Sensors & diagnostics最新文献

Early and accurate detection of HIV-1 p24 antigen is crucial for timely diagnosis and treatment, particularly in resource-limited settings where traditional methods often lack the necessary sensitivity for early-stage detection or is expensive. Here, we developed a layer-by-layer signal amplification platform employing fluorescent silica nanoparticles functionalized via bioorthogonal TCO/TZ chemistry. We evaluated nanoparticles of different sizes (25, 50, and 100 nm) and two dye-doped nanoparticle formulations to optimize signal intensity, detection limits, and nonspecific binding. The 25 nm RITC-doped nanoparticles demonstrated superior performance, achieving an ultra-low detection limit of 7 fg mL⁻¹ with a broad linear range up to 1 ng mL⁻¹. Compared to FITC-doped nanoparticles, RITC-doped nanoparticles provided enhanced brightness and signal strength. Further optimization revealed that using 50 μg of 25 nm nanoparticles yielded the best sensitivity while minimizing nonspecific binding. This nanoparticle-based assay significantly outperformed commercial ELISA kits, offering a broad dynamic range and improved sensitivity. Our platform presents a highly sensitive and adaptable approach for HIV-1 p24 antigen detection, with broad potential applications in point-of-care diagnostics and detection of other low-abundance biomarkers, ultimately enhancing early disease detection and treatment accessibility.

The analysis of down-regulator of transcription 1 (DR1) offers significant information for the rapid and non-invasive diagnosis of Hashimoto's thyroiditis (HT). In this study, we report a novel dual-signal amplification electrochemical biosensor for the sensitive detection of DR1. Gold nanoparticle (AuNP)-modified molybdenum disulfide (MoS₂@AuNPs), which has extremely strong electron transfer ability and abundant binding sites, is first modified on an electrode surface as a substrate material to implement the first signal amplification. After the formation of the sandwich structure based on the specific recognition of antigens and antibodies, the electroactive molecules hyaluronic acid-based thionine (HA@Thi) are introduced to achieve the second signal amplification. Using this dual-signal amplification strategy, the proposed biosensor achieves a linear range of 1 × 10⁻⁴–1 × 10² ng mL⁻¹ with a low detection limit of 10.99 fg mL⁻¹. In addition, the electrochemical biosensor has high selectivity and good stability, and is applicable to the assay of DR1 in the presence of complex biological matrices, which is expected to provide a scientific approach for the clinical application of serum DR1 monitoring. More importantly, our method may extend the application of protein-based biosensors in disease diagnosis techniques.

Poisoning of agricultural products through the use of pesticides has created a high risk to the environment and human health. In recent years, substantial research has been devoted to replacing harmful chemical pesticides with naturally derived organic compounds and the safer detection of pernicious pesticide residues by selective and sensitive methods using suitable sensor systems has also been given equal priority. Among various sensing methods that are currently available, fluorescence-based sensing has acquired widespread acceptance and become a feasible technique for the trace analysis of pesticide residues due to several practical advantages. In this review article, we provide a systematic overview of the recent progress made in using fluorescence-based chemosensing of different classes of pesticides and their success in real-world applications. Various fluorescence chemosensors highlighted in this article are categorized based on their sensing propensity for a particular class of pesticides. In the initial section of the article, we have highlighted a detailed discussion on the classification of pesticides, and various methods available for pesticide detection, and the later sections report various chemosensors reported to date for sensing different classes of pesticides. Finally, we put forward a short discussion on the advantages and existing practical difficulties in employing fluorescent chemosensors for pesticide detection and also state the future perspective of this field toward developing practically useful sensing systems.

Photodynamic therapy (PDT) represents an innovative and highly promising modality for tumor treatment, attracting considerable attention within the medical community. However, it still faces several challenges, including limited selectivity, inadequate tissue penetration of light, and suboptimal generation of reactive oxygen species (ROS). The utilization of probes, which are activated by nitroreductase (NTR) , an enzyme that is overexpressed in hypoxic tumor tissues, for imaging and PDT represents a compelling strategy for diagnosing and treating cancerous tumors. In this review, we summarize and discuss the current progress in NTR-responsive photosensitizers for cancer imaging and therapy. We also discuss current challenges and perspectives for NTR-activatable photosensitizers. We believe these probes offer promising modalities for precise cancer therapy.

This paper reports the development of a highly sensitive and rapid electrochemical biosensor for the detection of pathogen nucleic acids. The primary objective was to enhance the detection sensitivity of DNA biosensors for pathogen nucleic acids commonly found in fresh and wastewaters, the food industry, and clinical samples. This enhanced sensitivity was achieved through the addition of a [Co(GA)₂(aqphen)]Cl intercalating complex to increase the electrostatic field at the sensor surface/solution interface. Voltammetric and impedance-based detection techniques were employed to characterize the intercalation and redox-active properties of the compound. Additionally, non-faradaic impedance and voltammetric methods were characterized as appropriate techniques for electrochemical detection. Implementing the [Co(GA)₂(aqphen)]Cl intercalator led to increased voltammetric signal output using DPV, facilitating the rapid and sensitive detection of target DNA sequences. Notably, the [Co(GA)₂(aqphen)]Cl permitted detection using non-faradaic impedance in the absence of [Fe(CN)₆]^3−/4−. Characterization by cyclic voltammetric measurements revealed a surface-controlled redox mechanism and reversible electrochemistry of the compound intercalated with double-stranded DNA (dsDNA). Upon binding of 1 μM target DNA and 200 μM [Co(GA)₂(aqphen)]Cl, a 2250% current peak increase was achieved. This increase enabled the sensitive detection of a target DNA sequence representative of E. coli DNA in buffer with an LOD of 67.5 pM, 100-fold more sensitive than the standard unlabeled assay while maintaining assay simplicity, low cost, and quick response. The use of [Co(GA)₂(aqphen)]Cl among similar compounds in DNA biosensors offers a cost-effective and sensitive method for detecting waterborne pathogens such as E. coli. This approach could significantly improve environmental monitoring and pollution control by enabling more reliable and rapid monitoring of pathogens in water sources. Additionally, it has the potential to be of great use within the food industry and in point-of-care clinical settings.

Due to the slow progression of most cancers, speed of diagnosis is not of primary concern. However, the diagnosis of acute promyelocytic leukemia (APL) is unusually urgent because its hemorrhagic complications can result in death within a few days. APL is highly treatable, but the turnaround time for standard molecular testing often exceeds the window for life-saving treatment, even in advanced medical centers. The hallmark of APL is the fusion of the PML and RARα genes (t(15;17)) resulting in the expression of a growth-promoting PML–RARα fusion protein. Toward timely screening for APL, we have developed a sensitive europium-based lateral flow immunoassay for direct detection of nuclear PML–RARα fusion oncoprotein. We demonstrated a limit of detection of 11% fusion protein positive NB4 cells spiked into healthy peripheral blood mononuclear cells and an integrated filter-based sample preparation workflow showcasing its potential for clinically actionable utility in prompt APL screening. With further validation with clinical human samples this lateral flow immunoassay has the potential to enable fusion-protein based cancer diagnostics at true point-of-care.

Conventional diagnosis for male-factor infertility primarily comprises standard microscopic semen analysis, including sperm count or concentration, motility, and morphology of sperm. Unfortunately, this standard analysis offers limited predictive value for pregnancy or the success of assisted reproduction treatments. There is an urgent need for diagnostic tools that effectively probe sperm function. This study discloses a novel diagnostic tool, JUNO-Checked, comprising an electrochemical biosensor for sperm function inspired by the molecular mechanisms of fertilization, utilizing immobilized JUNO protein of oocyte origin. We show that the JUNO-Checked biosensor can quantify sperm binding to the JUNO functionalized biosensor, represented here as the JUNOScore. This score provides a unique insight into sperm function that is inaccessible through standard microscopic semen analysis. Our results underscore the novelty and potential utility of the JUNO-Checked biosensor in clinical settings for diagnostics and personalized assisted reproduction treatments.

A method for detecting CpG methylation is required in clinical settings because CpG methylation is associated with various diseases. CpG methylation leads to structural changes in single-stranded DNA and also changes the stability of double-stranded DNA. We hypothesized that the amplification efficiency of DNA polymerase, with its strand displacement ability, might be altered by CpG methylation. We chose loop-mediated isothermal amplification (LAMP), which uses strand displacement DNA synthesis, for its validation. The LAMP products from the synthetic DNA of the upstream region of the dopamine receptor D2 (DRD2) and the androgen receptor (AR) promoter region were detected by turbidity and fluorescence intensity measurements. The methylated synthetic DNA was amplified more slowly than the unmethylated synthetic DNA. The LAMP products from the human genomic DNA were detected by fluorescence intensity measurement and electrophoresis. The highly methylated genomic DNA was amplified slower than the less methylated genomic DNA in the AR promoter region. CpG methylation detection through differences in the amplification efficiency of LAMP reaction may be used for a rapid and easy detection method of CpG methylation.

Recently, there has been a growing demand for the development of lab-on-a-chip (LOC) platforms with new assays and detection protocols for point-of-care-test (POCT) applications. So far, chemiluminescence (CL) detection-based immunoassays have shown promising performance for the high-sensitive POCT, but they require automated machines or multiple manual steps to perform the CL-based assay. In this work, a fully automated CL-based immunoassay was developed using a new sequential dual flow LOC with on-chip lyophilized CL substrate, and then a highly specific and sensitive immunoassay using a pair of single chain variable fragment (scFv) capture and detection antibodies was successfully performed. The concept of sequential and automatic control of dual flows, which was strongly desired for ensuring that the reconstituted detection antibody conjugated with horseradish peroxidase flowed first through the reaction zones and then the reconstituted CL substrate flowed, was newly developed and implemented on the LOC. In addition, a new one-component CL substrate in liquid format was introduced and lyophilized for the on-chip lyophilized substrate, developing a new lyophilization process. To evaluate the assay performance on the developed new LOC platform, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was chosen as a demonstration vehicle. The nucleocapsid (N) protein of SARS-CoV-2 was analyzed using the custom-developed scFv antibody pair from a phage display library system, which showed a better limit of detection (LoD) over the commercially available rapid diagnostic test (RDT) kits for detecting SARS-CoV-2. Finally, a portable reader for reading the CL signal from the CL-based microchannel lateral flow assay (CL-mLFA) was developed and used for evaluating the performance of the SARS-CoV-2 assay on the developed LOC platform. An LoD of approximately 1.6 ng mL⁻¹ was achieved, which was acceptable for the early diagnosis of SARS-CoV-2 infection. The new CL-mLFA platform developed in this work, adopting the sequential dual flow LOC and the lyophilized one-component CL substrate, can be applied to other high-sensitive immunoassays in POCT for diagnosing various chronic or infectious diseases.

In this work, different surface treatment and modification procedures (KCl, Na₂CO₃, H₂O₂, O₂ plasma, multi-walled carbon nanotubes (MWCNTs)) are applied to a screen-printed carbon-based electrode on bioabsorbable silk-fibroin, aiming to reduce the applied working potential in operation. The screen-printed carbon electrode houses the enzyme glucose oxidase for glucose monitoring, and is encapsulated by the biocompatible material Ecoflex. The working electrode is characterized amperometrically at different working potentials (0.6 to 1.2 V vs. the Ag/AgCl reference electrode) at physiological glucose concentrations ranging from 0.5 to 10 mM. The surface morphology of the electrode is analyzed utilizing scanning electron microscopy and contact angle measurements. Addition of 2 wt% MWCNTs to the carbon screen-printing paste allowed the reduction of the applied working potential from 1.2 to 0.8 V, resulting in a mean glucose sensitivity of 2.5 ± 0.6 μA cm⁻² mM⁻¹. Moreover, the bioabsorbability (i.e., the degradation behavior) of the different surface-treated carbon electrodes on silk-fibroin is studied over several months using the enzyme protease XIV from Streptomyces griseus.