Simultaneous determination of insulin and glucose in human serum based on dual emissive fluorescent nano-aptasensor of carbon dots and CdTe/CdS/ZnS quantum dots

A dual emissive fluorescent nano aptasensor was designed for simultaneous detection of human serum glucose and insulin levels. CdTe/CdS/ZnS quantum dots and carbon dots were synthesized and conjugated with the aptamers of glucose and insulin, respectively. The fluorescence of these conjugates was quenched by nano-graphite based on the static quenching and inner filter effect, and restored on the addition of the analytes. All reaction parameters were optimized using analysis of variance, and a polynomial regression model was constructed and verified to explain the effects of reaction parameters on the outcome. The linear ranges of insulin and glucose were 0.2-2 nM and 0.5-7 mM, respectively. The limits of detection for insulin and glucose were 0.018 nM and 0.058 mM, respectively. All the values of relative error % were within the range of - 5.00-4.00%, and the values of relative standard deviation % were <= 3.77%. The changes in fluorescence intensity restoration of the probe in the presence of various interfering species were less than 5%, and all the recoveries for glucose and insulin were in the range of 90-110%. The probe was validated and applied successfully to the determination of the stated analytes in human serum. The fabricated aptasensor can be used to diagnose diabetes and its type with a single assay in clinical diagnostic labs.