Selective visual detection of histamine and ascorbic acid through the rapid gel-sol transition of luminescent alginate hydrogel

A fluorescent hydrogel has been synthesized by crosslinking sodium alginate with Ni2+ in the presence of PEI-derived carbon dots. Such a hydrogel shows a quick selective visual response towards histamine through rapid gel-to-sol transition followed by the release of CD into the sol solution. The amount of histamine can be quantified by measuring the fluorescence intensity of sol solution at an excitation wavelength3 360 nm. The sensor's detection limit in the turn-on intensity mode goes up to 0.63 nM. Utilizing the detoxification reaction of histamine by ascorbic acid, the present sensing platform has been explored to detect ascorbic acid. Due to low-cost and easy synthesis, such hydrogel-based fluorescent chemosensors are potentially suitable for monitoring histamine in serum and fish samples.