Nucleic Acid Engineering (2017 spring)
Research area
- Nucleic acid bioengineering
- Microarray technology
- Electrochemical diagnostics
- Nanobiotechnology
Current project
HOME > Research > Research area > Nanobiotechnology



1. Nanobiosensor


Magnetic nanoparticles (MNPs), which were generally recognized to be biologically and chemically inert, have recently been reported to show intrinsic peroxidase activity (Gao et al., Nat. Nanotechnol. 2, 577-583, 2007). In order to accelerate and widen the utility of MNPs as next-generation alternatives to peroxidases, we have developed a nanostructured multi-catalyst system that consists of MNPs and an oxidative enzyme simultaneously entrapped in large pore sized mesoporous silica for convenient colorimetric detection of biologically important target molecules. The results of the investigations demonstrate that the multi-catalyst system, incorporating various oxidases such as glucose oxidase, cholesterol oxidase, galactose oxidase, or pyruvate oxidase, has high selectivities and sensitivities for the detection of the corresponding target molecules along with excellent reusabilities and highly enhanced stabilities. Since the current system enabled rapid visual detection of target molecule in a quite reliable and cost-effective manner together with long-term stability, it should find practical applications

in facility-limited or POCT-environments. It is envisaged that future applications of this technology will range from

biosensors to multi-catalyst reactors.





2. Cell-based biosensor


Determining amino acid concentrations is of broad interest in numerous aspects of biological research, clinical diagnosis

and medicine, food technology, etc. In particular, measurement of free amino acid concentrations in physiological fluids such as blood, cerebrospinal fluid (CSF), and urine has been used as biochemical indicators of newborn errors of metabolism (aminoacidopathies), nutritional status, and therapeutic monitoring. Thus, there is significant incentive to develop a new approach to enable more convenient, reliable, and economical detection of amino acid concentrations. Along these lines, we have developed a solid-phase multiplexed amino acid diagnostic array, which comprises 16 different amino acid E. coli auxotrophs yielding rapid, specific, and sensitive cell growth as a direct response to the concentration of corresponding amino acids. To obtain the resulting cell-based signal, bioluminescence-based measurement of cell density was employed. As a result, an amino acid specific, concentration-dependent luminescence response is produced. The clinical validity of this approach was verified by reliably determining the concentrations of amino acids in newborn human blood specimens.

Such an approach may also be extended to other rapid cell-based sensing of simple metabolites that are relevant

to other clinical disorders, including homocysteine, galactose, various vitamins, folic acid, and lipids.





       3. Polydiacetylene (PDA)-based colorimetric biosonsor


Colorimetric biosensors possess an inherent advantage in that they do not require any instrumentation

or power  supply, making them ideal for low-resource settings. Among the many approaches that have been

developed, polydiacetylene (PDA) is particularly interesting because it yields a significant chromatic change from

blue to red in response to a variety of external stimuli such as temperature, pH and molecular recognition.

We have developed the colorimetric method for the detection of nucleic acids, based on ionic interactions

by PDA liposomes. Amine-modified PDA sensors showed a dramatic color change from blue to red upon the

addition of nucleic acids amplified by using the polymerase chain reaction (PCR) due to the stimuli caused by

ionic interactions between the positively charged PDA and negatively charged phosphate backbone of the

nucleic acids. By using the PDA-based colorimetric sensor, nucleic acids amplified by common PCR reaction,

whose typical concentration is around 100 nM, was readily detected. Since implementation of this universal

colorimetric method is simple, rapid and does not require any sophisticated instrumentation,

it should find its great applications in the area of genetic diagnosis.