The Research And Application Of Bio-sensors Based On Photoluminescence Nanoparticles

The biosensor based on photoluminescence nanoparticles plays an important role in bio-analysis methods and researches.One kind of the carbon nanoparticles known as the newest promising material is graphene quantum dot?GQD?.Scholars have focused on GQDs for their particular surface activity,special electron character,great biocompatibility and hypotoxicity,which is important for the application in biomedicine and bio-analysis methods.While making some changes in proceed of GQDs synthesis,other elements such as nitrogen,oxygen,sulfur,and silicon can be doped into the graphene-like structure.The doped GQDs show bunch of new properties which varies in photoluminescence and surface activities from the original GQDs with hydrogen and carbon.Doped GQDs have been deeply studied in the applications of bio-imaging,drug delivery and photoluminescence biosensors.The other nanoparticles,polydopamine NPs,also have great biocompatibility and surface activity.Polydopamine can be prepared with the self-polymerization reaction of dopamine.Since a lot of functional groups exist in polydopamine,such as amino,imino and 1-2-Benzenediol,polydopamine nanopariticles have great eletrophilicity,easily attached with multiple functional groups through covalent bonding or non-covalent bonding mostly.Acting as a median layer between the coated material and functional groups,polydopamine makes it possible to dope poly-materials in a facile and low-cost way.Moreover,polydopamine also have been studied in the field of battery energy,bio-imaging and drug delivery.So in chapter 1,we introduced the synthesis methods and characteristics of GQDs have been discussed.In chapter 2,a new photoluminescence biosensor for the detection of formaldehyde has been designed.Firstly,the hydrogen peroxide was added into N-GQDs resulting in large amount of carboxyl forming on the surface.The amino of melamine can react with the carboxyl groups of N-GQDs.As a result,melamine attached to GQDs surface and?-?stacking has effect on the photoluminescence recovery.After the specific reaction between melamine and formaldehyde,most of melamine were removed from GQDs surface.Therefore,the photoluminescence of GQDs was quenched again.Based on the change of photoluminescence with formaldehyde,we designed a novel biosensor for the detection of formaldehyde was successfully established.In chapter 3,a facile immunoassay for HSA detection is established with a complex of Fe₃O₄ NPs and polydopamine.Fe₃O₄ NPs were loaded in the core of the self-polymerized polydopamine shell.This structure maintains magnetic property of Fe₃O_4.Then adequate anti-HSA attached to polydopamine.HSA could be captured specifically by the anti-HSA on the surface of Fe₃O₄/polydopamine NPs.By competitive reaction with HSA-Au NPs,the novel Fe₃O₄/polydopamine NPs can be used to detect HSA based on immunoassay method with a satisfied result.