A sandwich-type photoelectrochemical immunosensor for NT-pro BNP detection based on F-Bi2WO6/Ag2S and GO/PDA for signal amplification

Photoelectrochemical sensor based on AuNPs@WO3@TpPa-1-COF for quantification of DNA methylation levels

A "signal-off" photoelectrochemical (PEC) sensing platform has been designed for the ultrasensitive detection of DNA methylation levels and multiple methylated sites. The platform employs tungsten trioxide and TpPa-1-COF loaded by gold nanoparticle (AuNPs@WO3@TpPa-1-COF) composite material as the photoactive component and p-type reduced graphene (rGO) as an efficient quencher. The PEC signal of AuNPs@WO3@TpPa-1-COF composite is effectively quenched in the presence of p-type rGO, because p-type rGO can compete with AuNPs@WO3@TpPa-1-COF to deplete light energy and electron donors. In addition, a hybrid strand reaction (HCR) amplification strategy fixes more target DNA and then combines with rGO-modified anti-5-methylcytosine antibody to facilitate ultrasensitive DNA methylation detection. Under optimal conditions, DNA methylation can be measured within a linear concentration range of 10-14 to 10-8 M, with an exceptionally low detection limit of 0.19 fM (S/N = 3). At the same time, the platform can conduct quantitative determination of multi-site methylation, with the linear equation △I = 44.19LogA + 61.43, and the maximum number of methylation sites is 5. The sensor demonstrates high sensitivity, excellent selectivity, and satisfactory stability. Furthermore, the proposed signal-off PEC strategy was successfully employed to detect DNA methylation in spiked human serum samples, with recoveries ranging from 93.17 to 107.28% and relative standard deviation (RSD) ranging from 1.15 to 5.49%.

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.

Biosensors for natriuretic peptides in cardiovascular diseases. A review

Heart failure (HF) is a complex clinical syndrome associated with high rates of morbidity and mortality. Over the years, it has been crucial to find accurate biomarkers capable of doing a precise monitor of HF and provide an early diagnosis. Of these, it has been established an important role of natriuretic peptides in HF assessment. Moreover, the development of biosensors has been garnering interest as new diagnostic medical tools. In this review we first provide a general overview of HF, its pathogenesis, and diagnostic features. We then discuss the role of natriuretic peptides in heart failure by characterizing them and point out their potential as biomarkers. Finally, we adress the evolution of biosensors development and the available natriuretic peptides biosensors for disease monitoring.

A sensitive dual-signal electrochemiluminescence immunosensor based on Ru(bpy)32+@HKUST-1 and Ce2Sn2O7 for detecting the heart failure biomarker NT-proBNP

A sensitive dual-signal electrochemiluminescence (ECL) immunosensor was proposed based on Ru(bpy)₃²⁺@HKUST-1/TPA and Ce₂Sn₂O₇/K₂S₂O₈ probes for detecting the NT-proBNP biomarker of heart failure. HKUST-1 with a high specific surface area facilitates the loading of more Ru(bpy)₃²⁺, effectively improving the anodic signal intensity, while the emerging Ce₂Sn₂O₇ emitter displays a potential-matching cathodic emission with moderate intensity. Two ECL probes were characterized with field emission scanning electron microscopy, X-ray diffraction, XPS, FT-IR spectroscopy and UV-Vis diffuse reflectance spectroscopy. This dual-signal immunosensor has a wide linear range (5 × 10^-4-1 × 10⁴ ng mL^-1) and a low quantitative detection limit, simultaneously showing high sensitivity, stability and reproducibility, as well as the detection capability of actual serum samples. This dual signal-calibrated immunoassay platform not only reduces the false positive rate of detection results but also provides a promising method for the early diagnosis of heart failure.

Advances in immunoassay-based strategies for mycotoxin detection in food: From single-mode immunosensors to dual-mode immunosensors

Mycotoxin contamination in foods and other goods has become a broad issue owing to serious toxicity, tremendous threat to public safety, and terrible loss of resources. Herein, it is necessary to develop simple, sensitive, inexpensive, and rapid platforms for the detection of mycotoxins. Currently, the limitation of instrumental and chemical methods cannot be massively applied in practice. Immunoassays are considered one of the best candidates for toxin detection due to their simplicity, rapidness, and cost-effectiveness. Especially, the field of dual-mode immunosensors and corresponding assays is rapidly developing as an advanced and intersected technology. So, this review summarized the types and detection principles of single-mode immunosensors including optical and electrical immunosensors in recent years, then focused on developing dual-mode immunosensors including integrated immunosensors and combined immunosensors to detect mycotoxins, as well as the combination of dual-mode immunosensors with a portable device for point-of-care test. The remaining challenges were discussed with the aim of stimulating future development of dual-mode immunosensors to accelerate the transformation of scientific laboratory technologies into easy-to-operate and rapid detection platforms.

In Vivo Tracking of Persistent Organic Pollutants via a Coaxially Integrated and Implanted Photofuel Microsensor

In vivo tracking of persistent organic pollutants (POPs) is of great significance for assessing their risks to the ecological environment and human health. However, existing in vivo POPs detection methods are limited by the lethal sampling of living organisms, complex sample preparation processes, or bulky testing equipment. Photoelectrochemical (PEC) sensing with the merits of high sensitivity and simple equipment is a fast-developed method for in vivo analysis. A major obstacle for in vivo PEC sensors is the separated implantation of multiple electrodes and a light source, which raises concerns like multielectrode biofouling and electroactive molecules interference in the complex environment, uncertain electrode implant distance, and multiple insertion operations. Here, a coaxially implanted photofuel microsensor was developed by hiding the optical fiber-based photoanode inside the glass capillary-based biocathode, and the model target PCB77 can be detected with an ultralow detection limit (2.8 fg/mL). This unique photoanode-biocathode-light source integrated structure ensures excellent selectivity, good antifouling ability and biocompatibility, high accuracy, and less implant mechanical damage. Combined with a handheld pH meter, our sensor achieved convenient and direct tracking of the bioaccumulation levels of PCB77 in freely swimming fish.

Advances in Electrochemical Biosensors Based on Nanomaterials for Protein Biomarker Detection in Saliva

The focus on precise medicine enhances the need for timely diagnosis and frequent monitoring of chronic diseases. Moreover, the recent pandemic of severe acute respiratory syndrome coronavirus 2 poses a great demand for rapid detection and surveillance of viral infections. The detection of protein biomarkers and antigens in the saliva allows rapid identification of diseases or disease changes in scenarios where and when the test response at the point of care is mandated. While traditional methods of protein testing fail to provide the desired fast results, electrochemical biosensors based on nanomaterials hold perfect characteristics for the detection of biomarkers in point-of-care settings. The recent advances in electrochemical sensors for salivary protein detection are critically reviewed in this work, with emphasis on the role of nanomaterials to boost the biosensor analytical performance and increase the reliability of the test in human saliva samples. Furthermore, this work identifies the critical factors for further modernization of the nanomaterial-based electrochemical sensors, envisaging the development and implementation of next-generation sample-in-answer-out systems.

Shape dependency of gold nanorods through TMB2+-mediated etching for the visual detection of NT-proBNP

Heart failure (HF) is a major public health problem triggered by heart circulation disorders. Early detection and diagnosis are conducive to the prevention and treatment of HF. Hence, it is necessary to establish a simple and sensitive method to monitor the diagnostic biomarkers of HF. The N-terminal B-type natriuretic peptide precursor (NT-proBNP) is acknowledged as a sensitive biomarker. In this study, a visual detection method for NT-proBNP was developed based on the oxidized 3,3′,5,5′-tetramethylbenzidine (TMB²⁺)-mediated etching of gold nanorods (AuNRs) and double-antibody-sandwich ELISA. The etching color for different amounts of NT-proBNP was obvious and significant differences could be ascertained based on the blue-shift of the longitudinal localized surface plasmon resonance (LLSPR) of the AuNRs. The results could be observed by the naked eye. The constructed system showed a concentration range from 6 to 100 ng mL⁻¹ and a low detection limit of 6 ng mL⁻¹. This method exhibited negligible cross-reactivity toward other proteins, and the recoveries of the samples ranged from 79.99% to 88.99%. These results demonstrated that the established method is suitable for the simple and convenient detection of NT-proBNP.

Visual detection of NT-proBNP based on the principle of HRP-catalyzed TMB conversion into TMB²⁺ to mediate gold nanorods etching and an ELISA system.

Bismuth Tungstate-Silver Sulfide Z-Scheme Heterostructure Nanoglue Promotes Wound Healing through Wound Sealing and Bacterial Inactivation

Rapid wound closure and bacterial inactivation are effective strategies to promote wound healing. Herein, a versatile nanoglue, bismuth tungstate (Bi₂WO₆)-silver sulfide (Ag₂S) direct Z-scheme heterostructure nanoparticles (BWOA NPs), was designed to accelerate wound healing. BWOA NPs' hollow structure and rough surface could effectively close wound tissues acting as a barrier between external bacteria and the wound. More importantly, the unique Z-scheme heterostructure endows BWOA NPs with an effective electron and hole separating ability with potent redox potential, where electrons and holes could effectively react with water and oxygen to produce reactive oxygen species, leading to a higher antibacterial activity against both endogenous and external bacteria at the wound site. A series of in vitro and in vivo biological assessments demonstrated that BWOA NPs could rapidly close wounds and promote wound healing. With sunlight irradiation, the inhibiting rates of BWOA NPs against Escherichia coli and Staphylococcus aureus are 61.62 ± 2.85 and 73.40 ± 3.28%, respectively. Also, the wound healing rate in BWOA NP-treated mice is 25.90 ± 5.85% higher than PBS. This design provides a new effective strategy to promote bacterial inactivation and accelerate wound healing.

A novel photoelectrochemical immunosensor based on TiO2@Bi2WO6 hollow microspheres and Ag2S for sensitive detection of SARS-COV-2 nucleocapsid protein

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2) is a cluster of β coronaviruses. The 2019 coronavirus disease (COVID-19) caused by SARS-COV-2 is emerging as a global pandemic. Thus, early diagnosis of SARS-COV-2 is essential to prevent severe outbreaks of the disease. In this experiment, a novel label-free photoelectrochemical (PEC) immunosensor was obtained based on silver sulfide (Ag₂S) sensitized titanium dioxide@bismuth tungstate (TiO₂@Bi₂WO₆) nanocomposite for quantitative detection of SARS-COV-2 nucleocapsid protein. The constructed TiO₂@Bi₂WO₆ hollow microspheres had large specific surface area and could produce high photocurrent intensity under visible light illumination. Ag₂S was in-situ grown on the surface of thioglycolic acid (TGA) modified TiO₂@Bi₂WO₆. In particular, TiO₂@Bi₂WO₆ and Ag₂S formed a good energy level match, which could effectively enhance the photocurrent conversion efficiency and strength the photocurrent response. Ascorbic acid (AA) acted as an effective electron donor to effectively eliminate photogenerated holes. Under optimal experimental conditions, the constructed immunosensor presented a supersensitive response to SARS-COV-2 nucleocapsid protein, with a desirable linear relationship ranged from 0.001 to 50 ng/mL for nucleocapsid protein and a lower detection limit of 0.38 pg/mL. The fabricated sensor exhibited a wide linear range, excellent selectivity, specificity and stability, which provided a valuable referential idea for the detection of SARS-COV-2.

A "signal-on" photoelectrochemical sensor for human epidermal growth factor receptor 2 detection based on Y6/CdS organic-inorganic heterojunction

A "signal-on" photoelectrochemical (PEC) immunosensor was successfully constructed for determination of human epidermal growth factor receptor 2 (HER2) based on organic-inorganic heterojunction Y6/CdS as photoactive material. Compared with single organic semiconductor, Y6, Y6/CdS exhibited higher photoelectric conversion efficiency due to the formation of heterojunction. In the presence of HER2, sandwich immune structure was formed between HER2 aptamer and anti-HER2 antibody (Ab) by specific recognition. The polydopamine (PDA) nanoparticles were used for signal amplification to enhance photocurrent intensity as PDA can act as electron donor to eliminate holes and promote electron-hole pairs separation. The developed PEC sensor displayed a wide detection range of 5-1000 pg mL^-1 and a low detection limit of 2.2 pg mL^-1 for HER2 (S/N = 3). The sensor was successfully used for the detection of HER2 in serum with recoveries between 94.8 and 104% and relative standard deviations (RSDs) in the range of 1.2-4.3%. Furthermore, the designed immunosensor possessed good stability, selectivity, and reproducibility, which can find potential clinical applications for disease diagnosis. A "signal-on" photoelectrochemical sensor was reported for human epidermal growth factor receptor 2 detection based on Y6/CdS organic-inorganic heterojunction.

Ultrasensitive and Rapid Detection of N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP) Using Fiber Optic Nanogold-Linked Immunosorbent Assay

The N-terminal pro-brain natriuretic peptide (NT-proBNP) is considered an important blood biomarker for heart failure. Herein, we report about a fiber optic nanogold-linked immunosorbent assay (FONLISA) method for the rapid, sensitive, and low-cost detection of NT-proBNP. The method is based on a sandwich immunoassay approach that uses two monoclonal NT-proBNP antibodies, a capture antibody (Ab^C), and a detection antibody (Ab^D). Ab^D is conjugated to a free gold nanoparticle (AuNP) to form the free AuNP@Ab^D conjugate, and Ab^C is immobilized on an unclad segment of an optical fiber. The detection of analyte (A), in this case NT-proBNP, is based on the signal change due to the formation of an AuNP@Ab^D–A–Ab^C complex on the fiber core surface, where a green light transmitted through the optical fiber will decrease in intensity due to light absorption by AuNPs via the localized surface plasmon resonance effect. This method provides a wide linear dynamic range of 0.50~5000 pg·mL⁻¹ and a limit of detection of 0.058 pg·mL⁻¹ for NT-proBNP. Finally, the method exhibits good correlation (r = 0.979) with the commercial central laboratory-based electrochemiluminescent immunoassay method that uses a Roche Cobas e411 instrument. Hence, our method is potentially a suitable tool for point-of-care testing.

Photoelectrochemical sandwich immunoassay of CYFRA21-1 based on In2O3/WO3 type-II heterojunction and CdS quantum dots-polydopamine nanospheres labeling

Using an In₂O₃/WO₃ type-II heterojunction modified fluorine-doped tin oxide (FTO) electrode as the photoanode and CdS quantum dots (QDs)-polydopamine nanospheres (PDA NSs) as the secondary antibody (Ab₂) label, the photoelectrochemistry (PEC) sandwich immunosensing of the lung cancer marker CYFRA21-1 was studied. WO₃ nanoplates were prepared by a hydrothermal method, In₂O₃ nanoporous spheres were prepared by a hydrothermal method followed by calcination, and the In₂O₃/WO₃ type-II heterojunction with high PEC activity was prepared by ultrasonic mixing and cast-coating. PDA NSs with a high surface area can be loaded with abundant Ab₂ molecules and many CdS QDs with an energy level well matched with the heterojunction, so the photocurrent signal can be amplified by the formation of a sandwich immunostructure. Through the simulation experiments of photoelectrode-modified chitosan films of varying thickness, the effective transport distance of photogenerated charges is preliminarily discussed. Under the optimized conditions, the photocurrent was linear with the common logarithm of CYFRA21-1 concentration from 100 fg mL^-1 to 50 ng mL^-1, with a limit of detection of 56 fg mL^-1 (S/N = 3). The immunoassay of CYFRA21-1 in human serum samples gave satisfactory recovery results.

Ultrasensitive dual enhanced electrochemical immunosensor to detect ancient wool relics

The identification of ancient wool is of great significance in archaeology; however, conventional methods are unwieldy or even ineffective when testing contaminated or severely degraded ancient samples. Therefore, it is highly desirable to develop an ultrasensitive detection method for ancient wool. In this study, an ultrasensitive electrochemical immunosensor is proposed and developed to detect ancient wool, where graphene oxide (GO), aldehyde-functionalized ionic liquid (AFIL) composites and gold nanoparticles (AuNPs) are synthesized as efficient signal amplifiers. With their large surface area and excellent electron transfer efficiency, the combination of GO-AFIL and AuNPs endows the immunosensor with excellent electrochemical properties. The fabricated immunosensor measures over a wide linear range of 0.01-100 ng mL^-1 with a low detection limit of 0.9 ± 0.2 pg mL^-1. Moreover, the immunosensor demonstrates excellent performance for detecting ancient wool. The identification of wool fabrics unearthed from Xinjiang, Tibet and Kazakhstan supports the historicity of prosperous sheepherding and wool trade in Central Asia during the Bronze Age.

Recent Advances of Nanostructured Materials for Photoelectrochemical Bioanalysis

Nowadays, the emerging photoelectrochemical (PEC) bioanalysis has drawn intensive interest due to its numerous merits. As one of its core elements, functional nanostructured materials play a crucial role during the construction of PEC biosensors, which can not only be employed as transducers but also act as signal probes. Although both chemical composition and morphology control of nanostructured materials contribute to the excellent analytical performance of PEC bioassay, surveys addressing nanostructures with different dimensionality have rarely been reported. In this review, according to classification based on dimensionality, zero-dimensional, one-dimensional, two-dimensional, and three-dimensional nanostructures used in PEC bioanalysis are evaluated, with an emphasis on the effect of morphology on the detection performances. Furthermore, using the illustration of recent works, related novel PEC biosensing patterns with promising applications are also discussed. Finally, the current challenges and some future perspectives in this field are addressed based on our opinions.

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.

Proton-Regulated Catalytic Activity of Nanozymes for Dual-Modal Bioassay of Urease Activity

Benefiting from the merits of high stability and superior activity, nanozymes are recognized as promising alternatives to natural enzymes. Despite the great leaps in the field of therapy and colorimetric sensing, the development of highly sensitive nanozyme-involved photoelectrochemical (PEC) biosensors is still in its infancy. Specifically, the investigation of multifunctional nanozymes facilitating different catalytic reactions remains largely unexplored due to the difficulty in synergistically amplifying the PEC signals. In this work, mesoporous trimetallic AuPtPd nanospheres were synthesized with both efficient oxidase and peroxidase-like activities, which can synergistically catalyze the oxidation of 4-chloro-1-naphthol to produce benzo-4-chlorohexadienone precipitation on the surface of photoactive materials, and thus lead to the decreased photocurrent as well as increased charge-transfer resistance. Inspired by the proton-dependent catalytic activity of nanozymes, a self-regulated dual-modal PEC and electrochemical bioassay of urease activity was innovatively established by in situ regulating the activity of AuPtPd nanozymes through urease-mediated proton-consuming enzymatic reactions, which can remarkably improve the accuracy of the assay. Meanwhile, the determination of urease activity in spiked human saliva samples was successfully realized, indicating the reliability of the biosensor and its application prospects in clinical diagnosis.

An on-chip microfluidic-based electrochemical magneto-immunoassay for the determination of procalcitonin in plasma obtained from sepsis diagnosed preterm neonates

A novel on-chip electrochemical magneto-immunoassay for the determination of procalcitonin (PCT) has been proposed. The strategy involved the on-line performing of the biorecognition event and detection on the thin-film microfluidic gold electrode chamber operating at E = -0.20 V (vs. Au). The complete assay was performed in less than 15 minutes using only 25 μL of the sample, covering the entire range of clinically relevant PCT concentrations in sepsis diagnosis with a limit of detection and quantification of 0.02 ng mL-1 and 0.05 ng mL-1, respectively (the sepsis diagnosis threshold: 0.5 ng mL-1). The on-chip electrochemical magneto-immunoassay provided excellent results in the analysis of very unique samples obtained from preterm neonates admitted with suspected sepsis, in which the sample volume is hardly available. These characteristics fulfill the POCT requirements for PCT determination in the whole clinically relevant concentration range. Because of the high clinical relevance and the important role of PCT in sepsis, this approach opens new perspectives for sepsis diagnosis and therapy guidance using low volume samples.

Facile assembled N, S-codoped corn straw biochar loaded Bi2WO6 with the enhanced electron-rich feature for the efficient photocatalytic removal of ciprofloxacin and Cr(VI)

To the best of our knowledge, in few studies, biochar (BC)-based materials have been used as the photocatalyst for water purification, and their application is limited to a great extent due to catalyst agglomeration and inefficient electron migration. In this study, a novel Bi₂WO₆ loaded N, S co-doping corn straw biochar (Bi₂WO₆/NSBC) was successfully synthesized with a simple solvothermal method for the removal of ciprofloxacin (CIP) and Cr(VI) under visible light irradiation. The Bi₂WO₆/NSBC was featured with efficient and rapid catalytic removal toward CIP (5 mg/L) and Cr(VI) (10 mg/L), with efficiencies of ∼90.33% and ∼99.86% within 75 min, respectively. More attractively, this composite can be applied in a wide pH range (3.0-9.0) and with weak effects by coexisting ions (Cl^-, CO₃^2-, SO₄^2-, and Ca²⁺). The facile synthesized porous graphitized structure demonstrates an outstanding performance of superior conductivity and promoted photoelectron transport. Meanwhile, it is found that N, S co-doping of the BC induces highly interconnected fibrous structures, high catalytic property, and favorable specific surface areas, which is considered to avoid agglomeration of Bi₂WO_6. The increased photocatalytic activity results from the synergistic effects of Bi₂WO₆ and NSBC by the optimized band gap and enhanced visible light response, due to higher migration and utilization efficiency of photoinduced carriers in photocatalytic reactions. In this approach, a cheap catalyst is provided, and at the same time, a synergistic effect of N, S co-doping is formed to rapidly remove contaminants in wastewater treatment.

A chemiluminescence immunoassay for the detection of NT-proBNP

BACKGROUND

The aim of the study was to assess the analytical performance of the HISCL NT-proBNP assay, a newly developed chemiluminescence immunoassay, for the detection of NT-proBNP.

METHODS

The within-run and total imprecision of the NT-proBNP assay were determined with HISCL cardiac marker controls. The linear ranges of the NT-proBNP assays were evaluated based on the CLSI EP6-A document using selected serum samples. Two hundred serum samples were evaluated to compare the HISCL NT-proBNP and Elecsys NT-proBNP assays. Five additional high NT-proBNP concentrations serum samples were evaluated to assess if there was high-dose hook effect in the HISCL NT-proBNP assay.

RESULTS

The total and within-run imprecision values of the HISCL NT-proBNP assay were 5.85%, 0.81%, 2.56% and 0.54% and 6.07%, 0.73%, 2.61% and 0.59% at 6.1, 129.83, 3732.84and39737.33 pg/ml, respectively. The assay was verified to be linear for NT-proBNP levels ranging between 6.1 and 39737.33 pg/ml. The assay comparison showed that HISCL NT-proBNP = 0.9803 × Elecsys NT-proBNP -4.383. The sensitivity of HISCL NT-proBNP was 87.23%, and the specificity was 85.61%. The AUC of HISCL NT-proBNP (0.90 (95% CI, 0.86-0.93)) did not differ from that of Elecsys NT-proBNP(0.89 (95% CI, 0.85-0.93)) (P = 0.638). The results of five high NT-proBNP concentrations samples (44448, 54206, 55634, 55728 and 109406 pg/ml, measured with the Elecsys NT-proBNP assay) tested with HISCL NT-proBNP assay were all displayed with ">40000 pg/ml".

CONCLUSIONS

The HISCL NT-proBNP chemiluminescence immunoassay showed good analytical and diagnostic performance for the detection of NT-proBNP and could be used in routine clinical practice.

Visible-light-driven photocatalytic degradation of rhodamine B using Bi2WO6/GO deposited on polyethylene terephthalate fabric

Abstract

The environmental repercussions of wastewater from the dye process mean that it is very important to obtain an eco-friendly photocatalyst that would degrade wastewater. Herein, bismuth tungstate/graphene oxide (Bi2WO6/GO) composites are fabricated through in-situ hydrothermal reaction and then the Bi2WO6/GO photocatalysts are deposited onto polyethylene terephthalate (PET) fabric. The obtained Bi2WO6/GO deposited PET fabrics are then characterized through XPS, Raman, SEM, TEM, XRD, UV-vis, BET method and photoluminescence spectroscopy (PL) to investigate their chemical and crystal structures, morphology, optical property, surface area and photochemical properties. Photocatalytic performance is studied through examining the rate of degrading rhodamine B (RhB) under visible light. Surface of PET fibers is densely covered with Bi2WO6/GO. Bi2WO6/GO deposited PET fabrics show a broad absorption band in the visible spectra. Removal rate of RhB on the Bi2WO6/GO deposited PET fabric is the highest with the GO content of 2 g/L (labeled as Bi2WO6/2 g/LGO). The result of active species experiment shows that superoxide radicals (·O2−) plays a major role in the degradation of RhB. Moreover, Bi2WO6/2 g/LGO deposited PET fabric shows excellent cycle stability of photocatalytic degradation for RhB. The findings in this work can be extended to preparation other types of composite on the textile for photocatalysis, which can be applied to remove dyes in the wastewater produced by the textile or leather industry.

Graphical abstract

Functional polymers in photoelectrochemical biosensing

Photoelectrochemical (PEC) analysis is a detection technique that has gained a wide attention in sensing applications. PEC presents the advantages of high sensitivity, low background signal, simple equipment and easy miniaturization. In PEC detection, light is used as an excitation source while current or voltage is measured as the output detection signal. The ability to couple the PEC process with specific bioreceptors gives PEC biosensing a unique advantage of being both selective and sensitive. The growing interest in PEC bioanalysis has resulted in essential progress in its analytical performance and biodetection applications. Functional polymers have different applications in the development of novel PEC biosensing platforms. Recently, the interest in polymer-based photoactive materials has emerged as they are efficient and less toxic alternatives to certain kinds of inorganic semiconductors and sensitizers. Moreover, molecularly imprinted polymers are a class of synthetic bioreceptors that are increasingly used in PEC bioanalytics. In this review, we will provide an overview on functional polymer-based PEC biosensing approaches. Novel classes of polymers as photoactive materials are reviewed and selected applications are described. Furthermore, molecularly imprinted polymers in the development of smart and sensitive PEC bioanalytical strategies are discussed.

Efficient BiVO4 photoanode decorated with Ti3C2TX MXene for enhanced photoelectrochemical sensing of Hg(II) ion

A highly sensitive photoelectrochemical (PEC) sensing platform was constructed for Hg²⁺ determination based on the Schottky heterojunction between an emerging 2D material Ti₃C₂T_X MXene and a promising semiconductor material BiVO₄. Through simply spin-coating the single-layer Ti₃C₂T_X onto the surface of BiVO₄ film, the modified electrode exhibited significantly enhanced PEC activity. However, the boost in photocurrent could be noticeably suppressed due to the consumption of hole-scavenging agents (reduced glutathione) by the added Hg²⁺. Owing to the selective decrease in the photocurrent with the addition of Hg²⁺, the PEC sensor based on BiVO₄/Ti₃C₂T_X displayed a wide linear range from 1 pM to 2 nM with the limit of detection down to 1 pM. Moreover, the PEC sensor also exhibited satisfactory accuracy and repeatability in practical sample water, the Yangtze River water, demonstrating the great potential for monitoring heavy metal ions in natural water resources.

Quench-Type Electrochemiluminescence Immunosensor Based on Resonance Energy Transfer from Carbon Nanotubes and Au-Nanoparticles-Enhanced g-C3N4 to CuO@Polydopamine for Procalcitonin Detection

A new type of sandwich electrochemiluminescence (ECL) immunosensor dependent on ECL resonance energy transfer (ECL-RET) to achieve sensitive detection of procalcitonin (PCT) has been designed. In brief, carbon nanotubes (CNT) and Au-nanoparticles-functionalized graphitic carbon nitride (g-C₃N₄-CNT@Au) and CuO nanospheres covered with polydopamine (PDA) layer (CuO@PDA) were synthesized and applied as ECL donor and receptor, respectively. g-C₃N₄-CNT nanomaterials were in situ prepared on the basis of π-π conjugation, and the CNT content in the composite were optimized to achieve a strong and stable ECL signal. At the same time, Au nanoparticles were used to functionalize g-C₃N₄-CNT to further increase the ECL intensity and the loading amount of primary antibody (Ab₁). Moreover, CuO@PDA was first used to successfully quench the ECL signal of g-C₃N₄-CNT@Au. Under the optimum experimental conditions, the linear detection range for PCT concentration was within 0.0001-10 ng mL^-1 and the detection limit was 25.7 fg mL^-1 (S/N = 3). Considering prominent specificity, reproducibility, and stability, the prepared immunosensor was used to assess recovery rate of PCT in human serum according to the standard addition method and the result was satisfactory. In addition, it is worth mentioning that a novel ECL-RET pair of g-C₃N₄-CNT@Au (donor)/CuO@PDA (acceptor) was first developed, which offered an effective analytical tool for sensitive detection of biomarkers in early disease diagnostics.

Preparation of a novel sandwich-type electrochemical immunosensor for AFP detection based on an ATRP and click chemistry technique

It is extremely important to explore the synthesis methodology and application scope of functional polymer brush-based nanocomposites.

A novel approach to photoelectrochemical immunoassay for procalcitonin on the basis of SnS2/CdS

A label-free photoelectrochemical (PEC) immunoassay system based on the one-step synthesis of SnS₂/CdS nanocomposites is successfully constructed for sensitively analyzing procalcitonin (PCT).

Recent progress of heterostructure-based photoelectrodes in photoelectrochemical biosensing: a mini review

The heterostructure photoelectrodes have witted the rapid development to improve the performance of PEC biosensors recently.

Photoelectrochemical biosensor for CEA detection based on SnS2-GR with multiple quenching effects of Au@CuS-GR

A novel signal on-off type photoelectrochemical (PEC) biosensing system was designed for sensitive detection of carcinoembryonic antigen (CEA) based on tin disulfide nanosheets loaded on reduced graphene cxide (SnS₂-GR) as the photoactive material and gold nanoparticles coated on reduced graphene oxide-functionalized copper sulfide (Au@CuS-GR) for signal amplification. It's the first time for SnS₂-GR was exploited as a sensing matrix. Here, the photocurrent signals of SnS₂ were amplified attributed to the sensitization effect of graphene. As signal amplifier, Au@CuS-GR could quench the photocurrents of SnS₂-GR not only through the p-n type semiconductor quenching effect as well as the steric hindrance effect, but also as peroxidase mimetics to catalyze the oxidation of 4-Chloro-1-naphthol (4-CN) to produce insoluble product on the electrode surface. Based on the multiple signal amplification ability of Au@CuS-GR, CEA was detected sensitively with a linear range from 0.1 pg mL^-1 to 10 ng mL^-1 and limit of detection down to 59.9 fg mL^-1 (S/N = 3). Meanwhile, the PEC biosensor displayed excellent performance in the assay of human serum sample, showing good application prospects for various target analysis.