Highly sensitive and selective AIE-based fluorometric sensor to detect heparin via the fluorescent Ni nanoclusters

Metal nanoclusters play a significant role in emerging nano biosensing. We reported highly fluorescent Ni Nanoclusters and their possible application in heparin detection. Heparin can be identified as an important anticoagulant which also serves as a biomarker for a few diseases, including sepsis and diseases related to the immune system. The fluorescent nickel nanoclusters was synthesized with thiolate ligand surface capping by using the probe ultrasonication method. Here, thiourea was used as the capping agent and NaOH was applied as the reducing agent. The as-synthesized nickel nanoclusters have shown a significantly high greenish fluorescence with a decent quantum yield which stays stable over one month. The as-synthesized nanoclusters were functionalized with BSA protein for the selectivity towards heparin sensing and developed into an Aggregation Induced Emission (AIE)-based fluorescent sensor. In the sensing platform, the positively charged amino acid groups in BSA protein form electrostatic interactions with the negatively charged carboxyl groups and hydroxyl groups of Heparin to induce aggregation. The increase in fluorescence intensity had a wide linear range from 2.5-100 nM with an R² = of 0.98 and the reported LOD value was 9.448 nM in water and 19.02 nM in the serum sample. The quantum yield of the synthesized nanoclusters is 7.1 %. This highly sensitive and selective sensing platform with good stable fluorescence can be used as a potential AIE fluorescence sensor for the future biomedical field. This study reveals the possibilities of using the novel Ni NCs as a novel platform for sensors in the near future in various application fields.