One-pot synthesis of poly (acrylic acid)-stabilized Fe3O4 nanocrystal clusters for the simultaneously qualitative and quantitative detection of biomarkers in lateral flow immunoassay

Advanced Nanomaterial-Based Biosensors for N-Terminal Pro-Brain Natriuretic Peptide Biomarker Detection: Progress and Future Challenges in Cardiovascular Disease Diagnostics

Cardiovascular diseases (CVDs) represent a significant challenge in global health, demanding advancements in diagnostic modalities. This review delineates the progressive and restrictive facets of nanomaterial-based biosensors in the context of detecting N-terminal pro-B-type natriuretic peptide (NT-proBNP), an indispensable biomarker for CVD prognosis. It scrutinizes the escalation in diagnostic sensitivity and specificity attributable to the incorporation of novel nanomaterials such as graphene derivatives, quantum dots, and metallic nanoparticles, and how these enhancements contribute to reducing detection thresholds and augmenting diagnostic fidelity in heart failure (HF). Despite these technological strides, the review articulates pivotal challenges impeding the clinical translation of these biosensors, including the attainment of clinical-grade sensitivity, the substantial costs associated with synthesizing and functionalizing nanomaterials, and their pragmatic deployment across varied healthcare settings. The necessity for intensified research into the synthesis and functionalization of nanomaterials, strategies to economize production, and amelioration of biosensor durability and ease of use is accentuated. Regulatory hurdles in clinical integration are also contemplated. In summation, the review accentuates the transformative potential of nanomaterial-based biosensors in HF diagnostics and emphasizes critical avenues of research requisite to surmount current impediments and harness the full spectrum of these avant-garde diagnostic instruments.

Developing an ultrasensitive immunochromatographic assay for authentication of an emergent fraud aminopyrine in herbal tea

Aminopyrine is a nonsteroidal anti-inflammatory drug only for medical purposes, however, it has been illegally added in traditional Chinese herbal teas for fraud activity recently. In this study, a specific antibody against aminopyrine with IC₅₀ of 3.00 ng/mL was obtained for the first time by a rational hapten design. Furthermore, an ultrasensitive gold nanoparticles immunochromatographic assay (AuNPs-ICA) for determination of aminopyrine based on a portable reader was firstly developed, with cut-off value of 100.00 ng/mL, limit of detection (LOD) of 4.80 ng/mL and limit of quantification (LOQ) of 5.71 ng/mL for herbal tea, respectively. The recovery rates ranged from 93.21 % to 105.61 %, with inter-assay coefficient of variation (CV) from 1.08 % to 3.82 %. Additionally, 24 blind samples were examined simultaneously by AuNPs-ICA and LC-MS/MS, demonstrating a good consistency for each other. The proposed AuNPs-ICA is an ultrasensitive and reliable tool for on-site surveillance screening of fraud additives in herbal tea.

Au/Fe3O4-based nanozymes with peroxidase-like activity integrated in immunochromatographic strips for highly-sensitive biomarker detection

Because of their simplicity, rapidity, and cost-effectiveness, immunochromatographic strips (ICTs) have been widely used as an effective tool in various fields. However, typical strips for the preliminary screening suffer from limited detection sensitivity, particularly in biomarker detection with trace concentration. Herein, to tackle this challenge, we integrated homemade gold-decorated Fe₃O₄ nanoparticles (Au/Fe₃O₄ NPs) with flexible strips, exploring the excellent peroxidase-like activity of this labeled material, and then enhancing the detection sensitivity via signal amplification. The limit of detection (LOD) of the strips is as low as 0.05 mIU mL^-1 when human chorionic gonadotropin (hCG) is as a biomarker model, which is 500 times lower than that of the traditional color-based strip. Overall, our results demonstrated the potential for Au/Fe₃O₄ NP based-ICTs for the rapid detection of the biomarker in an instrument-free and point-of-care testing format.

Improving the sensitivity of lateral flow immunoassay for Salmonella typhimurium detection via flow-rate regulation

Application of the traditional immunochromatographic assay (ICGA) has been limited by its poor sensitivity. The objective of this study was to increase the sensitivity of the traditional ICGA. A dual-mode ICGA (D-M ICGA) was developed by combining a nanozyme-assisted signal-amplification strategy with a magnetic-nanoparticle-based flow-speed-control strategy. Salmonella typhimurium can be detected simultaneously based on color and magnetic signals in the detection area of the D-M ICGA strip. The calculated limits of detection of 50 cfu·mL^-1 and 75 cfu·mL^-1 in the color and magnetic modes, respectively, were approximately 1000 times lower than those of the traditional ICGA. The selectivity and practical applicability of the D-M ICGA were also confirmed in this study. The results prove that the D-M ICGA is an assay that could be used for Salmonella typhimurium detection and can be easily adapted to detect other pathogenic bacteria.

Ultrasensitive Magnetic Assisted Lateral Flow Immunoassay Based on Chiral Monoclonal Antibody against R-(-)-Salbutamol of Broad-Specificity for 38 β-Agonists Detection in Swine Urine and Pork

Screening for ″zero tolerance″ β-agonists requires broad-specificity and sensitivity methods. Herein, R-(-)-salbutamol (SAL) is chirally separated and designed as a hapten, and a monoclonal antibody (mAb) was first prepared with an IC₅₀ of 0.27 ng/mL, which can recognize 38 β-agonists simultaneously. The broad-specificity of chiral mAb was explored by molecular simulation technology. Magnetic nanoparticles (MNPs) were then synthesized and applied as a signal tracer to develop a lateral flow immunoassay (LFIA). The limits of detection of MNPs-LFIA for SAL in swine urine and pork were 0.05 and 0.09 μg/kg, which was (2-125)-fold lower than that of the reported LFIAs. The recoveries were between 95.8 and 116.7%, with the coefficient of variation from 2.7 to 15.4%. Parallel analysis of 44 samples by commercial ELISA kits confirmed the reliability. Therefore, our work not only provides a broad-specificity and ultrasensitive method for β-agonists but also suggests that chirality is the new general theory that guided the rational hapten design.

A review of biosensors for the detection of B-type natriuretic peptide as an important cardiovascular biomarker

Heart disease, as the most serious threat to human health globally, is responsible for rising mortality rates, largely due to lifestyle and diet. Unfortunately, the main problem for patients at high risk of heart disease is the validation of prognostic tests. To this end, the detection of cardiovascular biomarkers has been employed to obtain pathological and physiological information in order to improve prognosis and early-stage diagnosis of chronic heart failure. Short-term changes in B-type natriuretic peptide are known as a standard and important biomarker for diagnosis of heart failure. The most important problem for detection is low concentration and short half-life in the blood. The normal concentration of BNP in blood is less than 7 nM (25 pg/mL), which increases significantly to more than 80 pg/mL. Therefore, the development of new biosensors with better sensitivity, detection limit, and dynamic range than current commercial kits is urgently needed. This review classifies the biosensors designed for detection of BNP into electrochemical, optical, microfluidic, and lateral-flow immunoassay techniques. The review clearly demonstrates that a variety of immunoassay, aptasensor, enzymatic and catalytic nanomaterials, and fluorophores have been successfully employed for detection of BNP at low attomolar ranges. Dtection of B-type natriuretic peptide with biosensors.

Facile Strategy to Fabricate the Flame Retardant Polyamide 66 Fabric Modified with an Inorganic-Organic Hybrid Structure

Recently, traditional flame retardant finishing with a single metal compound has been rarely applied owing to its low effectiveness and durability. This study reports metal ion finishing in combination with surface photografting modification (M/P technology) as a novel approach to incorporate an inorganic-organic hybrid structure containing an Fe³⁺ ion onto the surface of the polyamide (PA) 66 fabric. Specifically, the PA fabric was first surface-modified in the presence of acrylic acid (AA) and N,N'-methylene bisacrylamide (MBAAn) during photografting pretreatment under UV irradiation (step I), then further reacted with the Fe³⁺ ion in the metal ion finishing (step II). After treatment with M/P technology, the fabric exhibits the required excellent flame retardancy and dripping resistance. Here, flame retardant tests show that the treated PA fabric has the highest limiting oxygen index (LOI) value of 33.4 and no melt dripping during combustion. An interesting inorganic/organic composite thermal barrier consisting of an inorganic iron oxide nanoparticle (NP) outer layer and an organic micro-intumescent inner layer can be observed on the surface of the burnt fabric. This structure could be responsible for the significant enhancement in the fire performance of the treated fabric. Importantly, the treated fabric is also highly stable during the laundering procedure, which could retain a high Fe/C ratio and an acceptable LOI value of 27.8 after washing 45 times. This confirms the achievement of durable flame retardancy after treatment with M/P technology, and its possible interaction mechanism has been discussed here.

Magnetic Lateral Flow Immunoassays

A new generation of magnetic lateral flow immunoassays is emerging as powerful tool for diagnostics. They rely on the use of magnetic nanoparticles (MNP) as detecting label, replacing conventional gold or latex beads. MNPs can be sensed and quantified by means of external devices, allowing the development of immunochromatographic tests with a quantitative capability. Moreover, they have an added advantage because they can be used for immunomagnetic separation (IMS), with improvements in selectivity and sensitivity. In this paper, we have reviewed the current knowledge on magnetic-lateral flow immunoassay (LFIA), coupled with both research and commercially available instruments. The work in the literature has been classified in two categories: optical and magnetic sensing. We have analysed the type of magnetic nanoparticles used in each case, their size, coating, crystal structure and the functional groups for their conjugation with biomolecules. We have also taken into account the analytical characteristics and the type of transduction. Magnetic LFIA have been used for the determination of biomarkers, pathogens, toxins, allergens and drugs. Nanocomposites have been developed as alternative to MNP with the purpose of sensitivity enhancement. Moreover, IMS in combination with other detection principles could also improve sensitivity and limit of detection. The critical analysis in this review could have an impact for the future development of magnetic LFIA in fields requiring both rapid separation and quantification.

A PCR-lateral flow assay system based on gold magnetic nanoparticles for CYP2C19 genotyping and its clinical applications

Presently, clopidogrel is the standard therapeutic drugs for antiplatelet therapy. Variants in the CYP2C19 gene influence the clinical response of clopidogrel. Thus, the US Food and Drug Administration suggested CYP2C19 genotyping needs to identify before taking medicine. Due to high cost, time consuming, and sophisticated instruments, current single nucleotide polymorphism detection methods are limited in clinical application. In the present study, we established a genotyping method for CYP2C19, which combines amplification refractory mutation system (ARMS)-PCR with a lateral flow assay used gold magnetic nanoparticles (GMNPs) named as PCR-gold magnetic lateral flow assay system (PCR-GoldMag LFA). The PCR products with specific genotype can be explained within 5 minutes, either through visual or by a magnetic reader automatically according to the captured GMNPs probes on the test lines of the LFA strips. The limit of detection of this method is 5 ng of genomic DNA. The PCR-GoldMag LFA system was applied in a clinical trial with 1356 samples of Han Chinese. The concordance rate between the LFA system and sequencing is 99.93%. The allele frequency of CYP2C19*2 and CYP2C19*3 are 30.38 and 7.08% in Han Chinese, respectively. This method provides a new way in the clinical application of CYP2C19 genotyping to guide the clopidogrel medication.

Superparamagnetic nanoarchitectures for disease-specific biomarker detection

Synthesis, bio-functionalization, and multifunctional activities of superparamagnetic-nanostructures have been extensively reviewed with a particular emphasis on their uses in a range of disease-specific biomarker detection and associated challenges.