A Label-free Multicolor Colorimetric and Fluorescence Dual Mode biosensing of HIV-۱ DNA based on the Bifunctional NiFe۲O۴@UiO-۶۶ Nanozyme

Finding DNA of the human immune deficiency virus (HIV) with simple and sensitive detectionis the main challenge in early diagnosis of AIDS. Herein, two-point separation strategies basedon the colorimetric and fluorescence is introduced. The naked-eye qualitative andsemiquantitative colorimetric, and also accuracy fluorescence quantification of HIV-۱ DNAwere applied using label-free NiFe۲O۴@UiO-۶۶ nanozyme with both functions of peroxidasemimeticlike and emitting fluorescence. The DNA probe-conjugated nanozyme is employed tohybridize a sequence of HIV-۱. NiFe۲O۴@UiO-۶۶ nanozymes catalyze the decomposition ofH۲O۲ to •OH which can produce a remarkable fluorescent product ۲-hydroxyterephthalic acid(TAOH) by the oxidation of the bridging ligand of weakly fluorescent terephthalic acid (TA).The accessibility of H۲O۲ toward confined-NiFe۲O۴ MNPs was reduced by increasing the HIV-۱target DNA concentration, resulting in the fluorescence intensity of TAOH was decreased.Meanwhile, remaining the unreacted H۲O۲ was transferred to acidic colorimetric solutioncontaining of FeSO۴ and gold nanorods (AuNRs). Increasing the amount of H۲O۲ available forlongitudinal etching of AuNRs due to •OH-generating Fe+۲-catalyzed H۲O۲ is reponsible todifferent colors from brownish to colorless depending on the HIV-۱ target DNA concentration.The fluorescence intensity and obtained colors have offered the sensitive biosensing methodswith a linear range from ۰.۰۵-۳۰۰ and ۱-۲۰۰ pM, respectively with a detection limit as low as ۱fM. Our study revealed that the applied sensing assay provides a cost-effective andstraightforward qualitative, semiquantitative and sensitive quantitation visible monitoringwithout the necessity of high-end instruments HIV-۱ detection in human blood plasma sample.