Electrolyte-gated InGaZnO Thin-film Transistors For Bacterial Biofilm And DNA Sensing

Amorphous indium gallium zinc?IGZO?based thin film transistors?TFTs?have been widely used in biosensor applications due to their various advantages such as high-mobility,low-preparation temperature and high stability.Compared with common IGZO TFTs,electrolyte-gated IGZO TFTs have lower operation voltage?¹ V?,which is very suitable for highly sensitive biological detection and real-time monitoring.In this paper,we propose an electrolyte-gated IGZO TFT based biosensor.The detection of methicillin-resistant staphylococcus aureus?MRSA?biofilm and the drug screening of the MRSA biofilm inhibition and eradication based on this biosensor have been systematically studied,as well as the highly sensitive detection of DNA.Firstly,a very uniform and compact amorphous IGZO film was fabricated by pulsed laser deposition?PLD?,and it was applied to the fabrication of electrolyte-gated IGZO TFT.This electrolyte-gated IGZO TFT had high performance with low threshold voltage?about0.15 V?,and the on-off ratio reached a magnitude of 10⁶¹0⁷ when the gate voltage varied of within 1 V.In addition,this thin film transistor can keep stable for about 7 days in PBS solution and keep sensitive to cations with different concentrations.Therefore,we think the electrolyte-gated IGZO TFT is very suitable for biosensor applications.On the basis of electrolyte-gated IGZO TFT,we monitored the growing and eradicating process of MRSA biofilm in real time.The results showed that the growth rate of MRSA biofilm was rapid after 4 hours cultivation,and biofilm formation kept nearly the same after12 hours.After 24 hours,there was a shift of the transfer cure about 145 mV.In the monitoring of biofilm eradication,we found that the MRSA biofilm detached faster in the previous 6 hours under the influence of butenolide?BU?,and in the latter 6 hours the detachment was mild.After 12 hours BU treatment,86.9%of MRSA biofilm was eradicated.The test result of TFT was consistent with the growth rule detected by crystal violet staining and scanning electron microscopy.Therefore,the electrolyte-gated IGZO TFT based biosensor is reliable and suitable for MRSA biofilm detection.For further,we studied the drug screening of various antibiotics and furanone derivatives for MRSA biofilm inhibition and eradication.In the study of the effect of ten different antibiotics on biofilm inhibition,we found that ciprofloxacin hydrochloride,chloramphenicol,tetracycline hydrochloride,streptomycin sulfate,and vancomycin,with a low concentration?5?g/mL?,could efficiently inhibit biofilm formation.In the study of the effect of five different furanone derivatives on biofilm inhibition,we found that at the concentration of 50?g/mL,BU performed good while furanone C30 and furanone C56 only showed certain effect on biofilm inhibition.In the study of biofilm eradication,antibiotics could not eradicate mature MRSA biofilm.However,BU was able to eradicate biofilm efficiently at the concentration of200?g/mL,while furanone C30 and furanone C56 showed weak efficacy at the same concentration.Furthermore,we also proved that the combination of BU and vancomycin could enhance the biofilm eradication efficiency obviously than that of BU alone.Finally,the electrolyte-gated IGZO TFT based biosensor was also studied for highly sensitive and specific detection of DNA.By optimizing the testing process,the optimal detection performance of the device could be achieved when the DNA hybridization time was2 hours and the hybridization temperature was 37?.The DNA detection limit was 10^-13M?100 fM?,and it showed a good linear relationship within the concentration range of 10^-6M¹0^-13M.Moreover,the device had good selectivity and could effectively distinguish single base mismatch of DNA sequence.In conclusion,with simple device structure and high sensitivity,the electrolyte-gated IGZO TFT based biosensors can be supposed to be used for other bioanalysis,such as the detection of marine microbes,antigen-antibody,and cells.Furthermore,the device structure and testing principle make the TFT based biosensors easy to achieve trace detection and high throughput screening.