A green approach to nanoplastic detection: SERS with untreated filter paper for polystyrene nanoplastics.

Plastic pollution at the nanoscale continues to pose adverse effects on environmental sustainability and human health. However, the detection of nanoplastics (NPLs) remains challenging due to limitations in methodology and instrumentation. Herein, a "green approach" for surface-enhanced Raman spectroscopy (SERS) was exploited to detect polystyrene nanospheres (PSNSs) in water, employing untreated filter paper and a simple syringe-filtration set-up. This SERS protocol not only enabled the filtration of nano-sized PSNSs, which are smaller than the pore size of the ordinary filter paper, but also offered SERS enhancement by utilizing quasi-spherical-shaped silver nanoparticles (AgNPs) as the SERS-active substrate. The filtering of NPLs was accomplished by adding an aggregating agent to the nanoparticle mixture, which caused the aggregation of NPLs and AgNPs, resulting in a larger cluster and more hot spots for SERS detection. The optimal aggregating agent and its concentration, as well as the volume ratio between the AgNPs and NPLs, were also optimized. This SERS method successfully detected and quantified PSNSs of various sizes (i.e., 100, 300, 460, 600, and 800 nm) down to a limit of detection (LOD) of about 0.31 µg mL-1. The method was also validated against the presence of several interferents (i.e., salts, sugars, amino acids, and surfactants) and was proven practical, as evidenced by the detection of 800nm PSNSs in drinking and tap water (LODs of 1.47 and 1.55 µg mL-1, respectively).

Effect of Lavandula angustifolia and Cananga odorata on decrease of blood pressure in high blood pressure volunteers: A randomized controlled trial.

INTRODUCTION: Hypertension is one of the most dangerous diseases. However, medicine for hypertension may cause adverse effects. Thus, alternative treatments may be beneficial to patients. The aims of the study were to evaluate efficacy and safety of sticker pads containing lavender and ylang ylang oil (LY pads) on decrease blood pressure. MATERIALS AND METHODS: The LY pads had been developed since 2018. The safety of LY pads in healthy volunteers' study and the efficacy and safety of LY pads in high blood pressure volunteers' study were conducted at Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand in October 2020 to December 2022. In the safety of LY pads in healthy volunteers' study, the LY pad was attached to the shirts of 56 healthy volunteers for 2 h. Adverse reactions, irritation score, and quality of life were assessed. In the efficacy and safety of the LY pads in high blood pressure volunteers' study, 34 high blood pressure volunteers were randomly divided into the LY group or the placebo group. The volunteers attached the pad to their shirt for 14 days. Blood pressure, pulse rate, and adverse reactions were investigated. RESULTS: The LY pad was safe for humans. Using the LY pad for 2 h had no significant adverse reactions in healthy volunteers. Moreover, it significantly improved quality of life (p<0.05). The blood pressure of the LY pad group after at least 3 days use was significantly lower than before using the pad (p<0.05). The systolic blood pressure difference and pulse rate difference were also superior in the LY pad group compared to the placebo group (p<0.05). CONCLUSIONS: The LY pad was safe in healthy volunteers and could reduce blood pressure in high blood pressure volunteers without adverse effects. Thus, it may be a supportive or alternative treatment for hypertension.

Size-independent quantification of nanoplastics in various aqueous media using surfaced-enhanced Raman scattering.

In this work, we successfully developed an intriguing preparation strategy to reduce the size-dependent effect of nanoplastics (NPLs), which is the limitation of NPLs quantification by surface-enhanced Raman scattering (SERS). This simple and low-cost technique enabled us to quantify different sizes (i.e., 100, 300, 600, and 800 nm) of polystyrene nanospheres (PS NSs) in various aqueous media. The SERS substrate was simply prepared by sputtering gold particles to cover on a glass cover slide. By dissolving PS NSs in toluene and preconcentrating by coffee-ring effect, SERS measurement can quantify NPLs at a very low concentration with a limit of detection (LOD) of approximately 0.10-0.26 µg/mL. The experiment was also conducted in the presence of interferences, including salts, sugars, amino acids, and detergents. The method was validated for quantitative analysis using a mixture of 100-, 300-, 600-, and 800-nm PS NSs in a ratio of 1:1:1:1 in real-world media (i.e., tap water, mineral water, and river water), which successfully approaches the evaluation of PS NSs in the range of 10-40 µg/mL with an LOD of approximately 0.32-0.52 µg/mL.

Using polyvinyl alcohol-ionic hydrogels containing a wound healing agent to manage wounds in different environments.

OBJECTIVE: To explore the effects of pH on properties of polyvinyl alcohol (PVA)-ionic hydrogels containing wound healing promoters. METHOD: PVA was combined with a natural wound healing promoter (silk sericin (SS)), and an anionic agent (eosin (ES)) or cationic agent (methylene blue (MB)), and made into hydrogels. Properties of the hydrogels and behaviour at different pHs were investigated. RESULTS: The density and gel fraction of PVA/SS-ES hydrogel and PVA/SS-MB hydrogel were considerably lower compared with hydrogel without SS. The swelling ratio and degradation of the hydrogels increased with increasing SS concentration in all pH solutions. The influence of SS in interrupting long-chain PVA molecules was confirmed based on changes in Fourier-transform infrared spectroscopy (FTIR). The SS released from the gels was found to interact with the ionic agent and influenced the release profile of the ionic agent. Surprisingly, the anionic agent in PVA/SS-ES hydrogel showed 70% release in high pH solution whereas the cationic agent in PVA/SS-MB hydrogel showed 86% release in low pH solution. Moreover, the active agent could accumulate on the skin layer and had a positive effect on a specific wound area. CONCLUSION: Based on the results obtained in this study, it is suggested to use anionic hydrogels containing wound healing promoter for wounds at high pH and cationic hydrogels containing wound healing promoter for wounds with low pH. Ability to improve wound healing using a natural healing agent combined with ionic agents and controlling the pH of hydrogels will help in developing quick and low-cost treatment for wounds.

Selection of cryoprotectants for freezing and freeze-drying of gold nanoparticles towards further uses in various applications.

Recently, cryopreservation of AuNPs without aggregation has been attempted to improve their long-term stability. This study investigated criteria to select cryoprotectants for AuNPs using a variety of materials, including sugar (sucrose), surfactant (Tween 20), polymers (polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP)), and biopolymer (pectin). For cryoprotective performance, UV-vis spectroscopy reveals the potential of all cryoprotectants for preventing citrate-capped AuNPs (cit-AuNPs) from irreversible aggregation under freezing. While sucrose, PVP, and pectin were more suitable than Tween 20 and PVA as cryoprotectants for lyophilization of AuNPs with the maintained redispersability. For storage and further use, Luria-Bertani agar plate, dynamic light scattering (DLS), and transmission electron microscopy (TEM) results indicate impacts of the cryoprotectant coexisted with AuNPs after resuspension and imply that washing of the restored AuNPs is encouraged. Otherwise, running the restored AuNPs through applications, such as functionalization, protein conjugation, and surface-enhanced Raman scattering (SERS), without washing the cryoprotectant could lead to inaccurate results. This study also serves as a guideline for a comprehensive practice flow of AuNP handling, encompassing the synthesis step, cryopreservation, and use after resuspension.

Progress of tip-enhanced Raman scattering for the last two decades and its challenges in very recent years.

Tip-enhanced Raman scattering (TERS) has recently attracted remarkable attention as a novel nano-spectroscopy technique. TERS, which provides site-specific information, can be performed on any material surface regardless of morphology. Moreover, it can be applied in various environments, such as ambient air, ultrahigh vacuum (UHV), solutions, and electrochemical environments. This review reports on one hand progress of TERS for the last two decades, and on the other hand, its challenges in very recent years. Part of the progress of TERS starts with the prehistory and history of TERS, and then, the characteristics and advantages of TERS are described. Significant emphasis is put on the development of TERS instrumentation and equipment such as ultrahigh vacuum TERS, liquid TERS, electrochemical-TERS, and tip-preparations. Applications of TERS, particularly those with nanocarbons, biological materials, and surface and interface analysis, are mentioned in some detail. In the part on challenges, we focus on the very recent advances in TERS; progress in spatial resolution to the angstrom scale is the hottest topic. Recent TERS studies performed under UHV, for example chemical imaging at the angstrom scale and Raman detection of bond breaking and making of a chemisorbed up-standing single molecules at single-bond level, are reviewed. Of course, there is no clear border between the two parts. In the last part the perspective of TERS is discussed.

Development of Eugenol-Embedded Calcium Citrate Nanoparticles as a Local Anesthetic Agent.

Eugenol is a major phenolic component derived from clove oil with potential medical applications. Of particular interest, it has been used as a therapeutic agent in topical applications because of its analgesic and local anesthetic properties. However, topical formulations of eugenol produce skin irritation, which limits its clinical applications. One promising strategy to overcome this disadvantage is by using a biocompatible material that could be an appropriate topical vehicle for eugenol. Researchers have recently focused on the development of eugenol-embedded calcium citrate nanoparticles (Eu-CaCit NPs) without adverse effects. The Eu-CaCit NPs were developed as a topical delivery system and their biocompatibility and penetration ability were evaluated. Eu-CaCit NPs at 1.2 mg/mL did not show cytotoxicity effects in human cells. Moreover, the Eu-CaCit NPs presented the ability to penetrate the dermis layer of the human intact skin following 12 h exposure. All the results concluded that Eu-CaCit NPs have shown a potential as a carrier for topical delivery of eugenol. These novel nanoparticles represent a promising alternative for topical application of local anesthetic with natural pain relievers.

Superior Technique for the Production of Agarose Dressing Containing Sericin and Its Wound Healing Property.

Finding a simple and eco-friendly production technique that matches to the natural agent and results in a truly valuable natural scaffold production is still limited amongst the intensively competitive natural scaffold development. Therefore, the purpose of this study was to develop natural scaffolds that were environmentally friendly, low cost, and easily produced, using natural agents and a physical crosslinking technique. These scaffolds were prepared from agarose and sericin using the freeze-drying method (D) or freeze-thawing together with the freeze-drying method (TD). Moreover, plasticizers were added into the scaffold to improve their properties. Their physical, mechanical, and biological properties were investigated. The results showed that scaffolds that were prepared using the TD method had stronger bonding between sericin and other compounds, leading to a low swelling ratio and low protein release of the scaffolds. This property may be applied in the development of further material as a controlled drug release scaffold. Adding plasticizers, especially glycerin, into the scaffolds significantly increased elongation properties, leading to an increase in elasticity of the scaffold. Moreover, all scaffolds could activate cell migration, which had an advantage on wound healing acceleration. Accordingly, this study was successful in developing natural scaffolds using natural agents and simple and green crosslinking methods.

MCR-ALS with sample insertion constraint to enhance the sensitivity of surface-enhanced Raman scattering detection.

The multivariate curve resolution-alternative least squares (MCR-ALS) algorithm was modified with sample insertion constraint to deconvolute the overlapping peaks in SERS spectra. The developed method was evaluated by the spectral data simulated using a Gaussian distribution function to generate two independent peaks corresponding to a capping agent and an analyte. The spectra were generated with different overlapping levels and various intensity ratios of the analyte to the capping agent. By using MCR-ALS with the sample insertion constraint, the peak of the capping agent was completely excluded to obtain a calibration model of the analyte with R2 > 0.95 under all conditions. Furthermore, our developed method was later applied to a real SERS measurement to quantify carbofuran (analyte) using the azo-coupling reaction with p-ATP (capping agent) on silver nanoparticles as a SERS substrate. A calibration model of derivative carbofuran phenol was generated with R2 = 0.99 and LOD = 28.19 ppm. To assess the performance of the calibration model, the model was used to estimate the concentration of carbofuran in an external validation set. It was found that the RMSE of prediction was only 2.109 with a promising R2 = 0.97.

Luminescent nanohybrid of ZnO quantum dot and cellulose nanocrystal as anti-counterfeiting ink.

Luminescent quantum dot (QD) ink is currently a powerful tool for generating hidden information on paper substrates. Herein, we fabricated a nanohybrid ink of bacterial cellulose nanocrystal (BCNC) and UV-responsive ZnO QD via electrostatic self-assembly for improving solvent resistance and message encryption process. Under investigations on the printed areas, the nanohybrid can slightly infiltrate into the paper fibers and form a thin layer on the top of paper substrates, conferring an enhanced print permanence against wetting conditions while maintaining the daylight unobservability and its luminescent stability. The water resistance of the proposed nanohybrid ink enables developing a higher security level that the prints can be submerged in CuCl2 aqueous solutions to quench the luminescent message. The concealed message can eventually be revealed under UV light again after submerging in EDTA solution. Our ZnO QD/BCNC nanohybrid with eco-friendly nature therefore exhibits great potential as security marking ink for counterfeit protection with sustainable uses.

Distinguishing Enantiomers by Tip-Enhanced Raman Scattering: Chemically Modified Silver Tip with an Asymmetric Atomic Arrangement.

Discrimination between enantiomers is achieved by tip-enhanced Raman scattering (TERS) using a silver tip that is chemically modified by an achiral para-mercaptopyridine (pMPY) probe molecule. Differences in the relative intensities of the pMPY spectra were monitored for three pairs of enantiomers containing hydroxy (-OH) and/or amino (-NH2 ) groups. The N: or N+ -H functionality of the pMPY-modified tip participates in hydrogen-bond interactions with a particular molecular orientation of each chiral isomer. The asymmetric arrangement of silver atoms at the apex of the tip induces an asymmetric electric field, which causes the tip to become a chiral center. Differences in the charge-transfer (CT) states of the metal-achiral probe system in conjunction with the asymmetric electric field produce different enhancements in the Raman signals of the two enantiomers. The near-field effect of the asymmetric electric field, which depends on the number of analyte functional groups capable of hydrogen-bond formation, improves the degree of discrimination.

Antibiofilm activity and cytotoxicity of silk sericin against Streptococcus mutans bacteria in biofilm: an in vitro study.

OBJECTIVE: To investigate the potential of sericin extracted by different methods to inhibit biofilm formation (prevention) and disrupt already formed biofilm (treatment). METHOD: In this in vitro study, sericin was extracted by heat, acid, alkali and urea. Streptococcus mutans bacteria were cultivated in the presence of various concentrations of sericin to evaluate antibiofilm formation using cell density assay (inhibition effect before biofilm formed). Conversely, various concentrations of sericin were added to a biofilm already formed by Streptococcus mutans bacteria, and the viability of bacteria assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (disruption effects after biofilm formed). Structures of extracted sericin were evaluated using circular dichroism and Fourier-transform infrared spectrometer. RESULTS: The urea-extracted sericin at all concentrations (12.5mg/ml, 25mg/ml, 50mg/ml and 100mg/ml) showed the highest potential antibiofilm activity in terms of both inhibition and disruption effects, compared with sericin extracted by heat, acid or alkali. The heat-extracted and acid-extracted sericin were found to reduce the biofilm formation dose-dependently, while the alkali-extracted sericin did not show either inhibition or disruption effect on the bacterial biofilm. The urea-extracted sericin also killed the bacteria residing within the biofilm, possibly due to its modified structure which may destabilise the bacterial cell wall, leading to membrane disintegration and, finally, cell death. CONCLUSION: Our results demostrated the antibiofilm activity of sericin. This could form the basis of further research on the mechanism and application of sericin as a novel antibiofilm agent.

Silver nanoparticle/bacterial nanocellulose paper composites for paste-and-read SERS detection of pesticides on fruit surfaces.

This study aimed to develop an eco-friendly flexible surface-enhanced Raman scattering (SERS) substrate for in-situ detection of pesticides using biodegradable bacterial nanocellulose (BNC). Plasmonic silver nanoparticle- bacterial nanocellulose paper (AgNP-BNCP) composites were prepared by vacuum-assisted filtration. After loading AgNPs into BNC hydrogel, AgNPs were trapped firmly in the network of nanofibrous BNCP upon ambient drying process, resulting in 3D SERS hotspots within a few-micron depth on the substrate. The fabricated AgNP-BNCPs exhibited high SERS activity with good reproducibility and stability as demonstrated by the detection of 4-aminothiophenol and methomyl pesticide. Due to the optical transparency of BNCP, a direct and rapid detection of methomyl on fruit peels using AgNP-BNCPs can be achieved, demonstrating a simple and effective 'paste-and-read' SERS approach. These results demonstrate potential of AgNP-BNCP composites for user-friendly in-situ SERS analysis.

Tuning the reactivity of copper complexes supported by tridentate ligands leading to two-electron reduction of dioxygen.

A series of copper complexes bearing polypyridyl tridentate ligands have been prepared to fine tune their reactivity toward the oxygen reduction reaction (ORR). During the process of preparation of our copper complexes, we successfully obtained two new crystal structures which are [Cu2(µ-Cl)2(adpa)2](ClO4)2 (2b) and [Cu2(addpa)(CH3CN)2(ClO4)2](ClO4)2 (3a) and a new structure [Cu2(addpa)(CH3CN)2(H2O)2](ClO4)4 (3b) captured after the catalytic ORR. Electrochemical studies and stoichiometric chemical reduction of copper(ii) complexes by ascorbic acid indicated that the presence of an anthracene unit helps to facilitate the reduction of Cu(ii) as well as the stabilisation of Cu(i) species. Regarding oxygen activation, the dinuclear Cu(i) complex 3a showed significantly higher ORR activity than its analogous mononuclear complex 2a. Complex 3a was also found to be relatively robust and competent in catalytic O2 reduction. The observed H2O2 product after this catalysis, together with the data obtained from DFT calculations supported that 3a exhibited a 2H+, 2e- catalytic activity towards the ORR as opposed to the expected 4H+, 4e- process usually found in copper complexes with tridentate ligands. The proton (H+) source for this process was expected from ascorbic acid which also serves as a reducing agent in this reaction. This work highlighted an approach for tuning the ORR activity of the copper complexes by the introduction of a conjugated-π moiety to the supporting ligand.

Local structural changes in graphene oxide layers induced by silver nanoparticles.

Structural changes of graphene oxide (GO) in silver/graphene oxide (AGO) nanocomposites are investigated using tip-enhanced Raman scattering (TERS). Because of markedly high spatial resolution of the TERS technique, the measurements of molecular information at specific nano-scaled positions can be achieved by constructing line-profile TERS spectra straight from the center of silver nanoparticles (AgNPs) on GO layers. The results show evidences that AgNPs cause shortening of C-C bonds beneath AgNPs, flattening of GO layers, and critical bending on GO layers. Additionally, a connection of carbon atoms via a C-C network subsequently expands structural changes with a distance of 200-250 nm from the center of AgNPs, even though this distance is larger than the size of AgNPs. The proposed model of GO structural changes unveils new understanding about changes in properties from GO to AGO nanocomposites, which will contribute to a development of advanced nanostructures/nanocomposites in the near future.

Enhancing Passive Transport of Micro/Nano Particles into Cells by Oxidized Carbon Black.

Uses of micro-/nano-sized particles to deliver biologically active entities into cells are common for medical therapeutics and prophylactics and also for cellular experiments. Enhancing cellular uptake and avoiding destruction by lysosomes are desirable for general particulate drug delivery systems. Here, we show that the relatively nontoxic, negatively charged oxidized carbon black particles (OCBs) can enhance cellular penetration of micro- and nano-particles. Experiments with retinal-grafted chitosan particles (PRPs) with hydrodynamic sizes of 1200 ± 51.5, 540 ± 29.0, and 430 ± 11.0 nm (three-sized model particles) indicate that only the sub-micron-sized particles can penetrate the first layer of multilayered liposomes. However, in the presence of OCBs, the micron-sized PRPs and the two submicron-sized PRPs can rapidly enter the interiors of all layers of the multilayered liposomes. Very low cellular uptakes of micro- and submicron-sized PRPs into keratinocytes cells are usually observed. However, in the presence of OCBs, faster and higher cellular uptakes of all of the three-sized PRPs are clearly noticed. Intracellular traffic monitoring of PRP uptake into HepG2 cells in the presence of OCBs revealed that the PRPs did not co-localize with endosomes, suggesting a nonendocytic uptake process. This demonstration of OCB's ability to enhance cellular uptake of micro- and submicron-particles should open up an easy strategy to effectively send various carriers into cells.

Analysis of cosmetic residues on a single human hair by ATR FT-IR microspectroscopy.

In this work, ATR FT-IR spectra of single human hair and cosmetic residues on hair surface are successfully collected using a homemade dome-shaped Ge µIRE accessary installed on an infrared microscope. By collecting ATR spectra of hairs from the same person, the spectral patterns are identical and superimposed while different spectral features are observed from ATR spectra of hairs collected from different persons. The spectral differences depend on individual hair characteristics, chemical treatments, and cosmetics on hair surface. The "Contact-and-Collect" technique that transfers remarkable materials on the hair surface to the tip of the Ge µIRE enables an identification of cosmetics on a single hair. Moreover, the differences between un-split and split hairs are also studied in this report. These highly specific spectral features can be employed for unique identification or for differentiation of hairs based on the molecular structures of hairs and cosmetics on hairs.

Oxidized Carbon Black: Preparation, Characterization and Application in Antibody Delivery across Cell Membrane.

Modulating biomolecular networks in cells with peptides and proteins has become a promising therapeutic strategy and effective biological tools. A simple and effective reagent that can bring functional proteins into cells can increase efficacy and allow more investigations. Here we show that the relatively non-toxic and non-immunogenic oxidized carbon black particles (OCBs) prepared from commercially available carbon black can deliver a 300 kDa protein directly into cells, without an involvement of a cellular endocytosis. Experiments with cell-sized liposomes indicate that OCBs directly interact with phospholipids and induce membrane leakages. Delivery of human monoclonal antibodies (HuMAbs, 150 kDa) with specific affinity towards dengue viruses (DENV) into DENV-infected Vero cells by OCBs results in HuMAbs distribution all over cells' interior and effective viral neutralization. An ability of OCBs to deliver big functional/therapeutic proteins into cells should open doors for more protein drug investigations and new levels of antibody therapies and biological studies.

Epigallocatechin gallate-zinc oxide co-crystalline nanoparticles as an anticancer drug that is non-toxic to normal cells.

Decreased uptake and cellular accumulation of zinc is a common characteristic in cancer of the liver, pancreas and prostate, because these malignant cells are intolerant to the physiological concentrations of zinc. A tea polyphenol, epigallocatechin-3-gallate (EGCG), can enhance the cytotoxicity of zinc ions to cancer, but the application of this is limited by the low stability of EGCG. In this work, we have prepared a material that can simultaneously preserve the EGCG stability and facilitate zinc uptake and accumulation in cancer cells, under conditions that are not harmful to normal cells. Thus, we co-crystallize zinc oxide with EGCG to obtain hybrid EGCG-ZnO crystalline nanoparticles of 16.5 ± 5.3 nm in diameter. The EGCG-ZnO particles effectively kill PC-3 prostate adenocarcinoma cells at concentrations that are not cytotoxic to normal cells, WI-38 human embryonic lung fibroblasts. The EGCG-ZnO particles are two times more cytotoxic against PC-3 cells than the standard ZnO particles. In PC-3 cells, the EGCG-ZnO particles are taken up by endocytosis, followed by lysosomal disruption to release zinc and EGCG into the cytoplasm, finally resulting in nuclear accumulation of zinc.

Facile and Sensitive Detection of Carbofuran Carbamate Pesticide in Rice and Soybean Using Coupling Reaction-based Surface-Enhanced Raman Scattering.

In this research, a sensitive and selective method for detecting one of the most toxic insecticides, "carbofuran", in rice and soybean is presented. This method is based on the coupling reaction of diazonium ion combined with a surface-enhanced Raman scattering technique. Diazonium ion produced from p-aminothiophenol reacts specifically with carbofuran phenol from the hydrolysis of carbofuran. The generated azo compounds attach to the surface of silver nanoparticles via the Ag-S bond. Therefore, a strong Raman intensity can be obtained. The concentration of carbofuran can be determined by following the intensity of the peak at 1201 cm-1, attributed to the C-N stretching vibration of the azo compound. The result shows a good linear correlation (R2 = 0.9786) against carbofuran concentrations (0.1 - 5 ppm) with a detection limit of 0.452 ppm. Our proposed protocol is insignificantly influenced by various common interferences. Moreover, this method has been successfully validated to determine carbofuran concentrations in rice and soybean with detection limits of 0.446 and 0.520 ppm, respectively.