An Electrochemical Biosensor For Hypoxanthine Detection In Vitreous Humor

Objective: To develop a simple electrochemical method for fast and convenient detection of hypoxanthine(Hx)and subsequent estimation of the post-mortem interval(PMI)in forensic cases.Methods: The pre-nanofibers were fabricated by electrostatic spinning,then they were carbonized and turned to be carbon nanofibers.A polydopamine modified carbon nanofibers(CNFs)electrode was utilized with xanthine oxidase(XOD)for Hx detection in vitreous humor(VH).Scanning electron microscopy(SEM)and Fourier Transform Infrared(FT-IR)spectra were uesed to investigate the morphological changes of electro-spun nanofibers,CNFs and functional group changes of PDA-CNFs,Moreover,electrochemical characterization were conducted to test the detection performance towards Hx of XOD/GA/PDA-CNFs/GCE,and PMI was estimated with the concentration of Hx detected by XOD/GA/PDA-CNFs/GCE electrochemical biosensor.Results: PDA-coated CNFs exhibited good biocompatibility for XOD immobilization and fast electron transfer.Under optimal conditions,acceptable stability and reproducibility of the assay were achieved.Additionally,this enzymatic electrochemical biosensor showed a good linear relationship between the current response and Hx concentrations in the range of 5-60 ?M and a detection limit of 2 ?M.Consequently,XOD/GA/PDA-CNFs/GCE showed excellent detection specificity of this assay for analysis of real samples.Moreover,the recycling experiments conducted in VH samples showed the practical application of this micro-device and the analysis of Hx concentration allowed for accurate PMI prediction,compared with known PMI values.Conclusion: These results indicated that the Hx biosensor may be a promising tool for the estimation of PMI in forensic investigations.