Protein-Inorganic Hybrid Films Of BSA With LDH Colloid For Adsorption And Fluorescence Detection Of Pb²⁺

Heavy metal contamination is a tough global environmental problem,and the latest statistic reveals that millions of tons of toxic heavy metals are released into environment annually,of which there are 34.6 tons of lead,12 tons of mercury,14.7 tons of copper,12.5 tons of arsenic and 3.9 tons of cadmium.Heavy metal contamination is a huge threat to people's daily life and even life safety,lets take lead ion pollution as an example,high blood lead level is associated with anemia,cancer,distortion,intelligence deterioration, head atrophy and other serious health problems.So heavy metal targeted recycle and detection has realistic significance for human health,ecosystem and sustainable harmonious development strategy.Here in the paper protein-inorganic hybrid films are fabricated for the adsorption and detection of Pb²⁺.Firstly,anionized Bovine Serum Albumin (BSA) colloidal solution was taken for self-assembly with LDH colloid.XRD technique,FT-IR/ATR-FTIR,UV-Vis and fluorescence spectroscopy were selected to study the self-assembly behavior of BSA with LDHs,the structures of pure and assembled BSA,and results show that BSA secondary structure maintains well with little decrease ofα-helix.Subsequently,protein-inorganic hybrid films were prepared by Layer by Layer alternative self-assembly of BSA with LDHs and direct-deposition of BSA/LDHs self-assembly nano-particles on certain substrate according to the optimal assembly conditions between BSA and LDHs,and the film structure can be repeated and controlled with satisfaction.Both SEM and AFM images show uniform surface morphology,and LDH nano-sheets lie parallel to the substrate surface.The above prepared BSA/LDHs hybrid films were utilized for adsorption of Pb²⁺,and ICP,UV-Vis,fluorescence spectroscopy and FT-IR characterization techniques were used to study the adsorption performance and mechanism.The results demonstrate that the adsorption of Pb²⁺ on the BSA/LDHs hybrid films comply with Langmuir adsorption model,and the adsorption amount increases with increasing the reaction system pH values. Adsorption of Pb²⁺ on the BSA/LDHs hybrid films is a comprehensive result of ionized carboxyl and others factors,while ionized carboxyl groups play a leading role in the whole process.The fluorescence quenching experimental data were plotted with both Stern-Volmer and Lineweaver-Burk models,which indicate that the fluorescence quenching of Pb²⁺ over BSA is static fluorescence quenching and stable compounds form between Pb²⁺ and BSA fluorophores.As a result,the BSA/LDHs hybrid films can be utilized as fluorescence sensors for direct detection of Pb²⁺ with resort to the good linearity between BSA fluorescence intensity changes and Pb²⁺ initial concentration,which demonstrate satisfactory performances in both sensitivity and accuracy.