Detection Of Serum Albumin Based On The Functionalized Gold Nanoclusters Fluorescent Probe

Human serum albumin（HSA）is an important protein that is synthesized by the liver and circulated in the blood.HSA has a variety of physiological functions,including maintaining plasma osmotic pressure,transporting biomolecules（such as drugs and hormones）,and playing a role in immune response.The content of albumin in human serum can reflect the state of liver and kidney function,so the quantitative detection of albumin is of great significance in clinical diagnosis.In this study,multifunctional fluorescent probes were successfully assembled using Bromocresol green（BCG）and Indocyanine green（ICG）as recognition units for the quantitative detection of HSA,where reduced glutathione capped gold nanoclusters（AuNCs）and its complexes were utilized as loading carriers.The main research contents of this paper are concluded as follows:（1）HSA detection based on GSH-AuNCs@BCG fluorescent probe:Bromocresol green（BCG）was assembled with AuNCs and the assembly was used as a fluorescent probe for HSA.After BCG assembling,the fluorescence of GSH-AuNCs was almost quenched.In acidic solution,HSA can combine with BCG on the assembly to form a complex,which recovered the fluorescence of the solution.Meanwhile,the single emission was transformed into dual emissions.With the increase of HSA concentrations,the emission intensities of double peaks were enhanced at different degrees.The ratiometric quantification of HSA was achieved by recording the fluorescence intensity ratios after the addition of HSA.The sensing mechanism of the proposed method was characterized and experimentally verified by various means.Under the optimal condition,the linear equation between the fluorescence ratio and HSA concentration was F/F₀=0.0932C_HSA（mg/m L）+1.0779,R²=0.9915.The detection limit of this method was 0.27 mg/m L.Compared with BCG method used in clinical detection of HSA,this method is more rapid and sensitive,has good anti-interference,and overcomes the time sensitivity of traditional BCG method.（2）HSA detection based on[AuNCs-ZIF-8]@BCG fluorescent probe:Zeolite imidazole ester skeleton material（ZIF-8）with MOFs（metal-organic framework）structure was prepared by the reaction of Zn²⁺with dimethylimidazole.Contributing to the spatial confinement effect of MOFs,AuNCs-ZIF-8 composite with higher fluorescence intensity was prepared.TEM,XRD,XPS,FT-IR and other methods were used to characterize the morphology and fluorescence properties of the composite.Using the adsorbability of ZIF-8,the binding of ZIF-8 to BCG was investigated.When AuNCs-ZIF-8 was combined with BCG,the fluorescence of the gold cluster was almost quenched,and the color of the solution changed from milky yellow to blue.After adding HSA,there was no significant change in the color of the solution,and the ratiometric fluorescence detection of HSA was achieved by recording the change in fluorescence intensity ratio.The linear equation was expressed as F/F₀=0.0687C_HSA（mg/m L）+1.1404,R²=0.9965,LOD=0.13 mg/m L.The sensing system also has good specificity,stability and repeatability.（3）HSA detection based on ICG-GS-AuNCs fluorescent probe:ICG-GS-AuNCs was synthesized by the reaction of GSH-AuNCs with indocyanine green-succinimidyl ester（ICG-NHS）.The effective photoinduced electron transfer（PET）effect between ICG and GSH-AuNCs was used to design the"off-on"fluorescent probe.In the presence of HSA,HSA was bound to ICG and released ICG from the Aucluster surface,resulting in fluorescence recovery.Quantitative detection of HSA was achieved by recording the incremental change in ICG fluorescence intensity at 820 nm.The linear relationship between increment I and HSA concentration was I=10.7236C_HSA（mg/m L）+1.1301,with a correlation coefficient of R²=0.9955 and LOD=0.032 mg/m L.（4）These three fluorescent probes are simple to prepare and low cost.The detection sensitivity and detection limit of two probes with BCG as recognition unit for HSA are better than those of BCG kits.However,ICG-GS-AuNCs has a lower detection limit and higher accuracy when detecting HSA.