Negatively Charged Research Articles

Dialdehyde cellulose nanofibrils/polyquaternium stabilized ultra-fine silver nanoparticles for synergistic antibacterial therapy

Dialdehyde cellulose nanofibrils (DACNF) and Polyquaternium-10 (PQ: chloro-2-hydroxy-3-(trimethylamino) propyl polyethylene glycol cellulose) have become increasingly favored as antibacterial substances due to their advantageous characteristics. DACNF exhibits exceptional mechanical properties and biocompatibility, whereas PQ demonstrates a positive charge that enhances its antibacterial activity. Combined in a DACNF/PQ mixture, they provide an excellent template material for preparing and stabilizing ultra-fine (~ 10.3 nm) silver nanoparticles (AgNPs) at room temperature. Here, the dialdehyde group of DACNF functions as a reducing agent, while the quaternary ammonium of PQ and carboxylate groups of DACNF synergistically helped in-situ generation of AgNPs uniformly. The synthesized nanocomposites, namely PQ@AgNPs, AgNPs@DACNF, and AgNPs@DACNF/PQ, were subjected to comprehensive characterization using various advanced analytical techniques. The films containing AgNPs@DACNF and AgNPs@DACNF/PQ, fabricated via vacuum filtration, exhibited excellent mechanical properties of 9.78 ± 0.21 MPa, and demonstrated superior antibacterial activity against both Escherichia coli and Staphylococcus aureus. Additionally, the silver ion leaching from the prepared composite films was well controlled. The fabricated nanocomposites also effectively inhibited bacterial biofilm formation. It was also found to be highly biocompatible and non-toxic to human skin fibroblast cells. Furthermore, the nanocomposites exhibited enhanced migration of human dermal fibroblasts, suggesting their potential in facilitating wound healing processes.

Zwitterionic Amino‐Acid‐Derived Polyacrylamides with a Betaine Twist – Synthesis and Characterization

AbstractAmino‐acid‐derived polyzwitterions and polybetaines (PBs) are two promising alternatives to non‐ionic polymers, for example, to increase tumor permeability. In this study, amino‐acid‐derived polyzwitterions are synthesized and a strategy to quarternize the amine in the side chain functional group is developed to combine the advantages of both types. The functional monomer is polymerized via reversible addition−fragmentation chain‐transfer polymerization for which a kinetic study is performed. Further, the impact of the permanent positive charge on amino‐acid‐derived polyzwitterions is studied based on two zwitterionic polymers obtained via post‐polymerization modification (PPM) of Poly(N‐acryloxysuccinimide) to allow good comparison between methylated and non‐methylated polymers. Circular dichroism shows that the stereocenter remains intact during PPM. pH titration and ζ‐potential measurements show that the methylated polymer has a negative ζ‐potential over the measured pH range and, therefore, the polymer remains zwitterionic over a broader pH range than its non‐methylated equivalent. Both polymers are well tolerated by mammalian cells up to concentrations of 1 mg mL−1. The study introduces a path to a new polymer class that combines the advantages of both PBs and amino‐acid‐derived polyzwitterions and highlights the impact a permanent charge has on the physiochemical properties.

CrSe2 based single-cluster catalysts with controllable charge states for the oxygen reduction and hydrogen evolution reactions

Development of affordable catalysts for the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) represents a central task for advancing electrochemical systems such as fuel cells and metal-air batteries. This study reported the ORR and HER performance of a set of single cluster catalysts (SCCs) with atomically dispersed 3d/4d/5d transition metal cluster (TM3) embedded in a two-dimensional (2D) defective CrSe2 substrate. Distinguishing from the conventional SCCs with positive charge active center, the unique electronegativity discrepancy between the metal clusters and the substrate renders the active center controllable charge states from negative to positive. Our investigations indicate that the TM3 cluster helps tuning the adsorption performance of the intermediates, and therefore enhancing the electrocatalytic activity of the SCCs. Among all the candidates, we demonstrated that the less reported elements of Ir and Ag exhibit the best performance of HER and ORR with low overpotentials of −0.059 and 0.61 V, respectively. Our work provides a prototype to rationally regulate the charge states of catalysts, which could potentially contribute to the development of new kinds of catalysts and serve as a valuable theoretical reference for the experimental rationalization of SCCs.

Capture of live circulating tumor cells via unique surface charges from cancer patients by a novel nanotechnology

AbstractCirculating tumor cells (CTCs) serve as a pivotal foundation for both fundamental oncological research and the precise evaluation of therapeutic interventions. However, the isolation of CTCs from clinical blood samples presents a multitude of sophisticated challenges, predominantly associated with the specificity of biomarkers and the sensitivity of detection techniques. In our previous study, we proposed a novel detection concept for CTCs based on a signature biophysical feature on the surface of cancer cells: a negative charge regulated by glycolytic processes. In this study, we have conducted experiments to ascertain the efficacy of this proposed method in capturing CTCs from clinical blood samples of individuals afflicted with solid tumors and leukemia. Our findings indicate that the method is capable of isolating tens of thousands of viable cancer cells from various metastatic solid cancers and leukemia using a mere 1 mL of blood. These cells were enumerated using cytological imaging that identified morphological characteristics indicative of malignancy. The outcomes of our study suggest that the negatively charged surface of cancer cells is a ubiquitous trait across both cultured cancer cell lines and fresh blood samples derived from cancer patients. Moreover, the capture technology employed in this study demonstrated superior performance in comparison to antecedent methodologies, enhancing the detection and documentation of CTCs for subsequent verification and analysis. This advancement holds significant promise for the improvement of diagnostic accuracy and the monitoring of therapeutic responses in oncology.

Chemical Derivatization and Paper Spray Ionization Mass Spectrometry for Fast Screening of Retinoic Acid in Cosmetics.

As a prescription drug, retinoic acid is listed as a banned cosmetic additive in the EU and China regulations. Currently, spectrophotometric methods, including thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and HPLC-MS/MS, are commonly used for the determination of retinoic acid. As these conventional methods require complex pretreatment and are time-consuming, chemical derivatization combined with paper spray ionization mass spectrometry was developed for the fast detection of retinoic acid in cosmetics. N,N-dimethylpiperazine iodide (DMPI) was utilized as a derivatization reagent. Carboxylic acid in retinoic acid was derivatized to carry a positive charge and was subjected to mass spectrometry analysis. Results showed that compared with non-derivatized compounds, the detection limit was increased by about 50 times. The linearity in the range of 0.005-1 μg·mL-1 was good. The limit of detection (LOD) was 0.0013 μg·mL-1, and the limit of quantification (LOQ) was 0.0043 μg·mL-1. The recoveries of spiked samples were in the range of 95-105%, and the RSDs were below 5%. Derivatization and paper spray ionization MS render a quick, sensitive, and accurate method for the detection of retinoic acid in a complex matrix.

Triboelectrification of Active Pharmaceutical Ingredients: Amines and Their Hydrochloride Salts.

The triboelectric properties of active pharmaceutical ingredients (APIs) contribute to problems during the manufacturing of pharmaceuticals. However, the triboelectric properties of APIs have not been comprehensively characterized. In this study, the effect of salt formulation on the triboelectric properties of APIs was investigated. The triboelectric properties of three groups of amines, namely tertiary amines, purine bases, and amino acids, and their hydrochlorides were evaluated using a suction-type Faraday cage meter. Most of the hydrochloride salts exhibited more negative charges than the corresponding free bases, and the degree by which the triboelectric property changed upon hydrochlorination depended on the structural groups of the compounds. In the case of tertiary amines, the change in the zero-charge margin upon hydrochlorination was negatively correlated with the zero-charge margin of the free base. In contrast, hydrochlorination of the amino acids led to a significant change in the zero-charge margin. In most cases, salt formation also affected the triboelectric properties of API powders. Controlling the triboelectric properties of APIs solves various problems caused by the electrification of raw material powders and granules during the production of pharmaceuticals, thereby increasing the quality of produced pharmaceuticals.

Negative Charges, Not Necessary Phosphorylation, are Required for Ligand Recognition by 14-3-3 Proteins.

Protein-protein interactions involving 14-3-3 proteins regulate various cellular activities in normal and pathological conditions. These interactions have mostly been reported to be phosphorylation-dependent, but the 14-3-3 proteins also interact with unphosphorylated proteins. In this work, we investigated whether phosphorylation is required, or, alternatively, whether negative charges are sufficient for 14-3-3ε binding. We substituted the pThr residue of pT(502-510) peptide by residues with varying number of negative charges, and investigated binding of the peptides to 14-3-3ε using MD simulations and biophysical methods. We demonstrated that at least one negative charge is required for the peptides to bind 14-3-3ε while phosphorylation is not necessary, and that two negative charges are preferable for high affinity binding.

Hydrophobic and positively charged magnetic nanoparticles for enhanced oil recovery from concentrated emulsion wastewaters

With the development of petroleum industry, a large amount of oil-in-water (O/W) emulsion wastewaters were produced, resulting in serious environmental pollution and resource waste. Up till now, magnetic nanoparticles (MNPs) were frequently reported in emulsion wastewater treatment and mainly focused on the water purification, but little effort was devoted to the facile recovery of oil resource. In the present work, a class of hydrophobic and positively charged MNPs, namely dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DOTAC)-coated MNPs (M−DOTAC), was carefully synthesized by regulating DOTAC anchoring density on Fe3O4@SiO2, and then employed to treat the concentrated emulsion wastewaters stabilized by anionic sodium dodecyl benzene sulfonate (SDBS) or nonionic Tween-80. M−DOTAC with relatively high DOTAC density (M−DOTAC 1.8) exhibited higher positive charge density and hydrophobicity, and hence could significantly promote the oil droplet coalescence and mergence via the electrostatic attraction and hydrophobic adsorption bridging as well as the hydrophilic-lipophilic transition of interfacial adsorption layer. Accordingly, with addition of moderate dosage of M−DOTAC 1.8, the emulsion was broken and divided into three layers: (1) a continuous oil layer was formed in the upper layer which could be directly recycled; (2) the middle layer was composed of MNPs-tagged oil droplets/flocs; (3) the bottom layer was the clearer water phase. The optimal recovery rate of oil resource reached ∼ 60 % in SDBS stabilized system, and further increased to ∼ 98 % in Tween-80 stabilized system. However, the oil recovery rate was declined at an excessive dosage of M−DOTAC 1.8 due the formation of double emulsion. Besides, M−DOTAC 1.8 exhibited good reusability. These results indicated the fabricated M−DOTAC had great application prospect in treating emulsion wastewaters containing high oil content.

Deciphering Chemical Rules for Drug Penetration into Strongyloides.

Background: Strongyloidiasis, a parasitic infection, presents a significant public health challenge in tropical regions due to the limited repertoire of effective treatments. The screening of chemical libraries against the therapeutically relevant third-stage larvae (L3) of the model parasite Strongyloides venezuelensis yielded meager success rates. This situation is reminiscent of Gram-negative bacteria, where drug entry is a limiting factor. Methods: Here, we set out to determine whether similar barriers are in place and establish whether structural and property requirements exist for anti-strongyloides drug discovery. We focused on dyes as their uptake and effects on viability can be independently assessed in the multicellular parasite, thus providing a means to study the possibility of similar entry rules. We tested different dyes in in vitro assays on L3s. Results: We found that staining was necessary to reduce parasite viability, with some dyes achieving anti-strongyloides effects at concentrations similar to those of the reference drug, ivermectin (IV). Some dyes also showed activity against female adults at concentrations well below that of ivermectin. Unfortunately, the most potent dye, Methylene Blue, was unable to prevent the infection in a preliminary in vivo mouse model assay, presumably due to fast dye clearance. Structural analysis showed that positive charges facilitated the access of the compounds to the L3 tissue, thus providing a structural tool for the introduction of activity. For female adults, low globularity is additionally required. As a proof of concept, we added a positive charge to an inactive compound of one of our chemical libraries and re-determined the activity. Conclusions: These findings allow us to establish structural rules for parasite entry that could be of interest for future drug screening or drug development campaigns. These rules might also be applicable to other related parasites.

Fast and scalable preparation of metal–organic coordination polymeric precursor for bifunctional electrocatalysts for high performance lithium–oxygen batteries

The Metal-organic coordination polymers (MOCPs) with structural and functional diversity are considered effective cathode materials for Lithium-oxygen batteries (LOBs). Conventional synthesis methods make it difficult to obtain large quantities of materials. Here, A highly active low-cost Co-decorated N-doped carbon oxygen cathode catalyst (Co–N–C) was synthesized using a fast and scalable method based on positive and negative charge coordination. Rapid synthesis of MOCPs depends on the addition of base sites. A theory of “Lewis’s base-assisted rapid synthesis” was proposed. Co-N-C as LOBs air cathode showed 150 cycles with 1000 mAh g-1 at 500 mA g-1. The fast and scalable synthesis method can provide a feasible strategy for large-scale production of oxygen electrocatalysts for LOBs.

Piezo-photocatalysis synergy in γ-GeSe for highly efficient oxygen evolution reaction

Solar-driven semiconductor photocatalysts are highly appealing in applications of environmental remediation and energy conversion. However, photocatalytic reactions, particularly oxygen evolution reaction (OER), are often constrained by the swift recombination of electron–hole pairs, thereby resulting in low reaction efficiency. Although it is effective to separate charge carriers by constructing heterojunctions to form built-in electric field, the lattice mismatch and inefficient interlayer charge transfer of heterojunctions in the photocatalysts limit their further development. Here, we propose a new strategy by constructing an internal electric field for OER through an individual piezoelectric two-dimensional material. The results indicate that the piezoelectric effect regulates the electronic structure, reduces bandgap, improves light absorption efficiency, and that the displacement of positive and negative charge centers is the key factor in the enhanced OER. This research indicates the feasibility of combining piezoelectric properties of two-dimensional materials with OER (1.19 eV), providing new insights and guidance for applying the piezoelectric effect in the OER and opening up a way to promote efficient separation of charge carriers.

Porous CrO[formula omitted]: A ferromagnetic half-metallic member in sparse hollandite oxide family

A stable polymorph of CrO2 is predicted using PBE+U method. The porous material is isostructural with α−MnO2 making it the second transition metal oxide in sparse hollandite group of materials. However, unlike the anti-ferromagnetic semiconducting character of the α−MnO2, it is found to be a ferromagnetic half-metal. At Fermi level, the hole pocket has ample contribution from O−2p orbital, though, the electron pocket is mostly contributed by Cr−3dxy and Cr−3dx2−y2. A combination of negative charge transfer through orbital mixing and extended anti-bonding state near Fermi level is responsible for the half-metallic ferromagnetic character of the structure. A comparative study of rutile and hollandite CrO2 and hollandite MnO2 structures delineate the interplay between structural, electronic and magnetic properties. The material shows a robust magnetic character under hydrothermal pressure, as well as, the band topology is conserved under uniaxial strain. Moderate magneto-crystalline anisotropy is observed and it shows a correspondence with the anisotropy of elastic constants. Occurrence of type−II Weyl nodes and their evolution under pressure is explored.

Nano-vesicular systems for melanocytes targeting and melasma treatment: In-vitro characterization, ex-vivo skin retention, and preliminary clinical appraisal

Melasma represents an acquired melanogenesis disorder resulting in skin’s hyperpigmentation effect. Although several approaches are adopted for melasma treatment, nanotechnology presents the most convenient one. Therefore, the present work aimed to formulate and characterize three nano-vesicular systems namely, liposomes, penetration enhancer containing vesicles (PEVs) and invasomes to enhance the topical delivery of the skin whitening agent; alpha arbutin (α-arbutin) for the treatment of melasma. Liposomes were prepared according to a 23 full factorial design and the selected formula was further employed for the preparation of PEVs and invasomes. Results showed that the three vesicular systems exhibited nano-sizes ranging from 151.95 to 672.5 nm, negative charges ranging from −12.50 to −28.20 mV, high entrapment efficiencies ranging from 80.59 to 99.53 %, good stability and prolonged-release of α-arbutin for 24 h after dispersion in hydrogel form. The deposition study from the vesicular hydrogel confirmed their effectiveness for the drug’s accumulation in the skin reaching an average of 1.6-fold higher in the stratum corneum, 1.6–1.8-fold higher in the epidermis, and 1.6–1.8-fold higher in the dermis compared to the free drug dispersion in hydrogel. A preliminary clinical split-face study on patients suffering from melasma revealed that α-arbutin-loaded liposomes and PEVs in hydrogel forms showed better clinical outcomes compared to the free α-arbutin hydrogel as well as to the previously published α-arbutin encapsulated in chitosan nanoparticles and dispersed in hydrogel form. This delineates the aforementioned nano-vesicular systems as effective and clinically superior delivery means for melasma management.

Osteoinductivity enhancement by tailoring the surface chemical bond status: A strategy to mobilize host bone growth factors for in situ bone regeneration

The incorporation of growth factors and biomaterials is a promising strategy for improving osseointegration. However, current strategies to develop biomaterials with exogenous growth factors present disadvantages like inefficiency, difficult deployment, and potential off-target activation, making their translation into clinical practice challenging. This study reveals a bioactive N-doped tantalum carbide (TaC) solid solution film that can be used to construct a TaCN film via bionic interface engineering to recruit host bone growth factors to the wounded site and improve bone regeneration. X-ray photoelectron spectroscopy (XPS) and protein absorption analysis reveal that the performance of TaCN is related to the surface chemical bonds of films. The introduction of N to TaC causes a cascade effect wherein negative charges enrich on the TaCN surface, and the recruitment of positively charged bone growth factors around the TaCN film is facilitated. Under these circumstances, the endogenous bone growth factors enhance bone healing. The TaCN film shows an outstanding performance for in vivo osteogenic differentiation along with a superior in vitro cytocompatibility. Incorporation of N atoms into TaC provides a new clinically translatable strategy to mobilize host bone growth factors for in situ bone regeneration without the need for incorporation of exogenous growth factors.

PH-Sensitive Tacrolimus loaded nanostructured lipid carriers for the treatment of inflammatory bowel disease

Inflammatory Bowel Disease is the chronic tissue inflammation of the lower part of the Gastrointestinal tract (GIT). Conventional therapeutic approaches face numerous challenges, often making the delivery system inadequate for treating the disease. This study aimed to integrate a pH-sensitive polymer and nanostructured lipid carriers (NLCs) to develop a hybrid nanocarrier system. Tacrolimus-loaded NLCs coated with Eudragit® FS100 (TAC-NLCs/E FS100) nanoparticles were prepared via double emulsion technique followed by an aqueous enteric coating technique. Various parameters, such as particle size, entrapment efficiency, and zeta potential were optimized using Design Expert software®. Cetyltrimethyl ammonium bromide (CTAB) was used as a cationic surfactant which induces a positive charge on the nanoparticles. These cationic NLCs can adhere to the mucosal surface, thereby enabling prolonged retention. In vitro drug release was assessed, and the results demonstrated that drug release was retarded at pH 1.2 corresponding to upper GIT pH and maximum drug was released at pH 7.4 (colonic pH). Moreover, we evaluated TAC-NLCs/E FS100 nanoparticles in murine colitis models to gauge the efficacy of both coated and uncoated NLCs formulation. The TAC-NLCs/E FS100 showed a pronounced reduction in induced colitis, as evident from the restoration of morphological features, improved histopathological scores, antioxidant levels, and decreased the levels of proinflammatory cytokines. Thus, pH-sensitive TAC-NLCs/EFS 100 are attributed to the enhanced localization and targeted delivery at the specific site.

Anionic Ionomer: Released Surface-Immobilized Cations and an Established Hydrophobic Microenvironment for Efficient and Durable CO2-to-Ethylene Electrosynthesis at High Current over One Month.

Electrosynthesis of multicarbon products, such as C2H4, from CO2 reduction on copper (Cu) catalysts holds promise for achieving carbon neutrality. However, maintaining a steady high current-level C2H4 electrosynthesis still encounters challenges, arising from unstable alkalinity and carbonate precipitation caused by undesired ion migration at the cathode under a repulsive electric field. To address these issues, we propose a universal "charge release" concept by incorporating tiny amounts of an oppositely charged anionic ionomer (e.g., perfluorinated sulfonic acid, PFSA) into a cationic covalent organic framework on the Cu surface (cCOF/PFSA). This strategy effectively releases the hidden positive charge within the cCOF, enhancing surface immobilization of cations to impede both outward migration of generated OH- and inward migration of cations, inhibiting carbonate precipitation and creating a strong alkaline microenvironment. Meanwhile, the ionomer's hydrophobic chains create a hydrophobic environment within the cCOF, facilitating efficient gas transport. In situ characterizations and theoretical calculations demonstrate that the cCOF/PFSA catalyst establishes a hydrophobic strong alkaline microenvironment, optimizing the adsorption strength and configuration of *CO intermediates to promote the C2H4 formation. The optimized catalyst achieves a 70.5% Faradaic efficiency for C2H4 with a partial current density over 470 mA cm-2. Notably, it delivers a high single-pass carbon efficiency of 96.5% for CO2RR and sustains an exceptional stability over 760 h. When implemented in a large-area MEA electrolyzer and a 5-cell MEA stack, the system achieves an industrial current of 15 A and continuous C2H4 production exceeding 19 mL min-1, marking a significant step toward industrial feasibility in CO2RR-to-C2H4 conversion.

Computational Designed and Optimized Liposomal Curcumin-Embedded Bifunctional Cross-Linked Hydrogels for Wound Healing.

Curcumin (CUR) bifunctional cross-linked nanocomposite hydrogels are presented as an efficient method for CUR delivery in wound healing. CUR-loaded liposomes (CUR-Ls) were optimized using the Box-Behnken design to augment particle size, size distribution, zeta potential, and CUR concentration. The antioxidant activity and cytotoxicity of CUR-Ls were assessed. Hyaluronic acid (HA)/poly(vinyl alcohol) (PVA) hydrogels were optimized with a central composite design; then, poly(N-vinylpyrrolidone-co-itaconic acid) (PNVP-ITA) was synthesized to enrich the properties of the hydrogels. The drug release kinetics of the CUR-L@HA/PVA/PNVP-ITA hydrogels were studied. Skin recovery was investigated in vivo on rat dorsal skin. The optimized CUR-Ls were constructed from 2.7% Tween® 20, 0.04% oleic acid, and 8.1% CUR, yielding nano-CUR-L with a narrow size distribution, negative surface charge, and CUR content of 19.92 ± 0.54 µg/mg. CUR-Ls improved the antioxidant effects of CUR. The optimized hydrogel contained 5% HA and 10% PVA. PNVP-ITA improved the properties of the hydrogels via enhanced cross-linking. CUR-Ls exhibited a more rapid release than CUR, whereas the hydrogels enhanced CUR release via a diffusion-controlled mechanism. CUR-L@HA/PVA/PNVP-ITA hydrogels improved the skin recovery rate compared to the commercial patch after 5 days. Therefore, the optimized CUR-L@HA/PVA/PNVP-ITA hydrogels facilitated skin recovery and could be a promising nanocomposite for wound dressings.

Synthesis of Mesoporous Catechin Nanoparticles as Biocompatible Drug-Free Antibacterial Mesoformulation.

While polyphenolic substances stand as excellent antibacterial agents, their antimicrobial properties rely on the auxiliary support of micro-/nanostructures. Despite offering a novel avenue for enhancing polymer performance, controllable fabrication of mesoporous polymeric nanomaterials encounters significant challenges due to intricate intermolecular forces. In this article, mesoporous catechin nanoparticles have been successfully fabricated using a balanced multivariate interaction approach. The harmonization of the water-ethanol ratio and ionic strength effectively balances the forces of hydrogen bonding and π-π stacking, facilitating the controlled assembly of mesostructures. The mesoporous catechin nanoparticles exhibit a uniform spherical structure (∼100 nm), open mesopores with a diameter of ∼15 nm, and a high surface area of ∼106 m2 g-1. While exhibiting a good biocompatibility and negative surface charge, the mesoporous catechins possess outstanding antibacterial ability and function as an antibiotic mesoformulation without the necessity of loading any drugs. This mesoformulation inhibits 50% in vitro Staphylococcus aureus growth with a low concentration of ∼10 μg mL-1 and achieves complete inhibition at ∼25 μg mL-1. In a mouse wound model, accelerated wound healing and complete closure within 6-8 days are achieved. Proteomics of bacteria reveals that the excellent antibacterial property is attributed to the synergetic effect of mesoformulation's mesostructure and the catechin molecule intervening in bacterial metabolism. Overall, this work may pave a novel way for the future exploration of polymer nanomaterials and antibiotic formulations.

Synthesis and Characterization of Multifunctional Chitosan-Silver Nanoparticles: An In-Vitro Approach for Biomedical Applications.

Antibiotics are successful in promoting health quality by preventing various infectious diseases and minimizing mortality and morbidity all over the world. However, the indiscriminate use of antibiotics has led to the emergence of multi-drug-resistant bacteria, which pose a serious threat to health care sector. Therefore, it is necessary to develop novel antimicrobial agents with versatile characteristics, such as antibacterial activity, low toxicity, wound healing potency, and antioxidant property. In this context, silver chitosan nanoparticles were synthesized in the present study, and their physical characterization revealed that the size of synthesized chitosan-silver nanoparticles was 14-25 nm, with positive surface charge. The functional groups and crystalline nature of the nanoparticles were confirmed by FT-IR and XRD analysis. Further, the silver chitosan nanoparticles showed antibacterial activity against two important clinical pathogens, S. aureus and E. coli. The MTT assay carried out in the present study showed that the synthesized nanoparticles are non-toxic to host cells. A scratch assay on fibroblast cells (L292) demonstrated that the silver chitosan nanoparticles showed promising wound healing activity. A fluorescent DCFH-DA staining assay revealed anantioxidant property of the synthesized nanoparticles. Overall, the study emphasizes the versatile nature of synthesized chitosan-silver nanoparticles, suggesting their great compatibility for biomedical applications.

Laser-synthesized TiN-based nanoparticles as novel efficient electrostatic nanosorbent for environmental water cleaning

Abstract Dyes used in industries such as textile, paper, and leather are known to be harmful to both human health and aquatic ecosystems, which makes critically important the search of effective and sustainable methods for their removal from wastewater in order to mitigate the detrimental pollution effects. Here, we show that titanium nitride nanoparticles (TiN NPs) synthesized by scalable methods of pulsed laser ablation in liquid ambient (water, acetone and acetonitrile) can serve as extremely efficient sorbents for water decontamination from dye molecules (methylene blue, crystal violet, and malachite green). Our tests show that adsorption of TiN NPs is associated with the electrostatic effect due to a strong negative charge of laser-synthesized TiN NPs and the presence of pores in the NPs. Comprehensive characterization using scanning and transmission electron microscopy, along with Raman spectroscopy, evidenced that the appearance of surface charge is related to the formation of under-stoichiometric TiN (TiN1-x), associated with the predominance of nitrogen vacancies. This study identifies an optimal configuration of vacancy defects that maximizes dye adsorption, with TiN NPs synthesized in water exhibiting superior performance, achieving a dye sorption capacity of 136.5 mg/g at room temperature for methylene blue, which corresponds to best earlier reported values for nanomaterials. This study not only extends the utility of TiN NPs to environmental remediation but also highlights the critical influence of synthesis conditions on their functional properties, offering a pathway towards the design of more effective materials for pollution control.