Detection Of Biological Thiol And Alkaline Phosphatase Activities Based On Fluorescent Nanomaterials

Fluorescent nanomaterials,as the name implies,have both superlative fluorescence properties and the merits of nanomaterials.In recent years,they have been brought into focus by investigators and widely used in basic scientific research and a variety of biological applications.This paper aims to study fluorescent nanomaterials,making the best of two typical fluorescent nanomaterials,fluorescent coordination polymer and gold nanoclusters to explore their applications in biosensing.Fistly,a new type of coordination polymer nanoparticles based on AIE molecules is designed and constructed through the coordination of the central metal ion and the aggregation-induced emission molecule,which inhibit non-radiative transitions due to intramolecular rotation constraints during self-assembly into coordination polymer,the radiation transition channel was activated and the fluorescence was enhanced greatly.Thus obtaining spherical nano-materials with strong fluorescence emission and nano-properties,which were applied to biothiol sensing.Secondly,we also synthesized a kind of dual-emitting fluorescent gold nanoclusters,which can be used to build a ratio-type fluorescence sensor with reference signal.A novel fluorescent biosensor with high sensitivity,good selectivity,low detection limit and strong anti-interference is constructed by using the ratio strategy to detect alkaline phosphatase activity.（1）Fluorescent coordination polymer and its fluorescence sensing performance:a fluorescence sensing method based on coordination polymer nanoparticles functionalized by AIE molecules is proposed for simple and sensitive detection of biological thiols.In this sensing system,when the AIE molecule HDBB(4,4’-（hydrazine-1,2-diylidene bis（methanylylidene））bis（3-hydroxybenzoic acid）is forming a coordination polymer,due to the limited intramolecular rotation,the radiation transition channel is activated,and the fluorescence is greatly enhanced.Further experiments show that the biothiols has a high quenching efficiency for the fluorescence of Zn-HDBB-CPNs,which is due to the fact that the affinity of Zn2+ for-SH group of biothiols is much greater than that for-COOH group on HDBB surface.The existence of biothiols can competitively bind Zn2+,and destroy the structure of Zn-HDBB-CPNs,which leads to the fluorescence quenching of Zn-HDBB-CPNs.Therefore,we propose a sensing method for rapid detection of biothiols.In this study,a new type of fluorescent nanosensor synthesized by a one-step method provides a new way to detect biological thiols.（2）Dual-emitting fluorescent gold nanoclusters and its fluorescence sensing performance:a original and easy strategy for the detection of alkaline phosphatase activity by ratio fluorescence is presented.It is based on the inter filter effect（IFE）between bovine serum albumin stabilized gold nanoclusters（BSA-AuNCs）and p-nitrophenol（PNP）.First of all,PNP can be generated by the hydrolysis of nitrophenyl phosphate（PNPP）catalyzed by ALP,because the absorption spectrum of PNP and the fluorescence spectrum of BSA-AuNCs at 410 nm have a good overlap,PNP can effectively quench the emission peak of BSA-AuNCs at 410 nm,the peak at 650 nm was almost unaffected.Hence,a sensitive ratiometric method for detection of ALP activity was developed using the fluorescence intensity of BSA-AuNCs at 650 nm as a reference signal.ALP activity versus the ratio of fluorescence intensities at 410 and 650 nm showed good linearity,which could realize the high sensitivity detection of ALP.The detection range of the proposed IFE method is between 0.2 and 5.0 mU/mL（R2=0.9931）,and the detection limit is 0.03 mU/mL（S/N=3）.The suggested detection way has been triumphantly applied to the detection of ALP in serum samples and the investigate of inhibitors.This work not only provides a new way for ALP sensing in clinical diagnosis,but also expands the potential application of metal nanoclusters.