Assembly And Characterization Of Polystyrene Microspheres On Protein Chips

In this article,size controllable monodispersed polystyrene microspheres(PSMs)were prepared by changing the reaction conditions.PSMs films were assembled on glass substrates by Langmiur-Blogget technology,forming a new protein chip with high fixation rate of proteins?With the holding of adding Au nanopartieles and acidis silver colloids,the detective sensitivity of this glass substrates to proteins was improved for Surface-enhancement Raman Scattering mean.Size controllable monodispersed polystyrene microspheres were prepared by a dispersion polymerization with styrene as monomer.The effects of stirring speed.water-ethanol ratio,amount of emulsion agent,initiator and monomer on particle size distribution were discussed.The results showed that the polystyrene microspheres prepared by this method with the size from 100 nm to 800 nm were uniform and monodisperse,and the fluorescence spectra results showed that the exciter fluorescence in polystyrene is at 390 nm,which is independent of the diameter.The polystyrene microspheres were self-assembled and pretreated by LB technology on glass slides.A new protein chip was prepared after being modified by organisilane.The advantage of this chip is the full integration of the large specific surface area of PS and the strong bonding with proteins of organisilane.It is found that the protein fixation rate of the carrier was as high as 96%and the immune responsiveness was fine represented by signal-to-noise ratio,which was as high as 2.98.These parameters certified that the high throughput of proteins can be realized by modifying substrates on carriers.The detective sensitivity of these substrates to proteins is impaired by adding gold nanoparticles.Goat-anti-rabbit immunoglobulin(IgG)on substrates was detected by Raman technology.The peaks of IgG on PS substrates were relatively lower compared to the characteristic peaks of polystyrene.After adding gold nanoparticles on the PS substrates,the peak intensity of IgG was enhanced a little,but not obvious.In order to avoid the influence of the substrates,we added the acidic silver colloids.The sandwich structure of gold-proteins-silver was formed to enhance the detection sensitivity by SERS.The results showed that after adding acidic silver colloids,Raman intensity of proteins significantly raises about two orders of magnitude.More interestingly.after adding acidic silver colloids,only the Raman intensity of proteins is enhanced while the signs of other substrates are hidden in Raman spectra.By detecting different concentrations,we found that the minimum detectability of IgG on Au@PS substrates treated with acidic silver colloids can come to as low as 0.25 ng/L.SERS activities of Au@PS composites as raman probes were investigated by detecting methylene blue as a raman expression.The SERS signal of methylene blue absorbed on Au@PS was enhanced.We also studied optical properties of PS and Au@PS microspheres and their films.The results showed that the fluorescence intensity was increased obviously after being modified by gold nanoparticles.The reason was fluorescence quenching of gold nanoparticles to PSMs.