Preparation of Chitin Nanofibers and Natural Rubber Composites and Their Triboelectric Nanogenerator Applications.

Triboelectric nanogenerators (TENGs) have gained significant attention as promising energy-harvesting devices that convert mechanical energy into electrical energy through charge separation induced by friction and electrostatic induction. In this study, we explore the utilization of biowaste shrimp shell-extracted chitin nanofiber (ChNF) as a viable eco-friendly material for TENG applications. Composite materials were prepared by incorporating ChNF into natural rubber (NRL) at loading levels of 0.1 and 0.2 wt% (NRL/ChNF) to form the TENG triboelectric layer. ChNFs with a uniform width of approximately 10-20 nm were successfully extracted from the shrimp shells through a simple mechanical procedure. The NRL/ChNF composites exhibited enhanced mechanical properties, as evidenced by a higher Young's modulus (3.4 GPa) compared to pure NRL. Additionally, the NRL/ChNF composites demonstrated an increased dielectric constant of 3.3 at 0.1 MHz. Moreover, the surface potential difference of NRL increased from 0.182 V to 1.987 V in the NRL/ChNF composite. When employed as the triboelectric layer in TENG, the NRL/ChNF composites exhibited significant improvement in their output voltage, with it reaching 106.04 ± 2.3 V. This enhancement can be attributed to the increased dielectric constant of NRL/ChNF, leading to enhanced charge exchange and charge density. This study presents a straightforward and environmentally friendly technique for preparing sustainable natural materials suitable for energy-harvesting devices.

Photoinduced charge generation of nanostructured carbon derived from human hair biowaste for performance enhancement in polyvinylidene fluoride based triboelectric nanogenerator.

Carbon nanostructures derived from human hair biowaste are incorporated into polyvinylidene fluoride (PVDF) polymer to enhance the energy conversion performance of a triboelectric nanogenerator (TENG). The PVDF filled with activated carbon nanomaterial from human hair (AC-HH) exhibits improved surface charge density and photoinduced charge generation. These remarkable properties are attributed to the presence of graphene-like nanostructures in AC-HH, contributing to the augmented performance of PVDF@AC-HH TENG. The correlation of surface morphologies, surface charge potential, charge capacitance properties, and TENG electrical output of the PVDF composites at various AC-HH loading is studied and discussed. Applications of the PVDF@AC-HH TENG as a power source for micro/nanoelectronics and a movement sensor for detecting finger gestures are also demonstrated. The photoresponse property of the fabricated TENG is demonstrated and analyzed in-depth. The analysis indicates that the photoinduced charge carriers originate from the conductive reduced graphene oxide (rGO), contributing to the enhanced surface charge density of the PVDF composite film. This research introduces a novel approach to enhancing TENG performance through the utilization of carbon nanostructures derived from human biowaste. The findings of this work are crucial for the development of innovative energy-harvesting technology with multifunctionality, including power generation, motion detection, and photoresponse capabilities.

Highly Sensitive and Selective Formaldehyde Gas Sensors Based on Polyvinylpyrrolidone/Nitrogen-Doped Double-Walled Carbon Nanotubes.

A highly sensitive and selective formaldehyde sensor was successfully fabricated using hybrid materials of nitrogen-doped double-walled carbon nanotubes (N-DWCNTs) and polyvinylpyrrolidone (PVP). Double-walled carbon nanotubes (DWCNTs) and N-DWCNTs were produced by high-vacuum chemical vapor deposition using ethanol and benzylamine, respectively. Purified DWCNTs and N-DWCNTs were dropped separately onto the sensing substrate. PVP was then dropped onto pre-dropped DWCNT and N-DWCNTs (hereafter referred to as PVP/DWCNTs and PVP/N-DWCNTs, respectively). As-fabricated sensors were used to find 1,2-dichloroethane, dichloromethane, formaldehyde and toluene vapors in parts per million (ppm) at room temperature for detection measurement. The sensor response of N-DWCNTs, PVP/DWCNTs and PVP/N-DWCNTs sensors show a high response to formaldehyde but a low response to 1,2-dichloroethane, dichloromethane and toluene. Remarkably, PVP/N-DWCNTs sensors respond sensitively and selectively towards formaldehyde vapor, which is 15 times higher than when using DWCNTs sensors. This improvement could be attributed to the synergistic effect of the polymer swelling and nitrogen-sites in the N-DWCNTs. The limit of detection (LOD) of PVP/N-DWCNTs was 15 ppm, which is 34-fold higher than when using DWCNTs with a LOD of 506 ppm. This study demonstrated the high sensitivity and selectivity for formaldehyde-sensing applications of high-performance PVP/N-DWCNTs hybrid materials.

Thermoresponsive C22 phage stiffness modulates the phage infectivity.

Bacteriophages offer a sustainable alternative for controlling crop disease. However, the lack of knowledge on phage infection mechanisms makes phage-based biological control varying and ineffective. In this work, we interrogated the temperature dependence of the infection and thermo-responsive behavior of the C22 phage. This soilborne podovirus is capable of lysing Ralstonia solanacearum, causing bacterial wilt disease. We revealed that the C22 phage could better infect the pathogenic host cell when incubated at low temperatures (25, 30 °C) than at high temperatures (35, 40 °C). Measurement of the C22 phage stiffness revealed that the phage stiffness at low temperatures was 2-3 times larger than at high temperatures. In addition, the imaging results showed that more C22 phage particles were attached to the cell surface at low temperatures than at high temperatures, associating the phage stiffness and the phage attachment. The result suggests that the structure and stiffness modulation in response to temperature change improve infection, providing mechanistic insight into the C22 phage lytic cycle. Our study signifies the need to understand phage responses to the fluctuating environment for effective phage-based biocontrol implementation.

Development of Tea Seed Oil Nanostructured Lipid Carriers and In Vitro Studies on Their Applications in Inducing Human Hair Growth.

Synthetic drugs used to treat hair loss cause many side-effects. Natural tea seed oil possesses many activities that can suppress hair loss. However, it is oily and sticky in direct application. In this study, tea seed oil loaded nanostructured lipid carriers (NLC) using Tween 80 (NLC-T), Varisoft 442 (NLC-V), and a combination of both surfactants (NLC-C) was developed. The obtained nanoformulations showed spherical particles in the size range 130-430 nm. Particle size and size distribution of NLC-C and NLC-T after storage at 4, 25, and 40 °C for 90 days were unchanged, indicating their excellent stability. The pH of NLC-T, NLC-V, and NLC-C throughout 90 days remained at 3, 4, and 3.7, respectively. NLC-C showed significantly greater nontoxicity and growth-stimulating effect on human follicle dermal papilla (HFDP) cells than the intact oil. NLC-T and NLC-V could not stimulate cell growth and showed high cytotoxicity. NLC-C showed melting point at 52 ± 0.02 °C and its entrapment efficiency was 96.26 ± 2.26%. The prepared hair serum containing NLC-C showed better spreading throughout the formulation than that containing the intact oil. Using 5% NLC-C showed a 78.8% reduction in firmness of the hair serum while enhancing diffusion efficiency by reducing shear forces up to 81.4%. In conclusion, the developed NLC-C of tea seed oil is an effective alternative in stimulating hair growth. Hair serum containing NLC-C obviously reduces sticky, oily, and greasy feeling after use.

Polymers with Hemiaminal Ether Linkages for pH-Responsive Antibacterial Materials.

Antibacterial materials containing biocides suffer from the fact that biocides are usually quickly released and hence display a limited antibacterial ability over a long period of time. To overcome this problem, the antibacterial agent 6-chloropurine is conjugated to a monomer via a hemiaminal ether linkage. The functional monomer is then reacted with a urethane acrylate by photopolymerization to yield thin polymer coatings. The release of the antibacterial agent from the coatings is sustained due to the slow kinetics of the hydrolysis of the hemiaminal ether linkage. Antibacterial performance is achieved against S. aureus and E. coli bacteria. This simple strategy can be applied for the rapid preparation of antibacterial coatings on various substrates and other applications such as antifouling or anticorrosion coatings.

Carbon nanotube/polydimethylsiloxane composite micropillar arrays using non-lithographic silicon nanowires as a template for performance enhancement of triboelectric nanogenerators.

Carbon nanotube/polydimethylsiloxane composite micropillar (CNT/PDMS MP) arrays were successfully fabricated using non-lithographic silicon nanowire (SiNW) arrays as a template for performance enhancement of triboelectric nanogenerators (TENG). The CNT/PDMS MP arrays were obtained by pouring CNT/PDMS composites on the SiNW arrays and peeled off. Surface topology of CNT/PDMS composites directly depends on morphology of SiNW arrays, which can be varied by the etching time of the typical metal-assisted chemical etching process. The micropatterned CNT/PDMS composites was mostly depicted to the SiNW array template pattern when the morphologies of the SiNW were optimized with a length of approximately 10 mm. Next, the CNT/PDMS MP arrays were utilized as a triboelectric layer of TENGs, generating the maximum output voltage of 22.84 ± 0.85 V, enabling an approximately 18-fold improvement in an electrical output compared to the flat PDMS-based TENG. The performance enhancement of TENGs based on CNT/PDMS MP arrays are attributed to synergic effects of (1) an enhancement of electrostatic induction by CNT composites, increasing dielectric constant, and (2) an enhancement of electrification by surface texturing using non-lithographic pattern and CNT composites.

C22 podovirus infectivity is associated with intermediate stiffness.

Bacteriophages have potential for use as biological control agents (biocontrols) of pathogenic bacteria, but their low stability is limiting for their utilization as biocontrols. Understanding of the conditions conducive to storage of phages in which infectivity is maintained over long periods will be useful for their application as biocontrols. We employed a nanomechanical approach to study how external environmental factors affect surface properties and infectivity of the podovirus C22 phage, a candidate for biocontrol of Ralstonia solanacearum, the agent of bacterial wilt in crops. We performed atomic force microscopy (AFM)-based nano-indentation on the C22 phage in buffers with varying pH and ionic strength. The infectivity data from plaque assay in the same conditions revealed that an intermediate range of stiffness was associated with phage titer that remained consistently high, even after prolonged storage up to 182 days. The data are consistent with the model that C22 phage must adopt a metastable state for maximal infectivity, and external factors that alter the stiffness of the phage capsid lead to perturbation of this infective state.

Improvement in insulin absorption into gastrointestinal epithelial cells by using molecularly imprinted polymer nanoparticles: Microscopic evaluation and ultrastructure.

A molecularly imprinted polymer nanoparticle (MIP) was prepared by integrating a mixed functional monomer into a highly cross-linked polymer. The nanosized insulin as a template transferred into the binding cavities, anchored functional monomer(s) that the insulin structure formed within free space of the molecular size region by MIP nanoparticles. The oral administration with the insulin-loaded MIP resulted in higher fluorescence intensity of rhodamine-labeled insulin into the epithelial cells. We observed the correlation between the lipophilic domains of dye over the affected areas of sites with the interplay of the intestinal epithelial layer on the different intestinal sections. And, the detection with guinea pig anti-insulin antibody followed by goat anti-guinea pig antibody clearly elicited the efficient insulin function in the necessary biological milieu. The root mean square roughness of the MIP indicated difference of the surface density, significantly lower compared with the polymer attributed to the protein-mucin uptake that efficiently promoted the insulin penetration. Eventually electron microscopy data of the conjugated biotin-gold nanoparticles showed the transport of insulin across the intestinal epithelium via transcellular pathway, and the development of the pancreatic ß cell in the streptozocin-induced diabetic rats. Histopathological observation exhibited no obvious toxic effect after orally treated with MIP loaded insulin (100mg/kg) daily for 14days compared to control group. The use of an insulin-loaded MIP was proven to be an effective therapeutic protein delivery through transmucosal oral route.

Biomimetic insulin-imprinted polymer nanoparticles as a potential oral drug delivery system.

In this study, we investigate molecularly imprinted polymers (MIPs), which form a three-dimensional image of the region at and around the active binding sites of pharmaceutically active insulin or are analogous to b cells bound to insulin. This approach was employed to create a welldefined structure within the nanospace cavities that make up functional monomers by cross-linking. The obtained MIPs exhibited a high adsorption capacity for the target insulin, which showed a significantly higher release of insulin in solution at pH 7.4 than at pH 1.2. In vivo studies on diabetic Wistar rats showed that the fast onset within 2 h is similar to subcutaneous injection with a maximum at 4 h, giving an engaged function responsible for the duration of glucose reduction for up to 24 h. These MIPs, prepared as nanosized material, may open a new horizon for oral insulin delivery.

pH-Responsive polymeric micelles based on amphiphilic chitosan derivatives: Effect of hydrophobic cores on oral meloxicam delivery.

The amphiphilic chitosan derivatives, N-naphthyl-N,O-succinyl chitosan (NSCS), N-octyl-N-O-succinyl chitosan (OSCS) and N-benzyl-N,O-succinyl chitosan (BSCS), were synthesized. Meloxicam (MX) was loaded into polymeric micelles (PMs), and the effects of hydrophobic moieties of the inner core segment on the loading efficiency, stability of MX-loaded PMs, cytotoxicity, drug release, and porcine small intestine permeation were investigated. Among the hydrophobic cores, the N-octyl moiety revealed the highest MX loading efficiency and most stable MX-loaded PMs compared to the other hydrophobic cores. All PMs were spherically shaped (size 213-282 nm) and had low toxicity against Caco-2 cells. The release of MX from PMs was found to be dependent on both hydrophobic cores and hydrophilic shells. In acidic medium at 0-2h, low cumulative MX release was obtained in the MX-loaded OSCS PMs compared to MX-loaded NSCS PMs and MX-loaded BSCS PMs as well as MX free drug. However, when the pH was increased to 6.8, the MX release significantly increased in all MX-loaded PMs. Furthermore, the intestinal permeation rates of MX from all MX-loaded PMs were not significantly different. These results suggest that MX was successfully incorporated into the PMs at high efficiency and good stability by optimizing the hydrophobic moieties of the inner core segments.

Layer-by-layer engineered nanocapsules of curcumin with improved cell activity.

Nanocarriers based on electrostatic Layer-by-layer (LbL) assembly of CaCO3 nanoparticles (CaCO3 NPs) was investigated. These inorganic nanoparticles was used as templates to construct nanocapsules made from films based on two oppositely charged polyelectrolytes, poly(diallyldimethylammonium chloride), and poly (sodium 4-styrene-sulfonate sodium salt), followed by core dissolution. The naked CaCO3 NPs, CaCO3 NPs coated with the polyelectrolytes and hollow nanocapsules were found with hexagonal shape with average sizes of 350-400 nm. A reversal of the surface charge between positive to negative zeta potential values was found, confirming the adsorption of polyelectrolytes. The loading efficiency and release of curcumin were controlled by the hydrophobic interactions between the drug and the polyelectrolyte matrix of the hollow nanocapsules. The quantity of curcumin released from hollow nanocapsules was found to increase under acidic environments, which is a desirable for anti-cancer drug delivery. The hollow nanocapsules were found to localize in the cytoplasm and nucleus compartment of Hela cancer cells after 24 h of incubation. Hollow nanocapsules were non-toxic to human fibroblast cells. Furthermore, curcumin loaded hollow nanocapsules exhibited higher in vitro cell inhibition against Hela cells than that of free curcumin, suggesting that polyelectrolyte based-hollow nanocapsules can be utilized as new carriers for drug delivery.

Synthesis and fluorescence properties of N-substituted 1-cyanobenz[f]isoindole chitosan polymers and nanoparticles for live cell imaging.

Highly fluorescent N-substituted 1-cyanobenz[f]isoindole chitosans (CBI-CSs) with various degrees of N-substitution (DS) were synthesized by reacting chitosan (CS) with naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide under mild acidic conditions. Introduction of 1-cyanobenz[f]isoindole moieties into the CS backbone resulted in lowering of polymer thermal stability and crystallinity. The fluorescence quantum yield (Φf) of CBI-CS was found to be DS- and molecular-weight-dependent, with Φf decreasing as DS and molecular weight were increased. At similar DS values, CBI-CS exhibited 26 times higher Φf in comparison with fluorescein isothiocyanate-substituted chitosan (FITC-CS). CBI-CS/TPP nanoparticles were fabricated using an ionotropic gelation method in which pentasodium triphosphate (TPP) acted as a cross-linking agent. CS and CBI-CS exhibited low cytotoxicity to normal skin fibroblast cells over a concentration range of 0.1-1000 µg/mL, while an increased cytotoxicity level was evident in CBI-CS/TPP nanoparticles at concentrations greater than 100 µg/mL. In contrast with CBI-CS polymers, the CBI-CS/TPP nanoparticles exhibited lower fluorescence; however, confocal microscopy results showed that living normal skin fibroblast cells became fluorescent on nanoparticle uptake. These results suggest that CBI-CS and fabricated nanoparticles thereof may be promising fluorescence probes for live cell imaging.

Chemical and structural investigation of lipid nanoparticles: drug-lipid interaction and molecular distribution.

Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of gamma-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812 as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the gamma-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance ((1)H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the (1)H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of gamma-oryzanol inside the lipid nanoparticles, the (1)H-NMR revealed that the chemical shifts of the liquid lipid in gamma-oryzanol loaded systems were found at rather higher field than those in gamma-oryzanol free systems, suggesting incorporation of gamma-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of gamma-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models representing the distribution of gamma-oryzanol and lipids (solid and liquid) inside the lipid nanoparticle systems are proposed.