Nanobiotechnology for health-care

Biofunctionalization of semiconductor nanocrystals for the development of impediometric DNA sensors for early diagnosis of genetic diseases
Nesterenko E.O.1, Grynko D.O.1,2
1 Institute of Molecular Biology and Genetics of the NAS of Ukraine
Zabolotnogo str. 150, Kyiv-03143, Ukraine
2 V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine,
41, prospect Nauky, Kyiv-03680, Ukraine,		 E-mail: dgrynko@gmail.com 

The aim of the paper is the development of oligonucleotides biofunctionalization techniques for  nanostructured electrodes with an array of CdS nanocrystals on its surface. Optimization of the biofunctionalization procedure is necessary for the formation of bioselective sensor elements based on semiconductor nanocrystals, thiolated oligonucleotides and low molecular weight thiols for the detection of specific nucleic acid sequences.
Based on the analysis of the scientific literature on the methods of immobilization of oligonucleotides on the surface of semiconductor CdS nanocrystals we can draw a conclusion that the most promising method is the direct binding of thiolated oligonucleotides to CdS. Experimental studies of CdS nanocrystals arrays with using experimental methods such as electric impedance spectrometry, and piezoelectric nano-weighing were performed to identify thiol immobilization processes.
The fact of functionalization is proved and the optimal conditions for CdS nanocrystals are clarified. Electrochemical studies of the processes of formation of molecular shells of the modPh oligonucleotide on the surface of electrodes with different morphology are carried out. The fact of functionalization is proved and the optimal conditions for CdS nanocrystals are determined. 
The process of hybridization of oligonucleotide P1, which is complementary to modPh, on the surface of nanocrystals with the immobilized modPh layer is demonstrated. Range of experimentally tested P1 concentrations was from 0.001 nM to 100 nM in SSC buffer solution. Peculiarities of interaction are investigated for immobilized probe oligonucleotide modPh with complementary (P1), partially complementary (BCRex14) and non-complementary (npt02) nucleic acid sequences.