Immobilization Of Nucleic Acid Aptamers On Gold Substrate And Its Bioassay Properties

Bacteria as a microorganism are widely distributed in ecosystems,and some of them become a hinder in the development of social,economicand and human health.At present,the detection of pathogenic bacteria by traditional detection methods has certain limitations,prompting people to develop rapid,specific,robust and highly sensitive methods to detect microorganisms to ensure public health.Because the high sensitivity,no need to mark,less sample to be tested and dynamic real-time analysis,surface plasmon resonance(SPR)technology has become a hot research topic.In this study,a nucleic acid aptamer was used as a probe to fixed to a gold-plated ZF13 glass by a strong interaction of oligo-.adenine sequence with gold.there are two ways to obtain the SPR chip with high graft density:one is to change the ionic strength in the buffer solution;the other is to replace the chloride ion in the buffer solution with bromide ion.By varying the SPR angle shown by the surface plasmon resonance spectrometer,the effective thickness of the probe can be simulated to convert the lateral density of the probe on the gold surface.X-ray photoelectron spectroscopy(XPS)can be used to supplement the graft density of the chip surface.In terms of bacterial detection:Firstly,the high-graft density SPR chip prepared in several ways was tested for E.coli,and the signal intensity was compared to obtain the SPR chip with the highest sensitivity,and the detection limit was determined.The SPR chip with high sensitivity was then used to detect Staphylococcus aureus and its detection limit was determined.The bacterial adsorption on the surface of the gold piece was characterized by scanning electron microscopy.The results show that the self-assembly of the gold surface can be controlled by changing the ionic strength in the buffer solution,and the smaller ionic strength is favorable for self-assembly.E.coli and Staphylococcus aureus were successfully detected by using Aptamer as a probe with detection limits of 9.34×10 4 CFU/ml and 3.87×10 5 CFU/ml,respectively.