Wusi C. Maki

A novel homogeneous bioluminescence resonance energy transfer element for biomolecular detection with CCD camera or CMOS device

A novel optical signal element based on homogeneous bioluminescence resonance energy transfer (BRET) was developed for biomolecular detection. A fluorescent dye and alkaline phosphatase (AP) conjugate was used as a reporter and light-generation element for imaging detection platforms that use a CCD camera or CMOS chip-based devices. In the presence of a luminescence substrate, the energy from the first light emission of a bioluminescence enzymatic reaction was transferred to fluorescent dyes which were conjugated to an enzyme. This resulted in a second light emission with a shorter wavelength. The second light was localized at the position of target molecules without the diffusion problems present in current technology. To optimize energy transfer efficiency, the ratio of enzyme to fluorophore in the conjugates, the fluorescent dyes used in the conjugates and the luminescence substrates used for BRET were investigated. BRET was demonstrated by using both a CCD camera and a CMOS imaging device. Image spatial resolution was greatly improved compared with conventional chemiluminescence detection. This new signal element opens a door for the direct measurement of fluorescent signals on an imaging chip without an external light source and portable instrumentation normally required for the fluorescent detection of biomolecules.

An enzymatic bionanotransduction system for multianalyte biological detection

Aim:  The aim of this study was to develop and optimize a system for the detection of multiple biological targets in a single sample based on enzymatic bionanotransduction.

Radiation tolerant nano-FED biosensing for space application

A p-type polysilicon nanowire and silicon nano-channel combination based biosensor was developed, which has the potential to detect pathogens and thus protect crew safety aboard long-term manned flight programmes in high radiation space flights. This study outlines structures, which compose the biosensor, and demonstrates that the nano-device utilised herein is total dose radiation hardened. Highly doped polysilicon nanowires (30–100 nm) in nano-field-effect device (FED) were fabricated on silicon/silicon dioxide wafers and insulated with a thin polyimide layer. When the targeted gene, Escherichia coli DH5 alpha 16S rRNA, incubated on the device surface, the constant overall impedance increased or decreased depending on the electronic charge, mass and composition of the target molecule. All measurements were carried under 25 MeV S-Band linear accelerator followed by impedance measurements. Current sets of experiments show these nano-FED can form the basis of a robust, very sensitive handheld tool for pathogen detection in space application.

Hybridization Study of PNA-DNA in the Solution and Surface-Solution Interface for Biosensor Application

Abstract Hybridization of 12-mers peptide nucleic acid (PNA) to complementary DNA was investigated in solution and on gold surfaces. The oligomers were designed to improve mismatch discrimination and minimize formation of secondary structures. Thermal denaturation experiments indicate high thermal stabilities for PNA-DNA hybrid with T m values close to calculated values. Hybridization of PNA-DNA at 45°C and room temperature showed no difference. Hybridization on gold surface was also investigated with complementary and noncomplementary DNAs. The results show that 12-mer PNA and DNA hybridization at room temperature retained high specificity within ∼5 ng.

Non‐enzymatic aqueous peroxyoxalate chemiluminescence immune detection using a CCD camera and a CMOS device

A new method for non-enzymatic aqueous peroxyoxalate chemiluminescence (POCL) biomolecular detection using imaging chip-based devices has been developed. A water-soluble amide of oxalic acid was synthesized and used in the investigation and characterization of POCL immunodetection in an aqueous environment. Six fluorescent dyes commonly used in biological detection were tested, and the intensity of light generated from the aqueous POCL reactions was characterized in the liquid phase. Direct detection sensitivity comparisons between a standard fluorescent method and this POCL method were performed in both liquid and solid phases. Results showed that detection sensitivity using the POCL method is comparable to that of the fluorescent method. POCL biomolecular detection on a nitrocellulose membrane was also investigated using a charge-coupled device (CCD) camera. Again, POCL detection sensitivity proved to be comparable to that using the fluorescent detection method. In an application of aqueous POCL biomolecular detection, Staphylococcus aureus enterotoxin B (SEB) and its antibody were used to demonstrate immuno- and affinity detection. For further applications, such as DNA and protein arrays, simultaneous detection of biomolecules labelled with different fluorescent labels was investigated, using a complementary metal oxide semiconductor (CMOS) colour imaging chip.