Separation Of Chiral Amino Acids Based On Functionalized Gold Nanotubes

Nanochannels are the pores or tubules with diameter from0.1to100nm.Because of their highly specific surface area and special nano-structure, nanochanneitechnolgy has benn extensively used in the ifled of separation and analysis. Theseparation and detection of chemical substances will be greatly promoted because thecharacteristics of nanochannels can be significantly changed by chemicalmodification.Chiral molecules are racemic mixtures of enantiomers. The amino acidenantiomers are important compounds in the ifelds of medicinal chemistry,agricultural chemistry，food chemistry and biochemistry. Amino acids show nearlyidentical structures, physical and chemical properties, but they often exhibitsignificant differences in biological and pharmacological activity. The separation ofenantiomers is an arduous and challenging task. Currently, enantioseparations aretypically performed by high performance liquid chromatography and capillaryelectrophoresis, the separation of chiral substances based on the nanochanneitechnology is significant.Surface-enhanced Raman scatteirng (SERS) spetroscopy, a sensitive,andpowerful analytical tool, has been used for the chemical and biological detection.Therefore, it is siginificantly important for the separation and detection of chiralsubstances based on the nanotubules and surface-enhanced Raman scatteringspectroscopy.Details are presented in this research work as follows:(1)An electroless deposition method was used to deposit gold within pore wallsof the porous polycarbonate membrane template or alumina membrane. Themophology of the gold nanochannei array with different diameters werecharacterized by scanning electron spectroscopy and electrochemical methds. Thenanochannels with high reproducibility prepared by the proposed method in this paperare controlled in size of the pore and can be repeatedly used.(2)The lysozyme protein with chiral site can identiyf the D-,4L-isomer. Gold and lysozyme has a strong force. This chapter studied the adsorption betweenlysozyme and gold nanoiubule membrane surface under different conditions.(3)Using the gold nanotubule membrane as the carrier. Lvsozvme protein，achiral selector providing a chiral environment, was modified in the pores of thenanotubes. Based on the differences of transport rate between the targets within thenanopore, the chiral D,L-tr\ptophan can be separated. The effects of pH value of thesolution，ionic concentration of the solution, the pore size of the nanochannels and theconcentration of the target substance on the separation of chiral DX-uypiophan wereinvestigated.(4)Using the gold nanotubule membrane as the can*iei\the gold nanochannelswas modified with chitosan by a classical HDC/NHS coupling reaction, and thenanochannels modified with chitosan showed a chiral environment. The separation ofhistidine enantiomer based on modiifed gold nanochannels membrane was discussed.To increase the sensitivity of detection of these two substances, Ag nanopanicles wasused to enhance the SERS activity. The results showed that the chitosan-modifiedgold nanochannels can be used to separate chiral histidine based on this uniqueselective nanochannel membrane.