Gold nanoparticles enhanced fluorescence for highly sensitive biosensors based on localized surface plasmon resonance applied in determination C-reactive protein

Introduction: C-reactive protein (CPR) is known as an inflammation marker related to numerous pathology. Optical biosensor based on the fluorescence dyed is widely used in diagnosis. There are still limitations on the fluorescence signal detection due to the photobleaching effect. The localized surface plasmon resonance (LSPR) performed by gold nanoparticles (Au NPs) is testified for the enhancement of photo-signal gathered from the dye molecules. Methods: In this study, Au NPs were used for their significant optical properties and biocompatibility additionally. The seed-mediated synthesis method provided stable NPs with all the essential qualities. A series of modification steps were done on a glass substrate before the bio-bonding for fluorescence-based sensing by a transmission mode (T-mode) detection system which is introduced for the first time in Viet Nam. Results: The synthetic Au NPs in nanosphere structure evinced the absorbance at a maximum wavelength is 521 nm. All the followed alterations showed the accomplishment in forming the in need linking proved through the basic analysis methods. Finally, CRP with the Alexa 488 dye was observed for average at 4.8 folds of enhancement factor compared between the Au NPs coating and non-coating substrate detected by the T-mode system. The low coefficient of variation at under 0.7% appeared for the repeatability and stability of this sensor. Conclusion: The completely modern approach of the T-mode system combined with the LSPR applied in fluorescence sensors enhanced is developed successfully. Also, the future prospect of this designed sensing method is promising by changing the materials' structures and ingredients. Keywords: LSPR, gold nanoparticles, fluorescence enhancement, C-reaction protein, optical biosensors