was evaluated. It was found that the PUU sensor demonstrated good H2S-sensing performance, with a sensitivity of 0.1269 ppm-1 H2S. The H2S-gas-sensing results indicated that the PUU-AC composites showed a higher response, compared with PUU-AC0. The enhanced H2S-response of the PUU-AC composites was speculated to be due to the high surface-area and abounding reaction-sites, which accelerated gas diffusion and adsorption and electron transfer. When detecting trace levels of H2S gas at 20 ppm, the sensitivity of the sensors based on PUU-AC1 and PUU-AC3 increased significantly. An observed 1.66 and 2.42 times' enhancement, respectively, in the sensors' sensitivity was evident, compared with PUU-AC0 alone. Moreover, the as-prepared sensors exhibited significantly high selectivity toward H2S, with minimal to almost negligible responses toward other gases, such as SO2, NO2, NH3, CO, and CO2.

Healing Wounds Efficiently with Biomimetic Soft Matter: Injectable Self-Healing Neutral Glycol Chitosan/Dibenzaldehyde-Terminated Poly(ethylene glycol) Hydrogel with Inherent Antibacterial Properties.

The high prevalence of acquiring skin wounds, along with the emergence of antibiotic-resistant strains that lead to infections, impose a threat to the physical, mental, and socioeconomic health of society. Among the wide array of wound dressings developed, hydrogels are regarded as a biomimetic soft matter of choice owing to their ability to provide a moist environment ideal for healing. Herein, neutral glycol chitosan (GC) was cross-linked via imine bonds with varying concentrations of dibenzaldehyde-terminated polyethylene glycol (DP) to give glycol chitosan/dibenzaldehyde-terminated polyethylene glycol hydrogels (GC/DP). These dynamic Schiff base linkages (absorption peak at 1638 cm-1) within the hydrogel structure endowed their ability to recover from damage as characterized by high-low strain exposure in continuous step strain rheology. Along with their good injectability and biodegradability, the hydrogels exhibited remarkable inhibition against E. coli, P. aeruginosa, and S. aureus. GC/DP hydrogels demonstrated high LC50 values in vivo using zebrafish embryos as a model system due to their relative biocompatibility and a remarkable 93.4 ± 0.88% wound contraction at 30-dpw against 49.1 ± 3.40% of the control. To the best of our knowledge, this is the first study that developed injectable glycol chitosan/dibenzaldehyde-terminated polyethylene glycol self-healing hydrogels for application in wound healing with intrinsic bacteriostatic properties against the three bacteria.

Polyaniline Composites Containing Eco-Friendly Biomass Carbon from Agricultural-Waste Coconut Husk for Enhancing Gas Sensor Performance in Hydrogen Sulfide Detection.

Hydrogen sulfide, a colorless, flammable gas with a distinct rotten egg odor, poses severe health risks in industrial settings. Sensing hydrogen sulfide is crucial for safeguarding worker safety and preventing potential accidents. This study investigated the gas-sensing performance of an electroactive polymer (i.e., polyaniline, PANI) and its composites with active carbon (AC) (i.e., PANI-AC1 and PANI-AC3) toward H2S at room temperature. PANI-AC composites-coated IDE gas sensors were fabricated and their capability of detecting H2S at concentrations ranging from 1 ppm to 30 ppm was tested. The superior gas-sensing performance of the PANI-AC composites can be attributed to the increased surface area of the materials, which provided increased active sites for doping processes and enhanced the sensing capability of the composites. Specifically, the incorporation of AC in the PANI matrix resulted in a substantial improvement in the doping process, which led to stronger gas-sensing responses with higher repeatability and higher stability toward H2S compared to the neat PANI-coated IDE sensor. Furthermore, the as-prepared IDE gas sensor exhibited the best sensing response toward H2S at 60% RH. The use of agricultural-waste coconut husk for the synthesis of these high-performance gas-sensing materials promotes sustainable and eco-friendly practices while improving the detection and monitoring of H2S gas in industrial settings.

Effect of Sulfonation Group on Polyaniline Copolymer Scaffolds for Tissue Engineering with Laminin Treatment under Electrical Stimulation.

Sulfonated copolyanilines (SPANs), SPAN-40 and SPAN-75, were prepared and applied in this tissue engineering study. SPAN scaffolds (SPANs) and control group polyaniline (PANI) were synthesized by performing oxidative polymerization. To further research the effects of neuron regeneration, PC12 cells were cultured on as-prepared PANI and SPANs with laminin (La) treatment under electrical stimulation. The effects on PC12 cell differentiation were investigated by controlling the amount of sulfonated groups (-SO3H) in the SPAN chain, the electrical stimulation voltage, and the presence or absence of La coating. The adhesion and proliferation of cells increased with the degree of sulfonation; La and electrical stimulation further promoted neuronal cell differentiation as increased neurite length was demonstrated in the micrograph analyses. In summary, the sulfonated copolyaniline coated with La had the best effect on neuronal differentiation under electrical stimulation, suggesting its potential as a substrate for nerve tissue engineering.

An aniline trimer-based multifunctional sensor for colorimetric Fe3+, Cu2+ and Ag+ detection, and its complex for fluorescent sensing of L-tryptophan.

The detection of metal ions and amino acids by the aniline oligomer-based receptor has not been reported yet, to the best of our knowledge. In this study, an efficient multifunctional cation-amino acid sensor (CAS) with aniline moiety and chiral thiourea binding site was synthesized by the reaction of aniline trimer and (S)-(+)-1-phenyl ethyl isothiocyanate. CAS can sense Fe3+, Cu2+, Ag+ ions, and L-tryptophan. These results can be recognized by the naked eye. The appropriate pH range for the quantitative analysis of Fe3+, Cu2+, and Ag+ by CAS in DMSO/water (30 vol% water) was evaluated. The interaction between CCS and metal ions was analyzed by 1H NMR titration. The detection limits of CAS for the Cu2+, Ag+, and Fe3+ were 0.214, 0.099, and 0.147 µM, respectively. Moreover, the CASCu2+ complex can act as a turn-on fluorescence sensor for L-tryptophan. On the contrary, there is no response upon the addition of other amino acids, such as L-histidine, L-proline, L-phenylalanine, L-threonine, L-methionine, L-tyrosine, and L-cystine to CASCu2+ complex.

Mussel-Inspired Conducting Copolymer with Aniline Tetramer as Intelligent Biological Adhesive for Bone Tissue Engineering.

Electrically conducting polymers have been emerging as intelligent bioactive materials for regulating cell behaviors and bone tissue regeneration. Additionally, poor adhesion between conventional implants and native bone tissue may lead to displacement, local inflammation, and unnecessary secondary surgery. Thus, a conductive bioadhesive with strong adhesion performance provides an effective approach to fulfill fixation and regeneration of comminuted bone fracture. Inspired by mussel chemistry, we designed the conductive copolymers poly{[aniline tetramer methacrylamide]-co-[dopamine methacrylamide]-co-[poly(ethylene glycol) methyl ether methacrylate]} [poly(ATMA-co-DOPAMA-co-PEGMA); AT:conductive aniline tetramer; DOPA:dopamine; PEG:poly(ethylene glycol))] with AT content 3.0, 6.0, and 9.0 mol %, respectively. The adhesive strength of this copolymer was enhanced during tensile process perhaps due to the synergistic effects of H-bonding, π-π interactions, and polymer long-chain entanglement, reaching up to 1.28 MPa with 6 mol % AT. Biological characterizations of preosteoblasts indicated that the bioadhesives exhibited desirable biocompatibility. In addition, the osteogenic differentiation was synergistically enhanced by the conductive substrate and electrical stimulation with a square wave, frequency of 100 Hz, 50% duty cycle, and electrical potential of 500 mV, as indicated by ALP activity, calcium deposition, and expression of osteogenic genes. The ALP activity at 14 days and calcium deposition at 28 days on the 9 mol % AT group were significantly higher than that on PLGA under electrical stimulation. The expression value of OPN for 9 mol % AT group was notably upregulated by 5.9-fold compared with PLGA at 7 days under electrical stimulation. Overall, the conductive polymers with strong adhesion can synergistically upregulate the cellular activity combining with electrical stimulation and might be a promising bioadhesive for orthopedic and dental applications.

A Novel Application of Electroactive Polyimide Doped with Gold Nanoparticles: As a Chemiresistor Sensor for Hydrogen Sulfide Gas.

This research paper presents a new application of electroactive polyimide doped with gold nanoparticles (PI/AuNPs) as a chemiresistor sensor for detecting hydrogen sulfide gas. The synthesis of PI/AuNPs was done in a simple 3-step process of polymerization using the as prepared amine-capped aniline trimer (ACAT), followed by imidization, and doping. Spectral analyses via FTIR, LC-MS and 1H-NMR confirmed the formation of amine-capped aniline trimer with a MW of 288 g mol-1. Comparison of ACAT, BSAA, and PI FTIR spectra showed successful polymerization of the last, while XRD validated the incorporation of metal nanoparticles onto the polymer matrix, showing characteristic diffraction peaks corresponding to gold. Furthermore, TEM, and FE-SEM revealed the presence of well-dispersed Au nanoparticles with an average diameter of about 60 nm. The electroactive PI/AuNPs-based sensor showed a sensitivity of 0.29% ppm-1 H2S at a linear concentration range of 50 to 300 ppm H2S (r = 0.9777). The theoretical limit of detection was found at 0.142 ppm or 142 ppb H2S gas. The sensor provided a stable response reading at an average response time of 43 ± 5 s, which was easily recovered after an average time of 99 ± 5 s. The sensor response was highly repeatable and reversible, with RSD values of 8.88%, and 8.60%, respectively. Compared with the performance of the conventional conducting polyaniline also doped with gold nanoparticles (PANI/AuNPs), the fabricated electroactive PI/AuNPs exhibited improved sensing performance making it a potential candidate in monitoring H2S in the environment and for work-related safety.

Electroactive Composite of FeCl3 -Doped P3HT/PLGA with Adjustable Electrical Conductivity for Potential Application in Neural Tissue Engineering.

Conducting polymers (CPs) is one of intelligent biomaterials with the specific properties of reversible redox states, which have a significant effects on the cell behaviors and nerve tissue regeneration. However, the effects of CPs with different electrical conductivity on the behaviors of nerve cells are rarely reported. Therefore, a kind of Poly(3-hexylthiophene) (P3HT) with certain molecular weight is synthesized by Kumada catalyst transfer polymerization (KCTP) method and employed to prepare bioabsorbable and electroactive intelligent composites of Poly(3-hexylthiophene)/Poly(glycolide-lactide) (P3HT/PLGA). FeCl3 doping electroactive membranes with different electrical conductivities are prepared to investigate the cell behaviors. On the substrate with higher electrical conductivity, the proliferation of rat adrenal pheochromocytoma cells (PC12 cells) is significantly promoted and neurite length is increased obviously. In particular, the most significant improvements are the neuron gene expression of Synapsin 1 and microtubule-associated protein 2 (MAP2) by the composites with high conductivity. These results suggest that P3HT/PLGA with suitable electrical conductivity have a positive role in promoting neural growth and differentiation, which is promising for advancing potential application of nerve repair and regeneration.

Hazardous impacts of silver nanoparticles on mouse oocyte maturation and fertilization and fetal development through induction of apoptotic processes.

Silver nanoparticles (AgNPs) are antibacterial materials widely used in numerous products and medical supplies. Previously, we showed that AgNPs trigger apoptotic processes in mouse blastocysts, leading to a decrease in cell viability and impairment of preimplantation and postimplantation embryonic development in vitro and in vivo. In the present study, we further investigated the hazardous effects of AgNPs on mouse oocyte maturation, in vitro fertilization (IVF), and subsequent preimplantation and postimplantation development in vitro and in vivo. Data from in vitro experiments revealed that AgNPs impair mouse oocyte maturation, decrease IVF rates, and induce injury effects on subsequent embryonic development to a significant extent. In an animal model, intravenous injection of AgNPs (5 mg/kg body weight) led to a significant decrease in mouse oocyte maturation and IVF concomitant with impairment of early embryonic development in vivo. Importantly, pretreatment with N-acetylcysteine effectively prevented AgNP-triggered reactive oxygen species (ROS) production and apoptosis, clearly suggesting a critical role of ROS as an upstream initiator or key regulator of AgNP-induced hazardous effects on oocyte maturation and sequent embryonic development. Furthermore, preincubation of oocytes with Ac-DEVD-cho, a caspase-3-specific inhibitor, effectively prevented hazardous effects, highlighting the potential involvement of caspase-dependent apoptotic signaling cascades in AgNP-mediated events. Expression levels of p53 and p21 of blastocysts were upregulated upon preincubation of mouse oocytes with AgNPs. Our collective results imply that cell apoptosis in mouse blastocysts derived from the AgNP-pretreated oocytes via intracellular ROS generation, which is further mediated through p53-, p21-, and caspase-3-dependent regulatory mechanisms.

Detection and discrimination of maintenance and de novo CpG methylation events using MethylBreak.

Understanding the principles governing the establishment and maintenance activities of DNA methyltransferases (DNMTs) can help in the development of predictive biomarkers associated with genetic disorders and diseases. A detection system was developed that distinguishes and quantifies methylation events using methylation-sensitive endonucleases and molecular beacon technology. MethylBreak (MB) is a 22-mer oligonucleotide with one hemimethylated and two unmethylated CpG sites, which are also recognition sites for Sau96I and SacII, and is attached to a fluorophore and a quencher. Maintenance methylation was quantified by fluorescence emission due to the digestion of SacII when the hemimethylated CpG site is methylated, which inhibits Sau96I cleavage. The signal difference between SacII digestion of both MB substrate and maintenance methylated MB corresponds to de novo methylation event. Our technology successfully discriminated and measured both methylation activities at different concentrations of MB and achieved a high correlation coefficient of R2=0.997. Additionally, MB was effectively applied to normal and cancer cell lines and in the analysis of enzymatic kinetics and RNA inhibition of recombinant human DNMT1.

Curcuminoids and resveratrol as anti-Alzheimer agents.

Alzheimer disease (AD) is by far the most common cause of dementia globally. This neurodegenerative disorder of the brain is chronic and progressive, characterized clinically by the deterioration in the key symptoms of behavioral and cognitive abilities. Treatment options for this disease currently are limited. Deposition of amyloid-ß and tau hyperphosphorylation are cardinal pathologic features of AD that lead to the formation of neuronal plaques and neurofibrillary tangles, respectively. In addition to mounting research on herbal compounds for the treatment of AD, curcuminoids and resveratrol appear to be beneficial as anti-AD agents. Curcuminoids (curcumin and demethoxycurcumin) and resveratrol possess unique properties that make them especially worthy of further studies. This review article revisits and presents the current research done on the potential of the curcuminoids curcumin and demethoxycurcumin and the polyphenolic compound resveratrol as anti-AD compounds.

Effects of curcumin and demethoxycurcumin on amyloid-ß precursor and tau proteins through the internal ribosome entry sites: a potential therapeutic for Alzheimer's disease.

OBJECTIVE: This study aims to determine the effects of curcumin and demethoxycurcumin on the internal ribosome entry site of the amyloid-ß precursor protein (APP) and tau protein through a bi-cistronic reporter assay for screening of anti-Alzheimer's disease agents. MATERIALS AND METHODS: A bi-cistronic assay was performed wherein the expression of the first cistron, a ß-galactosidase gene under the control of a cytomegalovirus promoter, represents the canonical cap-dependent mechanism of translation initiation; while the second cistron involves the utilization of the APP or the tau IRES elements to drive the expression of secreted alkaline phosphatase (SEAP) under a cap-independent mechanism. Bioactive natural products reported to have therapeutic potential for AD such as curcumin and demethoxycurcumin were screened in an murine neuroblastoma (N2A) cell model. Western blot analyses for the expression of APP C-terminal protein, human tau-1, and phosphorylated tau at Serine 262 (p(262)) and Serine 396 (pS(396)) were done after treatment of N2A cells with the test compounds. RESULTS: The bi-cistronic reporter assay revealed that curcumin was more effective than demethoxycurcumin, a structural analog of curcumin, in inhibiting both APP and tau IRES-dependent translation initiation. This result was further confirmed by Western blot analysis for the expression of APP C-terminal protein, human tau-1, pS(262) and pS(396) suggesting that curcumin may play a role in AD pathology alleviation through the inhibition of the APP and tau IRES-mediated translation mechanism. On the other hand, demethoxycurcumin was observed to inhibit the phosphorylation of both tau pS(262) and pS(396). CONCLUSION: A novel assay system using the bi-cistronic reporter constructs for the identification of compounds with activity against the translation directed by APP and tau IRES was developed. The results provide novel suggestive insights for the potential use of the mentioned compounds as prophylactic and therapeutic anti-AD agents.

Nano-sized micelles of block copolymers of methoxy poly(ethylene glycol)-poly(epsilon-caprolactone)-graft-2-hydroxyethyl cellulose for doxorubicin delivery.

The amphiphilic block copolymers methoxy poly(ethylene glycol)-poly(epsilon-caprolactone) was grafted to 2-hydroxyethyl cellulose to produce the water-soluble copolymers. Doxorubicin loaded nanoparticles were prepared by dialysis method and the sizes of nanoparticles were determined by dynamic light scattering in solution and atomic force microscopes. As results the sizes were detected in a range of 197.4 to 340.7 nm. The in-vitro release of Dox was studied in phosphate and acetate buffered solution at 37 degrees C. The results showed that 43 and 53% of Dox remained after an incubation period of 7 days. The cytotoxicity of Dox loaded micelles was investigated in two different human MCF-7/wild type and MCF-7/Adriamycin drug resistant cells lines. The Dox-loaded micelles showed reduced cytotoxicity compared to free Dox in MCF-7/wild type and MCF-7/Adriamycin drug resistant cells.