Abstract
Information about the characteristics of measuring chips according to their storage conditions is of great importance for clinical diagnosis. In our present work, we have studied the capability of chips to detect nanowire biosensors when they are either freshly prepared or have been stored for either one or two years in a clean room. Potential to detect DNA oligonucleotides (oDNAs)—synthetic analogues of microRNAs (miRNAs) 198 and 429 that are associated with the development of prostate cancer (PCa)—in buffer solution was demonstrated using a nanowire biosensor based on silicon-on-insulator structures (SOI-NW biosensor). To provide biospecific detection, nanowire surfaces were sensitized with oligonucleotide probes (oDNA probes) complimentary to the known sequences of miRNA 183 and 484. In this study it is demonstrated that freshly prepared SOI-NW biosensor chips with n-type conductance and immobilized oDNA probes exhibit responses to the addition of complimentary oDNAs in buffer, leading to decreases in chips’ conductance at a concentration of 3.3 × 10−16 M. The influence of storage time on the characteristics of SOI-NW biosensor chips is also studied herein. It is shown that a two-year storage of the chips leads to significant changes in their characteristics, resulting in “inverse” sensitivity toward negatively charged oDNA probes (i.e., through an increase in chips’ conductance). It is concluded that the surface layer makes the main contribution to conductance of the biosensor chip. Our results indicate that the detection of target nucleic acid molecules can be carried out with high sensitivity using sensor chips after long-term storage, but that changes in their surface properties, which lead to inversed detection signals, must be taken into account. Examples of the applications of such chips for the detection of cancer-associated microRNAs in plasma samples of patients with diagnosed prostate cancer are given. The results obtained herein are useful for the development of highly sensitive nanowire-based diagnostic systems for the revelation of (prostate) cancer-associated microRNAs in human plasma.
Highlights
Prostate cancer (PCa) is a malignant tumor of the prostate, whose etiology and pathogenesis are still understudied
Our present research has demonstrated the possibility to detect DNA oligonucleotides—the synthetic analogues of prostate cancer (PCa)-associated miRNAs—in buffer solution, using silicon-on-insulator nanowires (SOI-NWs) biosensor chips
We have investigated the possibility of biospecific detection of model DNA oligonucleotides complimentary to a probe for PCa-associated miRNAs
Summary
Prostate cancer (PCa) is a malignant tumor of the prostate, whose etiology and pathogenesis are still understudied. Prostate cancer has been ranked second after lung cancer among other malignant tumors in men across Russia over the past decade. The incidence rate of prostate cancer in Russia has tripled from 19.01 to 57.22 cases per 100,000 people over the past 15 years from 2001 to 2015 (according to the National Medical Research Radiological Center of the Ministry of Health of the Russian Federation). Such a difficult situation is mainly associated with late diagnosis of the disease [1]. The development of novel methods for PCa diagnosis at an early stage is an important field of research
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