Differential immobilization of cadmium and changes in soil surface charge in acidic Ultisol by chitosan and citric acid: effect of their functional groups.

Soil organic matter plays an important role in cadmium adsorption and immobilization. Since different organic matter components affect cadmium adsorption processes differently, selecting the right organic substrate and knowing how to apply it could improve cadmium remediation. This study compares the effects of two contrasting organic molecules; chitosan and citric acid, on cadmium adsorption and speciation in acidic Ultisol. The adsorption of chitosan to Ultisol significantly increased the soil positive charge while adsorption of citric acid increased the soil negative charge. At pH 5.0, the maximum amount of cadmium adsorbed in excess chitosan was 341% greater than that in excess citric acid. About 73-89% and 60-62% of adsorbed cadmium were bound to Fe/Mn oxides and organic matter/sulfide at pH 4.0 while this fraction was 77-100% and 57-58% for citric acid and chitosan at pH 5.0, respectively. This decrease in the complexing ability of chitosan was related to the destabilizing effect of high pH on chitosan's structure. Also, the sequence through which chitosan, citric acid, and cadmium were added into the adsorption system influenced the adsorption profile and this was different along a pH gradient. Specifically, adding chitosan and cadmium together increased adsorption compared to when chitosan was pre-adsorbed within pH 3.0-6.5. However, for citric acid, the addition sequence had no significant effect on cadmium adsorption between pH 3.0-4.0 compared to pH 6.5 and 7.5, with excess citric acid generally inhibiting adsorption. Given that the action of citric acid is short-lived in soil, chitosan could be a good soil amendment material for immobilizing cadmium.

Understand the Stabilization Engineering of Ascorbic Acid, Mapping the Scheme for Stabilization, and Advancement.

Vitamin C is extensively used in cosmetic formulation, howbeit stability is the supreme demerit that limits its use in beautifying products. Numerous techniques are being employed to inhibit the degradation of vitamin C caused by formulation components to facilitate the use in skin rejuvenating products. Diverse materials are being exercised in formulation to stabilize the ascorbic acid and ingredients selected in this formulation composition help for stabilization. The initial stable prototype is developed and further optimization is accomplished by applying the design of experiment tools. The stable pharmaceutical formulations were evaluated for the evaluation parameters and designated as two optimized formulations. The analytical method for the assay of ascorbic acid from the United States pharmacopeia and the related substance method from European pharmacopeia has been modified to be used for cream formulation. The DoE design exhibited that the stability of formulation is impacted by citric acid and tartaric acid but not by propylene glycol and glycerin. The analysis results of topical formulations for the evaluation parameter exhibited satisfactory results. The in-vitro release study method has been developed, optimized, and validated to fit the analysis. The in-vitro studies have been performed for selected compositions and both the formulation has similar kinds of release patterns. The stability study as per ICH guidelines exhibited that the product is stable for accelerated, intermediate, and room-temperature storage conditions. The optimized formulation shows constant release and permeation of ascorbic acid through the skin. The formulation with the combinations of citric acid, tartaric acid, and tocopherol is more stable and the degradation of vitamin C has been reduced significantly. The beaucoup strategies in the unique composition help to protect the degradation by inhibiting the multitudinous degradation pathways.

Impact of low molecular weight organic acids on heavy metal(loid) desorption in biochar-amended paddy soil.

Low molecular weight organic acids (LMWOAs) are important soil components and play a key role in regulating the geochemical behavior of heavy metal(loid)s. Biochar (BC) is a commonly used amendment that could change LMWOAs in soil. Here, four LMWOAs of oxalic acid (OA), tartaric acid (TA), malic acid (MA), and citric acid (CA) were evaluated for their roles in changing Cd and SB desorption behavior in contaminated soil with (S1-BC) or without BC (S1) produced from Paulownia biowaste. The results showed that OA, TA, MA, and CA reduced soil pH with rising concentrations, and biochar partially offset the pH reduction by LMWOAs. The LMWOAs reduced Cd desorption from the soil at low concentrations but increased Cd desorption at high concentrations, and CA was the most powerful in this regard. The LMWOAs had a similar effect on Sb desorption, and CA was the most effective species of LMWOAs. Adding BC to the soil affects Cd and Sb dynamics by reducing the Cd desorption but increasing Sb desorption from the soil and increasing the distribution coefficient (Kd) values of Cd but lowering the Kd values of Sb. This study helped understand the effects of LMWOAs on the geochemical behavior of Cd and Sb in the presence of biochar, as well as the potential risks of biochar amendment in enhancing Sb desorption from contaminated soil.

Structure characterization and gelling properties of RG-I-enriched pectins extracted from citrus peels using four different methods.

To facilitate the application of rhamnogalacturonan-I (RG-I)-enriched pectins (RGPs) as novel, healthy, and gelling food additives, this study compared the structural characteristics and gelling properties of RGPs extracted from citrus peel via four methods (alkali: AK, high-temperature/pressure: TP, citric acid: CA, and enzyme-assisted: EA extractions). AK and CA yielded pectins with the highest RG-I proportions (54.8 % and 51.9 %, respectively) by disrupting the homogalacturonan region; TP and EA increased the RG-I proportions by ~10 %. Among the four methods, AK induced the lowest degree of esterification (DE) (6.7 %) and longer side chains that form strong entanglement, contributing to its highest gel hardness. The relatively low DE (18.5 %) of CA RGP facilitated stable gel formation. Notably, its highly branched RG-I region afforded more intramolecular hydrophobic interactions, making a more highly cross-linked gel network of better gel resilience. In contrast, TP induced the highest DE (57 %) and curved molecular chains; it inhibited Ca2+ binding, entanglement, and intramolecular hydrophobic interactions, and thus no gel formed. EA RGP was associated with the lowest molecular size, rendering it more difficult for Ca2+ to form links, which resulted no gel. These findings offer insights into the relationship among the extraction methods, molecular structures, and gelling properties of RGPs.

Toward a Sustainable Approach for Durably Hydrophilic and UV Protective PET Fabric through Surface Activation and Immobilization Integrating Epigallocatechin Gallate and Citric Acid.

Enhancing the hydrophilicity and UV protective property of poly(ethylene terephthalate) (PET) fabric are two significant ways to upgrade its quality and enlarge the applicable area. Biobased finishes are greatly welcomed for the fabrication of sustainable textiles; however, their application on PET fabric is still challenging compared with the case of natural fabric. This study presents a strategy that immobilizes epigallocatechin gallate (EGCG) onto PET fabric using citric acid (CA) for durably hydrophilic and UV-proof properties with negligible color change. A controllable surface-activating method integrating alkaline and deep eutectic solvent (DES) is customized for the PET fabric to promote the reactions among PET, CA, and EGCG. The hydrophilic, antistatic, and UV protective properties of functionalized PET fabric were explored. Results show that the hydrophilicity of the PET fabric after direct EGCG treatment increases but drops sharply after first-round washing due to weak interactions. The combined alkaline/DES pretreatment increases the number of hydrophilic groups and the roughness of PET fibers. After EGCG modification, the moisture regain (MR) of PET fabric increases from 0.41 to 0.64%. The contact angle and electrostatic charge half-life (T1/2) decreases from >120 to 23°, and from >60 to 0.13 s, respectively. The MR and T1/2 are well retained after a 10-cycle washing. In addition, the UV protective factor of the PET fabric increases from 18 to 36. A very slight yellowing phenomenon occurs on the PET fabric after the treatment. In all, this research attempts to integrate a biobased finishing agent and an eco-friendly cross-linker on synthetic fiber for durable functions, which is transferrable to the sustainable fabrication of other polymeric materials such as fibers or films.

Dual- or single rinse? The tubular sealer penetration of endodontic chelating agents.

INTRODUCTION: In this study, we aimed to compare the effectiveness of various chelating agents, ethilenediaminetetraacetic acid (EDTA), citric acid (CA), and etidronic acid (HEDP) mixed in two different forms, in removing the smear layer and promoting the penetration of an endodontic sealer into the dentinal tubules of extracted single-rooted teeth. METHODS: The study used 75 teeth divided into five groups: 17% EDTA, 10% CA, 9% HEDP + NaOCl, 9% HEDP + distilled water (DW), and a control (DW) group. Scanning electron microscopy was used to assess smear layer removal and confocal laser microscopy was used to evaluate tubular sealer penetration at different depths from the apical tip. RESULTS: Sealer penetration was highest with 17% EDTA and 10% CA as compared with the other agents (p<0.001). At the cervical third, the sealer penetration for EDTA, HEDP + NaOCl, and HEDP + DW groups were significantly different than those in DW (p = 0.020). For the middle third, EDTA, CA, and HEDP + NaOCl groups were significantly higher than those of the DW group (p<0.001). Cervical-level values were significantly higher than apical-level values for HEDP + NaOCl, HEDP + DW, and DW (p<0.001). Smear layer removal was lower with 9% HEDP + DW than with 17% EDTA and 10% CA at all depths (p<0.001). A significancy in smear layer removal was observed between 10% CA and control (p = 0.015) in middle depth. CONCLUSION: Within the limitations of this study, highest values were seen in EDTA and CA in terms of sealer penetration and smear layer removal. In the light of these findings, the use of strong chelating agents highlights better clinical efficiency than dual-rinse or single HEDP irrigation.

Effect of Organic Acid-Aided Extraction on Characteristics and Functional Properties of Pectin from Cannabis sativa L.

The extraction of cannabinoids from the inflorescence and leaves of Cannabis sativa L. is gaining interest from researchers, in addition to addressing the under-utilization of the by-products in the stems and roots of the trees. The present study investigated the recovery of pectin from the left-over parts of hemp tress using an eco-friendly method with the aid of organic acids. Different cannabis cultivars-Chalotte's Angels (CHA) and Hang-Krarog (HKR)-were used as plant materials. The stems of both cannabis cultivars contained more pectin than the roots, and tartaric acid-aided extraction provided higher yields than from citric acid. Extracting the acid solution affected some characteristics, thereby differentiating the functional properties of the derived pectin. Extraction using tartaric acid provided pectin with a higher galacturonic acid content, whereas pectin with a higher methylation degree could be prepared using citric acid. The pectin samples extracted from the stems of CHA (P-CHA) and HKR (P-HKR) had low methoxyl pectin. P-CHA had better free radical scavenging capability, whereas P-HKR showed more potent reducibility. Considering the functional properties, P-CHA showed greater emulsion formability and foaming activity, whereas P-HKR possessed a better thickening effect. The present work suggests the feasible utilization of P-CHA and P-HKR as food additives with bioactivity.

An Attempt to Replace Pure Citric Acid with Natural Lemon Juice during Potato Starch Esterification.

The application of chemical operations in food processing, in which pure chemical compounds are used to modify food ingredients, often raises social concerns. One of the most frequently modified dietary substances is starch, e.g., E1401-E1404, E1412-E1414, E1420, E1422, E1440, E1442, and E1450-E1452. An alternative solution to chemical treatments seems to be the use of raw materials naturally containing substrates applied for starch modification. Heating starch with a lemon juice concentrate can be considered a novel and effective method for producing starch citrate, which is part of the so-called "green chemistry". The modified preparations obtained as a result of potato starch esterification with natural lemon juice had a comparable degree of esterification to that of the esters produced with pure citric acid. In addition, the use of the juice doubled their resistance to amylolytic enzymes compared to the preparations made with pure acid. Replacing citric acid with lemon juice can facilitate the esterification process, and the analyzed properties of both types of modified preparations indicate that starch esters produced with pure citric acid can be successfully replaced by those produced using natural lemon juice, which may increase the social acceptance of these modified preparations.

Detection of Low-Concentration Biological Samples Based on a QBIC Terahertz Metamaterial Sensor.

Quasi-bound state in the continuum (QBIC) can effectively enhance the interaction of terahertz (THz) wave with matter due to the tunable high-Q property, which has a strong potential application in the detection of low-concentration biological samples in the THz band. In this paper, a novel THz metamaterial sensor with a double-chain-separated resonant cavity structure based on QBIC is designed and fabricated. The process of excitation of the QBIC mode is verified and the structural parameters are optimized after considering the ohmic loss by simulations. The simulated refractive index sensitivity of the sensor is up to 544 GHz/RIU, much higher than those of recently reported THz metamaterial sensors. The sensitivity of the proposed metamaterial sensor is confirmed in an experiment by detecting low-concentration lithium citrate (LC) and bovine serum albumin (BSA) solutions. The limits of detection (LoDs) are obtained to be 0.0025 mg/mL (12 µM) for LC and 0.03125 mg/mL (0.47 µM) for BSA, respectively, both of which excel over most of the reported results in previous studies. These results indicate that the proposed THz metamaterial sensor has excellent sensing performances and can well be applied to the detection of low-concentration biological samples.

Reduction of surface treatment time by combination of citric acid and ascorbic acid while restoring shear bond strength of metal brackets bonded to bleached enamel: a pilot study.

BACKGROUND: To investigate the effect of a 50% ascorbic acid with 50% citric acid solution on the immediate shear bond strength (SBS) of metallic brackets after tooth bleaching. The enamel etching pattern and the required quantity of these combined acids as antioxidants following 35% hydrogen peroxide (HP) bleaching were also determined. METHODS: The stability of the solution at room temperature was assessed at various time intervals. Fifty teeth were randomly divided into five groups: non-bleached (G1), bleached then acid etched (G2), bleached followed by a 10-minute treatment with 10% sodium ascorbate and acid etched (G3), 5-minute treatment with 50% ascorbic acid (G4), and 5-minute treatment with a combination of 50% ascorbic acid and 50% citric acid (G5). Groups G2, G3, G4 and G5 were bleached by 35% HP gel for a total of 32 min. Acid etching in groups G1, G2, and G3 was performed using 37% phosphoric acid (Ormco®, Orange, CA, USA) for 15 s. In all groups, metal brackets were immediately bonded using Transbond™ XT primer and Transbond™ PLUS adhesive, with light curing for 40 s. The SBS was tested with a universal testing machine, and statistical analysis was conducted using one-way ANOVA followed by Tukey's HSD test. The level of significance was set at p < 0.05 for all statistical tests. RESULTS: Stability tests demonstrated that the combined acids remained effective for up to 21 days. Group G5 significantly increased the SBS of bleached teeth to the level of G1 (p < 0.05), while G3 did not achieve the same increase in SBS (p > 0.05). SEM analysis revealed enamel etching patterns similar to those of both control groups (G1 and G2). Kinetic studies at 6 min indicated that the antioxidation in G5 reacted 0.2 mmole lower than in G3 and G4. CONCLUSION: 5-minute application of the combined acids enhanced the SBS of bleached teeth comparable to unbleached teeth. The combined acids remain stable over two weeks, presenting a time-efficient, single-step solution for antioxidant application and enamel etching in orthodontic bracket bonding.

Cell Wall Modification Based on Combination Reagents to Improve Dimensional Stability of Wood with High Efficiency.

Although γ-methacryloxypropyltrimethoxysilane (MPS) was proved to be an effective reagent for improving the dimensional stability of wood, a bottleneck in ASE value (around 50%) existed. The reason was that MPS with low polarity opened few hydrogen bonds in the amorphous region of cellulose, while these hydrogen bonds could be reopened by water. Therefore, citric acid (CA) is chosen to cooperate with MPS to further enhance the dimensional stability of wood. In this paper, MPS and CA were used to modify wood individually (MW and CW) or with different combinations, that is, one-step modification (M/CW) and two-step modification with MPS first (M-CW) or CA first (C-MW). CA and MPS concentrations were optimized at 5 wt%. The ASE value for M/CW was only 25.74% at a weight percent gain (WPG) of 6.43%, which was only 0.6 times to MW or 0.7 times to CW. For M-CW, the ASE value gradually decreased with the soaking cycles, from 65.64% at a WPG of 9.05% to 51.20%. The C-MW had the best dimensional stability, with the ASE value 75.35% at a WPG of 11.50%. Although it decreased during the first soaking cycle, it stabilized at 62.20% at last. SEM and EDS images showed that the polymer mainly distributed in cell walls and few in cell lumen in C-MW. Thus, the enhanced dimensional stability of C-MW could be explained by CA opening the hydrogen bonds in the amorphous region of cellulose first, which provided more binding sites for MPS.

Modification and characterization of a novel and fluorine-free cellulose nanofiber with hydrophobic and oleophobic properties.

In this study, a brand-new, easy, and environmentally friendly approach for chemically functionalizing 2,2,6,6-tetramethylpiperidinyloxyl radical (TEMPO)-oxidized cellulose nanofiber (TOCNF) to produce modified cellulose nanofiber (octadecylamine-citric acid-CNF) was proposed. Effects of octadecylamine (ODA)/TOCNF mass ratio on the chemical structure, morphology, surface hydrophobicity and oleophobicity were studied. According to Fourier transform infrared spectroscopy (FTIR) analysis, ODA was successfully grafted onto the TOCNF by simple citric acid (CA) esterification and amidation reactions. Scanning electron microscopy (SEM) showed that a new rough structure was formed on the ODA-CA-CNF surface. The water contact angle (WCA) and the castor oil contact angle (OCA) of the ODA-CA-CNF reached 139.6° and 130.6°, respectively. The high-grafting-amount ODA-CA-CNF was sprayed onto paper, and the OCA reached 118.4°, which indicated good oil-resistance performance. The low-grafting-amount ODA-CNF was applied in a pH-responsive indicator film, exhibiting a colour change in response to the pH level, which can be applied in smart food packaging. The ODA-CA-CNF with excellent water/oil-resistance properties and fluorine-free properties can replace petrochemical materials and can be used in the fields of fluorine-free oil-proof paper.

Study on the enhancement of citric acid chemical leaching of contaminated soil by modified nano zero-valent iron.

This study aimed to evaluate the effect of modified nanoscale zero-valent iron (SAS-nZVI) on chemical leaching of lead and cadmium composite contaminated soil by citric acid (CA). The synthesized SAS-nZVI was used as a leaching aid to improve the removal rate of soil heavy metals (HMs) by CA chemical leaching. The effects of various factors such as SAS-nZVI dosage, elution temperature and elution time were studied. At the same time, the effect of chemical leaching on the basic physical and chemical properties of soil and the morphology of HMs was evaluated. The results show that when the SAS-nZVI dosage is 2.0 g/L, the leaching temperature is 25 °C, and the leaching time is 720 min, the maximum removal rates of Pb and Cd in the soil are 77.64% and 97.15% respectively. The experimental results were evaluated using elution and desorption kinetic models (Elovich model, double constant model, diffusion model). The elution and desorption process of Pb and Cd in soil by SAS-nZVI-CA fitted well with the double-constant model, indicating that the desorption kinetic process of Pb and Cd is a heterogeneous diffusion process, and the elution process is controlled by diffusion factors. After leaching with SAS-nZVI-CA, the physical and chemical properties of the soil changed little, the mobility and toxicity of HMs in the soil were reduced, and the HMs content in the leaching waste liquid was reduced. It can be concluded that SAS-nZVI enhances the efficiency of CA in extracting Pb and Cd from soil, minimizes soil damage resulting from chemical leaching technology, and alleviates the challenges associated with treating leaching waste liquid.

Effect of citric acid modification on the properties of hydrochar and pyrochar and their adsorption performance toward methylene blue: crucial roles of minerals and oxygen functional groups.

Modification is widely used to enhance the adsorption performance of pristine hydrochar (HBC) and pyrochar (BC). However, comparisons between modified HBC and BC toward pollutant removal have rarely been reported. In this study, pristine HBC and BC derived from rice straw were first produced, and then citric acid (CA) was used as a modifier to synthesize CA-modified HBC (CAHBC) and CA-modified BC (CABC). Furthermore, the adsorption performance of biochars toward methylene blue (MB) was investigated. The results showed that BC exhibits relatively rough surfaces and contains more minerals (ash), whereas HBC has plentiful O-containing functional groups and fewer minerals. CA modification partially removed minerals from the surface of BC, which weakened the ion exchange, surface complexation, and n-π interaction, resulting in a lower adsorption ability toward MB. By contrast, CA produced more O-containing functional groups on the surface of HBC, which strengthened the hydrogen bonding and electrostatic interaction, thus increasing the adsorption capacity toward MB. The two-compartment model showed a good fit to the adsorption process of MB on CAHBC, and the isotherm data for MB adsorption by HBC and CAHBC are suitable for the Freundlich model. The highest adsorption amount of MB using CAHBC was 80.13 mg·g-1, which was 27.66% higher than that for CABC. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis indicated that the carboxyl groups in the surface functional groups of CAHBC played a crucial role in the MB adsorption process. In addition, CAHBC showed a good performance for a wide range of pH values (4.0-10.0) and under the interference of coexisting ions, and also presented a recycling ability. Furthermore, the adsorption of MB on CAHBC biochar was a spontaneous, exothermic, degree-of-randomness-increasing process. Consequently, CA modification of HBC is a promising strategy and could be used for MB removal from aquatic environments.

Study on the effect of sodium removal from citric acid pretreated red mud on the physical properties of red mud.

Red mud is a highly alkaline solid waste discharged from the alumina industry, and its high sodium content is the key factor limiting its wide utilization. Therefore, effective control of the "frosting" phenomenon during the application of red mud has received significant attention. In this study, the changes of particle size, phase, morphology, and pore size of red mud after sodium removal with different amounts of citric acid pretreatment were investigated. The single-factor experiment shows that the Na+ leaching rate is 86.33% under a citric acid dosage of 15%, liquid-to-solid ratio of 7 mL/g, leaching temperature of 80 °C, stirring speed of 300 rpm, and leaching time of 10 min. The leachate is characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. The results reveal that Na+ mainly exists in a combined state in the form of cancrinite. With the increase of citric acid dosage, red mud agglomerates, calcite, and cancrinite are dissolved, and new phases such as calcium oxalate and magnesium aluminum hydroxide are formed. The specific surface area, pore volume, and pore diameter show irregular changes with the increase in the citric acid dosage. Citric acid pretreatment can effectively reduce the sodium content in red mud, the treatment cost of leaching solution is low, and the leaching residue is neutral, which is helpful to promote the practical application of red mud.

Citric acid cross-linked pomegranate peel extract-loaded pH-responsive ß-cyclodextrin/carboxymethyl tapioca starch hydrogel film for diabetic wound healing.

Pomegranate peel extract (PPE) hydrogel films filled with citric acid (CA) and ß-cyclodextrin-carboxymethyl tapioca starch (CMS) were designed mainly to prevent wound infections and speed up the healing process. FTIR and NMR studies corroborated the carboxymethylation of neat tapioca starch (NS). CMS exhibited superior swelling behavior than NS. The amount of CA and ß-CD controlled the physicochemical parameters of developed PPE/CA/ß-CD/CMS films. Optimized film (OF) exhibited acceptable swellability, wound fluid absorptivity, water vapor transmission rate, water contact angle, and mechanical properties. Biodegradable, biocompatible, and antibacterial films exhibited pH dependence in the release of ellagic acid for up to 24 h. In mice model, PPE/CA/ß-CD/CMS hydrogel film treatment showed promising wound healing effects, including increased collagen deposition, reduced inflammation, activation of the Wingless-related integration site (wnt) pathway leading to cell division, proliferation, and migration to the wound site. The expression of the WNT3A gene did not show any significant differences among all the studied groups. Developed PPE-loaded CA/ß-CD/CMS film promoted wound healing by epithelialization, granulation tissue thickness, collagen deposition, and angiogenesis, hence could be recommended as a biodegradable and antibacterial hydrogel platform to improve the cell proliferation during the healing of diabetic wounds.

Preparation of citric acid cross-linked chitosan quaternary phosphonium/polyvinyl alcohol composite film and its application in strawberry preservation.

Chitosan quaternary phosphine salts (NPCS) were synthesized with enhanced antimicrobial properties using a two-step method. Composite films (CNSP) were prepared by incorporating NPCS and polyvinyl alcohol (PVA) as the base material, citric acid as the crosslinker and functional additive, exhibiting antibacterial and UV-blocking properties. The composite film showed a maximum tensile strength of 20.4 MPa, an elongation at break of 677%, and a UV light barrier transmittance of 70%. Application of these composite membranes in preserving strawberries demonstrated effectiveness in maintaining freshness by preventing water loss, inhibiting microbial growth, and extending shelf life. In addition, the composite film demonstrated biosafety. These results indicate that CNSP composite films holds significant promise for safe and sustainable food packaging applications.

An electrochemical sensing potential of cobalt oxide nanoparticles towards citric acid integrated with computational approach in food and biological media.

Although citric acid (CA) has antioxidant, antibacterial, and acidulating properties, chronic ingestion of CA can cause urolithiasis, hypocalcemia, and duodenal cancer, emphasizing the need for early detection. There are very few documented electrochemical-based sensing methods for CA detection due to the challenging behavior of electrode fouling caused by reactive oxidation products. In this study, a novel, non-enzymatic, and economical electrochemical sensor based on cobalt oxide nanoparticles (CoOxNPs) is successfully reported for detection CA. The CoOxNPs were synthesized through a simple thermal decomposition method and characterized by SEM, FT-IR, EDX, and XRD techniques. The proposed sensing platform was optimized by various parameters, including pH (7.0), time (15 min), and concentration of nanoparticles (100 mM) etc. In a linear range of 0.05-2500 µM, a low detection limit (LOD) of 0.13 µM was achieved. Theoretical calculations (ΔRT), confirmed hydrogen bonding and electrostatic interactions between CoOxNPs and CA. The detection method exhibited high selectivity in real media like food and biological samples, with good recovery values when compared favorably to the HPLC method. To facilitate effective on-site investigation, such a sensing platform can be assembled into a portable device.

Shining light on carbon dots: Toward enhanced antibacterial activity for biofilm disruption.

In spite of tremendous efforts dedicated to addressing bacterial infections and biofilm formation, the post-antibiotic ear continues to witness a gap between the established materials and an easily accessible yet biocompatible antibacterial reagent. Here we show carbon dots (CDs) synthesized via a single hydrothermal process can afford promising antibacterial activity that can be further enhanced by exposure to light. By using citric acid and polyethyleneimine as the precursors, the photoluminescence CDs can be produced within a one-pot, one-step hydrothermal reaction in only 2 h. The CDs demonstrate robust antibacterial properties against both Gram-positive and Gram-negative bacteria and, notably, a considerable enhancement of antibacterial effect can be observed upon photo-irradiation. Mechanistic insights reveal that the CDs generate singlet oxygen (1O2) when exposed to light, leading to an augmented reactive oxygen species level. The approach for disruption of biofilms and inhibition of biofilm formation by using the CDs has also been established. Our findings present a potential solution to combat antibacterial resistance and offer a path to reduce dependence on traditional antibiotics.

Preparation of sodium alginate modified silver-metal organic framework and application in citric acid/PVA antimicrobial packaging.

Silver-metal organic framework (Ag@MOF) has exhibited outstanding antimicrobial activity in antimicrobial applications, and reducing the biotoxicity associated with silver has become a research priority. In this study, Ag@MOF was initially modified with sodium alginate (SA) to form SA-Ag@MOF. The results showed that SA could control the release of Ag+, reducing the release by about 8% at 24 h, and the biotoxicity was significantly reduced. Finally, SA-Ag@MOF was applied as an antimicrobial agent in citric acid-modified PVA film to develop a novel composite antimicrobial film. When added at 2 MIC, the CA3-M2 film can effectively inhibit the growth of E. coli and S. aureus, and the inhibition rate has reached 98%. For white radish packaging applications, CA3-M2 film inhibited the growth of surface microorganisms, while ensuring moisture and tissue hardness to extend shelf-life up to 7 days. Overall, the strategy conceived here can be a theoretical basis for novel antimicrobial packaging.