Magnetic nanosystem a tool for targeted delivery and diagnostic application: Current challenges and recent advancement

Over the last two decades, researchers have paid more attention to magnetic nanosystems due to their wide application in diverse fields. The metal nanomaterials' antimicrobial and biocidal properties make them an essential nanosystem for biomedical applications. Moreover, the magnetic nanosystems could have also been used for diagnosis and treatment because of their magnetic, optical, and fluorescence properties. Superparamagnetic iron oxide nanoparticles (SPIONs) and quantum dots (QDs) are the most widely used magnetic nanosystems prepared by a simple process. By surface modification, researchers have recently been working on conjugating metals like silica, copper, and gold with magnetic nanosystems. This hybridization of the nanosystems modifies the structural characteristics of the nanomaterials and helps to improve their efficacy for targeted drug and gene delivery. The hybridization of metals with various nanomaterials like micelles, cubosomes, liposomes, and polymeric nanomaterials is gaining more interest due to their nanometer size range and nontoxic, biocompatible nature. Moreover, they have good injectability and higher targeting ability by accumulation at the target site by application of an external magnetic field. The present article discussed the magnetic nanosystem in more detail regarding their structure, properties, interaction with the biological system, and diagnostic applications.

Robust cooperative of cadmium sulfide with highly ordered hollow microstructure coordination polymers for regulating the photocatalytic performance

Accurately controlling and achieving selective reactivity at difficult-to-access reaction sites in organic molecules is challenging owing to the similar local and electronic environments of multiple reaction sites. In this work, we regulated multiple reaction sites in a highly selective and active manner using cobalt coordination polymers (Co-CP) 1 and 1a with various particle sizes and morphologies ranging from large granular to ordered hollow hemispheres by introducing sodium dodecyl sulfate (SDS) as a surfactant. The size and morphology of the catalysts could be tuned by controlling the amount of SDS. An SDS concentration of 0.03 mmol generated 1a having a highly ordered hollow hemispherical microstructure with a well-defined platform as a pre-made building unit. Cadmium sulfide (CdS), as a typical photocatalyst, was subsequently uniformly anchored in-situ on the premade building unit 1a to produce CdS@1a composites, that inherited the originally ordered hollow hemispherical microstructure while integrating CdS as well-dispersed catalytic active sites. Furthermore, the well-established CdS@1a composites were used as photocatalysts in selective oxidation reactions under air atmosphere with blue irradiation. The CdS0.109@1a composite with unique structural characteristics, including uniformly distributed and easily accessible catalytic sites and excellent photoelectrochemical performance, served as a highly efficient heterogeneous photocatalyst for promoting the selective oxidation of sulfides to sulfoxides as the sole products. This work presents an approach for fabricating CPs as premade building units that function as well-defined platforms for integration with photocatalysts, enabling tuning of the structure-selectivity-activity relationships.

One pot fabrication of diamino naphthalene -AuNPs decorated graphene nanoplatform for the MRSA detection in the biological sample

Early monitoring of MRSA can effectively mitigate the disease risk by using Penicillin-binding protein 2a (PbP2a) biomarker. Diamino naphthalene-AuNPs decorated graphene (AuNPsGO-DN) nanocomposite was synthesized for a rapid and sensitive immunosensor detecting PbP2a. The synthesized AuNPsGO-DN nanocomposites were characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and X-ray diffraction spectroscopy (XRD). Electrochemical characterization done with cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrical impedance spectroscopy (EIS) techniques. Anti-PbP2a monoclonal antibodies immobilized at AuNPsGO-DN/GCE via covalent bonding. AuNPs enhanced the electrode surface area and the antibodies' loading. Mercaptopropionic acid (MPA) was a linker between the AuNPs and antibodies, orientated the antibodies as opposite to the PbP2a antigen, and improved the sensitivity and specificity. The antiPbP2a/MPA/AuNPsGO-DN/GCE electrode displayed sensitive and selective detection towards the PbP2a antigen in phosphate buffer saline (PBS pH 7.4). The broad linear range from 0.01 to 8000 pg/mL was obtained with LOD of 0.154 pg/mL and 0.0239 pg/mL, respectively. A label-free, simple, and sensitive immunosensor was developed with a 98-106 % recovery rate in spiked biological samples. It shows the potential applicability of the developed immunoelectrode.

"On/off"-switchable crosslinked PTX-nanoformulation with improved precise delivery for NSCLC brain metastases and restrained adverse reaction over nab-PTX

Non-small cell lung cancer (NSCLC) brain metastases present a significant treatment challenge due to limited drug delivery efficiency and severe adverse reactions. In this study, we address these challenges by designing a "on/off" switchable crosslinked paclitaxel (PTX) nanocarrier, BPM-PD, with novel ultra-pH-sensitive linkages (pH 6.8 to 6.5). BPM-PD demonstrates a distinct "on/off" switchable release of the anti-cancer drug paclitaxel (PTX) in response to the acidic extratumoral microenvironment. The "off" state of BPM-PD@PTX effectively prevents premature drug release in the blood circulation, blood-brain barrier (BBB)/blood-tumor barrier (BTB), and normal brain tissue, surpassing the clinical PTX-nanoformulation (nab-PTX). Meanwhile, the "on" state facilitates precise delivery to NSCLC brain metastases cells. Compared to nab-PTX, BPM-PD@PTX demonstrates improved therapeutic efficacy with a reduced tumor area (only 14.6%) and extended survival duration, while mitigating adverse reactions (over 83.7%) in aspartate aminotransferase (AST) and alanine aminotransferase (ALT), offering a promising approach for the treatment of NSCLC brain metastases. The precise molecular switch also helped to increase the PTX maximum tolerated dose from 25 mg/kg to 45 mg/kg This research contributes to the field of cancer therapeutics and has significant implications for improving the clinical outcomes of NSCLC patients.

Semiconducting polymer dots for multifunctional integrated nanomedicine carriers

The expansion applications of semiconducting polymer dots (Pdots) among optical nanomaterial field have long posed a challenge for researchers, promoting their intelligent application in multifunctional nano-imaging systems and integrated nanomedicine carriers for diagnosis and treatment. Despite notable progress, several inadequacies still persist in the field of Pdots, including the development of simplified near-infrared (NIR) optical nanoprobes, elucidation of their inherent biological behavior, and integration of information processing and nanotechnology into biomedical applications. This review aims to comprehensively elucidate the current status of Pdots as a classical nanophotonic material by discussing its advantages and limitations in terms of biocompatibility, adaptability to microenvironments in vivo, etc. Multifunctional integration and surface chemistry play crucial roles in realizing the intelligent application of Pdots. Information visualization based on their optical and physicochemical properties is pivotal for achieving detection, sensing, and labeling probes. Therefore, we have refined the underlying mechanisms and constructed multiple comprehensive original mechanism summaries to establish a benchmark. Additionally, we have explored the cross-linking interactions between Pdots and nanomedicine, potential yet complete biological metabolic pathways, future research directions, and innovative solutions for integrating diagnosis and treatment strategies. This review presents the possible expectations and valuable insights for advancing Pdots, specifically from chemical, medical, and photophysical practitioners' standpoints.

Tris-assisted one-step fabrication of functional carbon dots for specific folate receptor positive-expressed cancer cell imaging

Specific staining of cancer cells is momentous for cancer research. Nanoprobe with multivalent recognition is emerging as powerful tools for bioimaging, but the nonspecific cell uptake and complex functional modification procedures are still obstacles for specific detection and convenient synthesis. Carbon dots (CDs) with an intrinsic targeting ability, excellent optical properties and biocompatibility acquired from an efficient one-step fabrication procedure were urgently desired in specific cancer cells visualization. Herein, inspired by the interrelationships between interface and biomolecular mechanisms, we suggested that it was possible to construct CDs with the desired characteristics for folate receptor (FR) positive-expressed cancer cell imaging via rich hydroxyl groups Tris-assisted one-step hydrothermal treatment of folate acid (FA) and l-Arginine (L-Arg) precursors. The prepared small-sized F-CDs were equipped with abundant hydroxyl, pterin and negative charge surface, and possessed environmental friendliness, outstanding photostability and biocompatibility. Moreover, F-CDs had an intrinsic FR positive-expressed cancer cell targeting ability without any post-modification of the ligands. Rich hydroxyl groups play a vital role in endowing the optical properties and biological effects of F-CDs. F-CDs could be used as a promising candidate for FR-expressed cancer cell labeling and tracking. In addition, the caveolae-mediated endocytosis pathway of F-CDs was ascertained. More importantly, experimental results confirmed that the combination of physicochemical properties may provide an efficient strategy to overcome non-specific cell uptake interactions for cell labeling. Our strategy put forward a promising alternative to design fluorescent CDs for extensive chemical and biomedical applications.

Ru nanoparticles modified Ni3Se4/Ni(OH)2 heterostructure nanosheets: A fast kinetics boosted bifunctional overall water splitting electrocatalyst

Properly design and manufacture of bifunctional electrocatalysts with superb performance and endurance are crucial for overall water splitting. The interfacial engineering strategy is acknowledged as a promising approach to enhance catalytic performance of overall water splitting catalysts. Herein, the Ru nanoparticles modified Ni3Se4/Ni(OH)2 heterostructured nanosheets catalyst was constructed using a simple two-step hydrothermal process. The experimental results demonstrate that the abundant heterointerfaces between Ru and Ni3Se4/Ni(OH)2 can increase the number of active sites and effectively regulate the electronic structure, greatly accelerating the kinetics of the hydrogen evolution reaction (HER)/oxygen evolution reaction (OER). As a result, the Ru/Ni3Se4/Ni(OH)2/NF catalyst exhibits the low overpotential of 102.8 mV and 334.5 mV at 100 mA cm-2 for HER and OER in alkaline medium, respectively. Furthermore, a two-electrode system composed of the Ru/Ni3Se4/Ni(OH)2/NF requires a battery voltage of just 1.51 V at 10 mA cm-2 and remains stable for 200 h at 500 mA cm-2. This work provides an effective strategy for constructing Ru-based heterostructured catalysts with excellent catalytic activity.

Iron nanoparticles surface decorated MXene via molten salts etching as selenium host for ultrafast sodium ion storage

Sodium-selenium (Na-Se) batteries have gained attention due to their high energy density and power density, resulting from the liquid-liquid reaction at the interface in the dimethoxyethane electrolyte. Nevertheless, the pronounced shuttle effect of polyselenides causes low coulomb efficiency and inadequate cycling stability for Na-Se batteries. Herein, the iron nanoparticles surface modified accordion-like Ti3C2Tx MXene (MXene/Fe) synthesized via the molten salt etching is utilized as the host of Se species for high-performance Na-Se battery cathode. Benefiting from the layered structure and chemical adsorption of accordion-like MXene, the shuttle effect of the cathode is effectively inhibited. Simultaneously, electrochemical kinetics is boosted due to the catalytic effect of Fe nanoparticles, which facilitate the transformation of polyselenide from long-chain to short-chain, contributing to pseudocapacitive capacity. Consequently, the Se-based cathode delivers a steady capacity of 575.0 mA h g-1 at 0.2 A/g, and even a high capacity of 500 mAh/g at 50 A/g based on the mass of Se@MXene/Fe electrode, indicating the ultrafast Na+ ion storage. Most notably, this structure demonstrated remarkable long-term cycling stability for 5000 cycles with a high capacity retention of 97.4 %. The electrochemical energy storage mechanism is further revealed by in situ Raman. Herein, the confinement-catalysis structure shines light on inhibiting shuttling and facilitating ultrafast ion storage.

Cuproptotic nanoinducer-driven proteotoxic stress potentiates cancer immunotherapy by activating the mtDNA-cGAS-STING signaling

Proteotoxic stress, caused by the accumulation of abnormal unfolded or misfolded cellular proteins, can efficiently activate inflammatory innate immune response. Initiating the mitochondrial proteotoxic stress might go forward to enable the cytosolic release of intramitochondrial DNA (mtDNA) for the immune-related mtDNA-cGAS-STING activation, which however is easily eliminated by a cell self-protection, i.e., mitophagy. In light of this, a nanoinducer (PCM) is reported to trigger mitophagy-inhibited cuproptotic proteotoxicity. Through a simple metal-phenolic coordination, PCMs reduce the original Cu2+ with the phenolic group of PEG-polyphenol-chlorin e6 (Ce6) into Cu+. Cu+ thereby performs its high binding affinity to dihydrolipoamide S-acetyltransferase (DLAT) and aggregates DLAT for cuproptotic proteotoxic stress and mitochondrial respiratory inhibition. Meanwhile, intracellular oxygen saved from the respiratory failure can be utilized by PCM-conjugated Ce6 to boost the proteotoxic stress. Next, PCM-loaded mitophagy inhibitor (Mdivi-1) protects proteotoxic products from being mitophagy-eliminated, which allows more mtDNA to be released in the cytosol and successfully stimulate the cGAS-STING signaling. In vitro and in vivo studies reveal that PCMs can upregulate the tumor-infiltrated NK cells by 24% and enhance the cytotoxic killing of effector T cells. This study proposes an anti-tumor immunotherapy through mitochondrial proteotoxicity.

High-Performance enrichment and sensitive analysis of bisphenol and its analogues in water and milk using a novel Ni-Based cationic Metal-Organic framework

A novel cationic metal-organic framework (iMOF-Ni) was designed and synthesized by a solvothermal method. It was fabricated as a solid-phase extraction (SPE) cartridge and exhibited high adsorption performance for Bisphenols (BPs). The theoretical simulation demonstrated that the adsorption mechanism between iMOF-Ni and BPs was attributed to cation-π bonding, π-π interaction, and electrostatic interactions. Under optimized SPE, a method for analyzing BPs was established by combining high-performance liquid chromatography-diode array detection (HPLC-DAD). The developed method has good linearity (R2 ≥ 0.994), low detection limits (0.07-0.16 ng/mL), and good reproducibility (1.72-6.35 %, n = 6). The applicability of the method was further evaluated by analyzing water and milk samples. Recoveries of four BPs in spiked samples were from 72.2 % to 96.6 %.

Aromatic and magnetic properties in a series of heavy rare earth-doped Ge6 cluster anions

A series of pentagonal bipyramidal anionic germanium clusters doped with heavy rare earth elements,REGe 6 - (RE = Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), have been identified at the PBE0/def2-TZVP level using density functional theory (DFT). Our findings reveal that the centrally doped pentagonal ring structure demonstrates enhanced stability and heightened aromaticity due to its uniform bonding characteristics and a larger charge transfer region. Through natural population analysis and spin density diagrams, we observed a monotonic decrease in the magnetic moment from Gd to Yb. This is attributed to the decreasing number of unpaired electrons in the 4f orbitals of the heavy rare earth atoms. Interestingly, the system doped with Er atoms showed lower stability and anti-aromaticity, likely due to the involvement of the 4f orbitals in bonding. Conversely, the systems doped with Gd and Tb atoms stood out for their high magnetism and stability, making them potential building blocks for rare earth-doped semiconductor materials.

Label-free colorimetric detection platform based on catalytic hairpin self-assembly and G-quadruplex/hemin DNAzyme for comprehensive biomarker profiling

The expression level of human apurinic/apyrimidinic endonuclease 1 (APE1) is closely associated with the onset of various diseases, establishing it as a crucial clinical biomarker and a target in anti-cancer efforts. This study accomplished colorimetric and visual detection of APE1 by harnessing its endonuclease activity through catalytic hairpin self-assembly (CHA) and G-quadruplex/hemin DNAzyme. Optimization of the freedom degrees of the G-rich sequence significantly improved the detection performance of the strategy by influencing DNAzyme formation. Additionally, we replaced the signal reporting system with a molecular beacon to develop a fluorescence detection strategy, which served as an extension of the signal amplification system for validation and signal readout. The fluorescent probe method achieved a detection limit of 3.37 × 10-4 U/mL, while the colorimetric method yielded a detection limit of 6.5 × 10-3 U/mL, with a linear range spanning from 0.01 to 0.25 U/mL. Subsequently, the colorimetric approach effectively assessed APE1 activity in biological samples and facilitated the screening of APE1 activity inhibitors. Furthermore, this CHA/G-quadruplex/hemin DNAzyme strategy was adapted for the colorimetric detection of adenosine, showcasing its broad applicability across various biomarkers. The developed colorimetric analytical strategy represents a pivotal biosensing platform for diagnosing and treating diseases.

BMSCs-laden mechanically reinforced bioactive sodium alginate composite hydrogel microspheres for minimally invasive bone repair

Minimally invasive, efficient, and satisfactory treatment for irregular and lacunar bone defects is still a challenge. Alginate hydrogels serve as promising stem cell (SC) delivery systems for bone regeneration but are limited by low cellular viability, poor osteogenic differentiation, and insufficient mechanical support. Herein, we developed a BMSCs-laden mechanically reinforced bioactive sodium alginate composite hydrogel microspheres (BCHMs) system via a microfluidic method that possesses 1) a uniform size and good injectability to meet clinical bone defects with complex shapes, 2) high cellular viability maintenance and further osteogenic induction capacity, and 3) improved mechanical properties. As the main matrix, the sodium alginate hydrogel maintains the high viability of encapsulated BMSCs and efficient substance exchange. Enhanced mechanical properties and osteogenic differentiation of the BCHMs in vitro were observed with xonotlite (Ca6Si6O17(OH)2, CSH) nanowires incorporated. Furthermore, BCHMs with 12.5 % CSH were injected into rat femoral bone defects, and satisfactory in situ regeneration outcomes were observed. Overall, it is believed that BCHMs expand the application of polysaccharide science and provide a promising injectable bone substitute for minimally invasive bone repair.

Nitrogen-oxygen co-doped carbon@silica hollow spheres as encapsulated Pd nanoreactors for acetylene dialkoxycarbonylation

The introduction of heteroatoms into hollow carbon spheres is imperative for enhancing catalytic activity. Consequently, we investigated the utilization of nitrogen-oxygen(N/O) co-doped hollow carbon (C)/silica (SiO2) nanospheres (NxC@mSiO2), which have a large internal volume and a nano-constrained environment that limits metal aggregation and loss, making them a potential candidate. In this study, we demonstrate the synthesis of nitrogen-oxygen (N/O) co-doped hollow carbon spheres using resorcinol and formaldehyde as carbon precursors, covered with silica, and encapsulated with palladium nanoparticles (NPs) in situ. The N/O co-doping process introduced defects on the surface of the internal C structure, which acted as active sites and facilitated substrate adsorption. Subsequent treatment with hydrogen peroxide (H2O2) introduced numerous carboxyl groups onto the C structure, increasing the catalytic environment as acid auxiliaries. The carboxyl group is present in the carbon structure, as determined calculations based on by density functional theory, reduces the adsorption energy of acetylene, thereby promoting its adsorption and enrichment. Furthermore, H2O2-treatment enhanced the oxygen defects in the carbon structure, improving the dispersion of Pd NPs and defect structure. The Pd/NxC@mSiO2-H2O2 catalysts demonstrated outstanding performance in the acetylene dialkoxycarbonylation reaction, showcasing high selectivity towards 1,4-dicarboxylate (>93 %) and remarkable acetylene conversion (>92 %). Notably, the catalyst exhibited exceptional selectivity and durability throughout the reaction.

Construction of an autofluorescence interference-free phosphorescence biosensor for the specific detection of TK1 mRNA

The anti-interference ability of biosensors is critical for detection in biological samples. Fluorescence-based sensors are subject to interference from self-luminescent substances in biological matrices. Therefore, phosphorescent sensors stand out among biosensors due to their lack of self-luminescence background. In this study, a phosphorescent sensor was constructed, which can accurately detect thymidine kinase 1 (TK1) mRNA in biological samples and avoid autofluorescence interference. When there is no target, polydopamine (PDA) is used as the phosphorescence resonance energy transfer (PRET) acceptor to quench the phosphorescence of the persistently luminescent (PL) nanomaterial. When there is a target, the DNA modified by the PL nanomaterial is replaced by the hairpin H and removed away from the PDA, resulting in a rebound in phosphorescence. The phosphorescent sensor exhibits a good linear relationship in the TK1 mRNA concentration range of 0-200 nM, and the detection limit was 1.74 nM. The sensor fabricated in this study can effectively avoid interference from spontaneous fluorescence in complex biological samples, and sensitively and precisely detect TK1 mRNA in serum samples, providing a powerful tool to more accurately detect biomarkers in biological samples.

Size-independent boosting of near-infrared persistent luminescence in nano-phosphors via a magnesium doping strategy

Near-infrared (NIR)-emitting persistent luminescence nanoparticles (PLNPs) are ideal optical imaging contrast reagents characterized by autofluorescence-free optical imaging for their frontier applications in long-term bioimaging. Preparation of uniform small-sized PLNPs with excellent luminescence performance is crucial for biomedical applications, but challenging. Here, we report a facile magnesium doping strategy to achieve size-independent boost of NIR persistent luminescence in typical and most concerned ZnGa2O4:Cr3+ PLNPs. This strategy relies on the doping of Mg2+ ions that with similar size of Zn2+ ions in the host lattice matrix, and concomitant to the electron traps tailoring tuned by varying the feed ratio of Mg2+. The optimum Mg2+-doped PLNPs give a long afterglow time (signal-to-noise ratio (SNR) = 31.6 at 30 d) without changing the desirable uniform sub-10 nm size of the original nanocrystals. The appropriate increase of the depth and concentration of electron trap contribute jointly to the enhancement of lifetime (488 % longer, 20.57 s) and afterglow time for 700 nm persistent luminescence. Meanwhile, these PLNPs keep the original excellent rechargeability and promote over 60 times increase of SNR in renewable in vivo imaging. This simple strategy provides a basis for new opportunities to address the critical challenge of effective optical performance boost in small-sized PLNPs.

Boric acid templating synthesis of highly-dense yet ultramicroporous carbons for compact capacitive energy storage

Carbon-based supercapacitors have shown great promise for miniaturized electronics and electric vehicles, but are usually limited by their low volumetric performance, which is largely due to the inefficient utilization of carbon pores in charge storage. Herein, we develop a reliable and scalable boric acid templating technique to prepare boron and oxygen co-modified highly-dense yet ultramicroporous carbons (BUMCs). The carbons are featured with high density (up to 1.62 g cm-3), large specific surface area (up to 1050 m2 g-1), narrow pore distribution (0.4-0.6 nm) and exquisite pore surface functionalities (mainly -BC2O, -BCO2, and -COH groups). Consequently, the carbons show exceptionally compact capacitive energy storage. The optimal BUMC-0.5 delivers an outstanding volumetric capacitance of 431 F cm-3 and a high-rate capability in 1 M H2SO4. In particular, an ever-reported high volumetric energy density of 32.6 Wh L-1 can be harvested in an aqueous symmetric supercapacitor. Our results demonstrate that the -BC2O and -BCO2 groups on the ultramicropore walls can facilitate the internal SO42- ion transport, thus leading to an unprecedented high utilization efficiency of ultramicropores for charge storage. This work provides a new paradigm for construction and utilization of dense and ultramicroporous carbons for compact energy storage.

Directional molecular transport in iron redox flow batteries by interfacial electrostatic forces

The mounting global energy demand urges surplus electricity generation. Due to dwindling fossil resources and environmental concerns, shifting from carbon-based fuels to renewables is vital. Though renewables are affordable, their intermittent nature poses supply challenges. In these contexts, aqueous flow batteries (AFBs), are a viable energy storage solution. This study tackles AFBs' energy density and efficiency challenges. Conventional strategies focus on altering molecule's solubility but overlook interface's transport kinetics. We show that triggering electrostatic forces at the interface can significantly enhance the mass transport kinetics of redox active molecules by introducing a powerful electrostatic flux over the diffusional flux, thereby exerting a precise directionality on the molecular transport. This approach of controlling the directionality of molecular flux in an all iron redox flow battery amplifies the current and power rating with approximately 140 % enhancement in the energy density.

Selective detection of salivary cortisol using screen-printed electrode coated with molecularly imprinted polymer

A novel electrochemical sensor was developed for the detection of salivary cortisol levels. The sensor employs a combination of a molecularly imprinted polymer (MIP) and gold nanoparticles (AuNPs) that are electrodeposited onto a screen-printed electrode (SPE). The study utilised density functional theory and molecular docking techniques to determine the geometry of molecular orbitals, electrostatic potential energies, and binding energy of cortisol and the polymers. The thin film of cortisol-imprinted polymer on the SPE was created by electro-polymerizing pyrrole and thiophene-3-carboxylic acid on the electrode surface along with cortisol as the template molecule. The MIP film was characterised using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and electrochemical techniques. The sensor exhibited a linear response in the concentration range of 0.05 nmol L-1 to 2.5 μmol L-1, with a limit of detection of 0.01 nmol L-1, as determined by differential pulse voltammetry. This method offers a simple yet efficient and sensitive approach to detecting cortisol levels in human saliva samples.

Ordered sulfonated polystyrene particle chains organized through AC electroosmosis as reinforcing phases in Polyacrylamide hydrogels

Polyacrylamide (PAM) hydrogels have garnered significant attention due to their unique swelling properties, biocompatibility, and stability, resulting in them being promising candidates for various applications, ranging from drug delivery to tissue engineering. However, traditional PAM hydrogels suffer from low strength and poor toughness, which limits their widespread use. In this study, based on the theory of filler-reinforced composites, we introduced ordered sulfonated polystyrene (SPS) particles into PAM hydrogels using electric field-assisted techniques. The effects of the geometric dimensions and filling concentration of SPS particles on thermal stability, swelling/deswelling behavior, and mechanical properties of composite hydrogels were investigated. When filled with ordered 100 nm SPS particles at a concentration of 2.0 g·L-1, the resulting SPS/PAM composite exhibited improved water retention capacity, as well as a fracture elongation of 316 % and a tensile strength of 23 kPa. These findings in the paper provide valuable insights into the understanding of PAM hydrogels and open up new avenues for the development of advanced hydrogel-based systems with enhanced performance and functionality.

Preparation of patterned hydrogels for anti-counterfeiting and directional actuation by shear-induced orientation of cellulose nanocrystals

Hydrogels with anisotropic structures are of great interest in the fields of bionic actuators, sensing and anti-counterfeiting due to their unique optical and stimulus response properties. Here we report an anisotropic cellulose nanocrystals/polyacrylamide (CNC/PAM) hydrogel with a patterned structure obtained by shear-induced orientation of CNC in precursor solution. Due to the difference in affinity between different slider surfaces and the precursor, patterned structures with different interference colors were realized by adhering the polypropylene (PP) film with a specific pattern to the bottom glass slider, which leads to differences in CNC orientation in different areas. These interfere color patterns can only be observed between crossed polarization, allowing the hydrogel to be used in applications of anti-counterfeiting and information encryption. Moreover, a complex and controllable 3D deformation is realized by introducing "zebra crossing" structure in the hydrogel. The opening and closing processes of flowers are vividly mimicked using the reversible swelling and shrinking properties of hydrogels in water and salt solutions, making the hydrogel promising for soft actuators.

Chitin whisker/chitosan liquid crystal hydrogel assisted scaffolds with bone-like ECM microenvironment for bone regeneration

Natural bone exhibits a complex anisotropic and micro-nano hierarchical structure, more importantly, bone extracellular matrix (ECM) presents liquid crystal (LC) phase and viscoelastic characteristics, providing a unique microenvironment for guiding cell behavior and regulating osteogenesis. However, in bone tissue engineering scaffolds, the construction of bone-like ECM microenvironment with exquisite microstructure is still a great challenge. Here, we developed a novel polysaccharide LC hydrogel supported 3D printed poly(l-lactide) (PLLA) scaffold with bone-like ECM microenvironment and micro-nano aligned structure. First, we prepared a chitin whisker/chitosan polysaccharide LC precursor, and then infuse it into the pores of 3D printed PLLA scaffold, which was previously surface modified with a polydopamine layer. Next, the LC precursor was chemical cross-linked by genipin to form a hydrogel network with bone-like ECM viscoelasticity and LC phase in the scaffold. Subsequently, we performed directional freeze-casting on the composite scaffold to create oriented channels in the LC hydrogel. Finally, we soaked the composite scaffold in phytic acid to further physical cross-link the LC hydrogel through electrostatic interactions and impart antibacterial effects to the scaffold. The resultant biomimetic scaffold displays osteogenic activity, vascularization ability and antibacterial effect, and is expected to be a promising candidate for bone repair.

Fe,Co co-implanted dendritic CeO2/CeF3 heterostructure@MXene nanocomposites as structurally stable electrocatalysts with ultralow overpotential for the alkaline oxygen evolution reaction

Exploring low-cost, high-activity, and structurally stable nonprecious metal electrocatalysts for sluggish oxygen evolution reaction (OER) is paramount for water electrolysis. Herein, we successfully prepare a novel Fe,Co-CeO2/CeF3@MXene heterostructure with Fe-Co dual active sites and oxygen vacancies for alkaline OER using an energy-free consumption co-deposition method. Impressively, Fe,Co-CeO2/CeF3@MXene achieves an ultralow overpotential of 192 mV and a long-term stability of 110 h at 10 mA cm-2 without structural changes, thereby outperforming the commercial IrO2 (345 mV). In addition, Fe,Co-CeO2/CeF3@MXene exhibits much superior activity (271 mV) and durability to IrO2 (385 mV) in the real seawater OER. Wind- and solar energy-assisted water electrolysis devices show their promising prospects for sustainable green hydrogen production. Characterization techniques and theoretical calculations reveal that the Fe,Co co-implanted CeO2/CeF3 heterostructure effectively degrades the energy barrier of the OER and optimizes the adsorption strength of *OH, *O, and *OOH intermediates. It exhibits the dual coupling mechanism of the adsorbed evolution and lattice oxygen mechanisms, which synergistically improves the OER performance. This work provides a facile and efficacious strategy for synthesizing a new class of heterostructures to achieve significant enhancement in the activity and stability of OER catalysts.

Pickering stabilization mechanism revealed through direct imaging of particles with tuneable contact angle in a phase-separated binary solvent

Pickering emulsions have attracted increasing attention from multiple fields, including food, cosmetics, healthcare, pharmaceutical, and agriculture. Their stability relies on the presence of colloidal particles instead of surfactant at the droplet interface, providing steric stabilization. Here, we demonstrate the microscopic attachment and detachment of particles with tunable contact angle at the interface underlying the Pickering emulsion stability. We vary the interfacial tension continuously by varying the temperature offset of a phase-separated binary liquid from its critical point, and employ confocal microscopy to directly observe the particles at the interface to determine their coverage and contact angle as a function of the varying interfacial tension. When the interfacial tension decreases upon approaching the binary liquid's critical point, the contact angle and detachment energy (ΔE) drop, and the particles move out of the interface. Microscopic imaging suggests necking and capillary interactions lead to clustering of the particles, before they eventually desorb from the interface. Macroscopic measurements show that concomitantly, coalescence takes place, and the emulsion loses its stability. These results reveal the interplay of interfacial energies, contact angle and surface coverage that underlies the Pickering emulsion stability, opening up ways to manipulate and design the stability through the microscopic behavior of the adsorbed particles.

Unveiling the exciton dissociation dynamics steered by built-in electric fields in conjugated microporous polymers for photoreduction of uranium (VI) from seawater

Developing highly efficient photocatalysts based on conjugated microporous polymers (CMPs) are often impeded by the intrinsically large exciton binding energy and sluggish charge transfer kinetics that result from their vulnerable driving force. Herein, a family of pyrene-based nitrogen-implanted CMPs were constructed, where the nitrogen gradient was regulated. Accordingly, the built-in electric field endowed by the nitrogen gradient dramatically accelerates the dissociation of exciton into free carriers, thereby enhancing charge separation efficiency. As a result, PyCMP-3N generated by polymerization of 1,3,6,8-tetrakis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyrene and 2,4,6-tris(4-bromophenyl)-1,3,5-triazine featured an optimized built-in electric field and exhibited the highest photocatalytic removal efficiency of uranium (VI) (99.5 %). Our proposed strategy not only provides inspiration for constructing the built-in electric field by controlling nitrogen concentration gradients, but also offers an in-depth understanding the crucial role of built-in electric field in exciton dissociation and charge transfer, efficiently promoting CMPs photocatalysis.

In situ characterization of silver nanoparticles sulfidation processes in aquatic solution by hollow fiber flow-field flow fractionation coupled with ICP-QQQ

The sulfidation is considered as one of the most important environmental transformation processes of silver nanoparticles (AgNPs), which affects their transport, uptake and toxicity. Herein, based on the hollow fiber flow-field flow fractionation coupled with triple quadrupole inductively coupled plasma mass spectrometry (HF5-ICP-QQQ), we developed an efficient approach to accurately characterize the sulfidation process of AgNPs in aquatic solutions. HF5 could efficiently remove interferential ions and separate nanoparticles with different sizes online, and ICP-QQQ could accurately detect S element through monitoring 32S16O+ in mass shift mode. By the proposed method, two kinds of AgNPs, citrate-coated AgNPs and PVP-coated AgNPs, were selected as models to trace their transfer behaviors during the sulfidation. The results showed once AgNPs were exposed to Na2S solution, the overlapping fractograms of 32S16O+ and 107Ag+ were rapidly detected by HF5-ICP-QQQ to indicate the co-presence of Ag and S, and thus confirming the production of Ag2S and AgNPs underwent a rapid sulfidation process. There were substantial differences in the influence of the two coated agents on the stability of the particles under the conditions examined. In the presence of sulfide, PVP-coated AgNPs could maintain initial size distribution with higher stability, while the size distribution of citrate-coated AgNPs changed considerably. The developed HF5-ICP-QQQ method provides a reliable tool to identify and characterize the transformation process of AgNPs in aquatic solution, which contributed to a deeper understanding of the environmental fate and behavior of AgNPs with different coating.

Efficient detection of 45 ppb ammonia at room temperature using Ni-doped CeO2 octahedral nanostructures

To meet the requirements in air quality monitors for the public and industrial safety, sensors are required that can selectively detect the concentration of gaseous pollutants down to the parts per million (ppm) and ppb (parts per billion) levels. Herein, we report a remarkable NH3 sensor using Ni-doped CeO2 octahedral nanostructure which efficiently detects NH3 as low as 45 ppb at room temperature. The Ni-doped CeO2 sensor exhibits the maximum response of 42 towards 225 ppm NH3, which is ten-fold higher than pure CeO2. The improved sensing performance is caused by the enhancement of oxygen vacancy, bandgap narrowing, and redox property of CeO2 caused by Ni doping. Density functional theory confirms that O vacancy with Ni at Ce site (VONiCe) augments the sensing capabilities. The Bader charge analysis predicts the amount of charge transfer (0.04 e) between the Ni-CeO2 surface and the NH3 molecule. As well, the high negative adsorption energy (≈750 meV) and lowest distance (1.40 Å) of the NH3 molecule from the sensor surface lowers the detection limit. The present work enlightens the fabrication of sensing elements through defect engineering for ultra-trace detection of NH3 to be useful further in the field of sensor applications.

Promoting hydrophilic cupric oxide electrochemical carbon dioxide reduction to methanol via interfacial engineering modulation

Copper-based catalysts have been extensively investigated in electrochemical carbon dioxide (CO2) reduction to promote carbon products generated by requiring multiple electron transfer. However, hydrophilic electrodes are unfavourable for CO2 mass transfer and preferentially hydrogen (H2) evolution in electrochemical CO2 reduction. In this paper, a hydrophilic cupric oxide (CuO) electrode with a grassy morphology was prepared. CuO-derived Cu was confirmed as the active site for electrochemical CO2 reduction through wettability modulation. To enhance the intrinsic catalytic activity, a metal-oxide heterogeneous interface was created by engineering modulation at the interface, involving the loading of palladium (Pd) on CuO (CuO/Pd). Both the electrochemically active area and the electron transfer rate were enhanced by Pd loading, and significantly the reduced work function further facilitated the electron transfer between the electrode surface and the electrolyte. Consequently, the CuO/Pd electrode exhibited excellent excellent performance in electrochemical CO2 reduction, achieving a 54 % Faraday efficiency at -0.65 V for methanol (CH3OH). The metal-oxide interfacial effect potentially improves the intrinsic catalytic activity of hydrophilic CuO electrodes in electrochemical CO2 reduction, providing a conducive pathway for optimizing hydrophilic oxide electrodes in this process.

Cu-nanoparticles@ graphene nanocomposite: A robust and efficient nanocomposite for micro-solid phase extraction of trace aflatoxins in different foodstuffs

Cu-nanoparticles-immobilized graphene (Cu@G) nanocomposite was fabricated in this study by reducing Cu(II) ions in the presence of graphene oxide using a simple chemical reduction step. Cu@G nanocomposite was applied as a sorbent for the SPE of four aflatoxins (AFs). A reusable syringe was filled with the fabricated nanocomposite and used as a sorbent for the micro-solid phase extraction of four AFs (AFB1, AFB2, AFG1, AFG2). The impact of different analytical factors was fully investigated and optimized. Excellent recoveries, ranging from 92.0 to 108.5 %, were detected when evaluating target AFs in samples of rice, maize, and pistachio. The LOD, LOQ, and linear ranges were attained under optimal circumstances in the ranges of 0.0062 µg kg-1, 0.0192 µg kg-1, and 0.0-20 µg kg-1, respectively. The discovered approach provided the dual benefits of a high enrichment capability of Cu-nanoparticles via AFs complexation and a huge porosity of graphene sheets.

Optimizing electrochemical performance of Na0.67Ni0.17Co0.17Mn0.66O2 with P2 structure via preparing concentration-gradient particles for sodium-ion batteries

P2-type layered oxides for rechargeable sodium-ion batteries have drawn a lot of attention because of their excellent electrochemical performance. However, these types of cathodes usually suffer from poor cyclic stability. To overcome this disadvantage, in this work, novel ball-shaped concentration-gradient oxide Na0.67Ni0.17Co0.17Mn0.66O2 with P2 structure modified by Mn-rich surface is successfully prepared using co-precipitation method. The concentration of Mn increased from the inner core to the surface, endowing the material with an excellent cyclic stability. The cathode exhibits enhanced electrochemical properties than that of the sample synthesized by solid-state method and concentration-constant material. It shows 143.2 mAh/g initial discharge capacity and retains 131 mAh/g between 2 V and 4.5 V after 100 rounds. The significant improvement in the electrochemical properties of the sample benefits from the unique concentration-gradient structure, and the Mn-rich surface that effectively stabilizes the basic P2 structure. The relatively higher Ni content in the core leads to a slight improvement in the discharge capacity of the sample. This strategy may provide new insights for preparing layered cathodes for sodium-ion batteries with high electrochemical performance.

High-performance flexible asymmetric supercapacitor based on hierarchical MnO2/PPy nanocomposites covered MnOOH nanowire arrays cathode and 3D network-like Fe2O3/PPy hybrid nanosheets anode

The configuration of asymmetric supercapacitors (ASCs) has proven to be an effective approach to increase the energy storage properties due to the expanded working voltage resulting from the well-separated potential windows of the cathode and anode. However, carbonaceous anode materials generally suffer from relatively low capacitance, which restricts the enhancement of the energy storage performance of the full device in a traditional asymmetrical design. Herein, a rational design of all-pseudocapacitive ASCs (APASCs) using pseudocapacitive materials with a novel hierarchical nanostructure on both electrodes was developed to optimize the electrochemical properties for high-performance ASC devices. The assembled APASC employed the MnO2/PPy nanocomposites covered MnOOH nanowire arrays with core-shell hierarchical architecture as the cathode and Fe2O3/PPy hybrid nanosheets with 3D porous network-like structure as the anode. Owing to the coordinated pseudocapacitive properties and unique hierarchical nanostructures, this assembled APASC exhibited an exceptional volumetric capacitance of 4.92F cm-3 in a stable voltage window of 2 V, a maximum volumetric energy density of 2.66 mWh cm-3 at 19.72 mW cm-3, and excellent cyclic stability over 10,000 cycles (90.6 % capacitance retention), as well as remarkable flexibility and mechanical stability, providing insights for the design of flexible energy storage systems with enhanced performance.

Pioneering superior efficiency in Methylene blue and Rhodamine b dye degradation under solar light irradiation using CeO2/Co3O4/g-C3N4 ternary photocatalysts

In this research work, we have successfully synthesized the CeO2/Co3O4/g-C3N4 ternary nanocomposite for hydrothermal method for photocatalytic applications. The synthesized nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy TEM, Photoluminescent spectra (PL), X-ray photoelectron spectroscopy (XPS), Brunauer- Emmett-Teller (BET) and Ultraviolet diffuse reflectance spectroscopy (UV-DRS) technique. As per the optical spectroscopic investigations CeO2/Co3O4/g-C3N4 ternary nanocomposite exhibited the high optical absorption range and its band gap is reduced from 2.95 eV to1.83 eV. The PL spectra showed the lowered emission peak intensity of ternary nanocomposite which is revealed that the better charge separation and slow recombination of electron hole pairs. The highest photocatalytic degradation efficiency of CeO2/Co3O4/g-C3N4 ternary nanocomposite showed 93 % and 86 % towards the pollutant methylene blue and Rhodamine B. Moreover, photodegradation of the pollutants followed pseudo-first order kinetics with a very high-rate constant of 0.02211 min-1 and 0.017756 min-1. Additionally, the ternary nano catalyst was delivered the remarkable stability performance even after five cycles. This research may provide a low-cost approach for synthesized visible light responsive catalysts for use in environmental remediation applications.

Polycarbonyl polymer with zincophilic sites as protective coating for highly reversible zinc metal anodes

The Zn anode of aqueous zinc ion batteries (AZIBs) have suffered from a series of rampant side reactions such as dendrite growth and corrosion, which seriously affect the reversibility and stability of Zn anodes. Herein, a polycarbonyl polymer poly(1,4,5,8-naphthalene tetracarboxylic anhydride anthraquinone) imine (PNAQI) as the protective coating is synthesized through a simple solvothermal method with the raw materials of the equimolar 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and 2, 6-aminoanthraquinone (2,6-DAAQ). A series of characterizations such as contact angle measurement and ex-situ XRD analysis confirm that it can effectively prevent some side reactions. Moreover, CO on PNAQI can regulate the uniform distribution of zinc, thereby preventing the occurrence of zinc dendrites. Finally, the PNAQI@Zn//PNAQI@Zn symmetrical cell demonstrates a long cycle life exceeding 1000 h at current density of 1.0 mA cm-2 and a capacity of 1.0 mAh cm-2. The result significantly outperforms the cycling performance of the cell with bare zinc anode. Especially, the full battery of PNAQI@Zn//NH4V4O10 demonstrates an excellent capacity retention and prolonged cycle life (96.9 mAh/g after 1000 cycles at 1.0 A/g) compared to Zn//NH4V4O10. This work provides an effective, simple and low-cost solution for developing high-performance AZIBs.

Rapid and sensitive in situ detection of heavy metals in fish using enhanced Raman spectroscopy

Heavy metals have been widely applied in industry, agriculture, and other fields because of their outstanding physics and chemistry properties. They are non-degradable even at low concentrations, causing irreversible harm to the human and other organisms. Therefore, it is of great significance to develop high accuracy and sensitivity as well as stable techniques for their detection. Raman scattering spectroscopy and atomic absorption spectrophotometer (AAS) were used parallelly to detect heavy metal ions such as Hg, Cd, and Pb of different concentrations in fish samples. The concentration of the heavy metals is varied from 5 ppb to 5 ppm. Despite the satisfactory recoveries of AAS, their drawbacks are imperative for an alternative technique. In Raman scattering spectroscopy, the intensities and areas of the characteristic peaks are increased with increasing the concentration of the heavy metals. For Hg concentration ≥ 1 ppm, a slight shift is observed in the peak position. The obtained values of peak intensity and peak area are modeled according to Elvoich, Pseudo-first order, Pseudo-second order, and asymptotic1 exponential model. The best modeling was obtained using the Elovich model followed by the asymptotic1 exponential model. The introduced Raman spectroscopy-based approach for on-site detection of trace heavy metal pollution in fish samples is rapid, low-cost, and simple to implement, increasing its visibility in food safety and industrial applications.

CDs-g-C3N4-oleaginous yeast hybrid system: Microbial lipid synthesis and fermentation residual reutilization

The utilization of solar energy and fast-growing heterotrophic microbes for biofuel production has been recognized as a promising approach to achieve carbon neutrality and address energy crisis. In this work, we synthesized different kinds of photocatalysts based on graphitic carbon nitride (g-C3N4). We found that carbon dots modified-graphitic carbon nitride (CDs-g-C3N4) showed the highest photocatalytic activity. Subsequently, we developed a photocatalyst-microbe hybrid (PMH) system by combining CDs-g-C3N4 with an oleaginous yeast strain, Cutaneotrichosporon dermatis ZZ-46. Under visible light irradiation, the lipid yield of this PMH system reached 1.70 g/L at 120 h, representing a 36 % increase compared to the control. The photocatalytic reaction-induced ROS and the reductive photogenerated electrons facilitated ZZ-46 cells to synthesize more lipids. Furthermore, the fermentation residual of this PMH system was reutilized to prepare biochar via pyrolysis. The biochar generated at 550 °C (BC-550) demonstrated exceptional adsorption capabilities, particularly with a 57 % adsorption rate for methylene blue (MB), and maintained its perfect adsorption efficacy even after five regeneration cycles. These results offer promising avenues for addressing energy shortages and environmental contamination.

Development of 3D printable stabilized earth-based construction materials using excavated soil: Evaluation of fresh and hardened properties

Soil excavated during construction and demolition can be utilized to reduce the demand for natural sand in 3D printed constructions. This research attempts to systematically develop 3D printable stabilized earth-based materials using excavated soil (clay content of 42.5 %) as 25 % and 50 % replacement of natural sand, and examine their compressive strength, water permeable porosity, and moisture sensitivity. The effectiveness of two binder systems - Ordinary Portland Cement (OPC) and a combination of OPC and ground granulated blast furnace slag (GGBS used to replace 30 % OPC by mass), was investigated. Non-expansive clay in the soil leads to a steeper reduction in apparent viscosity, 12-15 % higher flow retention, and 50-60 % lower plastic viscosity of soil-based mixes, thus contributing to superior extrusion quality at 35-40 mm lower initial flow than OPC-sand and OPC-GGBS-sand mixes. The addition of GGBS, due to its irregular particle morphologies and interlocking effects, further enhances the shape retention of the printed layers by 8-26 % compared to OPC-soil mortars. The structural build-ups in OPC-soil and OPC-GGBS-soil mortars increase with the increase in clay content, which enabled buildability up to a height of 1.2 m compared to only 0.51-0.55 m for OPC-sand and OPC-GGBS-sand mortars. Higher water demand due to the addition of natural clay increases the porosity of 3D printed OPC-soil mortars, thereby lowering compressive strength and increasing moisture sensitivity. However, a blend of OPC and GGBS substantially reduces the moisture sensitivity of the printed mortars at 28-day age, attributed to better stabilization of clay through hydraulic and pozzolanic action of GGBS. 28-day wet compressive strength of 14-25 MPa is obtained for the printed soil-based mixes depending on the soil dosage and loading direction. In summary, the study provides a feasible solution for the 3D printing of stabilized earth structures with lower demand for natural sand and OPC.

A multifunctional flexible sensor based on PI-MXene/SrTiO3 hybrid aerogel for tactile perception

The inadequacy of tactile perception systems in humanoid robotic manipulators limits the breadth of available robotic applications. Here, we designed a multifunctional flexible tactile sensor for robotic fingers that provides capabilities similar to those of human skin sensing modalities. This sensor utilizes a novel PI-MXene/SrTiO3 hybrid aerogel developed as a sensing unit with the additional abilities of electromagnetic transmission and thermal insulation to adapt to certain complex environments. Moreover, polyimide (PI) provides a high-strength skeleton, MXene realizes a pressure-sensing function, and MXene/SrTiO3 achieves both thermoelectric and infrared radiation response behaviors. Furthermore, via the pressure response mechanism and unsteady-state heat transfer, these aerogel-derived flexible sensors realize multimodal sensing and recognition capabilities with minimal cross-coupling. They can differentiate among 13 types of hardness and four types of material from objects with accuracies of 94% and 85%, respectively, using a decision tree algorithm. In addition, based on the infrared radiation-sensing function, a sensory array was assembled, and different shapes of objects were successfully recognized. These findings demonstrate that this PI-MXene/SrTiO3 aerogel provides a new concept for expanding the multifunctionality of flexible sensors such that the manipulator can more closely reach the tactile level of the human hand. This advancement reduces the difficulty of integrating humanoid robots and provides a new breadth of application scenarios for their possibility.

Hybrid plasmonic aerogel with tunable hierarchical pores for size-selective multiplexed detection of VOCs with ultrahigh sensitivity

Sensitive and rapid identification of volatile organic compounds (VOCs) at ppm level with complex composition is vital in various fields ranging from respiratory diagnosis to environmental safety. Herein, we demonstrate a SERS gas sensor with size-selective and multiplexed identification capabilities for VOCs by executing the pre-enrichment strategy. In particular, the macro-mesoporous structure of graphene aerogel and micropores of metal-organic frameworks (MOFs) significantly improved the enrichment capacity (1.68 mmol/g for toluene) of various VOCs near the plasmonic hotspots. On the other hand, molecular MOFs-based filters with different pore sizes could be realized by adjusting the ligands to exclude undesired interfering molecules in various detection environments. Combining these merits, graphene/AuNPs@ZIF-8 aerogel gas sensor exhibited outstanding label-free sensitivity (up to 0.1 ppm toluene) and high stability (RSD=14.8%, after 45 days storage at room temperature for 10 cycles) and allowed simultaneous identification of multiple VOCs in a single SERS measurement with high accuracy (error < 7.2%). We visualize that this work will tackle the dilemma between sensitivity and detection efficiency of gas sensors and will inspire the design of next-generation SERS technology for selective and multiplexed detection of VOCs.

Stability and dispersibility of microplastics in experimental exposure medium and their dimensional characterization by SMLS, SAXS, Raman microscopy, and SEM

The plastic production that contributes to the global plastic reservoir presents a major challenge for society in managing plastic waste and mitigating the environmental damage of microplastic (MP) pollution. In the environment, the formation of biomolecular corona around MPs enhance the stability of MP suspensions, influencing the bioavailability and toxicity of MPs. Essential physical properties including MP stability, dispersibility, agglomeration, and dimensional size must be precisely defined and measured in complex media taking into account the formation of a protein corona. Using static multiple light scattering (SMLS), small angle X-ray scattering (SAXS), Raman microscopy, and scanning electron microscopy (SEM), we measured the particle size, density, stability, and agglomeration state of polyethylene and polypropylene MPs stabilized in aqueous suspension by BSA. SEM analysis revealed the formation of nanoplastic debris as MP suspensions aged. Our results suggest that protein adsorption favors the formation of secondary nanoplastics, potentially posing an additional threat to ecosystems. This approach provides analytical methodologies by integrating SEM, SMLS, and SAXS, for characterizing MP suspensions and highlights the effect of the protein corona on size measurements of micro/nanoplastics. Our analysis demonstrates the detectability of secondary nanoplastics by SEM, paving the way for monitoring and controlling human exposure.

DFT insights into LaFeO3 with Mn substitution: A promising path to energy-efficient magneto-optical applications

In recent years, the demand for electronic materials has significantly increased, driven by industrial needs and the pursuit of cost-efficient alternatives. This comprehensive study investigates the effects of Mn substitution on LaFeO3 through the implementation of the GGA approach in density functional theory. The research findings demonstrate remarkable consistency with the experimental outcomes reported in the existing literature pertaining to the studied compounds. However, this study unveils novel insights into the mechanical and optical characteristics of the doped structures, which have not been previously reported. The structural stability is rigorously examined through multiple stability criteria, encompassing structural optimization, tests of elastic stability, and enthalpy of formation calculations. Furthermore, the electronic and optical properties of the compounds exhibit exceptional improvements in conductivity and reflectivity as a result of the doping process. The band structure analysis reveals the presence of a Moss-Burstein shift. Investigation of the magnetic properties indicates an increase in the magnetic moment value due to the Fe-Mn degeneracy resulting from increased Mn content. Mechanical analysis of the elastic moduli B, G, and Y demonstrates an enhanced strength and metal-like conductivity, attributed to the induced anharmonicity. Moreover, the internal strain factor suggests a higher degree of bond flexibility, implying potential applications of these compounds in flexible electronics.

Trapping and reversing neuromuscular blocking agent by anionic pillar[5]arenes: Understanding the structure-affinity-reversal effects

Selective relaxant binding agents (SRBA) have great potential in clinical surgeries for the precise reversal of neuromuscular blockades. Understanding the relationship between the structure-affinity-reversal effects of SRBA and neuromuscular blockade is crucial for the design of new SRBAs, which has rarely been explored. Seven anionic pillar[5]arenes (AP5As) with different aliphatic chains and anionic groups at both edges were designed. Their binding affinities to the neuromuscular blocking agent decamonium bromide (DMBr) were investigated using 1H NMR, isothermal titration calorimetry (ITC), and theoretical calculations. The results indicate that the capture of DMBr by AP5As is primarily driven by electrostatic interactions, ion-dipole interactions and C-H‧‧‧π interactions. The optimal size matching between the carboxylate AP5As and DMBr was ∼0.80. The binding affinity increased with an increase in the charge quantity of AP5As. Further animal experiments indicated that the reversal efficiency increased with increasing binding affinity for carboxylate or phosphonate AP5As. However, phosphonate AP5As exhibited lower reversal efficiencies than carboxylate AP5As, despite having stronger affinities with DMBr. By understanding the structure-affinity-reversal relationships, this study provides valuable insights into the design of innovative SRBAs for reversing neuromuscular blockade.

MoP quantum dots based multifunctional efficient electrocatalyst for stable and long-life flexible lithium-sulfur batteries

The commercialization of lithium-sulfur (Li-S) batteries is challenging, owing to factors like the poor conductivity of S, the 'shuttle effect', and the slow reaction kinetics. To address these challenges, MoP quantum dots were decorated on hollow carbon spheres (MoPQDs/C) in this study and used as an efficient lithium polysulfides (LiPSs) adsorbents and catalysts. In this approach polysulfides are effectively trapped through strong chemisorption and physical adsorption while simultaneously facilitating LiPSs conversion by enhancing the reaction kinetics. MXene serves as a flexible physical barrier (MoPQDs/C@MXene), further enhancing the confinement of LiPSs. Moreover, both materials are conductive, significantly facilitating electron and charge transfer. Additionally, the flexible MoPQDs/C@MXene-S electrode offers a large specific surface area for sulfur loading and withstand volume expansion during electrochemical processes. As a result, the MoPQDs/C@MXene-S electrode exhibits excellent long-term cyclability and maintains a robust specific capacity of 992 mA h g-1 even after 800cycles at a rate of 1.0C (1C = 1675 mA g-1), with a minimal capacity decay rate of 0.034 % per cycle. This work proposes an efficient strategy to fabricate highly efficient electrocatalysts for advanced Li-S batteries.

Synthesis and characterization of thermosensitive 2-hydroxypropyl-trimethylammonium chitin and its antibacterial sponge for noncompressible hemostasis and tissue regeneration

Noncompressible hemorrhage is a leading cause of preventable death in battlefield/civilian trauma. The development of novel injectable and biodegradable hemostatic sponges, with rapid shape recovery and excellent antibacterial activity that can control hemorrhage in noncompressible bleeding sites and promote in situ tissue regeneration is still urgently needed. In this study, thermo/pH sensitive 2-hydroxypropyl-trimethylammonium chitins (QCHs) with low degree of quaternization substitution (DS: 0.07-0.23) and high degree of acetylation (DA: 0.91-0.94) were synthesized homogeneously for the first time. Their chemical compositions including DS and DA were characterized accurately by proton NMR for the first time. High strength QCH based sponges with good water/blood absorbency, rapid shape recovery and good antibacterial activity were prepared without using any crosslinkers but only due to their thermosensitive property, since they are soluble at low temperature but insoluble at high temperature. Compared with commercial products, the QCH sponges with cationic groups had the stronger pro-coagulant ability, better hemostatic effect in normal/heparinized liver perforation and femoral artery models in rats and porcine subclavian arteriovenous resection model. Moreover, the porous structure and biodegradability of the QCH sponges could promote in situ tissue regeneration. Overall, the QCH sponges show great clinical translational potential for noncompressible hemorrhage and tissue regeneration.

Piezoelectric hydrogel for treatment of periodontitis through bioenergetic activation

The impaired differentiation ability of resident cells and disordered immune microenvironment in periodontitis pose a huge challenge for bone regeneration. Herein, we construct a piezoelectric hydrogel to rescue the impaired osteogenic capability and rebuild the regenerative immune microenvironment through bioenergetic activation. Under local mechanical stress, the piezoelectric hydrogel generated piezopotential that initiates osteogenic differentiation of inflammatory periodontal ligament stem cells (PDLSCs) via modulating energy metabolism and promoting adenosine triphosphate (ATP) synthesis. Moreover, it also reshapes an anti-inflammatory and pro-regenerative niche through switching M1 macrophages to the M2 phenotype. The synergy of tilapia gelatin and piezoelectric stimulation enhances in situ regeneration in periodontal inflammatory defects of rats. These findings pave a new pathway for treating periodontitis and other immune-related bone defects through piezoelectric stimulation-enabled energy metabolism modulation and immunomodulation.

Effect of chitin-architected spatiotemporal three-dimensional culture microenvironments on human umbilical cord-derived mesenchymal stem cells

Mesenchymal stem cell (MSC) transplantation has been explored for the clinical treatment of various diseases. However, the current two-dimensional (2D) culture method lacks a natural spatial microenvironment in vitro. This limitation restricts the stable establishment and adaptive maintenance of MSC stemness. Using natural polymers with biocompatibility for constructing stereoscopic MSC microenvironments may have significant application potential. This study used chitin-based nanoscaffolds to establish a novel MSC three-dimensional (3D) culture. We compared 2D and 3D cultured human umbilical cord-derived MSCs (UCMSCs), including differentiation assays, cell markers, proliferation, and angiogenesis. When UCMSCs are in 3D culture, they can differentiate into bone, cartilage, and fat. In 3D culture condition, cell proliferation is enhanced, accompanied by an elevation in the secretion of paracrine factors, including vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), Interleukin-6 (IL-6), and Interleukin-8 (IL-8) by UCMSCs. Additionally, a 3D culture environment promotes angiogenesis and duct formation with HUVECs (Human Umbilical Vein Endothelial Cells), showing greater luminal area, total length, and branching points of tubule formation than a 2D culture. MSCs cultured in a 3D environment exhibit enhanced undifferentiated, as well as higher cell activity, making them a promising candidate for regenerative medicine and therapeutic applications.

Fast-relaxing hydrogels with reversibly tunable mechanics for dynamic cancer cell culture

The mechanics of the tumor microenvironment (TME) significantly impact disease progression and the efficacy of anti-cancer therapeutics. While it is recognized that advanced in vitro cancer models will benefit cancer research, none of the current engineered extracellular matrices (ECM) adequately recapitulate the highly dynamic TME. Through integrating reversible boronate-ester bonding and dithiolane ring-opening polymerization, we fabricated synthetic polymer hydrogels with tumor-mimetic fast relaxation and reversibly tunable elastic moduli. Importantly, the crosslinking and dynamic stiffening of matrix mechanics were achieved in the absence of a photoinitiator, often the source of cytotoxicity. Central to this strategy was Poly(PEGA-co-LAA-co-AAPBA) (PELA), a highly defined polymer synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. PELA contains dithiolane for initiator-free gel crosslinking, stiffening, and softening, as well as boronic acid for complexation with diol-containing polymers to give rise to tunable viscoelasticity. PELA hydrogels were highly cytocompatible for dynamic culture of patient-derived pancreatic cancer cells. It was found that the fast-relaxing matrix induced mesenchymal phenotype of cancer cells, and dynamic matrix stiffening restricted tumor spheroid growth. Moreover, this new dynamic viscoelastic hydrogel system permitted sequential stiffening and softening to mimic the physical changes of TME.

Calcium-based MOFs as scaffolds for shielding immobilized lipase and enhancing its stability

The enzyme immobilization technology has become a key tool in the field of enzyme applications; however, improving the activity recovery and stability of the immobilized enzymes is still challenging. Herein, we employed a magnetic carboxymethyl cellulose (MCMC) nanocomposite modified with ionic liquids (ILs) for covalent immobilization of lipase, and used Ca-based metal-organic frameworks (MOFs) as the support skeleton and protective layer for immobilized enzymes. The ILs contained long side chains (eight CH2 units), which not only enhanced the hydrophobicity of the carrier and its hydrophobic interaction with the enzymes, but also provided a certain buffering effect when the enzyme molecules were subjected to compression. Compared to free lipase, the obtained CaBPDC@PPL-IL-MCMC exhibited higher specific activity and enhanced stability. In addition, the biocatalyst could be easily separated using a magnetic field, which is beneficial for its reusability. After 10 cycles, the residual activity of CaBPDC@PPL-IL-MCMC could reach up to 86.9%. These features highlight the good application prospects of the present immobilization method.

Synergistic interaction of nanoparticles and probiotic delivery: A review

Nanotechnology is an expanding and new technology that prompts production with nanoparticle-based (1-100 nm) organic and inorganic materials. Such a tool has an imperative function in different sectors like bioengineering, pharmaceuticals, electronics, energy, nuclear energy, and fuel, and its applications are helpful for human, animal, plant, and environmental health. In exacting, the nanoparticles are synthesized by top-down and bottom-up approaches through different techniques such as chemical, physical, and biological progress. The characterization is vital and the confirmation of nanoparticle traits is done by various instrumentation analyses like UV-Vis spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscopy, X-ray diffraction, atomic force microscopy, annular dark-field imaging, and intracranial pressure. In addition, probiotics are friendly microbes which while administered in sufficient quantity confer health advantages to the host. Characterization investigation is much more significant to the identification of good probiotics. Similarly, haemolytic activity, acid and bile salt tolerance, autoaggregation, antimicrobial compound production, inhibition of pathogens, enhance the immune system, and more health-beneficial effects on the host. The synergistic effects of nanoparticles and probiotics combined delivery applications are still limited to food, feed, and biomedical applications. However, the mechanisms by which they interact with the immune system and gut microbiota in humans and animals are largely unclear. This review discusses current research advancements to fulfil research gaps and promote the successful improvement of human and animal health.

Compliant substrates mitigate the senescence associated phenotype of stress induced mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) are a promising cell population for musculoskeletal cell-based therapies due to their multipotent differentiation capacity and complex secretome. Cells from younger donors are mechanosensitive, evidenced by changes in cell morphology, adhesivity, and differentiation as a function of substrate stiffness in both two- and three-dimensional culture. However, MSCs from older individuals exhibit reduced differentiation potential and increased senescence, limiting their potential for autologous use. While substrate stiffness is known to modulate cell phenotype, the influence of the mechanical environment on senescent MSCs is poorly described. To address this question, we cultured irradiation induced premature senescent MSCs on polyacrylamide hydrogels and assessed expression of senescent markers, cell morphology, and secretion of inflammatory cytokines. Compared to cells on tissue culture plastic, senescent MSCs exhibited decreased markers of the senescence associated secretory phenotype (SASP) when cultured on 50 kPa gels, yet common markers of senescence (e.g., p21, CDKN2A, CDKN1A) were unaffected. These effects were muted in a physiologically relevant heterotypic mix of healthy and senescent MSCs. Conditioned media from senescent MSCs on compliant substrates increased osteoblast mineralization compared to conditioned media from cells on TCP. Mixed populations of senescent and healthy cells induced similar levels of osteoblast mineralization compared to healthy MSCs, further indicating an attenuation of the senescent phenotype in heterotypic populations. These data indicate that senescent MSCs exhibit a decrease in senescent phenotype when cultured on compliant substrates, which may be leveraged to improve autologous cell therapies for older donors.