TiO2 nanotubes loaded with CdS nanocrystals as enhanced emitters of electrochemiluminescence: application to an assay for prostate-specific antigen

Silica Nanochannels as Nanoreactors for the Confined Synthesis of Ag NPs to Boost Electrochemical Stripping Chemiluminescence of the Luminol-O2 System for the Sensitive Aptasensor

Herein, we, for the first time, synthesize silver nanoparticles (Ag NPs) within the nanochannels of amino group-functionalized vertically ordered mesoporous silica films (NH2-VMSF) and investigate their coreaction accelerator role in the luminol-dissolved oxygen (O2) electrochemical stripping chemiluminescence (ESCL) system. The synthesized Ag NPs are capable of electrocatalytic reduction of O2 to superoxide radicals, and meanwhile, sliver ions (Ag+) electrochemically stripped from Ag NPs can promote the amount of luminol anion radicals, generating the boosted ECL intensity of the luminol-dissolved O2 system. This proposed Ag NPs@NH2-VMSF on the indium tin oxide electrode was applied to construct the ESCL aptasensor for quantitative determination of prostate-specific antigen (PSA), yielding a low detection limit [0.19 pg/mL (S/N = 3)] and a broad linear dynamic range (1 pg/mL to 100 ng/mL). Furthermore, good analytical performance of PSA in serum with satisfactory recoveries and low relative standard deviation values is achieved by our developed ESCL aptasensor, rendering it a convenient and sensitive method for PSA determination in clinical applications and further broadening the strategy of ESCL techniques.

Porphyrin-based metal-organic frameworks enhanced electrochemiluminescence (ECL) by overcoming aggregation-caused quenching: A new ECL emitter for the detection of trenbolone

The development of new electrochemiluminescence (ECL) luminophores has become a hot research topic in the field of ECL. Metal-organic frameworks (MOFs) are widely used in ECL sensors due to their excellent ECL performance, high porosity, and abundant surface functional groups. In the work, we developed a cerium-based organic backbone as an ECL luminophor using 5,10,15,20-tetrakis(4-carboxyphenyl)-porphyrin (TCPP) as organic ligand for the detection of trenbolone (TRE). Importantly, the Ce-MOFs can effectively prevent the self-aggregation and self-quenching of TCPP, so that the ECL signal is amplified. To further improve the conductivity and antigen loading capacity of the Ce-MOFs, platinum nanosheets (Pt NPs) were modified at its surface (Pt NPs@MOFs). The Au-ZnO with good biocompatibility is used as the substrate material to load that antibody through the Au-NH2. Based on the above strategy, we constructed a competitive immunosensor to achieve a highly sensitive detection of TRE. Under suitable circumstances, it was discovered that the ECL sensor had a linear relationship with the logarithm of the TRE concentration, with a limit of detection (LOD) of 3.61 fg/mL (S/N = 3). This work provides direction for the application of organic luminescent porphyrins and their derivatives in ECL sensors.

Biosensors for prostate cancer detection

Prostate cancer (PC) is one of the most common tumors and a leading cause of mortality among men, resulting in ~375 000 deaths annually worldwide. Various analytical methods have been designed for quantitative and rapid detection of PC biomarkers. Electrochemical (EC), optical, and magnetic biosensors have been developed to detect tumor biomarkers in clinical and point-of-care (POC) settings. Although POC biosensors have shown potential for detection of PC biomarkers, some limitations, such as the sample preparation, should be considered. To tackle such shortcomings, new technologies have been utilized for development of more practical biosensors. Here, biosensing platforms for the detection of PC biomarkers such as immunosensors, aptasensors, genosensors, paper-based devices, microfluidic systems, and multiplex high-throughput platforms, are discussed.

Research progress on the role and mechanism of DNA damage repair in germ cell development

In the complex and dynamic processes of replication, transcription, and translation of DNA molecules, a large number of replication errors or damage can occur which lead to obstacles in the development process of germ cells and result in a decreased reproductive rate. DNA damage repair has attracted widespread attention due to its important role in the maintenance and regulation of germ cells. This study reports on a systematic review of the role and mechanism of DNA damage repair in germline development. First, the causes, detection methods, and repair methods of DNA damage, and the mechanism of DNA damage repair are summarized. Second, a summary of the causes of abnormal DNA damage repair in germ cells is introduced along with common examples, and the relevant effects of germ cell damage. Third, we introduce the application of drugs related to DNA damage repair in the treatment of reproductive diseases and related surgical treatment of abnormal DNA damage, and summarize various applications of DNA damage repair in germ cells. Finally, a summary and discussion is given of the current deficiencies in DNA damage repair during germ cell development and future research development. The purpose of this paper is to provide researchers engaged in relevant fields with a further systematic understanding of the relevant applications of DNA damage repair in germ cells and to gain inspiration from it to provide new research ideas for related fields.

A sensitive label-free biosensor based on Ag2S-sensitived Bi2WO6/BiOBr heterojunction for photoelectrochemical immunoassay of prostate specific antigen

Prostate cancer is one of the most common cancers in the world, and its early diagnosis can effectively reduce mortality. A new label-free photoelectrochemical (PEC) immunosensor on the basis of Bi₂WO₆/BiOBr nanocomposite materials has been successfully prepared for the test of prostate-specific antigen (PSA) in human serum in this work. The Ag₂S-sensitized Bi₂WO₆/BiOBr heterojunction was used as a photosensitive material, which effectively improved the photocurrent response. On Bi₂WO₆/BiOBr surface, dopamine immobilized PSA antibody by self-polymerizing to form polydopamine membrane. Antigen and antibody are specifically combined to achieve quantitative detection of PSA according to the current changes at different concentrations of antigen. Under the optimal experimental conditions, the PEC immunosensor has an ideal linear relationship between 1 pg/mL - 50 ng/mL, and the detection limit is 0.084 pg/mL. In addition, the prepared immunosensor has good stability, reproducibility and selectivity, providing a new method for the detection of PSA in actual sample analysis.

Machine learning-assisted Te-CdS@Mn3O4 nano-enzyme induced self-enhanced molecularly imprinted ratiometric electrochemiluminescence sensor with smartphone for portable and visual monitoring of 2,4-D

Here, a novel and portable machine learning-assisted smartphone-based visual molecularly imprinted ratiometric electrochemiluminescence (MIRECL) sensing platform was constructed for highly selective sensitive detection of 2,4-Dichlorophenoxyacetic acid (2,4-D) for the first time. Te doped CdS-coated Mn₃O₄ (Te-CdS@Mn₃O₄) with catalase-like activity served as cathode-emitter, while luminol as anode luminophore accompanied H₂O₂ as co-reactant, and Te-CdS@Mn₃O₄ decorated molecularly imprinted polymers (MIPs) as recognition unit, respectively. Molecular models were constructed and MIP band and binding energies were calculated to elucidate the luminescence mechanism and select the best functional monomers. The peroxidase activity and the large specific surface area of Mn₃O₄ and the electrochemical effect can significantly improve the ECL intensity and analytical sensitivity of Te-CdS@Mn₃O₄. 2,4-D-MIPs were fabricated by in-situ electrochemical polymerization, and the rebinding of 2,4-D inhibits the binding of H₂O₂ to the anode emitter, and with the increase of the cathode impedance, the ECL response of Te-CdS@Mn₃O₄ decreases significantly. However, the blocked reaction of luminol on the anode surface also reduces the ECL response. Thus, a double-reduced MIRECL sensing system was designed and exhibited remarkable performance in sensitivity and selectivity due to the specific recognition of MIPs and the inherent ratio correction effect. Wider linear range in the range of 1 nM-100 μM with a detection limit of 0.63 nM for 2,4-D detection. Interestingly, a portable and visual smartphone-based MIRECL analysis system was established based on the capture of luminescence images by smartphones, classification and recognition by convolutional neural networks, and color analysis by self-developed software. Therefore, the developed MIRECL sensor is suitable for integration with portable devices for intelligent, convenient, and fast detection of 2,4-D in real samples.

Electrochemiluminescence with semiconductor (nano)materials

Electrochemiluminescence (ECL) is the light production triggered by reactions at the electrode surface. Its intrinsic features based on a dual electrochemical/photophysical nature have made it an attractive and powerful method across diverse fields in applied and fundamental research. Herein, we review the combination of ECL with semiconductor (SC) materials presenting various typical dimensions and structures, which has opened new uses of ECL and offered exciting opportunities for (bio)sensing and imaging. In particular, we highlight this particularly rich domain at the interface between photoelectrochemistry, SC material chemistry and analytical chemistry. After an introduction to the ECL and SC fundamentals, we gather the recent advances with representative examples of new strategies to generate ECL in original configurations. Indeed, bulk SC can be used as electrode materials with unusual ECL properties or light-addressable systems. At the nanoscale, the SC nanocrystals or quantum dots (QDs) constitute excellent bright ECL nano-emitters with tuneable emission wavelengths and remarkable stability. Finally, the challenges and future prospects are discussed for the design of new detection strategies in (bio)analytical chemistry, light-addressable systems, imaging or infrared devices.

Liposome-assisted enzyme catalysis: toward signal amplification for sensitive split-type electrochemiluminescence immunoassay

Developing an efficient signal amplification strategy is very important to improve the sensitivity of bioanalysis. In this paper, a liposome-assisted enzyme catalysis signal amplification strategy was developed for electrochemiluminescence (ECL) immunoassay of prostate specific antigen (PSA) in a split-type mode. The sandwich immunoreaction occurred in a 96-well plate, and glucose oxidase (GOx) encapsulated and antibody-modified liposomes were used as labels. The ECL detection was carried out using a rGO-Au NP modified glassy carbon electrode (GCE). The large amount of generated H2O2, i.e. the coreactant of the luminol system, and the excellent catalytic behavior of rGO-Au NPs greatly boosted the ECL signal, resulting in the signal amplification. The developed ECL immunosensor for detecting PSA achieved a wider linear range from 1.0 × 10-13 to 1.0 × 10-8 g mL-1 and a detection limit of 1.7 × 10-14 g mL-1. The application of the proposed strategy was demonstrated by analyzing PSA in human serum samples with recoveries from 89.0% to 113.0%, and relative standard deviations (RSDs) were less than 6.6%. This work provides a new horizon to expand the application of liposomes for ECL bioanalysis.

Signal-on electrochemical aptasensors with different target-induced conformations for prostate specific antigen detection

Prostate specific antigen (PSA) has become a potential biomarker for detecting prostate cancer (PCa) in the early stage. Herein, we report a target-induced resolution for the detection of PSA sensitively and specifically by amperometric electrochemical measurements. To meet a satisfactory performance, three conformations of pre-design DNA aptamers including two stem-loop structures and a double strand structure have been investigated and compared. All of them are immobilized on gold electrode as capture probes with redox-active molecular. The mechanism of signal transduction depends on molecular recognition events involving aptamer conformational changes, thus influencing the charge transfer. A short, single-stranded DNA (ssDNA) pseudoknot forming two stem-loop structural aptamers with labeled MB at the 3' -terminus was found to posse the highest signal variation than other structure when induced by PSA due to the strong conformational change. With the optimized capture strand, the aptasensor showed the peak current increase of MB by the binding relationship between PSA and the sensor over a wide concentration range of 4 magnitude orders. The proposed aptasensor exhibited a wide detection range from 10 pg/mL to 500 ng/mL with a low detection limit of 1.24 pg/mL (S/N = 3). Moreover, the electrochemical aptasensor demonstrated good reproducibility, sensitivity, selectivity, and reliability for the detection of PSA. We also found the aptasensor had a good response in the human serum samples, making this device easy to operate for the detection of the PSA physiological concentration.

Nanotreatment and Nanodiagnosis of Prostate Cancer: Recent Updates

The fabrication and development of nanomaterials for the treatment of prostate cancer have gained significant appraisal in recent years. Advancements in synthesis of organic and inorganic nanomaterials with charge, particle size, specified geometry, ligand attachment etc have resulted in greater biocompatibility and active targeting at cancer site. Despite all of the advances made over the years in discovering drugs, methods, and new biomarkers for cancer of the prostate (PCa), PCa remains one of the most troubling cancers among people. Early on, effective diagnosis is an essential part of treating prostate cancer. Prostate-specific antigen (PSA) or serum prostate-specific antigen is the best serum marker widely accessible for diagnosis of PCa. Numerous efforts have been made over the past decade to design new biosensor-based strategies for biomolecules detection and PSA miniaturization biomarkers. The growing nanotechnology is expected to have a significant effect in the immediate future on scientific research and healthcare. Nanotechnology is thus predicted to find a way to solve one of the most and long-standing problem, "early cancer detection". For early diagnosis of PCa biomarkers, different nanoparticles with different approaches have been used. In this review, we provide a brief description of the latest achievements and advances in the use of nanoparticles for PCa biomarker diagnosis.

An off-on electrochemiluminescence detection for microRNAs based on TiO2 nanotubes sensitized with gold nanoparticles as enhanced emitters

A sensitive electrochemiluminescence (ECL) assay for microRNAs (miRNAs) based on a semiconductor nanomaterial sensitized with noble-metal Au nanoparticles (NPs) is successfully developed. TiO₂ nanotubes (NTs) were equipped with Au NPs to obtain an enhanced ECL emitter. Then, an ECL assay for miRNA-21 was fabricated, which was based on the use of probe 2 DNA-functionalized Pt/PAMAM nanocomposites (NCs) assembled on the surface of Au/TiO₂ NT conjugate via DNA hybridization between probe 1 DNA and capture DNA. The Pt/PAMAM NCs act as an ECL quencher of Au/TiO₂ NTs via resonance energy transfer. After the binding of target miRNA-21 and the capture DNA, the Pt/PAMAM NCs were released and the ECL signal was recovered. An "off-on" ECL assay was achieved with a linear response from 0.01 to 10,000 pM. Finally, this method has been validated to be sensitive and specific for miRNAs in human serum samples. The ECL enhancement strategy opens a new way for fabricating various sensitive biosensors. Graphical abstract A sensitive "off-on" electrochemiluminescence analysis method was developed, which combined Au NP-enhanced ECL emission of TiO₂ nanotubes and an efficient energy-transfer system between Au/TiO₂ nanotubes and Pt/PAMAM nanocomposites.