Pornpimol Sritongkham

Inkjet-printed graphene-PEDOT:PSS modified screen printed carbon electrode for biochemical sensing

In this work, a novel method for electrode modification based on inkjet-printing of electrochemically synthesized graphene-PEDOT:PSS (GP-PEDOT:PSS) nanocomposite is reported for the first time. GP-PEDOT:PSS dispersed solution is prepared for use as an ink by one-step electrolytic exfoliation from a graphite electrode. GP-PEDOT:PSS layers are then printed on screen printed carbon electrodes (SPCEs) by a commercial inkjet material printer (Dimatrix Inc.) and their electrochemical behaviors towards three common electroactive analytes, including hydrogen peroxide (H2O2), nicotinamide adenine dinucleotide (NAD+/NADH) and ferri/ferro cyanide (Fe(CN)63−/4−) redox couples, are characterized. It is found that the oxidation signals for H2O2, NADH and K2Fe(CN)6 of PEDOT:PSS modified and GP-PEDOT:PSS modified SPCEs are ∼2–4 and ∼3–13 times higher than those of unmodified SPCE, respectively. In addition, excellent analytical features with relatively wide dynamic ranges, high sensitivities and low detection limits have been achieved. Therefore, the inkjet-printed GP-PEDOT:PSS electrode is a promising candidate for advanced electrochemical sensing applications.

QCM-Based DNA biosensor for Salmonella typhimurium detection

This work demonstrated a QCM biosensor for the detection of Salmonella typhimurium using the specific DNA probe. A thiol DNA probe was immobilized onto quartz surface coated with gold through self-assembly via Au-S bonding formation. 6-mercapto-1-hexanol (MCH) was used as blocking reagent against non-specific DNA binding. Target DNA with 94 bp (single strand) was hybridized with its probe resulted in a decrease in the resonance frequency of the QCM biosensor. It was demonstrated that the QCM biosensor could recognize the target DNA sequence within 40-70 min. The frequency shift signal was distinguishable along with the increase of target concentration from 0.1 to 1.0 μM.

Genotyping of α-thalassemias by the colorimetric nanogold probes.

BACKGROUND The novel colorimetric nanogold probe was created to genotype subgroups of the mostly found α-thalassemias. They are α-thalassemia 1 (SEA and THAI deletion) and α-thalassemia 2 (3.7-kb and 4.2-kb deletion). METHODS The genotyping was performed by two-steps hybridizations. First step was hybridization of target DNA with the nanogold mixed probes of either α-thalassemia 1 or α-thalassemia 2. No hybridization in both reactions showing blue color indicated absence of abnormal genes causing these α-thalassemias. Positive reaction showing either red or purple color was further analyzed in second hybridization with the nanogold single probe. Positive of α-thalassemia 1 was genotyped with the single probes of both SEA and THAI deletion while those of α-thalassemia 2 were genotyped with both 3.7-kb and 4.2-kb deletion. RESULTS Genotypic potency of the nanogold mixed and single probes was evaluated using both known diagnosed and suspected clinical samples. The results by naked eye were consistence with those analyzed by standard agarose gel electrophoresis. CONCLUSIONS Potency of the colorimetric nanogold α-thalassemia probes was accurate, precise, sensitive, specific, simple, cheap and field applicable. Color reaction was simply visualized by naked eye. This development is an example of colorimetric molecular diagnosis which can be applied in any genetic detection.

Integration of CNT-Based Chemical Sensors and Biosensors in Microfluidic Systems

We describe and discuss the different components necessary for the construction of a microfluidic system including micropump, microvalve, micromixer and detection system. For the microfluidic detector, we focus on carbon nanotube (CNTs) based electrochemical sensors. The properties, structure and nomenclature of CNTs are briefly reviewed. CNT modification and the use of CNTs in conjunction with electrochemical microfluidic detection are then extensively discussed.