Multifunctional biosensor based on ZnO nanostructures

Abstract

The present invention provides the multifunctional biological and biochemical sensor technology based on ZnO nanostructures. The ZnO nanotips serve as strong DNA or protein molecule binding sites to enhance the immobilization. Patterned ZnO nanotips are used to provide conductivity-based biosensors. Patterned ZnO nanotips are also used as the gate for field-effect transistor (FET) type sensors. Patterned ZnO nanotips are integrated with SAW or BAW based biosensors. These ZnO nanotip based devices operate in multimodal operation combining electrical, acoustic and optical sensing mechanisms. The multifunctional biosensors can be arrayed and combined into one biochip, which will enhance the sensitivity and accuracy of biological and biochemical detection due to strong immobilization and multimodal operation capability. Such biological and biochemical sensor technology are useful in detection of RNA-DNA, DNA-DNA, protein-protein, protein-DNA and protein-small molecules interaction. It can be further applied for drug discovery, and for environmental monitoring and protection.

1 . A method for detecting biological molecules comprising: 
 providing a conductivity mode ZnO nanotip biosensor including ZnO nanotips having binding sites including at least one biological probe;    exposing said binding site to a sample having a potential target molecule;    detecting a change in conductivity in said ZnO nanotips, wherein said change in conductivity being indicative of a chemical and biochemical reaction of the potential target molecule and the biological probe.    
   
   
       2 . The method of  claim 1  wherein said ZnO nanotips serve for immobilization of DNA or protein molecules to enhance detection of the corresponding targeted DNA, protein or small biomolecules.  
   
   
       3 . The method of  claim 2  wherein surface charge of the tips changes due to a biological and biochemical reaction of the immobilized DNA, protein molecules or small biomolecules on the ZnO nanotips with the corresponding targeted DNA or protein molecules.  
   
   
       4 . The method of  claim 1  wherein said biosensor operates in multiple modes due to multifunctional material properties of the ZnO nanotips such as semiconducting, piezoelectric, or transparent and combinations thereof.  
   
   
       5 . A method for detecting biological molecules comprising: 
 providing a semiconductor FET biosensor including ZnO nanotips having binding sites including at least one biological probe wherein said ZnO nanotips are deposited on gate region of the FET;    exposing said binding site to a sample having a potential target molecule;    detecting a change in conductivity in said ZnO nanotips, wherein said change in conductivity being indicative of a chemical and biochemical reaction of the potential target molecule and the biological probe.    
   
   
       6 . The method of  claim 5  wherein said ZnO nanotips serve as DNA or protein molecule binding sites to detect presence of the DNA, protein molecules or small biomolecules to be targeted.  
   
   
       7 . The method of  claim 6  wherein upon said detection of the targeted molecules, a change occurs in the surface charge of the ZnO nanotip-gate resulting in a change in the channel conductance.  
   
   
       8 . The method of  claim 5  wherein said FET biosensor includes Si MOSFET.  
   
   
       9 . The method of  claim 5  wherein said FET biosensor includes GAs MESFET.  
   
   
       10 . A method for detecting biological molecules comprising: 
 providing a ZnO based SAW sensor including ZnO nanotips having binding sites including at least one biological probe;    exposing said binding site to a sample having a potential target molecule;    detecting a decrease in phase velocity under said ZnO nanotips, wherein said decrease in phase velocity being indicative of a chemical and biochemical reaction of the potential target molecule and the biological probe.    
   
   
       11 . The method of  claim 10  wherein upon binding of the targeted molecules with said ZnO nanotips causes a mass loading on a SAW path resulting in said decrease of phase velocity under said ZnO nanotips.  
   
   
       12 . The method of  claim 10  wherein said ZnO nanotips serve as DNA, protein molecule or small biomolecule binding sites.  
   
   
       13 . The method of  claim 12  wherein said ZnO nanotips enhance binding strength and immobilization of the targeted DNA, protein molecules or small biomolecules.  
   
   
       14 . A method for detecting biological molecules comprising: 
 providing a ZnO based SAW sensor including ZnO nanotips having binding sites including at least one biological probe;    exposing said binding site to a sample having a potential target molecule;    detecting a change in UV absorption, wherein said change in UV absorption being indicative of a chemical and biochemical reaction of the potential target molecule and the biological probe.    
   
   
       15 . The method of  claim 14  wherein said ZnO nanotips serve as DNA, protein molecule or small biomolecule binding sides.  
   
   
       16 . The method of  claim 15  further includes illuminating UV light on said sensor and the change in UV absorption is detectable due to a biological and biochemical reaction of sensor layer of immobilized DNA, protein molecules on the ZnO nanotips with targeted DNA, protein molecules or small biomolecules.  
   
   
       17 . A method for detecting biological molecules comprising: 
 providing a ZnO based BAW sensor including ZnO nanotips having binding sites including at least one biological probe;    exposing said binding site to a sample having a potential target molecule;    detecting a change in resonance frequency of the sensor, wherein said change in resonance frequency being indicative of a chemical and biochemical reaction of the potential target molecule and the biological probe.    
   
   
       18 . The method of  claim 17  wherein upon binding of the targeted molecules with immobilized biomolecules on said ZnO nanotips causes a mass loading on the BAW resulting in the change in the resonance frequency of the sensor.