A novel metal enhanced fluorescence bio probe for insulin sensing based on poly vinyl alcohol-borax hydrogel functionalized by Ag dots

- A new bio-probe has been designed for insulin based on metal enhanced fluorescence.
- Ag dots were in situ synthesized and embedded into polyvinyl alcohol-borax hydrogel (PBH@AgD).
- The fluorescence intensity of PBH@AgD is enhanced in the presence of insulin.
- The sensing probe was used to detect insulin in human blood serums and regular insulin samples.
- The bio- sensing platform is convenient, fast and precise for insulin determination.

In this article, a new turn-on fluorescence bio-probe system has been designed for insulin monitoring based on in situ synthesis and embedding of Ag dots into polyvinyl alcohol and borax hydrogel (PBH). Simultaneously with the formation of a three-dimensional network of PBH, the silver ions enter the PBH, reduced to Ag dots and trapped into the hydrogel frame without adding any reducing agent. The characterization and morphology of this new hydrogel nanocomposite was investigated by energy dispersive X-ray microanalysis, TEM and average particle size analizer. It was also observed that the fluorescence intensity of PBH functionalized by Ag dots (PBH@AgD) was enhanced in the presence insulin hormone. The intensity enhancement of biocompatible PBH@AgD probe is depended on the presence of Ag dots with metal enhanced fluorescence (MEF) strategy. This probe shows a linear calibration curve in the range of 5-220 ng mL−1 with a detection limit of 0.1 ng mL−1. Moreover, relative standard deviation of bio sensing platform was 0.42 and 0.13% (n = 10) for two concentrations of 60 and 140 ng mL−1 respectively. The present sensing system was utilized for insulin assay in human blood serums and regular insulin with satisfactory results.

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