Miniaturized electrochemical detector as a tool for detection of DNA amplified by PCR

Influence of Magnetic Microparticles Isolation on Adenine Homonucleotides Structure

The electroactivity of purine and pyrimidine bases is the most important property of nucleic acids that is very useful for determining oligonucleotides using square wave voltammetry. This study was focused on the electrochemical behavior of adenine-containing oligonucleotides before and after their isolation using paramagnetic particles. Two peaks were detected-peak A related to the reduction of adenine base and another peak B involved in the interactions between individual adenine strands and contributes to the formation of various spatial structures. The influence of the number of adenine bases in the strand in the isolation process using paramagnetic particles was investigated too.

Integrated chip electrophoresis and magnetic particle isolation used for detection of hepatitis B virus oligonucleotides

Rapid and sensitive detection is a key step in the effective and early response to the global hazard of various viral diseases. In this study, an integrated isolation of hepatitis B virus (HBV)-specific DNA fragment by magnetic nanoparticles (MNPs) and its immediate analysis by microchip CGE was performed. Microfluidic CE chip was used to accommodate the complete process of viral DNA isolation by MNPs including hybridization and thermal denaturation followed by CE separation. Beforehand, calibration curves of HBV fragments were constructed. For isolation by MNPs, specific streptavidin-biotin interaction was used to bind complementary HBV fragment to magnetic particles. After analysis of isolated HBV by regular MNPs method, innovative approach was performed. The commercial CE chip (Bio-rad) was successfully used to execute HBV fragment isolation. Detection using LIF with detection limit of 1 ng/mL was accomplished.

Microfluidic tool based on the antibody-modified paramagnetic particles for detection of 8-hydroxy-2'-deoxyguanosine in urine of prostate cancer patients

Guanosine derivatives are important for diagnosis of oxidative DNA damage including 8-hydroxy-2'-deoxyguanosine (8-OHdG) as one of the most abundant products of DNA oxidation. This compound is commonly determined in urine, which makes 8-OHdG a good non-invasive marker of oxidation stress. In this study, we optimized and tested the isolation of 8-OHdG from biological matrix by using paramagnetic particles with an antibody-modified surface. 8-OHdG was determined using 1-naphthol generated by alkaline phosphatase conjugated with the secondary antibody. 1-Naphthol was determined by stopped flow injection analysis (SFIA) with electrochemical detector using a glassy carbon working electrode and by stationary electrochemical detection using linear sweep voltammetry. A special modular electrochemical SFIA system which needs only 10  μL of sample including working buffer for one analysis was completely designed and successfully verified. The recoveries in different matrices and analyte concentration were estimated. Detection limit (3 S/N) was estimated as 5  pg/mL of 8-OHdG. This method promises to be very easily modified to microfluidic systems as "lab on valve". The optimized method had sufficient selectivity and thus could be used for determination of 8-OHDG in human urine and therefore for estimation of oxidative DNA damage as a result of oxidation stress in prostate cancer patients.