Amperometric sarcosine biosensor based on hollow magnetic Pt-Fe3O4@C nanospheres.

Sarcosine is a recently identified biomarker for prostate cancer. However, the rapid detection methods for sarcosine are relatively lack because of the low concentration and the presence of complicated interfering substances in serum or urine. In this manuscript, hollow nanospheres of Fe3O4 was synthesized and used as carrier to disperse Pt (Pt) nanoparticles. In order to achieve excellent electron transfer ability, we use polyaniline to coat Pt-Fe3O4 nanoparticles, and pyrolyze the polyaniline to carbon (C). Thus, hollow magnetic Pt-Fe3O4@C nanocomposites with good electron transfer ability are formed. The Pt-Fe3O4@C nanocomposites have high catalytic activity and stability. The nanocomposites were immobilized on glassy carbon electrode (GCE) to construct a nonenzyme hydrogen peroxide (H2O2) sensor (Pt-Fe3O4@C/GCE). We further construct a sensitive sarcosine biosensor by immobilizing sarcosine oxidase (SOx) on the Pt-Fe3O4@C/GCE. The high catalytic activity and good biocompatibility of Pt-Fe3O4@C nanocomposites greatly retained the bioactivity of immobilized SOx, and the prepared sarcosine biosensor has good electrocatalytic performance towards sarcosine. It has a linear detection range between 0.5 and 60 µM with a limit of detection (LOD) of 0.43 µM (the signal to noise ratio is 3), and the sensitivity is 3.45 nA µM-1 (48.8 nA µM-1 cm-2), which has the potential to be used for rapid screening of prostate cancer.

Amperometric sarcosine biosensor with strong anti-interference capabilities based on mesoporous organic-inorganic hybrid materials.

Amperometric enzyme biosensors are some of the simplest and cheapest types of medical devices used in the rapid detection of biomarkers that have been developed in the past fifty years. When the concentrations of biomarkers are at micromoles per liter, such as for sarcosine, which was recently discovered as a biomarker for prostate cancer, the response signal of the interferences is huge, and the biosensor is hard to satisfy the requirements of practical applications. In this manuscript, we describe a strategy for synthesizing a surface electronegative organic-inorganic hybrid mesoporous material, which could reduce the interference signal much better than Nafion and Chitosan. We verify that the surface potential of the carrier nanomaterial plays an important role in excluding anionic interferences. We also prepare a sensitive (16.35 µA mM-1), low LOD (0.13 µM) and wide linear range (1-70 µM) amperometric sarcosine biosensor with excellent anti-interference properties. This mesoporous material provides a bio-composite platform for the development of simple amperometric biosensors for detecting micromoles per liter of analytes in serum or urine.

Platinum-loaded mesoporous nickel phosphonate and its electrochemical application for sarcosine detection.

In 2009, Sreekumar found that sarcosine, as an effective biomarker, can be used to identify prostate cancer. However, it is difficult to detect sarcosine in urine or plasma because of its low concentration. In this work, we describe a simple strategy for the preparation of sarcosine biosensor based on platinum-loaded mesoporous nickel phosphonate (Pt/MNP) and subsequently apply it to detect sarcosine. Mesoporous structure could increase the active sites on the MNP surface, which makes the Pt/MNP have excellent electrochemical performance for detecting hydrogen peroxide, one of the enzymatic products, and the sarcosine biosensor exhibited a superior electrochemical performance. The linear range of sarcosine biosensor is from 5 to 40 µM and the sensitivity is 123.51 µA mM-1 cm-2. The limit of detection is estimated to be 0.24 µM (S/N = 3). Additionally, the sarcosine biosensor based on Pt/MNP also shows an excellent performance in the anti-interference test and the real serum sample. This work manifests the potential application of Pt/MNP as a novel biosensor material for sarcosine detection, which could be extended to other oxidase-based detection systems.