Electrochemical Biosensing Research And Applications Based On Novel Biomimetic Nano-materials

The electrochemical biosensing research based on novel biomimetic nano-materials has showed the broad application prospect in the field of electrochemical catalysis, analytical determination, biomedical sciences and so on. Using the "green" synthesized nano-materials as the electrochemical sensing platform, it can not only introduce the peculiar property onto the electrode interface but also make the electrode surface equipped with greater specific surface area, higher surface free energy, better biocompatibility and faster electron transfer rate, eventually improving its resulted analytical performance. Electrochemical biosensors are provided with a large number of advantages, such as rapid response, enhanced sensitivity and specificity, apparatus miniaturization etc., developing a new strategy for biological assay with excellent reproducibility. This paper is devoted to the exploration of biosensing applications based on biomimetic nano-materials and the main researches are as follows.1. The use of a novel cytosensor, comprised of biomimetically synthesized Ag@BSA microspheres, for the detection of KB cells is described. The Ag@BSA composite microspheres were immobilized on Au electrodes via Au-thiol bonds. The immobilization of Ag@BSA composite microspheres onto Au electrodes is thought to increase the electrode surface area and accelerate the electron transfer rate while providing a highly stable matrix for the convenient conjugation of target molecules (such as folic acid) and the prolonged incubation of cells. Electrochemical impedance spectroscopy (EIS) studies showed that the fabricated cytosensor was able to detect KB cells ranging from6.0×101to1.2×108cells ml-1with a lower detection limit of20cells mL-1. This novel cytosensor described here could find multifarious uses in applications, such as cancer diagnosis, drug screening and cell adhesion studies.2. The level of urinary retinol-binding protein (RBP) can be estimated as a significant index of renal tubular injury. In this work, we used Ag@BSA microspheres as a sensing interface to crosslink RBP monoclonal antibody (RBP mAb) via glutaraldehyde for sensitive detection of RBP. The Ag@BSA microspheres covered on Au electrode could provide larger surface area and multifunctional substrate for the effective immobilization of RBP mAb and the outside BSA layer acted as a biocompatible support to maintain the bioactivity and stability of immobilized immunogen. This immunosensor had a best detection limit of18ng mL-1and a linear response range between50and4500ng mL-1. The proposed approach showed high specificity for RBP detection, acceptable reproducibility and good precision. Compared with the ELISA method by analyzing real urine samples from patient, this immunosensor revealed acceptable accuracy with a relative deviation lower than6.5%, indicating a potential alternative method for RBP detection in clinical diagnosis.3. An ultrasensitive electrochemical cytosensor for quantitative determination of carcinoembryonic antigen (CEA)-positive tumor cells was developed by using three-dimensional (3D) architecture Au@BSA microspheres as sensing layer with the conjugation of targeting molecule anti-CEA. The prepared Au@BSA microspheres exhibited satisfying biocompatibility for cell proliferation via evaluation from MTT assay, providing a suitable platform for cell adhesion study. Attributed to the excellent electroconductivity of Au@BS A, amplified electrochemical signals could be obtained and resulted in the greatly enhanced detection sensitivity. The attachment of CEA-positive BXPC-3cells onto the anti-CEA immobilized sensing layer led to the increased EIS responses, which changed linearly in the cell concentration range from5.2×101to5.2×107cells mL-1with a detection limit of18cells mL-1. This proposed cytosensing strategy revealed high specificity to CEA-positive cells, acceptable intra-assay precision, excellent fabrication reproducibility and good stability owing to the outside BSA biocompatible layer, developing a promising technique for early monitoring of tumor cells at a lower level.