Organic Field Effect Transistor Chiral Sensors Based On ?-Cyclodextrin And Hexadecafluoro Copper Phthalocyanine

Chiral discrimination has become an area of considerable interests in chemistry and biological science as well as food,medical and modern pharmaceutical industry.Because different enantiomers have identical physical and chemical properties but often exhibit different biological,pharmacological,toxicological and metabolism activities in living systems.Organic filed effect transistors?OFETs?can provide ideal sensing platform because of their rapid response,high sensitivity,on-line analysis,and potential applications in integrated microarray chips.By far,OFET sensors have been widely implemented for sensing of gases,pH,humidity,ions,glucose,amino acids,pressure,antibodies and DNA et al.However,there are limited works reporting chiral organic filed effect transistors?COFETs?since the enantiomer discrimination is difficult to achieve via organic conductive materials in OFETs.It is highly desirable to develop COFETs to afford fast and sensitive quantitative real-time chiral analysis.Herein,aiming at sensing the subtle change of weak interactions in the process of chiral discrimination,we constructed two effective chiral sensors based on OFETs.Firstly,a copper hexadecafluorophthalocyanine(F₁₆CuPc)OFET with?-CDs assembled on the exposed channel was constructed.The morphology and composition of the active layer modified by chiral recognition layers were characterized by AFM and XPS.It was shown that the chiral recognition molecule?-CD was successfully immobilized on the surface of the active layer.The amount of?-CD assembled on semiconductive layer was studied and the optimal concentration was 5 mmol/L.To gurantee stable operation in analytes solution,the surface of the active layer is passivated with PVB,the passivation layer and a chiral recognition layer integrated transistor are formed by doping the PVB with?-CD.The chiral sensor explored the optimal PVB resin film drop concentration of 15 mmol/L.The fabricated COFET sensor demonstrates good field-effect response that enables direct discrimination of eight racemic chemicals?phenylalanine,phenylpropionic acid,phenyllactic acid,mandelic acid,tartaric acid,chloromandelic acid,1,1,2-triphenyl-1,2-ethanediol,chiro inositol?.The influence of analyte structure and?-CD concentration on the sensing process was also investigated.Fast and real-time qualitative and quantitative detections of enantiomers in aqueous solution at nanomolar concentration were achieved.The chiral sensing ability of the COFET was further evaluated with“real world”pharmaceutical compound ibuprofen.The calibration curve was fitted using the Langmuir isotherm model with 1:1 stoichiometry and the affinity constant K for L-Phe and D-Phe is determined as?2.03±0.53??10⁸ and?6.82±1.83??10⁷ M^-1,respectively.The higher affinity between the L-Phe and CDs compared with its D-form suggestes that the complexation of L-Phe was more favorable over D-Phe,which is consistent with the more obvious sensor response to L-form.It is further proved that the constructed COFET can quantitatively distinguish the mixture of phenylalanine and ibuprofen,indicating that it has the potential to realize quantitative chirality analysis in a complex system.