ABSTRACT
Telomerase overexpression has been associated directly with cancer, and the enzyme itself is recognized within the scientific community as a cancer biomarker. BIDEA's biosensing strip (BBS) is an innovative technology capable of detecting the presence of telomerase activity (TA) using electrochemical impedance spectroscopy (EIS). This BBS is an interdigital gold (GID) electrode array similar in size and handling to a portable glucose sensor. For the detection of the biomarker, BBS was modified by the immobilization of a telomere-like single strand DNA (ssDNA) on its surface. The sensor was exposed to telomerase-positive extract from commercially available cancer cells, and the EIS spectra were measured. Telomerase recognizes the sequence of this immobilized ssDNA probe on the BBS, and the reverse transcription process that occurs in cancer cells is replicated, resulting in the ssDNA probe elongation. This surface process caused by the presence of TA generates changes in the capacitive process on the electrode array microchip surface, which is followed by EIS as the sensing tool and correlated with the presence of cancer cells. The telomerases' total cell extraction protocol results demonstrate significant changes in the charge-transfer resistance (R ct) change rate after exposure to telomerase-positive extract with a detection limit of 2.94 × 104 cells/mL. Finally, a preliminary study with a small set of "blind" uterine biopsy samples suggests the feasibility of using the changes in the R ct magnitude change rate (Δ(ΔR ct/R cti)/Δt) to distinguish positive from negative endometrial adenocarcinoma samples by the presence or absence of TA.
ABSTRACT
One of the most challenging problems when trying to recycle urine for different purposes is the removal of urea. In this project we studied an ureolysis system using the bacterium Proteus vulgaris for the transformation of urea to ammonia and its subsequent oxidation to nitrogen at a Pt working electrode. Our system was tested under different pH, microbial reaction times, and urea and bacteria concentrations. Our results indicate that a pH8 is optimal for the combined Proteus vulgaris urease activity and the ammonia oxidation reaction at a Pt electrode. The reaction time and concentration dependence on the ammonia oxidation reaction current densities was also studied. Results showed limited ammonia oxidation under high urea concentrations in ~2.5×109cfu/mL Proteus vulgaris in synthetic urine.
