Modification of cellulose substrate by in situ synthesis of metal-organic framework-5 for thin film microextraction of some non-steroidal anti-inflammatory drugs and their measurement by high-performance liquid chromatography-ultraviolet detector

This work, reports the successful preparation a thin film by a simple and inexpensive process for quantification of a model analytes in the urine sample using HPLC-UV. To this end, cellulose paper was employed as a substrate for the in-situ synthesis of MOF-5, to increase the resistance of the prepared film. The prepared film can be reused 26 times with no reduction in its performance. The thin film prepared by MOF-5 modified cellulose substrate was utilized in thin film microextraction (TFME) method for the extraction and preconcentration of naproxen, aspirin, tolmetin, and celecoxib. Under optimal conditions, the linear dynamic range of the target analytes was 2-500 µg L-1 with correlation coefficients (R2) ranging from 0.9961 to 0.9990. Also, the limits of detection (LODs), the limits of quantification (LOQs) and relative standard deviation (RSD%) of the proposed method for selected analytes ranged between 0.57 and 0.77 µg L-1, 1.7 to 2.3 and 3.5 % to 6.2 %, respectively. Moreover, relative recoveries varied from of 94 % to 108 %, indicating the absence of matrices effect in the proposed method. Eventually, the TFME was successfully used for the extraction of selected analytes from urine samples.

Assessment of heavy oil recovery mechanisms using in-situ synthesized CeO2 nanoparticles

This project investigated the impact of low-temperature, in-situ synthesis of cerium oxide (CeO2) nanoparticles on various aspects of oil recovery mechanisms, including changes in oil viscosity, alterations in reservoir rock wettability, and the resulting oil recovery factor. The nanoparticles were synthesized using a microemulsion procedure and subjected to various characterization analyses. Subsequently, these synthesized nanoparticles were prepared and injected into a glass micromodel, both in-situ and ex-situ, to evaluate their effectiveness. The study also examined the movement of the injected fluid within the porous media. The results revealed that the synthesized CeO2 nanoparticles exhibited a remarkable capability at low temperatures to reduce crude oil viscosity by 28% and to lighten the oil. Furthermore, the addition of CeO2 nanoparticles to the base fluid (water) led to a shift in the wettability of the porous medium, resulting in a significant reduction in the oil drop angle from 140° to 20°. Even a minimal presence of CeO2 nanoparticles (0.1 wt%) in water increased the oil production factor from 29 to 42%. This enhancement became even more pronounced at a concentration of 0.5 wt%, where the oil production factor reached 56%. Finally, it was found that the in-situ injection, involving the direct synthesis of CeO2 nanoparticles within the reservoir using precursor salts solution and reservoir energy, led to an 11% enhancement in oil production efficiency compared to the ex-situ injection scenario, where the nanofluid is prepared outside the reservoir and then injected into it.

Electrochemical biosensor based on PAMAM functionalized MXene nanoplatform for detection of folate receptor

The level of folate receptor (FR) has become one of the independent factors for measuring human tumor diseases. The precise quantification of FR is helpful for the early diagnosis and subsequent treatment of tumors. The modification of electrodes is a key issue in ensuring and enhancing the electrochemical biosensing ability. In this study, we in-situ synthesized a nanocomposite material with excellent conductivity and stability by grafting first-generation poly(amidoamine) dendrimers onto the MXene (Ti3C2TX) as the immobilized matrix (PAMAM@MXene). An electrochemical sensor was developed for FR monitor by loading the PAMAM@MXene on screen-printed carbon electrodes (SPCEs). Scanning electron microscopy (SEM) supported the effective synthesis of PAMAM@MXene. Under optimal conditions, the prepared sensor achieved the quantification of FR with a wide range of concentrations from 10 ng/mL to 1000 ng/mL with a detection limit (LOD) of 5.6 ng/mL. It also exhibited satisfactory selectivity, reproducibility, and stability, which provided the possibility for expanding new pathways in the detection of clinical FR.

A G-quadruplex-assisted target-responsive dual-mode aptasensor based on copper nanoclusters synthesized in situ in a DNA hydrogel for ultrasensitive detection of ochratoxin A

Developing ultrasensitive sensing platforms for trace ochratoxin A (OTA) in food safety is still challenging. Herein, we presented a novel dual-mode sensing strategy for fluorescence and colorimetric detection of OTA by combining the target-responsive hemin-encapsulated and copper nanoclusters (CuNCs) functionalized DNA hydrogel. Through simple assembly and in situ synthesis methods, fluorescence CuNCs are synthesized and modified on the 3D hydrophilic network structure of DNA cross-linked. OTA specifically recognized by Apt-linker can control the collapse of hydrogel, resulting in the fluorescence quenching of CuNCs and release of coated hemin. Interestingly, OTA could trigger Apt-linker conformational changes to form G-quadruplex structures, allowing the released hemin to form G-quadruplex/hemin DNAzyme via self-assembly. Fluorescence signal amplification could be achieved through further fluorescence quenching of CuNCs caused by DNAzyme-catalyzed hydrogen peroxide (H2O2) because of the peroxidase activity of DNAzyme. Simultaneously, DNAzyme could catalyze the H2O2-mediated oxidation of TMB to provide colorimetric signal. Thereafter, the DNA-CuNCs hydrogel exhibited low detection limits of 3.49 pg/mL in fluorescence mode and 0.25 ng/mL in colorimetric modality. Real sample analyses of foodstuffs showed satisfactory results, providing prospective potential for monitoring mycotoxin contaminant.

Synthesis and characterization of hydroxyapatite self-assembled nanocomposites on graphene oxide sheets from seashell waste: A green process for regenerative medicine

Bone transplantation is the second most common transplantation surgery in the world. Therefore, there is an urgent need for artificial bone transplantation to repair bone defects. In bone tissue engineering, hydroxyapatite (HA) plays a major role in bone graft applications. This study deals with a facile method for synthesizing HA hexagonal nanorods from seashells by a solid-state hydrothermal transition process. The synthesized HA nanorods (∼2.29 nm) were reinforced with carbon nanotube and chitosan on graphene oxide sheets with polymeric support by in-situ synthetic approach. Among the synthesized nanocomposites viz., hydroxyapatite-graphene oxide (HA-GO), hydroxyapatite-graphene oxide-chitosan (HA-GO-CS), hydroxyapatite-graphene oxide-chitosan-carbon nanotube-polylactic acid (HA-GO-CS-CNT-PLA). Among them, the HA-GO-CS-CNT-PLA composite exhibits micro and macro porosity (∼200 to 600 μm), higher mechanical strength, (Hardness ∼90.5 ± 1.33 MPa; Tensile strength 25.62 MPa), and maximum cell viability in MG63 osteoblast-like cells (80%). The self-assembled hybrid-nanocomposite of HA-GO-CS-CNT-PLA is a promising material for bone filler application and could efficiently utilize seashell waste through the green process.

Fluorescent Eu-MOF@nanocellulose-based nanopaper for rapid and sensitive detection of uranium (Ⅵ)

Radioactive uranium leaks into natural water bodies mainly in the form of uranyl ions (UO22+), posing ecological and human health risks. Fluorescent europium-based metal-organic frameworks (Eu-MOFs) have been demonstrated to be effective fluorescent sensors for UO22+, but the large size, powder state and poor dispersity limit their further application. In this work, fluorescent Eu-MOFs were in-situ grown on TEMPO-oxidized cellulose nanofibers (TOCNFs), which is the first time that spherical Eu-MOF crystals with sizes below 10 nm were prepared. Fluorescence spectral analysis revealed a nine-fold increase in the fluorescence intensity of TOCNF@Eu-MOF compared to Eu-MOF. The nanocomposites achieved rapid and sensitive fluorescence quenching to UO22+ through the "antenna effect" and unsaturated Lewis basic sites on the ligands binding with UO22+. Moreover, TOCNF@Eu-MOF demonstrated excellent selectivity and anti-interference for UO22+ detection. For the nanopaper-based sensor made from TOCNF@Eu-MOF, the Stern-Volmer quenching constant (KSV) was calculated as 8.21 × 104 M-1, and the lowest limit of detection (LOD) was 6.6 × 10-7 M, significantly lower than the 1.32 × 10-6 M of Eu-MOFs. In addition, the nanopaper exhibited good fluorescence stability and cyclic detection performance, enabling the rapid and convenient detection of UO22+ in the aqueous phase within 30 s by simple dipping.

In-situ microbial protein production by using nitrogen extracted from multifunctional bio-electrochemical system

Upgrading of waste nitrogen sources is considered as an important approach to promote sustainable development. In this study, a multifunctional bio-electrochemical system with three chambers was established, innovatively achieving 2.02 g/L in-situ microbial protein (MP) production via hydrogen-oxidizing bacteria (HOB) in the protein chamber (middle chamber), along with over 2.9 L CO2/(L·d) consumption rate. Also, 69% chemical oxygen demand was degraded by electrogenic bacteria in the anode chamber, resulting in the 394.67 J/L electricity generation. Focusing on the NH4+-N migration in the system, the current intensity contributed 4%-9% in the anode and protein chamber, whereas, the negative effect of -6.69% on contribution was shown in the cathode chamber. On the view of kinetics, NH4+-N migration in anode and cathode chambers was fitted well with Levenberg-Marquardt equation (R2 > 0.92), along with the well-matched results of HOB growth in the protein chamber based on Gompertz model (R2 > 0.99). Further evaluating MPs produced by HOB, 0.45 g/L essential amino acids was detected, showing the better amino acid profile than fish and soybean. Multifunctional bio-electrochemical system revealed the economic potential of producing 6.69 €/m3 wastewater according to a simplified economic evaluation.

In-situ constructing porous N-doped carbon skeleton with rich defects from modified polyamide acid to boost the high performance of Na3V2(PO4)3 cathode for full sodium-ion batteries

Generally, the transport of electrons and Na+ is seriously constrained in Na3V2(PO4)3 (NVP) due to intense interactions of V-O and PO bonds. Besides, polyamide acid (PAA) is hardly used in the sol-gel route due to insolubility. This work develops a facile liquid synthesis strategy based on modified PAA, achieving in-situ construction of a porous N-doped carbon framework with rich defects to improve the kinetics of NVP. The addition of triethylamine (TEA) reacts with carboxyls in PAA to achieve acid-base neutralization, turning PAA into polyamide salts with good solubility. The special morphology construction mechanism of this unique system was observed by ex-situ scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). Specifically, PAA undergoes in-situ conversion into chain-like polyimide (PI) through a thermal polymerization mechanism during the pre-sintering process. Meanwhile, NVP precursors are evenly dispersed in the PI fibers, efficiently reducing the particle size. After the final treatment, the favorable porous carbon skeleton could be generated derived from the partial decomposition of PI, on which small active grains are in situ grown. The resulting N-doped carbon substrate contains rich defects, benefiting from the migration of Na+. Furthermore, the porous construction is conducive to alleviating the stress and strain generated by the high current impact, increasing the contact area between electrodes/electrolytes to improve the utilization efficiency of active substances. Comprehensively, the optimized samples exhibit a capacity of 82.1 mAh g-1 at 15C with a retention rate of 95.45 % after 350 cycles. It submits a capacity of 67.6 mAh g-1 at 90C and remains 52.2 mAh g-1 after 1500 cycles. Even in full cells, it reveals a value of 110.6 mAh g-1. This work guides the application of in-situ multiple modifications of polymers in electrode materials.

In-situ synthesized V2CTx MXene-based immune tag for the electrochemical detection of Interleukin 6 (IL-6) from breast cancer cells

Interleukin-6 (IL-6) is a proinflammatory cytokine with a critical role in immune regulation and treatment of many diseases, including breast cancer. Herein, we developed a novel V2CTx MXene-based immunosensor for rapid and accurate IL-6 detection. The chosen substrate was V2CTx, a 2-dimensional (2D) MXene nanomaterial with excellent electronic properties. Prussian blue (Fe4[Fe(CN)6]3), used for its electrochemical properties, and spindle-shaped gold nanoparticles (Au SSNPs), used to combine with antibodies, were in-situ synthesized on the surface of the MXene. The in-situ synthesis ensures a firm chemical connection compared to other tags formed by a less stable physical absorption. Inspired by a sandwich ELISA test, the modified V2CTx tag was captured by the electrode surface with cysteamine to detect the analyte, IL-6, after being attached with a capture antibody (cAb). Benefiting from an increased surface area, an enhanced charge transfer rate, and a firm connection of the tag, this biosensor exhibited excellent analytical performance. The high sensitivity, high selectivity, and wide detection range covering the IL-6 level of both healthy individuals and breast cancer patients were obtained to meet clinical demands. Herein, this V2CTx MXene-based immunosensor is a potential therapeutic and diagnostic point-of-care alternative to routine ELISA IL-6 detection methods.

Preparation of the self-accelerating photocatalytic self-cleaning carboxymethyl cellulose sodium-based hydrogel for removing cationic dyes

Hydrogels loaded with photocatalysts have shown great potential in effectively degrading dye wastewater. In this work, carboxymethyl cellulose sodium-based hydrogels loaded with nitrogen-doped graphene oxide-zinc oxide-zinc peroxide (NGO-ZnO-ZnO2) were synthesized using hydrothermal reaction and in-situ synthesis method. NGO acts as an electron mediator, suppressing the recombination of photoinduced electrons and holes. ZnO2 decomposes to generate hydrogen peroxide (H2O2), promoting a self-enhanced photocatalytic reaction. Carboxymethyl cellulose sodium (CMC) acts as a dispersant, improving the uniformity and stability of NGO-ZnO-ZnO2 within the hydrogel. The results demonstrate that NGO-ZnO-ZnO2 exhibits high photocatalytic degradation efficiency towards methyl orange (MO) (10 mg/L) and rhodamine B (RhB) (50 mg/L), with degradation rates of 99.99 % (200 min) and 99.26 % (160 min), respectively. The carboxymethyl cellulose sodium-based hydrogel achieves a photocatalytic degradation rate of 95.85 % (220 min) for RhB (10 mg/L). After 5 cycles of repeated photocatalytic tests, the degradation efficiency of the hydrogel towards RhB reaches 80.81 %. This work provides a low-cost and convenient method for constructing novel hydrogel carriers with high photocatalytic stability and efficiency.

Parsimonious methodology for synthesis of silver and copper functionalized cellulose

Metal nanomaterials, such as silver and copper, are often incorporated into commercial textiles to take advantage of their Antibacterial and antiviral properties. The goal of this study was to identify the most parsimonious method for the synthesis of silver, copper, or silver/copper bimetallic treated textiles. To accomplish this eight different methods were employed to synthesize silver, copper, and silver/copper functionalized cotton batting textiles. Using silver and copper nitrate as precursors, different reagents were used to initiate/catalyze the deposition of metal, including: (1) no additive, (2) sodium bicarbonate, (3) green tea, (4) sodium hydroxide, (5) ammonia, (6, 7) sodium hydroxide/ammonia at a 1:2 and 1:4 ratio, and (8) sodium borohydride. The use of sodium bicarbonate as a reagent to reduce silver onto cotton has not been used previously in literature and was compared to established methods. All synthesis methods were performed at 80 °C for one hour following textile addition to the solutions. The products were characterized by x-ray fluorescence (XRF) analysis for quantitative determination of the metal content and x-ray absorption near edge structure (XANES) analysis for silver and copper speciation on the textile. Scanning electron microscopy (SEM) with energy dispersive x-ray (EDX) and size distribution inductively coupled plasma mass spectrometry (ICP-MS) were used to further characterize the products of the sodium bicarbonate, sodium hydroxide, and sodium borohydride synthesis methods following ashing of the textile. For the silver treatment methods (1 mM Ag +), sodium bicarbonate and sodium hydroxide resulted in the highest amounts of silver on the textile (8900 mg Ag/kg textile and 7600 mg Ag/kg textile) and for copper treatment (1 mM Cu +) the sodium hydroxide and sodium hydroxide/ammonium hydroxide resulted in the highest amounts of copper on the textile (3800 mg Ag/kg textile and 2500 mg Ag/kg textile). Formation of copper oxide was dependent on the pH of the solution, with 4 mM ammonia and other high pH solutions resulting in majority of the copper on the textile existing as copper oxide, with smaller amounts of ionic-bound copper. The identified parsimonious methods will lend themselves to the efficient manufacturing of antibacterial and antiviral textiles, or the development of multifunctionalized smart textiles.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10570-023-05099-7.

Antibacterial one-step self-etching dental adhesive with silver nanoparticles synthesized in situ

OBJECTIVES

The objective of this study is to value the long-term antibacterial capability and adhesive properties of one-step self-etching dental adhesive containing silver nanoparticles (AgNPs) synthesized in situ.

METHODS

One-step self-etching adhesives with various weight percentages of silver 2-ethylhezanoate (0%, 0.05%, 0.10%, and 0.20%) were obtained by in-situ synthesis; the sizes and distribution of the AgNPs in resin were observed. The antibacterial effects of dentin-resin specimens were assessed by various test methods after being aged for 1 week to 1 year. The microtensile bond strength (μTBS) and interfacial nanoleakage (NL) were evaluated using extracted human teeth after being aged for 1 day and 1 year.

RESULTS

Uniform distribution of AgNPs in resin was observed in all experimental groups, and the average size was 4.71 nm-4.81 nm. All groups containing AgNPs showed significant antibacterial differences from the control group (P<0.05) over the ageing of 1 year. Although the increase of concentration tended to improve antibacterial activity, significant differences were not observed between the 0.10% and 0.20% groups (P>0.05). No significant differences were observed between all experimental groups and the control group in μTBS testing and NL testing at 1-day and 1-year time points (P>0.05).

CONCLUSIONS

0.10% AgNPs synthesized in situ might be appropriate to impart a long-term antibacterial ability to the one-step self-etching adhesive, without affecting its adhesive performance.

CLINICAL SIGNIFICANCE

This study suggests that in-situ synthesis of AgNPs is an effective method to improve the antibacterial ability of dental adhesives with the potential to inhibit secondary caries.

A novel hybrid ferrous sulfide impregnated anion exchanger for trace removal of hexavalent chromium from contaminated water

To effectively remove trace concentration of potential cancer-causing Cr(VI) from impaired drinking water, a novel hybrid material was synthesized through an in-situ synthesis process by dispersing ferrous sulfide nanoparticles within an anion exchanger. Characterization studies revealed that the hybrid material, named hybrid ferrous sulfide impregnated anion exchanger (HISIIX), contained uniformly distributed ferrous sulfide nanoparticles of size 10-40 nm within the anion exchanger host. Apart from FeS₂ nanoparticles, it also included nanoparticles of FeO and FeOOH. The incorporation of ferrous sulfide nanoparticles within the anion exchanger contributed to the significant differences in the Cr(VI) uptake capacity of HISIIX. Validation studies using fixed-bed column proved that HISIIX had significantly high Cr(VI) uptake capacity and was able to run for 4200 bed volumes (BVs) before a breakthrough of 50 μg L^-1 when subjected to a synthetic aqueous solution containing 200 μg L^-1 Cr(VI). Cr(VI) uptake capacity of the parent anion exchanger and HISIIX were determined to be 1.39 mg g^-1 and 3.44 mg g^-1, respectively, when the columns were allowed to run until exhaustion. Ferrous sulfide nanoparticles acted as a reducing agent transforming Cr(VI) anions into Cr(III) precipitates. It also produced sites for further removal of Cr(VI) anions through ligand sorption upon oxidation. The anion exchanger substrate attracted anions selectively via the Donnan membrane principle, resulting in a synergy of three different processes - ion exchange, redox reaction, and ligand sorption that gave the HISIIX a high capacity for the selective Cr(VI) removal from contaminated water.

One-pot in-situ hydrothermal synthesis of ternary In2S3/Nb2O5/Nb2C Schottky/S-scheme integrated heterojunction for efficient photocatalytic hydrogen production

MXene-derived photocatalysts continue to fascinate the research community in developing photo-driven green and sustainable fuel production. However, the efficiency of MXene-derived photocatalyst is still low due to the wide bandgap and high recombination rate of photo-excited charge carriers. Here, we have synthesized the Nb₂C MXene-derived ternary photocatalyst via one-pot in-situ hydrothermal method for photocatalytic hydrogen (H₂) evolution. The partial oxidation of Nb₂C MXene into Nb₂O₅ nanorods and coupling with In₂S₃ nanoparticles via in-situ chemical anchoring were the key factors toward high efficiency and long-term stability during photocatalytic H₂ evolution. The optimized ternary photocatalyst composite manifested the highest H₂ evolution efficiency at 68.8 µmol g^-1 h^-1, which was 11 and 7.5 times higher than the Nb₂O₅/Nb₂C (NNC) and pure In₂S₃ photocatalyst, respectively. Moreover, the photocatalytic stability of the optimized ternary photocatalyst composite was analyzed for five consecutive cycles, and above 87% activity retention was observed even after the fifth cycle without any obvious decline. The separation efficiency of photoexcited charge carriers could be attributed to the synergic effect of the In₂S₃/Nb₂O₅ heterojunction and the redox reactions at different sites of the composite. More importantly, the participation of Schottky junction and S-scheme heterojunction charge transfer for the obtained novel ternary photocatalyst was evaluated via ultraviolet photoelectron spectroscopy (UPS) and electron paramagnetic resonance (EPR). This research will provide additional insight into the extended potential of MXene-derived ternary photocatalysts towards efficient H₂ production to meet future global energy demands.

In-situ synthesis silver nanoparticles in chitosan/Bletilla striata polysaccharide composited microneedles for infected and susceptible wound healing

A novel antibacterial strategy is urgently required to develop for solving bacterial biofilm obstruction and bacterial drug resistance in the infected wound healing process. Herein, the Chitosan/Bletilla striata polysaccharide composited microneedles were prepared by chitosan, tannic acid, AgNO₃ and Bletilla striata polysaccharide through step centrifugation. In our design system, the porous structure of microneedles gradually disappeared, and the mechanical properties were significantly improved after multiple fillings. Ag⁺ is reduced in-situ to silver nanoparticles by the abundant polyphenols of tannic acid, displaying antibacterial effects both in vitro and vivo, even for methicillin resistant Staphylococcus aureus. The addition of Bletilla striata polysaccharide increased the ability of piercing biofilm and promoted wound healing. The microneedles exhibited good biocompatibility and with function of piercing the bacterial biofilms, scavenging excessive free radicals, inhibiting inflammatory factors, and promoting wound healing. Therefore, the multifunctional composited microneedles show great potential to promote infected and susceptible wound healing.

Antibacterial aerogels with nano‑silver reduced in situ by carboxymethyl cellulose for fresh meat preservation

Bacterial cellulose (BC) was used as a reinforcing agent, citric acid (CA) as a cross-linking agent, and CMC@AgNPs as antibacterial nanomaterials, in which CMC@AgNPs were reduced from AgNO₃ in situ by carboxymethyl cellulose (CMC) as a reducing agent and stabilizer to fight microbial corruption. Its potential application in packaging fresh meat has been investigated. Results showed that the antibacterial CMC@AgNPs/BC/CA aerogels with excellent structural integrity and outstanding water absorption were developed by adding 0.3% BC and 0.25% CA. The CMC@AgNPs/BC/CA aerogel significantly reduced the color change and the total viable bacterial counts (TVC) in fresh meat after 7 days of refrigerated storage. The results indicated that CMC@AgNPs/BC/CA aerogels can effectively extend the shelf life of fresh meat, and can be used for meat packaging as a biologically active absorption pad.

Incorporation of perovskite nanocrystals into lanthanide metal-organic frameworks with enhanced stability for ratiometric and visual sensing of mercury in aqueous solution

In-situ growth of CsPbBr₃ nanocrystal into Eu-BTC was realized for synthesis of dual-emission CsPbBr₃@Eu-BTC by a facile solvothermal method, and a novel ratiometric fluorescence sensor based on the CsPbBr₃@Eu-BTC was prepared for rapid, sensitive and visual detection of Hg²⁺ in aqueous solution. The transmission electron microscopy (TEM), X-ray diffraction pattern (XRD), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) analysis were used to verify the successful incorporation of CsPbBr₃ into the Eu-BTC. Meanwhile, the CsPbBr₃@Eu-BTC nanocomposite maintained high fluorescence performance and stability in aqueous solution. After adding Hg²⁺, the green fluorescence of CsPbBr₃ was quenched and the red fluorescence of Eu³⁺ remained unchanged, while the color changed from green to red obviously. The occurrence of dynamic quenching and electron transfer were verified by fluorescence lifetime, Stern-Volmer quenching constant and XPS analysis. The ratiometric fluorescence sensor shows high analytical performance for Hg²⁺ detection with a wide linear range of 0-1 μM and a low detection limit of 0.116 nM. In addition, it also shows high selectivity for the detection of Hg²⁺ and can be successfully applied to detect Hg²⁺ in environmental water samples. More importantly, a novel paper-based sensor based on the CsPbBr₃@Eu-BTC ratiometric probe was successfully manufactured for the visual detection of Hg²⁺ by naked eyes. This new type of ratiometric fluorescent sensor shows great potential for applications in point-of-care diagnostics.

Building Polyvalent DNA-Functionalized Anisotropic AuNPs Using Poly-Guanine-mediated In-Situ Synthesis For LSPR-Based Assays: Case Study on OncomiR-155

DNA functionalized gold nanoparticles (DNA-AuNPs) hold great promise for numerous biomedical applications, especially the building of well-defined nanosystems. Previously reported methods for the preparation of DNA-AuNPs all rely on the use of DNA bearing free thiol or disulfide groups at their 3'/5' ends. But here we report a novel polyvalent DNA-AuNPs conjugation approach by in-situ fast synthesis of AuNPs at the polyguanine (G₁₂ ) strands. As confirmed by both TEM images and gel electrophoresis analysis, many poly G strand can form an individual anisotropic AuNP and so each AuNP functionalized with a dense layer of DNA, resulting in the formation of polyvalent (p)DNA-AuNPs. The general applicability of this novel approach was further verified in hybridization test and UV-Vis spectroscopy results show that pDNA-AuNPs conjugation is more attractive in biomedical diagnosis and specific sequence detection like microRNA-155 by using an extra-strand poly G with "sticky end" that are complementary to the target sequence.

Facile one-step synthesis of 3D honeycomb-like porous chitosan bead inlaid with MnFe bimetallic oxide nanoparticles for enhanced degradation of dye pollutant

Developing a sustainable, efficient and recyclable heterogeneous Fenton-like catalyst is important to wastewater treatment. Herein, well-dispersed MnO₂ and Fe₃O₄ nanoparticles inlaid in chitosan beads (MnO₂-Fe₃O₄/CH) was firstly fabricated and employed in the degradation of methylene blue (MB). The bead was prepared via a facile one-step method by dropwise addition of chitosan-metal salt solution into alkaline solution. Comparing with monometallic chitosan beads (MnO₂/CH, Fe₃O₄/CH) and naked MnO₂-Fe₃O₄, MnO₂-Fe₃O₄/CH displayed significantly higher activity for MB degradation with the assistance of hydrogen peroxide (H₂O₂), finally removing 96.8% MB under the optimal conditions (50 mg L^-1 MB, 4.0 g L^-1 catalyst, 30 g L^-1 H₂O₂, pH = 7, 60 min). Based on a series of characterizations, the large surface area (60.1 m² g^-1), well-developed porosity (0.3 cm³ g^-1), and intensified electron transport of MnO₂-Fe₃O₄/CH consequently enhanced the catalytic performance via a synergistic effect. Because the specific porous structure of MnO₂-Fe₃O₄/CH facilitated the adsorption/diffusion of reactants and exposure of active sites. Meanwhile, the electron transfer from Mn³⁺ to Fe³⁺ accelerated the Fe³⁺/Fe²⁺ cycle, which favored the production of dominant reactive species hydroxyl radical for MB degradation. Besides, the magnetic beads could be easily collected from the solution and reused for five times with a negligible leaching.

In-situ synthesis of manganese oxide‑carbon nanocomposite and its application in activating persulfate for bisphenol F degradation

In this work, manganese oxide‑carbon nanocomposite catalytic materials (MnO@CNs) with a "core-shell" structure were synthesized in the one-step synthesis using sodium alginate as a template. XRD and Raman spectroscopy proved that high calcination temperatures were beneficial to the graphitization of carbon and the formation of Mn₇C₃. Both SEM and TEM images of MnO@CNs identified that MnO nanoparticles were encapsulated in a three-dimensional carbon matrix and simultaneously protected by a "carbon-shell" with an adherent graphite structure, which could facilitate electron transfer. The MnO@CNs could activate PS to degrade BPF completely within 30 min in solutions with a wide pH range or coexisting anions and organics. The valence change of Mn could promote the generation and conversion of various free radicals and non-radicals, of which O₂·^- played a leading role in the decomposition of BPF. In addition, the potential degradation pathways and degradation mechanisms of BPF in the MnO@CNs/PS system were also explored according to DFT calculations and product detection results.

Carbon coating enhances single-electron oxygen reduction reaction on nZVI surface for oxidative degradation of nitrobenzene

Research on the in-situ generation of hydrogen peroxide (H₂O₂) using nano zero-valent iron (nZVI) has received more and more attention in recent years. However, the low utilization rate of nZVI, strict production conditions, and high energy consumption limit the application of this technology in actual environmental pollution remediation. In this study, carbon-coated nZVI (Fe⁰@C) was used to synthesize H₂O₂ in situ and realize the mineralization of nitrobenzene (NB). The results showed that the composite removed 91% of NB through adsorption, reduction, and oxidation within 120 min, of which oxidation accounts for 42.92%. Not only that, the composite material could achieve effective mineralization of NB under the wide pH range of 3-7. Quantitative experiments of hydroxyl radicals (HO) showed that the composite could generate 185.64 μM HO in 120 min without any extra energy consumption. The carbon-coated structure effectively inhibits the formation of the passivation layer on the surface of the nZVI, thereby ensuring the high activity of the Fe⁰. In addition, the carbon coating strengthens the sequential single-electron transfer process by changing the oxygen reduction pathway on the surface of the nZVI, so that the Fe⁰ can efficiently generate HO through the superoxide radical (O₂^-) pathway under neutral conditions. This study provides a fundamental understanding of the in-situ synthesis of H₂O₂ to mineralize NB by carbon-coated nZVI.

Facile d-band tailoring in Sub-10 nm Pd cubes by in-situ grafting on nitrogen-doped graphene for highly efficient organic transformations

We demonstrate for the first time the in-situ synthesis of Pd nanocubes (PdNC) on nitrogen-doped reduced graphene oxide (NRGO) for facile organic transformations wherein the cubic morphology of Pd can only be realized by precision-controlled acid additions in the tune of 0.02 pH variations in the reaction medium. Due to the intimate contact arising from atom-by-atom addition of Pd on NRGO, the composite has exhibited a pronounced catalyst to support charge transfer effect, shift in the d-band center, and lowering of charge-transfer resistance when compared with PdNC-NRGO ex-situ composites prepared by mixing of the preformed components of PdNC and NRGO or PdNCs alone. The activities of these catalysts were tested for the Suzuki coupling and nitroarene reduction reactions using water as an industry-friendly solvent. In both, the in-situ deposited sample exhibited substantially higher catalytic activity as well as stability when compared with an ex-situ sample or pure PdNCs. We show that a very high turnover frequency of ~31300 h^-1 and ~900 h^-1 are achievable by using the in-situ deposited PdNC-NRGO composite for Suzuki coupling reactions and nitroarene reduction respectively, better than the state-of-the-art catalysts developed recently, in addition to high recyclability.

Carbon dot/cellulose nanofiber composite: Dataset for its water treatment performance

Carbon dot (CD) obtained via one-step hydrothermal carbonization was attached to cellulose nanofiber (CNF) via physical blending and in-situ synthesis. The data represent the morphological, chemical and optical differences of the samples, according to the amount and introducing method of CD. The morphological durability of the samples was also shown. The water treatment membrane performance was analysed using methylene blue as a representative pollutant. The related article was published in Carbohydr. Polym. 255 (2021) 117387.

Antifungal property of acrylic denture soft liner containing silver nanoparticles synthesized in situ

OBJECTIVES

Denture soft liner is applied to relieve pain from candida-induced denture stomatitis and promote healing, but with shortage of antifungal activity and easily harbors fungi. To overcome this problem, the in-situ method was used to synthesize silver nanoparticles (AgNPs) in acrylic soft liner to obtain antifungal effects.

METHODS

Acrylic soft-liner with various weight percentage of silver 2-ethylhexanoate (0%, 0.1 %, 0.2 %, 0.3 %) were prepared in 10 mm × 10 mm × 3 mm. After chemical polymerization, the diameter of AgNPs synthesized in situ and the degree of conversion of each group were measured. After 3, 7, and 14 days of storage in water, the antifungal rate (AFR) of in vitro direct contact antifungal assays and the antifungal test of non-cumulative extract solution were measured respectively. The release profiles of silver ions from the specimen within 14 days were also evaluated.

RESULTS

Evenly distributed AgNPs (4.7 nm-5.3 nm) were observed, and the degree of conversion had no significant difference among these groups. The AFR increased as the silver concentration rose, while decreasing with the storage time. After 14 days of water storage, the AFR of 0.2 % and 0.3 % groups still reached 63.38 % and 75.51 %, respectively. The non-cumulative extract solution had no antifungal effect.

CONCLUSIONS

Within the service life, the acrylic soft liner containing AgNPs synthesized in situ had effective control of Candida albicans through direct contact.

CLINICAL SIGNIFICANCE

This study suggests that AgNPs synthesized in situ may be an effective strategy in modifying acrylic denture soft liner to treat and prevent denture stomatitis.

Synthesis of bimetallic silver-gold nanoparticle composites using a cellulose dope: Tunable nanostructure and its biological activity

Introducing functional metal nanoparticles (NPs) into flexible substrate is being increasingly attempted to expand their application. Here, we extend the synthesis of cellulose to its unmodified dope achieving freestanding nanocomposite decorated with bimetallic Ag-Au NPs through the one pot reaction. In the procedure, cellulose chain not only acts as a reducing agent but also a biocompatible support for NPs with a mean size of 7.9-9.7 nm. Meanwhile, changing the addition order of Ag⁺ and AuCl₄^- generated different atom arrangement in the bimetallic NPs. Moreover, the correlation of bioactivity to NP atom arrangement was studied. The result revealed that the nanocomposite containing NPs with an ultrathin Ag-rich outermost shell around an Au-rich core showed better bactericidal ability while lower cytotoxicity. In addition, the nanocomposite exhibited a sensitive SERS property for determination of R6G with a high enhancement factor of 10⁸.

In-situ construction of Bi/defective Bi4NbO8Cl for non-noble metal based Mott-Schottky photocatalysts towards organic pollutants removal

The strategy to improve the photocatalytic performance is still a challenge for the novel Sillen-Aurivillius perovskite type Bi₄NbO₈Cl. Herein, heterostructured Bi/Bi₄NbO₈Cl was fabricated via in-situ solvothermal method, without the additional introduction of Bi-sources. Simultaneously, the amount of oxygen vacancies (OVs) were increased, as the [Bi₂O₂] blocks released in the solvothermal process to serve as precursors for Bi particles. Due to the large work function of Bi, a Schottky barrier formed at the Bi/Bi₄NbO₈Cl interface, promoting photo-induced charge separation generated in the Bi₄NbO₈Cl semiconductor, supplying more holes for the organic compounds decomposition, which could be widely applied in water decontamination. Furthermore, the OVs facilitate the consumption of photo-induced electrons by assisting oxygen activation to produce superoxide radicals (·O₂^-), leaving more holes in the valence band of Bi₄NbO₈Cl, and thus result in the enhancement of Rhodamine B (RhB) degradation by 1.82 times over Bi/Bi₄NbO₈Cl photocatalysts. Through the synergistic effect of Bi and OVs, the Bi/Bi₄NbO₈Cl also exhibits enhanced photocatalytic performance towards various organic water-contaminants, such as methyl orange, acid orange 7, p-nitrophenol and tetracycline hydrochloride.

In-situ synthesis of Fe7S8 nanocrystals decorated on N, S-codoped carbon nanotubes as anode material for high-performance lithium-ion batteries

Fe₇S₈ has emerged as an attractive anode material for lithium-ion batteries (LIBs) due to its outstanding features such as low cost, high theoretical capacity, as well as environmental benignity. However, the rapid capacity fading derived from the tremendous volume change during the charging/discharging process hinders its practical application. Nanostructure engineering and the combination with carbonaceous material are essential to address this issue. In this work, Fe₇S₈ nanocrystals decorated on N, S-codoped carbon nanotubes (Fe₇S₈-NSC) were synthesized through a facile one-step pyrolysis of Fe-containing polypyrrole (PPy) nanotubes with sulphur powders under nitrogen atmosphere. When evaluated as anode of LIBs, Fe₇S₈-NSC demonstrates excellent cycling stability (718.8 mAh g^-1 at 100 mA g^-1 after 100 cycles) and superior rate ability (290.8 mAh g^-1 at 2000 mA g^-1). Moreover, Fe₇S₈-NSC shows a typical specific capacity recovery phenomenon, an extraordinary capacity of 744.4 mAh g^-1 at 2000 mA g^-1 after 1000 cycles can be achieved, which outperforms most of the Fe₇S₈-based anode materials reported before. The Fe₇S₈-NSC should be a promising anode material for high-performance LIBs.

Eu-metal organic framework@TEMPO-oxidized cellulose nanofibrils photoluminescence film for detecting copper ions

Metal-organic frameworks (MOFs) are emerging highly crystallized three-dimensional network complex formed by self-assembling metal ions and organic ligands. However, all MOFs are nanoscale and micro scale powder materials, which greatly impedes their further applications. In this study, a transparent Eu-MOF@TEMPO-oxidized cellulose nanofibrils (Eu-MOF@TOCNF) photoluminescence material for specifically detecting copper ions was fabricated via in-situ synthesis in hydroalcoholic medium. Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Fluorescence spectrometer and other equipment were applied to characterize functionalized TOCNF film samples, and the results confirmed the successful fabrication of the functionalized TOCNF film with stable fluorescence properties. The film performed a high selectivity toward copper ion in the presence of other interfering metal ions. The fluorescence intensity of the film decreased gradually with the increase of copper ion concentration, and I₀/I-1 developed a good linear relationship with [Cu²⁺], which made the film a promising material for detecting Cu²⁺ in water body.

Electrochemical determination of Salmonella typhimurium by using aptamer-loaded gold nanoparticles and a composite prepared from a metal-organic framework (type UiO-67) and graphene

An aptamer based assay is described for the determination of Salmonella typhimurium (S.typhimurium). A metal-organic framework-graphene composite of type UiO-67/GR is used as the substrate, and an aptamer-gold nanoparticles-horseradish peroxidase (Apt-AuNP-HRP) conjugate the signal amplification probe. A phosphate-terminal and partially complementary DNA (cDNA) of the aptamer is covalently bound to UiO-67/GR via the chemical complexation between phosphate and Zr-OH groups of UiO-67, and then S. typhimurium and cDNA will compete for the binding sites. The binding of Apt-AuNP-HRP to S.typhimurium leads to the formation of strong conjugates. The unbound signal probes then attach to the surface of a glassy carbon electrode via hybridization with cDNA. This generates a large current response (best measured at a potential as low as -0.02 V vs. saturated calomel electrode) under the catalytic action of HRP on the H₂O₂-hydroquinone system. Under the optimal conditions, the differential pulse voltammetric signal decreases linearly in the 2 × 10¹ - 2 × 10⁸ cfu·mL^-1 S.typhimurium concentration range, with a lower detection limit of 5 cfu·mL^-1 (based on S/N = 3). The method was successfully applied to the detection of S. typhimurium in spiked milk samples. Graphical abstract Schematic presentation of electrochemical determination of Salmonella typhimurium (S.typhimurium). A metal-organic framework (type UiO-67) and graphene (GR) composite were used as substrate, and gold nanoparticles carrying horseradish peroxidase (HRP) for signal amplification. HQ: hydroquinone; cDNA: complementary DNA of aptamer.

In-situ prepared ZnO-ZnFe2O4 with 1-D nanofiber network structure: An effective adsorbent for toxic dye effluent treatment

Current research on ZnFe₂O₄-based adsorbents rely mainly on its surface charge to remove Congo red (CR). However, the weak charge of ZnFe₂O₄ due its normal spinel structure makes this approach inefficient as evident from its low activity. Considering the potential of ZnFe₂O₄ as a low cost nontoxic adsorbent, it is important to improve its activity. Herein, we present an in-situ prepared 1-D ZnO-ZnFe₂O₄ with a heterojunction which adsorbs CR chemically instead of the generic physisorption. While its 1-D structure allows very low adsorbent loading to be employed. Together, these two unique properties make 1-D ZnO-ZnFe₂O₄ ˜3.3x more effective at treating CR effluent than reported ZnFe₂O₄-based adsorbents. The chemisorption reaction involves chelating/bridging bidentate bonding between sulfonic groups on CR and ZnO-ZnFe₂O₄ heterojunction. Its potency is regulated by the ZnO content of the composite which suggest a synergistic effect between the metal oxides phases. Interestingly, spent 1-D ZnO-ZnFe₂O₄ can be regenerated in NaOH solution and retains ˜75% of its adsorption capacity even after repeated use. These findings provide key insights into how interfacial interactions in mixed metal oxide composites and their morphology affect dye adsorption. This information may be useful to develop high performing adsorbents from metal oxides in general.

An amperometric zearalenone aptasensor based on signal amplification by using a composite prepared from porous platinum nanotubes, gold nanoparticles and thionine-labelled graphene oxide

The authors constructed a voltammetric zearalenone (ZEN) aptasensor based on use of porous platinum nanotubes, gold nanoparticles (p-PtNTs/AuNPs) and thionine (Thi) labelled graphene oxide (GO). The p-PtNTs were synthesized in-situ based on tellurium nanowires as sacrificial templates. Subsequently, thiol-modified aptamers were self-assembled on the AuNPs that had been electrodeposited on the surface of the modified electrode. The presence of p-PtNTs on the electrode increases the loading with AuNPs and aptamers. It also warrants that the Thi-labelled GO can be assembled onto the aptamer via π interactions. In the presence of ZEN, it will be bound by the aptamer. The GO/Thi conjugate will be released from the aptamer, and this causes a decrease in Thi current. Under the optimal conditions and at a typical working potential of -0.22 V (vs. Ag/AgCl), the method has a linear range that covers the 0.5 pg·mL^-1 to 0.5 μg·mL^-1 ZEN concentraion range and a lower detection limit of 0.17 pg·mL^-1. Graphical abstract Voltammetric zearalenone aptasensor based on use of porous platinum nanotubes/gold nanoparticles and thionine labelled graphene oxide was fabricated for the detection of zearalenone.

Removal of hexavalent chromium from groundwater by Mg/Al-layered double hydroxides using characteristics of in-situ synthesis

This study aimed to develop a novel in-situ method to directly remove toxic hexavalent chromium anions from groundwater. The characteristics of Mg/Al-layered double hydroxides (LDH) involving in-situ synthesis and interlayer exchangeable anions can facilitate to remove Cr(VI) from solution. Two different methods of LDH preparation were employed to explore the adsorption efficiency of (di)chromates, such as traditional coprecipitation (CO₃-LDH) and innovative in-situ synthesis (in-situ-LDH). The synthesized LDH samples were characterized using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and zeta potential. The results demonstrated that the adsorptive amount of Cr(VI) for the in-situ synthesis process dramatically increased with an increase in initial Cr(VI) concentrations from 100 mg/L to 900 mg/L. The kinetic study indicated that the constant rate (k₂) of the pseudo-second-order equation significantly decreased when the initial concentration of Cr(VI) exceeded 500 mg/L. The removal efficiency of Cr(VI) was slightly dependent on solution pH (5.0-12) values. The in-situ-LDH absorbent (339 mg/g) exhibited the significantly higher Langmuir maximum adsorption capacity than CO₃-LDH (246 mg/g). The primary adsorption mechanism was anion exchange; meanwhile, the adsorption-coupled reduction mechanism also played an integral role. The advanced in-situ synthetic method can be developed to efficiently remove toxic hexavalent chromium anions from groundwater.

Environmentally friendly procedure for in-situ coating of regenerated cellulose fibres with silver nanoparticles

This study introduces a novel green in-situ procedure for introduction of silver nanoparticles (Ag NPs) on and into cellulose fibres in a three-stage process. First-stage of the process includes the activation of cellulose fibres in alkaline solution, followed by reduction of silver nitrate to Ag NPs in the second stage, while the last stage of process involves washing and neutralization of fibres. Efficiency of the method towards incorporation of silver particles into the fibres' internal structure was characterized; the coatings' morphology and determination of spatial presence of Ag particles were imagining by the scanning electron microscopy and accompanying energy dispersive x-ray spectroscopy analysis; prepared fibres have superior durability of particles' coating against washing and excellent antimicrobial activity even after 20 washing cycles. Additionally, the water retention of silver treated fibres was improved, while the mechanical properties were not significantly impaired.

Graphene oxide directed in-situ synthesis of Prussian blue for non-enzymatic sensing of hydrogen peroxide released from macrophages

A novel electrochemical non-enzymatic hydrogen peroxide (H₂O₂) sensor has been developed based on Prussian blue (PB) and electrochemically reduced graphene oxide (ERGO). The GO was covalently modified on glassy carbon electrode (GCE), and utilized as a directing platform for in-situ synthesis of electroactive PB. Then the GO was electrochemically treated to reduction form to improve the effective surface area and electroactivity of the sensing interface. The fabrication process was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). The results showed that the rich oxygen containing groups play a crucial role for the successful synthesis of PB, and the obtained PB layer on the covalently immobilized GO has good stability. Electrochemical sensing assay showed that the modified electrode had tremendous electrocatalytic property for the reduction of H₂O₂. The steady-state current response increased linearly with H₂O₂ concentrations from 5μM to 1mM with a fast response time (less than 3s). The detection limit was estimated to be 0.8μM. When the sensor was applied for determination of H₂O₂ released from living cells of macrophages, satisfactory results were achieved.

Tragacanth gum/nano silver hydrogel on cotton fabric: In-situ synthesis and antibacterial properties

This paper is mainly focused on introducing cotton fabric with hydrogel and antimicrobial properties using Tragacanth gum as a natural polymer with hydrogel properties, silver nitrate as silver precursor, citric acid as a cross-linking agent and sodium hypophosphite as catalyst. The water absorption behavior of the treated fabrics was investigated with moisture regain, water retention, drying time of wetted fabric at room condition and vertical wicking tests. Antibacterial properties of the samples were evaluated against Escherichia coli and Staphylococcous aureus. The SEM pictures confirmed formation of nano silver and hydrogel layer on the fabric surface and XRD performed the crystal and particle size of the nano silver. The chemical structure of the fabric samples was identified with FTIR spectra. The central composite design (CCD) was used for statistical modelling, evaluated effective parameters and created optimum conditions. The treated cotton fabrics showed good water absorption properties along with reasonable antibacterial effectiveness.