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Graphical abstract Sandwich-type electrochemical immunosensor for highly sensitive determination of cardiac troponin I. Highlights • An immunosensor based on CIL-HCNT composite and IgG antibody-ferrocenecarboxylic acid was constructed. • CIL-HCNTs with carboxyl groups were used as an ideal platform for immobilizing antibodies. • Large surface area and high electrocatalytic activity make CIL-HCNTs a good platform. • IgG antibody-ferrocenecarboxylic acid functions as signal probe for cTnI detection. • The electrochemical immunosensor displayed high sensitivity and selectivity for cTnI detection. Abstract Herein we report a sandwich-type electrochemical immunosensor for sensitive detection of cardiac troponin I (cTnI) using a new composite of carboxyl-terminated ionic liquid and helical carbon nanotubes (CIL-HCNTs) as platform and ferrocenecarboxylic acid (Fc-COOH) as signal label. The composite of CIL-HCNTs was prepared by a simple and convenient one-step ultrasound method and was then characterized by Fourier transform infrared spectroscopy, scanning electron microscope, cyclic voltammetry and chronocoulometry. CIL-HCNTs, possessing large surface area and high electrical conductivity, provide a good platform for anti-cTnI monoclonal antibody immobilization through the carboxyl groups of CIL-HCNTs. The Fc-COOH, as a signal label based on the oxidation process, was combined with the CIL-HCNT platform to construct the electrochemical immunosensor for cTnI determination. Under optimal conditions, the electrochemical immunosensor exhibited desirable performance for cTnI determination with a wide range of linearity from 0.01 to 60.0 ng mL−1 and a relatively low detection limit of 0.006 ng mL−1. Importantly, the immunosensor showed excellent specificity and acceptable reproducibility as well as satisfactory reliability for human serum sample analysis. [ABSTRACT FROM AUTHOR]

Although photoacoustic imaging combined with second near infrared (NIR II) molecular probes for tumor diagnosis has drawn tremendous attention during the past few decades, the targeted photoacoustic imaging of orthotopic hepatocellular carcinoma (HCC) still remains a challenge due to high liver vascularization and non-specificity of probes in liver tumors. Herein, we report on cyclic arginine-glycine-aspartic acid (cRGD) peptide conjugated ultrasmall CuS nanoparticles (CuS@BSA-RGD NPs) which encapsulate bovine serum albumin (BSA) and possess high optical absorption at 1064 nm. The encapsulation of BSA results in great biocompatibility of CuS@BSA-RGD NPs along with excellent photostability and physiological stability. The cRGD conjugation enables the improvement of tumor uptake of CuS@BSA-RGD NPs by virtue of its positive tumor cell targeting capability. The efficient accumulation of CuS@BSA-RGD NPs in the tumor over time after intravenous administration to orthotopic HCC bearing mice was achieved, which resulted in highly sensitive photoacoustic visualization of the tumor region. Toxicity studies indicate that CuS@BSA-RGD NPs exhibited negligible systemic toxicity in vivo. The results demonstrate that the CuS@BSA-RGD NPs might hold great promise for future imaging and diagnosis of cancer.

Phototheranostic technology based on photoacoustic imaging (PAI) and photothermal therapy (PTT) is emerging as a powerful tool for tumor theranostic applications. For effective tumor eradication, a novel PAI/PTT theranostic nanoagent with an excellent optical absorption and photothermal capability is highly desired. Herein, we present a new PAI/PTT nanohybrid named sMoSe2-ICG NSs by covalently conjugating aminated indocyanine green (ICG) onto a single layer of molybdenum selenide nanosheets (sMoSe2 NSs). We first validate the sMoSe2-ICG NS agent for the PAI and PTT effect in vitro and then use it for highly-sensitive PAI guided highly efficient tumor PTT in vivo. The sMoSe2-ICG NS hybrid possesses several advantages for PAI/PTT applications: (1) the sMoSe2-ICG NSs have strong absorbance in the broad near-infrared (NIR) region, enabling a highly efficient PAI/PTT theranostic effect and the selection of the most widely used excitation wavelength of 808 nm for PTT; (2) the photothermal ability of ICG in sMoSe2-ICG NSs is augmented due to ICG aggregation induced fluorescence quenching and the re-absorbance of ICG fluorescence by sMoSe2 NSs, which further enhances the PAI/PTT theranostic effect. (3) The characteristic absorption peak of sMoSe2-ICG NSs is red-shifted compared to free ICG, resulting in a higher PAI signal-to-noise ratio (SNR) in vivo. Thus, combined with the good stability, high biocompatibility and minimal toxicity properties, the obtained sMoSe2-ICG NSs hybrid has bright prospects for use in future PAI/PTT clinical applications.