Protein-templated cobaltous phosphate nanocomposites for the highly sensitive and selective detection of platelet-derived growth factor-BB.

Abstract We synthesized novel Co 3 (PO 4 ) 2 -based nanocomposites with 3D porous architectures via self-assembly; here, bovine serum albumin (BSA) and aptamer were used as organic phases to produce Co 3 (PO 4 ) 2 @BSA and Co 3 (PO 4 ) 2 @Apt nanocomposites, respectively. The formation mechanism of Co 3 (PO 4 ) 2 -based nanocomposites was described based on characterizations of their physio-chemical performance, and the developed nanocomposites were applied as scaffold materials to construct a novel electrochemical aptasensor and detect platelet-derived growth factor-BB (PDGF-BB). The PDGF-BB targeting aptamer must be immobilized onto the Co 3 (PO 4 ) 2 @BSA-modified electrode to detect PDGF-BB, whereas Co 3 (PO 4 ) 2 @Apt-based aptasensor may be directly used to determine the target protein. Electrochemical impedance spectroscopy results showed that the developed Co 3 (PO 4 ) 2 @BSA- and Co 3 (PO 4 ) 2 @Apt-based aptasensors present highly sensitive detection ability toward PDGF-BB. Due to the special nanoflower structure, the Co 3 (PO 4 ) 2 @BSA-based aptasensor features a detection limit of 3.7 pg mL −1 ; while the limit of detection of the Co 3 (PO 4 ) 2 @Apt-based aptasensor is 61.5 pg mL −1 , which is the possible bioactivity loss of the aptamer in Co 3 (PO 4 ) 2 @Apt nanocomposite. The two detection limits obtained are still much lower than or comparable with those of previously reported aptasensors. The Co 3 (PO 4 ) 2 @BSA- and Co 3 (PO 4 ) 2 @Apt-based aptasensors showed high selectivity, stability, and applicability for detecting the desired protein. This finding indicates that the Co 3 (PO 4 ) 2 -based nanocomposites could be used as an electrochemical biosensor for various detection procedures in the biomedical field.