Search Results (442)

In the contemporary era of minimally invasive surgery, injectable biomaterial scaffolds have demonstrated significant potential in bone tissue engineering (BTE). Completely injectable hydrogel substratum with microscale bone graft particulates delivered through a needle-shaped orifice shifts a new paradigm for surgical interventions in clinical settings. Despite growing interest in biopolymer-based BTE systems, clinically applicable delivery platforms and a mechanistic understanding of cell–material interactions remain limited. This study developed a dual-syringe auto-mix system capable of generating an in situ cross-linking hydrogel–mineral construct composed of gelatin–hydroxyphenyl propionic acid, hyaluronic acid–tyramine, horseradish peroxidase, hydrogen peroxide, and calcium phosphate particles of varying sizes. Material distribution, rheological and mechanical properties, and swelling were characterized. Goat bone marrow-derived mesenchymal stem cells served as the basis for examining how the composite affected cell viability, morphology, proliferation, contractility, osteogenic differentiation, mineralization, and chemotactic behavior. To determine whether these biological findings were supported mechanically, an ex vivo cone-beam computed tomography model was used to evaluate volumetric stability and resistance to deformation at the graft–host interface. Cross-linking established a stable internal microarchitecture while remaining compatible with cell viability and nutrient-dependent survival. Formation of the gelatin–hyaluronan (GH) network significantly increased the storage modulus relative to gelatin (G) alone, whereas subsequent calcium phosphate incorporation (GH-CP) preserved this mechanical competence while attenuating the volumetric expansion of GH. These physical characteristics were accompanied by more organized cell morphology, enhanced osteogenic differentiation, and mineral deposition throughout a larger portion of the matrix. Heterogeneous interpenetrating gap striation (HIGS) appeared in regions of cellular aggregation and matrix deposition, and a new conceptualization of the osteogenic phenomenon, termed cling osteogenesis, has been proposed. These outcomes support an intricate relationship between early mechanical stabilization, mechanotransduction, and osteogenesis in injectable hydrogel–mineral systems. Full article

Amplex Red is a widely used fluorogenic probe for hydrogen peroxide (H₂O₂) detection. In the presence of horseradish peroxidase (HRP), it reacts with H₂O₂ to form fluorescent resorufin. However, during high-voltage electric pulse treatment, fluorescence readouts may be influenced not only by H₂O₂ generation but also by the medium composition, pulse conditions, pH-dependent effects, and metal ions released as a result of electrode corrosion. In this study, we examined how medium composition and selected metal ions relevant to electroporation conditions, such as Fe²⁺, Fe³⁺, Al³⁺, and Cr⁶⁺, affect the Amplex Red/HRP/H₂O₂ fluorescence signal. Fluorescence intensity differed markedly among media, with the highest signal in phosphate-buffered saline (PBS, ~34,000 a.u.), followed by HB1 buffer (~19,000 a.u.), cell culture medium (~9000 a.u.), and distilled water (~4100 a.u.). To model ion-mediated interference, metal ions were added directly to the assay mixture. All tested ions reduced fluorescence in a concentration-dependent manner. At 0.4 µM H₂O₂, Fe²⁺ reduced fluorescence by up to 92%, Fe³⁺ by 60%, Al³⁺ by 35%, and Cr⁶⁺ by 40%. At 10 µM H₂O₂, the quenching effect was reduced but remained evident. In addition, the fluorescence readout showed strong dependence on medium composition and its pH, further demonstrating its vulnerability to the chemical environment. These findings show that the Amplex Red assay is highly sensitive to the assay environment and metal-ion interference. Therefore, it should not be used as a standalone, interference-free measure of H₂O₂ in electroporation-related experiments without appropriate validation controls. Full article

We developed a site-directed immobilization strategy exploiting the competitive inhibitor Remazol Brilliant Blue R (RB) to orient horseradish peroxidase (HRP) on functionalized glass surfaces. RB was covalently bound to poly(ethylene-alt-maleic anhydride) (PEMA)-coated substrates, enabling HRP binding via its active site. Subsequent contact with a second PEMA-functionalized surface facilitated covalent immobilization of HRP with controlled orientation. Interfacial layer assembly and the comparative random control were characterized by AFM and XPS analyses, while successful RB acetylation was confirmed by NMR and ATR-IR spectroscopy. Directed contact approaches using stepwise RB and PEMA+RB functionalization yielded HRP loadings with specific activities approximately twofold higher than non-directed immobilization. Our inhibitor-mediated method preserves the native enzyme structure without genetic modification, offering a straightforward platform for enhancing enzyme performance. This strategy is promising for applications in biosensors, biocatalysis, and enzyme-based devices requiring efficient enzyme immobilization. Full article

Enzyme immobilisation within Metal–organic Frameworks (MOFs) provides a promising strategy for improving enzyme dispersion and local environment control, although the resulting performance depends strongly on the host materials, enzyme type and immobilisation conditions. Conventional in situ biomimetic mineralisation typically produces enzyme–MOF composites (enzyme@MOFs) with irregular morphologies, broad particle size distributions and aggregation, which can compromise catalytic performance and reproducibility. This study presents a flow-based microfluidic biomimetic mineralisation strategy for preparing horseradish peroxidase-encapsulated ZnBDC-NH₂ MOF composites. A flow-focusing microfluidic chip containing multiple rectangular baffle structures was designed to enhance transverse mixing, extend the effective residence time, and mitigate clogging during particle formation. Under the selected conditions, homogeneous HRP@ZnBDC-NH₂ particles with an average hydrodynamic diameter of 868.5 nm and a polydispersity index of 0.266 were obtained. The homogeneous HRP@ZnBDC-NH₂ showed an encapsulation efficiency of 56.17% and a loading content of 1.49%. Michaelis–Menten analysis gave a Km value of 52.49 μM for HRP@ZnBDC-NH₂, suggesting improved apparent substrate affinity compared with the corresponding bulk-synthesised sample. The results support the use of baffle-structured microfluidics as a controllable platform for enzyme@MOF synthesis, while further studies on enzyme leaching, reusability, long-term stability and extended chip operation are required to evaluate its operational robustness. Full article

Porcine circovirus type 2 (PCV2) is the primary causative agent of a spectrum of porcine circovirus-associated diseases (PCVDs) and remains a major threat to the global swine industry. In this study, ten monoclonal antibodies (mAbs) targeting the Cap protein of PCV2 were generated and characterized. One mAb, designated 4C4, which exhibited high reactivity, strong neutralizing activity, and superior blocking efficacy, was selected for horseradish peroxidase (HRP) labeling. After optimizing the reaction parameters, a blocking ELISA was developed for the detection of the anti-PCV2 antibody. Using receiver operating characteristic (ROC) curve analysis, a cutoff value of 40% was established to distinguish positive from negative serum samples. The sensitivity and specificity of this blocking ELISA method were 98.66% and 100%, respectively. No cross-reactivity was observed with serum antibodies against classical swine fever virus (CSFV), porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), porcine reproductive and respiratory syndrome virus (PRRSV), or pseudorabies virus (PRV). Intra-assay and inter-assay repeatability tests yielded coefficients of variation (CVs) all below 10%, confirming the assay’s excellent reproducibility. Simultaneous testing of 312 clinical porcine serum samples using the developed bELISA and a commercial indirect ELISA kit revealed an overall coincidence rate of 99.04%. In addition, the percentage inhibition (PI) in the bELISA was strongly correlated with serum anti-PCV2 neutralizing antibody titers. In conclusion, the blocking ELISA developed herein demonstrates high sensitivity, strong specificity, and good reproducibility, serving as a potentially effective tool for the detection of the anti-PCV2 antibody and epidemiological investigation. Full article

Brucellosis is a globally prevalent zoonotic disease that imposes considerable economic burdens on the livestock industry and remains a significant threat to public health. Although lipopolysaccharide (LPS)-based serological assays are widely used in routine diagnosis, their inherent limitations—particularly cross-reactivity with other Gram-negative bacteria—underscore the need for the development of diagnostic approaches based on non-LPS antigens. In this study, we developed a trivalent nanobody–horseradish peroxidase (3Nbs-HRP) fusion protein targeting Brucella OMP16 and established a cELISA for the serological detection of bovine brucellosis. The diagnostic performance of the assay was assessed using 204 Brucella antibody-negative and 123 Brucella antibody-positive bovine serum samples. ROC curve analysis yielded a sensitivity of 87.7% and a specificity of 89.4%, with no significant cross-reactivity observed. By employing a recombinant antigen and a 3Nbs-HRP probe, this assay enhances biosafety and demonstrates strong potential for standardization and large-scale application, serving as a complementary tool to conventional LPS-based assays for the surveillance, diagnosis, and control of bovine brucellosis. Full article

Background/Objectives: Colistin (COL), administered as a prodrug colistimethate sodium (CMS), is commonly used to treat infections caused by multidrug-resistant Gram-negative bacteria in critically ill patients. Given high CMS instability, very complex and variable pharmacokinetics (PK) and high incidence of toxicity, therapeutic drug monitoring (TDM) of active COL might play an important role. This study aimed to develop and validate an accessible immunoassay-based approach for COL monitoring in human serum. Methods: A direct competitive enzyme-linked immunosorbent assay (dcELISA) was developed using polyclonal (pAb) anti-polymyxin antibody alongside a polymyxin B–horseradish peroxidase conjugate. CMS conversion to COL along with serum deproteinization was achieved using 5% trichloroacetic acid (TCA) treatment at 37 °C. Assay accuracy and precision were assessed by spike-and-recovery experiments in healthy volunteer serum. The assay was applied to serum samples from critically ill patients with burns or pneumonia receiving CMS therapy. The reliability of the measurements was confirmed by parallel dcELISA based on a reference monoclonal antibody (mAb) against fragmented polymyxin molecule. Results: Both ELISA formats demonstrated high sensitivity, with limits of detection of 0.053 ng/mL (pAb) and 0.047 ng/mL (mAb). TCA treatment achieved maximal CMS hydrolysis under tested conditions within one hour. Clinical sample analysis showed excellent agreement between the two assays (R² = 0.996), with Bland–Altman analysis revealing a minimal bias of 3.7%. Exploratory PK analysis in burn patients demonstrated increased total drug volume of distribution (45.7–64.9 L) and clearance (8.3–16.3 L/h). Conclusions: This is the first report of ELISA for COL TDM in critically ill patients. The method offers acceptable analytical performance and practical simplicity, with potential to broaden TDM access beyond specialist centers. Full article

This work introduces a textile-based platform for biocatalysis by integrating a copper-based hybrid domain onto aminated/amidine-functionalized acrylic textile (TAC–Cu), producing a functional bio-textile capable of high-performance enzyme immobilization. The textile substrate was chemically modified with ethylenediamine to generate amine/amidine-type functional groups, enabling in situ formation of copper-based hybrid structures through either a conventional solvothermal approach or a plant-mediated route employing Costus speciosus extract. The green-synthesized TAC–Cu composite exhibited superior structural uniformity, improved porosity, and enhanced surface chemistry, resulting in a higher horseradish peroxidase (HRP) immobilization yield (92%) compared with the chemically synthesized analogue. The resulting HRP-functionalized bio-textile demonstrated markedly improved catalytic behavior, including a reaction rate constant nearly twice that of the free enzyme, and strong operational robustness. As a technical textile engineered for environmental applications, the composite achieved 90% bisphenol A (BPA) removal within 90 min and retained substantial enzymatic activity even at 80 °C, whereas free HRP was almost fully deactivated. Overall, this study highlights the potential of eco-engineered TAC–Cu materials as a new class of functional and sustainable bio-textiles, combining enzyme stabilization, high catalytic efficiency, and suitability for wastewater treatment and other technical textile applications. Full article

Protein–protein interactions (PPIs) are fundamental to viral replication, regulating processes such as assembly, genome packaging, and virion maturation. Despite their biological importance, these interactions remain challenging to study and are relatively underexploited as therapeutic targets. Split reporter systems, based on protein-fragment complementation, provide quantitative platforms to measure PPIs by reconstituting reporter activity when interacting protein partners are brought into proximity. These systems can be applied in vitro and in live cells which enables detection of dynamic and multimeric interactions in physiologically relevant contexts. Major classes of split reporter systems include β-lactamase, alkaline phosphatase, luciferase-based platforms, green fluorescent protein, and horseradish peroxidase. Assay performance depends on factors such as fusion protein stability, expression levels, and reporter kinetics, which influence sensitivity, dynamic range, and reliability. These approaches have been applied to study viral protein interactions across diverse systems, including HIV-1 matrix and nucleocapsid proteins, flaviviral capsid proteins, hepatitis B virus core protein, and chikungunya virus capsid. Split reporter assays also enable high-throughput screening for small-molecule inhibitors that disrupt viral PPIs and multimerization. This provides a functional readout linked to viral replication. Despite the challenges that exist in assay optimization and protein stability, the sensitivity and versatility of these systems provide a framework to interrogate viral protein interactions and support the development of antiviral therapeutics.: Full article

Foot-and-Mouth Disease (FMD) is caused by the FMD virus. Indirect Sandwich Enzyme-Linked Immunosorbent Assay (IS-ELISA) was standardized to characterize the FMD serotype “O” virus. Total protein content in the guinea pig serum (whole serum), ammonium sulfate precipitated guinea pig serum (ASPGPS) protein and ion-exchange-based purified guinea pig serum (IEGPS) protein was measured as 52 µg/mL, 24 µg/mL and 10 µg/mL respectively. The whole serum of guinea pigs and rabbits showed the 1:32 and 1:64 anti-FMD serotype “O” virus neutralizing antibody titers, while the anti-FMD serotype “O” virus neutralizing antibody titer was 1:128 in the IEGPS proteins. IEGPS protein with 1:128 neutralizing antibody titers were used as capture/trapping antibodies in the standardization of the assay. The IEGPS protein 1:1000 diluted with 10 µg/mL of protein content was found to be optimum for capture/trapping antibodies. To cover residual blank spaces, different available blocking buffers were evaluated and Skimmed Milk Solution 5% in Phosphate-Buffered Saline (PBS5%) proved best amongst blocking buffers. Coating of 1:1000 diluted IEGPS at 37 °C for 1 h followed by storage at 4 °C for overnight was best for incubation time. FMD serotype “O” virus 1:100 diluted was optimum in IS-ELISA. Similarly rabbit anti-FMD serotype “O” virus specific immune serum 1:10,000 diluted and goat anti-rabbit IgG horseradish peroxidase conjugate 1:4000 diluted were found to be optimum during the standardization of the assay. Lastly ELISA plates proved to be best amongst the available plates for assay. In each experiment, the plateau region, test background and plate background were recorded. Lastly it became possible for the establishment of an optimized and potentially cost-effective IS-ELISA requiring further diagnostic validation in research and diagnostic laboratories in the country. Full article

Cell encapsulation within semipermeable membranes is a promising strategy for protecting transplanted cells from host immune responses, while permitting the diffusion of nutrients and therapeutic molecules. Although alginate-based microcapsules are commonly used, ionically crosslinked capsules often exhibit limited structural stability and tunability in terms of membrane permeability. In this study, we developed covalently stabilized microcapsules. Alginate microgel beads were first prepared as sacrificial templates and subsequently coated with phenol-modified chitosan and hyaluronic acid (Chitosan–Ph and HA-Ph) via layer-by-layer assembly. The multilayer membrane was then covalently stabilized through horseradish peroxidase (HRP)-mediated oxidative coupling of phenol groups, followed by liquefaction of the alginate core. The crosslinked microcapsules maintained structural integrity after liquefaction, while markedly reducing γ-globulin permeation under in vitro conditions and preserving β-cell viability and glucose responsiveness. The findings of this study demonstrate the feasibility of this system as an in vitro platform for stable cell encapsulation, with potential relevance to cell therapy. Full article

Formalin-fixed paraffin-embedded (FFPE) tissues represent an invaluable resource for both basic and clinical research due to their stable preservation of tissue architecture and molecular integrity. Multiplex immunofluorescence (mIF) using tyramide signal amplification (TSA) enables the simultaneous detection of multiple antigens within a single FFPE section. Here, we describe a kit-independent and customizable TSA-based mIF protocol that utilizes commercially available horseradish peroxidase (HRP)-conjugated secondary antibodies and tyramide–fluorophore reagents. The method was applied using FFPE endometriosis tissue, targeting estrogen receptor alpha (ERα), progesterone receptor (PR), α-smooth muscle actin (αSMA), CD20 and CD31. Each staining round was followed by heat-induced epitope removal (HIER) of the bound antibodies while preserving covalently deposited signals. Fluorescence imaging was performed using a multi-channel slide scanner with carefully selected fluorophores to enable optical separation between detection channels. Under the conditions described, the protocol enabled clear visualization of maker-specific staining patterns with preserved tissue morphology. This study provides a practical and flexible TSA-based mIF protocol as a qualitative proof of concept, offering an accessible alternative to commercial kit-based approaches. Further studies will be required to establish quantitative performance and a broader applicability across tissue types. Full article

Early intervention is pivotal for mitigating the progression of Alzheimer’s disease (AD). This study presents an electrochemical immunosensor targeting synaptic vesicle glycoprotein 2A (SV2A) to facilitate early AD diagnosis. A sensing interface was engineered using a nanocomposite of graphene oxide (GO) and 3-carboxyl polypyrrole (3-COOH-PPy). Leveraging the synergistic effects between the large specific surface area of GO and the superior conductivity of 3-COOH-PPy, the composite established an efficient electron transport network. This architecture provided abundant active sites for capture antibody immobilization while significantly enhancing interfacial electron transfer kinetics. Coupling this interface with an enzyme-mediated signal amplification strategy based on the horseradish peroxidase (HRP)-catalyzed TMB/H₂O₂ system, the immunosensor achieved high sensitivity. It exhibited a wide linear range of 2 ng/mL to 16 μg/mL with a low limit of detection (LOD) of 0.15 ng/mL. Furthermore, successful detection in C57 mouse serum samples validated the method’s reliability and potential for clinical application. In conclusion, this immunosensor offers a sensitive and robust platform for the early diagnosis of AD. Full article

Cerium oxide (CeO₂) nanozymes, also known as nanoceria have emerged as a versatile class of catalytic nanomaterials capable of mimicking key redox enzymes, including oxidases and peroxidases. Their tunable Ce³⁺/Ce⁴⁺ redox cycling, high density of oxygen vacancies, and exceptional resistance to thermal, pH, and storage stress distinguish CeO₂ from conventional enzyme labels, such as horseradish peroxidase (HRP). In immunoassays, CeO₂ enables H₂O₂-free TMB (3,3′,5,5′-tetramethylbenzidine) oxidation, generating strong chromogenic signals with minimal background. Although CeO₂ nanozymes have been explored in colorimetric, chemiluminescent, and photoactive immunoassays, their integration into lateral flow immunoassays (LFIAs) remains limited, with only a few hybrid CeO₂-containing systems reported to date. This mini-review highlights the limitations of conventional peroxidase-based formats and explains how CeO₂’s redox cycling (Ce³⁺/Ce⁴⁺) and oxygen-vacancy-driven catalysis deliver stable, reagent-free signal amplification. Emphasis is placed on the synthetic control of CeO₂, conjugation chemistry with antibodies, and integration into LFIA architectures. CeO₂ enables hydrogen-peroxide-free colorimetric detection with improved robustness and sensitivity, positioning it as a promising catalytic label for point-of-care testing. However, it may aggregate in high-ionic-strength buffers, and its synthesis cost increases for highly uniform, vacancy-engineered materials. Surface functionalization with polymers or dopants and optimized dispersion strategies can mitigate these issues, guiding future practical implementations. Full article

Objective: This study compares the brain protective effects of L-borneolum and its main components (a combined application of L-borneol and L-camphor) on the rat model of middle cerebral artery occlusion/reperfusion (MCAO/R). It also makes clear the intrinsic regulatory mechanisms that link the neuroprotective effects of these compounds on IS to the blood-brain barrier (BBB), based on network pharmacology predictions. Furthermore, the study investigates the relationship between these compounds and the Major Facilitator Superfamily Domain-containing Protein 2A (MFSD2A)/Caveolin-1 (Cav-1) signaling axis. Methods: The MCAO/R model in rats was established to evaluate the therapeutic effect of L-borneolum (200 mg/kg) and its main components combination of L-borneol and L-camphor (6:4 ratio, 200 mg/kg). Neurological scores, 2,3,5-triphenyl tetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, and Nissl staining were performed to evaluate the neurological damage in the rats. Cerebral blood flow Doppler was applied to monitor the cerebral blood flow changes. Immunofluorescence analysis of albumin leakage and transmission electron microscopy (TEM) were conducted to evaluate blood-brain barrier (BBB) integrity. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the optimal drug concentration. Trans-epithelial electrical resistance (TEER) and horseradish peroxidase (HRP) assays were employed to confirm the successful establishment of an in vitro BBB co-culture model. Network pharmacology was utilized to predict the biological processes, molecular functions, and cellular components involved in the treatment of ischemic stroke (IS) by the main components of L-borneolum (L-borneol and L-camphor). Finally, immunofluorescence, real-time fluorescent quantitative PCR (RT-qPCR) and western blot analyses were performed to detect the expression of Major Facilitator Superfamily Domain Containing 2A (MFSD2A), caveolin-1 (CAV-1), sterol regulatory element-binding protein 1 (SREBP1) in brain tissue and hCMEC/D3 cells. Results: Network pharmacology prediction indicated that L-borneolum and its main components (L-borneol and L-camphor) in the treatment of IS are likely associated with vesicle transport and neuroprotection. Treatment of IS with L-borneolum and its main components significantly decreased neurological function scores and cerebral infarction area, while alleviating pathological morphological changes and increasing the number of Nissl bodies in the hippocampus. Additionally, it improved cerebral blood flow, reduced albumin leakage, and decreased vesicle counts in the brain. The trans-epithelial electrical resistance (TEER) of the co-culture model stabilized on the fifth day after co-culture, and the permeability to horseradish peroxidase (HRP) in the co-culture model was significantly lower than that of the blank chamber at this time. RT-qPCR and Western blot results demonstrated that, compared to the model group, the expression of SREBP1 and MFSD2A significantly increased, while the expression of Cav-1 decreased. Conclusions: L-borneolum and its main components combination (L-borneol/L-camphor, 6:4 ratio) may exert a protective effect in rats with IS by improving BBB transport function through modulation of the MFSD2A/Cav-1 signaling pathway. Full article