Optimization of Alkali Treatment for Production of Fermentable Sugars and Phenolic Compounds from Potato Peel Waste Using Topographical Characterization and FTIR Spectroscopy.

Potato peel waste (PPW) was utilized as a bio-template for the production of valuable compounds such as reducing sugars (RS), total sugar (TS) and total phenolic compounds (TPC). Two methods of alkali treatments, i.e., chemical (NaOH) and thermochemical (NaOH assisted with autoclaving) processes, were employed for the deconstruction of PPW. Response surface methodology (RSM) was used to study the effects of alkali concentration (0.6-1.0 w/v), substrate concentration (5-15 g) and time (4-8 h) on the extraction of RS, TS and TP from PPW. The application of alkali plus steam treatment in Box-Behnken design (BBD) with three levels yielded the optimum releases of RS, TS and TP as 7.163, 28.971 and 4.064 mg/mL, respectively, corresponding to 10% substrate loading, in 0.6% NaOH for 8 h. However, the alkali treatment reported optimum extractions of RS, TS and TP as 4.061, 17.432 and 2.993 mg/mL, respectively. The thermochemical pretreatment was proven a beneficial process as it led to higher productions of TP. FTIR and SEM were used to analyze the deterioration levels of the substrate. The present work was used to explore the sustainable management of PPW, which is a highly neglected substrate bioresource but is excessively dumped in open environment, raising environmental concerns. The cost-effective methods for the breakdown of PPW starch into fermentable sugars might be utilized to extract valuable compounds.

Experimental Study on the Mechanical Properties and Microstructure of Metakaolin-Based Geopolymer Modified Clay.

Clay is found in some countries all over the world. It usually has low compressive strength and cannot be used as a bearing material for subgrade soil. In this paper, the influence of basicity on a metakaolin-based polymer binder to improve clay was studied. The effects of the molar concentration of the alkali activator, different concentration of the metakaolin-based geopolymer and curing time on unconfined compressive strength were studied. The alkali activator-to-ash ratio was maintained at 0.7. The percentage of metakaolin added to the soil relative to metakaolin and soil mixture was 6%, 8%, 10% and 12%. The sodium hydroxide concentrations are 2M, 4M, 6M and 8M. Unconfined compressive strength (UCS) was tested on days 3, 7, 14 and 28, respectively. Compared with original clay, the results show that the unconfined compressive strength increases with the increase in metakaolin content and molar concentration of NaOH. The maximum compressive strength of the sample with NaOH concentration of 8M and percentage of 12% was 4109 kN on the 28th day, which is about 112% higher than that of the original clay. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results showed that the cementing compound covered the clay particles due to the reaction of the geopolymer with the clay, resulting in the formation of adhesive particles. The main purpose of this study is to verify the effectiveness and stability of metakaolin-based geopolymer binder polymerization under normal temperature and a strong alkali environment. The results can provide parameters for the application and promotion of metakaolin-based geopolymers in soil improvement engineering.

Characterization of Chemically-Induced Bacterial Ghosts (BGs) Using Sodium Hydroxide-Induced Vibrio parahaemolyticus Ghosts (VPGs).

Acellular bacterial ghosts (BGs) are empty non-living bacterial cell envelopes, commonly generated by controlled expression of the cloned lysis gene E of bacteriophage PhiX174. In this study, Vibrio parahaemolyticus ghosts (VPGs) were generated by chemically-induced lysis and the method is based on minimum inhibitory concentration (MIC) of sodium hydroxide (NaOH), acetic acid, boric acid, citric acid, maleic acid, hydrochloric acid, and sulfuric acid. The MIC values of the respective chemicals were 3.125, 6.25, <50.0, 25.0, 6.25, 1.56, and 0.781 mg/mL. Except for boric acid, the lysis efficiency reached more than 99.99% at 5 min after treatment of all chemicals. Among those chemicals, NaOH-induced VPGs appeared completely DNA-free, which was confirmed by quantitative real-time PCR. Besides, lipopolysaccharides (LPS) extracted from the NaOH-induced VPGs showed no distinctive band on SDS-PAGE gel after silver staining. On the other hand, LPS extracted from wild-type bacterial cells, as well as the organic acids-induced VPGs showed triple major bands and LPS extracted from the inorganic acids-induced VPGs showed double bands. It suggests that some surface structures in LPS of the NaOH-induced VPGs may be lost, weakened, or modified by the MIC of NaOH. Nevertheless, Limulus amoebocyte lysate assay revealed that there is no significant difference in endotoxic activity between the NaOH-induced VPGs and wild-type bacterial cells. Macrophages exposed to the NaOH-induced VPGs at 0.5 × 106 CFU/mL showed cell viability of 97.9%, however, the MIC of NaOH did not reduce the cytotoxic effect of wild-type bacterial cells. Like Escherichia coli LPS, the NaOH-induced VPGs are an excellent activator of pro-inflammatory cytokines (IL-1ß and iNOS), anti-inflammatory cytokine (IL-10), and dual activities (IL-6) in the stimulated macrophage cells. On the other hand, the induction of TNF-α mRNA was remarkable in the macrophages exposed with wild-type cells. Scanning electron microscopy showed the formation of trans-membrane lysis tunnel structures in the NaOH-induced VPGs. SDS-PAGE and agarose gel electrophoresis also confirmed that cytoplasmic proteins and genomic DNA released from the VPGs to culture medium through the lysis tunnel structures. Taken together, all these data indicate that the NaOH-induced VPGs show the potency of a safe, economical, and effective inactivated bacterial vaccine candidate.

Inhibitory effects of glutathione peroxidase on microbial spoilage of crayfish (Procambarus clarkii) during refrigerated storage.

The variety of enzyme-based biological preservatives is limited. This study evaluated the effects of glutathione peroxidase (GSH-Px) on the quality of crayfish during refrigerated storage by measuring the pH, total volatile basic nitrogen, trimethylamine, and microbial contamination in crayfish muscle simulation system. The results revealed that 0.3% GSH-Px (CK3) not only suppressed the degradation of nitrogenous substances but also decreased the contamination levels of total viable, Enterobacteriaceae, and Pseudomonas counts (P < 0.05). Furthermore, the populations of Lactococcus, Aeromonas, and Massilia differed in the CK3 group compared to the other groups (P < 0.05) at the end of the storage (day 15). Moreover, the principal coordinate analysis showed that the colony composition of CK3 stored for 15 days was similar to that of the control group stored for 10 days. Therefore, GSH-Px exhibits antibacterial activity against Gram-negative bacteria and has good application potential in freshwater aquatic product preservation.

Chitin nanofibrils assisted 3D printing all-chitin hydrogels for wound dressing.

The direct ink writing technique used in 3D printing technology is generally applied to designing biomedical hydrogels. Herein, we proposed a strategy for preparing all-chitin-based inks for wound dressing via direct ink writing technique. The ß-chitin nanofibers (MACNF) with a high aspect ratio were applied as a nanofiller to modulate the rheological properties of the alkaline dissolved chitin solution. The printing fidelity significantly depends on the MACNF introduction amount to the composite ink. 5-10 wt% MACNF ratio showed superior printing performance. The printed scaffold showed a uniform micron-sized pore structure and a woven network of nanofibers. Due to the good biocompatibility of chitin and the stereoscopic spatial skeleton, this scaffold showed excellent performance as a wound dressing, which can promote cell proliferation, collagen deposition and the angiogenesis of wounds, demonstrating its potential in biomedical applications. This approach successfully balanced the chitinous printability and biofunctions.

Inhibition of human cervical cancer development through p53-dependent pathways induced by the specified triple helical ß-glucan.

This study demonstrates that the purified ß-glucan (LNT) with a triple helix and relatively narrow molecular weight distribution, extracted and purified from artificially cultured Lentinus edodes, showed a significant cervical cancer inhibition with little cytotoxicity against normal cells in vitro and in vivo. From the in vitro data, the potential mechanism of anti-cervical cancer was preliminarily revealed as follows: LNT was firstly recognized by the human cervical cancer cell line of Hela and induced cell proliferation inhibition through p21 and apoptosis via a mitochondrion-dependent pathway by targeting the tumor suppressor of p53, indicated by an increase in reactive oxygen species (ROS) generation and a loss of mitochondrial membrane potential (Δψm), in a significant dosage-dependent manner. Meanwhile, LNT repressed tumor growth with an inhibition ratio of 61.2 % and induced tumor cell apoptosis through endogenous MDM2/p53/Bax/mitochondrion signal pathway by up-regulating the expression of p53, Bax, Cyt. c, caspase 9, and caspase 3, as well as down-regulating Bcl-2, MDM2, and PARP1 levels in Hela cells-transplanted BALB/c nude mice. This study provides a scientific basis for the clinical treatment of cervical cancer with LNT as a potential drug candidate characterized by the triple helix and specified molecular weight with a relatively narrow distribution.

A new non-enzymatic biosensor for the determination of bisphenol-A.

In this study, a new non-enzymatic carbon paste biosensor was developed for the determination of Bisphenol-A (BPA) based on Multiwalled Carbon Nanotube (MWCNT) modified Myoglobin (Mb). The measurement principle of the biosensor was developed based on the inhibition effect of BPA on the heme group of myoglobin in the presence of hydrogen peroxide. With the designed biosensor, measurements were taken in the potential range of (-0.15 V & +0.65 V) using the differential pulse voltammetry (DPV) method in the medium containing K4[Fe(CN)6]. The linear range for BPA was determined to be 100-1000 µM. Response time was calculated as 16 s. The limit of detection was set at 89 µM. As a result, it has been proven that MWCNT modified myoglobin based biosensor is an alternative method that can be used for BPA determination, giving very sensitive and fast results.

Dual-network polyacrylamide/carboxymethyl chitosan-grafted-polyaniline conductive hydrogels for wearable strain sensors.

Conductive, wearable, and flexible hydrogel-based sensors are considered as promising applications in human motion detection and physiological signal monitoring. However, it is still a problem to integrate multiple functions into one material for the next-generation smart devices. Herein, we fabricated an ionic/electronic dual conductive hydrogel by combining the chemically crosslinked polyacrylamide (PAM) and the physically crosslinked carboxymethyl chitosan-grafted-polyaniline (CMCS-g-PANI)/Ag+ network. The double-network hydrogel displays a high stretchability, repeatable adhesiveness, antibacterial activities, and biocompatibility. It also has high sensitivity and stable electrical performance for wearable strain sensors. Furthermore, we assembled a self-powered strain sensor based on the conversion of chemical energy to electrical energy. It can be used for human motion detection even without external power supply. This work provides an avenue for the development of multifunctional hydrogels with outstanding mechanical and electronic performances for application in wearable electronic devices.

High-performance triboelectric nanogenerator based on chitin for mechanical-energy harvesting and self-powered sensing.

Environment issues and energy crisis call for eco-friendly, biodegradable and low-cost natural materials for the extensive application of distributed energy harvesting triboelectric nanogenerators (TENGs) and multi-functional self-powered sensors. Here, flexible, robust and transparent chitin films fabricated via non-freezing dissolution approach in KOH/urea were used as tribopositive material to assemble TENGs, which served as outstanding mechanical energy harvesters and multi-functional self-powered sensors. The tensile strength and elongation at break of the chitin film reached 84.7 MPa and 14.5%, better than most existing biodegradable-based films. The chitin-based TENG (CF-TENG) achieved open-circuit voltage up to 182.4 V, short-circuit current of 4.8 µA and maximum power density over 1.25 W m-2. Furthermore, the CF-TENG can be utilized as tactile sensors for handwriting recognition and health monitoring of subtle pressures, as well as non-contact sensation, exhibiting great potential as self-powered sensors and human-machine interfaces.

Anisotropic chitosan/tunicate cellulose nanocrystals hydrogel with tunable interference color and acid-responsiveness.

A robust chitosan/tunicate cellulose nanocrystals (TCNCs) anisotropic hydrogel with bright interference colors was fabricated via combining the prestretching orientation method and chemically-physically dual cross-linking. The oriented regenerated chitosan nanofibrous network enabled the TCNCs alignment by covalent interaction and hydrogen bonding. The stretching alignment endows the chitosan/TCNCs hydrogel with enhanced tensile strength, from 0.63 MPa (draw ratio 1.0) to 2.06 MPa (draw ratio 3.5). Moreover, the orientation of chitosan nanofibers led to birefringence appearance, which could be regulated with the TCNCs introduction or draw ratios. The hydrogel swelled completely in 2 min in pH = 3 solution and the interference color disappeared. The oriented chitosan/TCNCs hydrogels showed distinct color change under acid stimulation, which could be quantitatively measured or directly observed under crossed polarizers. This work demonstrated a strategy for fabricating the interference color regulatable hydrogels with acid-response property for sensors and environmental monitoring.

Polyphenol-driving assembly for constructing chitin-polyphenol-metal hydrogel as wound dressing.

The metal-polyphenol networks have attracted appealing attention for diverse biomedical applications due to their remarkable characteristics. Though various of metal-polyphenolic materials have been prepared, the homogeneous metal-polyphenol based hydrogel fabrication remains a challenge (e.g., quick aggregation). Herein, a facile and low-cost polyphenol-mediating non-covalent driven assembly strategy was developed for fabricating homogeneous chitin-polyphenol-metal hydrogels. Polyphenols not only noncovalently crosslinked chitin chains, but simultaneously captured metal nanomaterials from metal substrates and immobilized in chitin-polyphenol networks. A range of metal (Fe, Cu, Ti, Zn) and polyphenol (tannic acid, gallic acid, quercetin, pyrogallic acid) could be incorporated into this hydrogel framework. As a demonstration, the chitin-tannic acid-Cu hydrogel showed excellent antibacterial properties and significantly enhanced infected wound repair via promoting the cell proliferation and angiogenesis, showing the potential in wound dressing. The low cost, versatility and flexibility assembly process can be used to fabricate diverse polymer-polyphenol-metal hydrogel, thereby enabling their use in various applications.

Multifunctional chitin-based hollow nerve conduit for peripheral nerve regeneration and neuroma inhibition.

The recoverability for peripheral nerve lesions with a long segment defect is much challenging. Conventional methods for sciatic nerve repair excepted for autografts are bridged with nerve guidance conduit (NGC). Herein, the chitin-based NGC (ChT NGC) is firstly reported by facile dissolution, molding and regeneration process, performed excellent nerve regeneration and neuroma inhibition after deposited with anti-inflammatory polydopamine (ChT-PDA NGC). In 10 mm sciatic nerve defect rat model, the restorative effects of ChT-PDA NGC groups are similar to autografts. That is mainly ascribed to the high activity of Schwann cells and claimed by immunofluorescence staining and Western blot analysis. Interestingly, ChT-PDA NGC presents outstanding neuroma inhibition during the nerve regeneration as for the anti-inflammatory activity of PDA. This work provides a facile and novel approach to prepare hollow chitin hydrogel tube, which presents well nerve regeneration and neuroma inhibition, improving the potential high-value application of chitin in biomedical fields.

Use of jackfruit leaf (Artocarpus heterophyllus L.) protein hydrolysates as a stabilizer of the nanoemulsions loaded with extract-rich in pentacyclic triterpenes obtained from Coccoloba uvifera L. leaf.

This study aimed to evaluate the encapsulating potential of a jackfruit leaf protein hydrolysate, through obtaining pentacyclic triterpenes-rich extract loaded nanoemulsion. Response surface methodology (RSM) was used to optimize the conditions to obtain an optimal nanoemulsion (NE-Opt). The effect of protein hydrolysate concentration (0.5-2%), oil loaded with extract (2.5-7.5%), and ultrasound time (5-15 min) on the polydispersity index (PDI) and droplet size of the emulsion (D[3,2] and D[4,3]) was evaluated. RSM revealed that 1.25% protein hydrolysate, 2.5% oil, and ultrasound time of 15 min produced the NE-Opt with the lowest PDI (0.85), D[3,2] (330 nm), and D[4,3] (360 nm). Encapsulation efficiency and extract loading of the NE-Opt was of 40.15 ± 1.46 and 18.03 ± 2.78% respectively. The NE-Opt was relatively stable during storage (at 4 and 25 °C), pH, temperature, and ionic strength. Then, the protein hydrolysate could be used as an alternative to conventional emulsifiers.

Edible pectin film added with peptides from jackfruit leaves obtained by high-hydrostatic pressure and pepsin hydrolysis.

Jackfruit (Artocarpus heterophyllus Lam.) is an evergreen tree that produces a high waste of leaves. This study evaluated the obtention of peptides from jackfruit leaves using pancreatin and pepsin, their antifungal activity, and their effect on pectin films. The protein content was 7.64 ± 0.12 g/100 g of jackfruit fresh leaves. Pancreatin produced a higher yield than pepsin in the obtention of peptides (p ≤ 0.05). However, peptides obtained after 2 h by pepsin hydrolysis (Pep-P) had six essential amino acids and inhibited > 99% of mycelial growth and spore germination of Colletotrichum gloeosporioides. Pectin films with Pep-P showed a slight brown color, lower thickness, water vapor permeability, and moisture content, as well as higher thermal stability and better inhibition properties against C. gloeosporioides than pectin films without Pep-P (p ≤ 0.05). Pectin films added with Pep-P from jackfruit leaf could be a green alternative to anthracnose control in tropical fruits.

An integrative study on biologically recovered polyhydroxyalkanoates (PHAs) and simultaneous assessment of gut microbiome in yellow mealworm.

Polyhydroxyalkanoates (PHAs) are produced in microbes as a source of carbon and energy storage. They are biodegradable and have properties similar to synthetic plastics, which make them an interesting alternative to petroleum-based plastics. In this study, a refined method of recovering PHA from Cupriavidus necator biomass was proposed by incorporating the use of the yellow mealworm (the larval phase of the mealworm beetle, Tenebrio molitor) as partial purification machinery, followed by washing of the fecal pellets with distilled water and sodium hydroxide. The PHA contents of the cells used in this study were 55wt% (produced from palm olein) and 60 wt% (produced from waste animal fats). The treatment of distilled water and NaOH further increased the purity of PHA to 94%. In parallel, analysis of the 16S rRNA metagenomic sequencing of the mealworm gut microbiome has revealed remarkable changes in the bacterial diversity, especially between the mealworms fed with cells produced from palm olein and waste animal fats. This biological recovery of PHA from cells is an attempt to move towards a green and sustainable process with the aim of reducing the use of harmful solvents and strong chemicals during polymer purification. The results obtained show that - purities of >90%, without a reduction in the molecular weight, can be obtained through this integrative biological recovery approach. In addition, this study has successfully shown that the cells, regardless of their origins, were readily consumed by the mealworms, and there is a correlation between the feed type and the mealworm gut microbiome.

Synthesis of a bioadsorbent from jute cellulose, and application for aqueous Cd (II) removal.

A low-cost, high-adsorption-capacity, eco-friendly bioadsorbent for removing Cd2+ from aqueous solution is reported. J-g-P(AM-co-AANa) was prepared by hydrolysis of the grafted copolymer, which was synthesized by free radical polymerization of acrylamide (AM) with jute fibers (JSE) pretreated by continuous screw-extrusion steam explosion. Fourier transform infrared and solid-state 13C nuclear magnetic resonance spectroscopies, confirmed that amino and carboxylate groups were introduced into J-g-P(AM-co-AANa). X-ray diffraction showed that the crystallinity of J-g-P(AM-co-AANa) was significantly lower than that of JSE. The surface morphology of bioadsorbent was investigated by scanning electron microscopy (SEM). The adsorption capacity of Cd2+ on J-g-P(AM-co-AANa) was evaluated for different solution pH values, contact times, and initial Cd2+ concentrations. The adsorption kinetics followed the pseudo-second-order kinetic model, and the rate controlling step was chemisorption. The adsorption isotherm was well fitted by the Freundlich model, and the adsorption process was multilayer adsorption. The maximum adsorption capacity was 344.8 mg/g, which indicated that the bioadsorbent was effective for removing Cd2+ from aqueous solution.

Pleurodesis: a comparison of two sclerosing agents for pleural effusions in Mozambique.

BACKGROUND: Pleural effusions constitute one of the most frequent pathologies encountered in the pulmonary service of Maputo Central Hospital (MCH) in Mozambique. Bleomycin and talc are commonly used for pleurodesis, but cost prohibitive, therefore we aimed to retrospectively compare the efficacy and safety of sodium hydroxide (NaOH) with bleomycin for pleurodesis. METHODS: Case records of pleurodesis using bleomycin and NaOH from 2002 to 2013 were reviewed. Standard of care for pleurodesis for recurrent pleural effusions at MCH was developed using the materials available. NaOH remained the agent of choice until 2006 when bleomycin became available. Clinical data regarding general complications, rate of success and lung expansion were noted for every patient who underwent pleurodesis at MCH during this time frame. RESULTS: Review of pleurodesis at MCH revealed 24 cases using bleomycin and 23 cases using NaOH as the sclerosing agent. Patient characteristics were balanced between the two groups with majority of pleural effusions malignant in etiology. CONCLUSIONS: There was no statistically significant difference between the use of bleomycin and NaOH as defined by lung expansion. General complications were observed less frequently in 2 (10%) of patients treated with NaOH compared with 8 (38%) of patients using bleomycin. Only three patients presented with recurrent pleural effusion after pleurodesis with NaOH. NaOH may offer a low cost alternative sclerosing agent for resource limited areas.

TCA precipitation.

Trichloroacetic acid (TCA) precipitation of proteins is commonly used to concentrate protein samples or remove contaminants, including salts and detergents, prior to downstream applications such as SDS-PAGE or 2D-gels. TCA precipitation denatures the protein, so it should not be used if the protein must remain in its folded state (e.g., if you want to measure a biochemical activity of the protein).