A novel multianalyte electrochemical immunoassay was developed for ultrasensitive detection of human cardiopathy biomarkers cardiac troponin I (cTnI) and human heart-type fatty-acid-binding protein (FABP) using metal ion functionalized titanium phosphate nanospheres (TiP-metal ion) as labels. The metal ions could be detected directly through square wave voltammetry (SWV) without metal preconcentration, and the distinct voltammetric peaks had a close relationship with each sandwich-type immunoreaction. The position and size of the peaks reflected the identity and level of the corresponding antigen. The large amount of metal ions loading on the TiP nanospheres greatly amplified the detection signals, and the good biocompatibility of graphene nanoribbons (GONRs) retained good stability for the sandwich-type immunoassay. The proposed immunoassay exhibited high sensitivity and selectivity for the detection of cTnI and FABP. The linear relationships between electrochemical signals and the concentrations of cTnI and FABP were obtained in the range of 0.05 pg/mL-50 ng/mL and 0.05 pg/mL-50 ng/mL, respectively. The detection limits of cTnI and HIgG were 1 and 3 fg/mL (S/N = 3), respectively. Moreover, the immunoassay accurately detected the concentrations of cTnI and FABP in human serum samples, which were demonstrated to have excellent correlations with the standard enzyme linked immunosorbent assay (ELISA) method. The results suggested that the electrochemical immunoassay would be promising in the point-of-care diagnostics application of clinical screening of acute myocardial infarction (AMI) biomarkers.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry is used to detect intact whole exosomes, yielding exosomal fingerprints within minutes. This rapid exosome detection approach is proposed as a potential tool for cancer studies. Melanoma, a dangerous form of skin cancer, is investigated as a cancer model. The approach allows classification of melanoma cell lines from the stage level through mathematical analysis of the fingerprints and enables the tracking of protein transfer from parental cells to the secreted exosomes by following up certain fingerprint peaks. Protein identities of exosomal fingerprint peaks were clarified by correlation with top-down and bottom-up proteomics. The protein-assigned fingerprints provide a qualitative and semiquantitative detection of melanoma biomarkers and help to explore melanoma progression via exosome-mediated intercellular communication. Targeting bloodstream-circulating exosomes, the proposed exosome fingerprinting approach also promises fast detection of melanoma diseases and dynamic monitoring of the disease state with proof of concept in mouse and human.

An immunoaffinity mass spectrometry method was proposed for quick BSI diagnosis.

A novel fluorescent immunosensor was developed based on the use of CuS nanoparticles (CuS NPs) as labels for the highly sensitive detection of human prostate cancer biomarker prostate specific antigen (PSA). In the presence of CuS NPs, the non-fluorescent substrate o-phenylenediamine could be oxidized into the stable fluorescent product 2,3-diamiophenazine at physiological pH. Throughout the reaction, no other oxidizing agents (e.g. hydrogen peroxide) were needed. The relatively mild oxidation conditions made the immunoassay robust, reliable and facile. The proposed immunoassay exhibited high sensitivity and specificity for the detection of PSA. A linear relationship between the fluorescent signals and the concentration of PSA was obtained in the range of 0.5 pg mL(-1) to 50 ng mL(-1), with a detection limit of 0.1 pg mL(-1) (S/N = 3). The proposed fluorescent immunoassay can be used as a promising platform for the detection of a variety of other biomarkers.

TiO2-facilitated MALDI–TOF-MS was proposed to improve intact bacteria fingerprinting, allowing rapid and convenient antimicrobial resistance-associated protein detection during bacteria identification.

A microfluidic platform to evaluate the expression of multi-glycans on a cell surface was developed using electrochemical impedance spectroscopy (EIS) and optical microscope technique. In the microfluidic channel, four indium tin oxide (ITO) electrodes were modified with three lectins and one passivation agent, respectively, to selectively recognize the corresponding carbohydrate epitopes on the cell surface. The binding of the cells on the electrode array was monitored by the electrochemical impedance to evaluate the expression of cell surface glycans. The excellent optical transparency of ITO electrode permitted the microscopic observation of the cell binding simultaneously to substantiate the impedance measurement. Compared with the individual technology, the double-check mode increased the sensitivity and accuracy of the assay. The experimental results using these two techniques indicated that the cell binding ability decreased in the order WGA > Con A > PNA, which was consistent with the expression difference of carbohydrate epitopes on K562 cell surface. The proposed strategy was further used for facile evaluating the variations of glycan expression on living cells in response to drugs. The consumption of cell sample for each sensing interface in the whole experiments is merely 5 × 10(3) cells. This platform offers great promise for cancer-associated glycol-biomarkers screening and further helps cancer diagnosis and treatment.

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A combination of an immuno-affinity enrichment strategy and sensitive amperometric read-out was implemented in a point-of-care platform intended for bacterial infection analysis. Bacterial cells, selectively captured and enriched from complex matrices through immuno-affinity, were detected by amperometric monitoring of the redox state of metabolic activity indicators, providing species identification and viable-cell quantification. The method was successfully employed for the diagnosis of bacterial infections including antimicrobial susceptibility testing with only several hours of total working time.