Glucose oxidase-encapsulated liposomes for amplified autofluorescence-free immunoassay of a prostate-specific antigen with photoluminescence of CePO4:Tb nanocrystals.

Lanthanide-doped inorganic nanocrystals have attracted extensive attention due to their long luminescence lifetime and large Stokes shift. In this work, an immunosensing platform based on CePO4:Tb (CPOT) was successfully constructed, which could avoid the autofluorescence interference of complex biological matrices. Specifically, CPOT was synthesized by a solvothermal method, which exhibited H2O2-responsive luminescence behavior. Taking advantage of this feature, an autofluorescence-free immunosensor with CPOT as the probe and H2O2 as the quencher was developed to detect prostate-specific antigen (PSA). Functionalized liposomes were used to encapsulate glucose oxidase (GOD) and labeled on detection antibodies to improve the sensitivity of the probe. Under the proven optimal experimental conditions, the developed autofluorescence-free immunosensor exhibited a linear luminescence response to the logarithm of PSA concentration (0.005-25 ng mL-1) with a limit of detection (LOD) of 3.25 pg mL-1. The performance shows that the autofluorescence-free immunosensor based on this strategy opens up a new field of vision for clinical PSA detection.

Persistent luminescence nanorods-based autofluorescence-free biosensor for prostate-specific antigen detection.

Persistent luminescent nanoparticles (PLNPs) are a class of materials with excellent optical properties, which can continue to emit light for a long time after removing the excitation light source. This feature enables PLNPs to be used for development of biological detection modes without autofluorescence background. In this study, we prepared Zn2GeO4: Mn2+, Pr3+ (ZGOMP) nanorods through a one-pot hydrothermal method. Using the pH-responsive luminescence behavior of ZGOMP, we developed an autofluorescence-free biosensor using ZGOMP as a probe and gluconic acid as a quencher to detect prostate-specific antigen (PSA). Hybridization chain reaction (HCR) and magnetic separation system were introduced in the design to achieve efficient signal amplification. Under the optimal conditions, the as-designed autofluorescence-free sensing platform showed high selectivity, and showed a good luminescence response to PSA within the linear range of 0.001-10 ng/mL at a detection limit of 0.64 pg/mL. The excellent analytical performance shows that the current strategy provides an effective platform for clinical sample analysis.

Ultrasensitive photoelectrochemical immunoassay for prostate-specific antigen based on silver nanoparticle-triggered ion-exchange reaction with ZnO/CdS nanorods.

Prostate-specific antigen (PSA), a glycoprotein that is most likely to cause prostate cancer, has attracted widespread attention in recent years due to its increasing threat to people's lives and health. Herein, we developed a new signal-amplified photoelectrochemical (PEC) immunosensing method for quantitative monitoring of the target PSA based on the ion-exchange reaction for the in situ formation of ZnO/CdS/Ag2S nanohybrids triggered by the as-released silver ions (Ag+) from silver nanolabels. Initially, the introduction of a target PSA caused the formation of a sandwich immunocomplex in an anti-PSA capture antibody (cAb)-coated microplate with the help of a silver nanoparticle-labeled detection antibody (AgNPs-dAb). Thereafter, the introduced AgNPs were dissolved with acid to release numerous silver ions. In this regard, an ion-exchange reaction occurred between the silver ions and ZnO/CdS nanorods on the photosensitive electrode, thus producing ZnO/CdS/Ag2S nanohybrids to generate a relatively strong photocurrent. Under optimal conditions, the ion-exchange reaction-based PEC immunoassay exhibited a good linear range of 0.05-50 ng mL-1 and allowed the detection of the target PSA at a concentration as low as 0.018 ng mL-1. In addition, the PEC immunoassay displayed satisfactory repeatability, high specificity, and acceptable method accuracy. Importantly, the ion-exchange reaction-based PEC immunoassay provides a new perspective for the detection of other disease-related biomarkers by controlling the corresponding antibodies.

Signal-on photoelectrochemical immunoassay mediated by the etching reaction of oxygen/phosphorus co-doped g-C3N4/AgBr/MnO2 nanohybrids.

We designed a signal-on photoelectrochemical (PEC) immunoassay for the sensitive monitoring of prostate-specific antigen (PSA) based on the etching reaction of hydrogen peroxide (H2O2) toward oxygen/phosphorus co-doped graphitic C3N4/AgBr/MnO2 nanosheets (OP-g-C3N4/AgBr/MnO2). Initially, glucose oxidase (GOX)-labeled detection antibodies were introduced into the capture antibody-coated microplate with a sandwich-type immunoreaction in the presence of PSA. Then, the as-generated H2O2 from the decomposition of glucose by GOX etched the manganese dioxide (MnO2) nanosheets into manganese ions (Mn2+), thereby causing the exposure of the underlying OP-g-C3N4/AgBr. Meanwhile, H2O2 could be also used as an electron scavenger, and restrain the recombination of the electron-hole pairs of OP-g-C3N4/AgBr. Two advantages of H2O2 enhanced the photocurrent synergistically. Under optimum conditions, the PEC immunoassay showed high sensitivity toward target PSA within a dynamic working range of 0.05-50 ng mL-1 with a limit of detection of 17 pg mL-1. In addition, our system possessed high specificity, favorable selectivity, and good stability. Relative to commercialized PSA ELISA kits, the accuracy of our strategy was acceptable. More importantly, our strategy can be easily extended to screen other biomarkers by controlling the corresponding antibodies.

Double ion-exchange reaction-based photoelectrochemical immunoassay for sensitive detection of prostate-specific antigen.

This work developed a double ion-exchange reaction-based photoelectrochemical (PEC) immunoassay with the split-type detection mode for sensitive detection of prostate-specific antigen (PSA, used as a model). The nanocomposite of cadmium sulfide and nickel sulfide (CdS@NiS nanocomposite), as the photoactive material, was rapidly synthesized by two-step hydrothermal treatment. In the presence of target PSA, the cupric oxide nanoparticle (CuO NP) labeled detection antibody was introduced into the detection system by sandwich immunoreaction and the copper (Cu2+) ions was released from CuO nanoparticles by acid to participate in double ion-exchange reaction. The double ion-exchange reaction on the photoelectric sensing interface between Cu2+ and CdS@NiS nanocomposites formed the weak photoactive material CuxS (x = 1, 2) to reduce the photocurrent. Under optimal conditions, the double ion-exchange reaction-based PEC immunoassay exhibited good photocurrent responses toward target PSA within the dynamic working range from 0.01 ng mL-1 to 50 ng mL-1 at a low limit of detection (LOD) of 2.9 pg mL-1. Besides, our work could achieve good reproducibility and high specificity under the split-type detection mode. Compared with human PSA ELISA kit, the accuracy obtained by our strategy was satisfactory. Importantly, this Cu2+-activated double ion-exchange reaction-based PEC immunoassay provides a promising platform for the detection of biomarkers.