Development and Practical Application of Biosensors Based on the Nanostructured Silicon N. Starodub * , N. Mel’nichenko ** , A. Shmireva *** , L.N. Shuljak * * National University of Life and Environmental Sciences, 15 Herojev Oboroni Str., Kiev, 03041 Ukraine, nikstarodub@yahoo.com ** Taras Shevchenko Kiev National University, Kyiv, Ukraine *** National Technical University of Ukraine “KPI”, Kyiv, Ukraine ABSTRACT Principle of the new instrumental methods of the biochemical diagnostics of the development of the autoimmune status in diabetics through the registration of the formation of the specific immune complexes of insulin- anti-insulin antibody (Ag-Ab) and vice versa with the help of the biosensor based on the structured nano-porous silicon (sNPS) is proposed. In spite of the traditional methods of the proposed approach may provide the express control as in special laboratory and domiciliary with the simple procedure of analysis fulfillment and with the minimum consumption of the materials. Keywords: immune biosensor, nanostructured silicon, photoluminescence, diabetes, anti-insulin antibody, control 1 INTRODUCTION Early we have developed biosensor based on the surface plasmon resonance (SPR) for the express revealing of some biochemical quantities [1-3]. The developed SPR based biosensor showed high working characteristics in the respect of the sensitivity, simplicity and rapidity of the analysis fulfilment. Nevertheless, it has some disadvantages and at first they connected with the high cost of the chips and the necessity to use not simple procedure of the preliminary transducer surface treatment from one site. From other site the SPR recorder has very high price and don’t allow fulfilling a number repeated analysis. To overcome some of these disadvantages we try to apply others types of the optical biosensors for solving of the problem of the express biochemical diagnostics of auto- immune status of dibetics. Among others such biosensors that based on the nano-porous structured silicon (sNPS) attract an especial attention. Similar biosensors based on the sNPS were developed early by us for the control of the myoglobin level in the blood and for the monitoring of the bacterial protein in the air of environment [18-22]. The registration of the specific signal was made by the measurement of the changes of the phtoluminescence (PhL) intensity. This approach met the practice requirements regarding the simplicity, sensitivity, selectivity and rapidity of the analysis fulfilment but the stability of the sNPS was very low and the signal registration demanded complicated device. To continue our investigations in this field we proposed a new variant of biosensor based on the sNPS. The main our attention was paid to the determination of insulin (I) and anti-insulin antibodies (anti-I Ab) level at the control of the autoimmune state development in diabetics. 2. EXPERIMENTAL The main problem which should be solved at the application of the sNPS as the transducer in the biosensors is providing of the PhL stability during long time. It depends on the sNPS structure, the content of the inter phase layers and the porosity level. These abilities of the sNPS may be determined by the method and the regimes of its forming. Our investigations of the sNPS shown that the samples prepared by the method of the chemical etching have the stable ChL, conductivity and photoconductivity characteristics which were preserved during several years. The layers of the sNPS for the photoresistors were obtained by the chemical etching of the monocrystalline silicon in the solution of HF and HNO 3 . Method of the chemical etching is most adapted to the mass manufacturing and is interested for the preparation of the thin layers of the sNPS for the devices. Nevertheless, at the application of this method there is necessary to solve problems connected with the reproducibility and homogeneity of the layers. So, due to changes of the surface state and the etching content there is possible to have the thin homogeneous luminescent layers of the porous silicon (PS) with the high level of the reproducibility obtained by the chemical method and without the application of the electrical field. We used the boron doped single-crystal silicon with the square wafers about 0.3 mm of thickness and with the resistance of 1 Ohm*cm. sNPS layers were prepared by the chemical way and their thickness were changed from 3 up to 60 nm. The parameters of the technological process at the chemical modification of the single-crystal silicon surface were controlled by the scanning electronic microscopy (SEM) and the chemical content – Auger electronic spectroscopy (Fig. 1). Preliminary it was developed the optimal way for the formation of the ohmic contact on the surface of the sNPS from alumina and indium by the magnetron sputtering with the application of NSTI-Nanotech 2010, www.nsti.org, ISBN 978-1-4398-3415-2 Vol. 3, 2010 114