Earticle

We fabricated DNA templated gold nanowire bridges on nanogap electrode arrays for electric detection of synthetic target DNA (HIV virus partial gene). The nanogap was fabricated using anisotropic silicon wet etching on SOI wafer substrate (bottom gap size was about 60nm). Target DNA of seven synthetic single-stranded DNA oligomers were designed for hybridization with capture DNAs immobilized on the nanogap gold electrode. Total 80 nm length double-stranded target DNA are connected on the two electrode nanogap forming many bridges along with the nanogap electrode. For electric detection of the DNA bridges, DNA templated conducting gold nano wire was fabricated with positive charged gold seed particles (1.5nm) and gold seed enhancement procedure on the DNA bridges. We detected increased electric signal extremely at the HIV capture DNA immobilized nanogap electrode after fabrication of conducting gold nanobridge.

We have formerly described a rapid and novel method of forming a suspended lipid bilayer by dispensing a buffer droplet into the oil and water. The technique of forming lipid bilayer through dispensing a buffer droplet has ameliorated laborious and technical requirements. Here, we demonstrate an innovative technique, implementing previous method of producing a lipid bilayer from a falling droplet, to make lipid bilayer storable. The technique of flash freezing the chamber using -80℃ methanol has enabled long-term storage of bilayer lipid membrane. Use of 4:1 mixture of hexadecane and n-decane with 1% asolectin ensures high freezing point, which is the optimal condition for capturing an aqueous droplet while it’s in the oil phase. Once frozen, the chamber is stored in a freezer below 0℃. In the thawing process, the gravity automatically draws the droplet down to the interface, where monolayer has formed, to initiate lipid bilayer formation, as reported in our previous work. This novel method has shown a potential not only for automated lipid bilayer formation, but also long-term storable lipid bilayer that could relieve laborious and expert task. Moreover, lipid bilayer technique, as an alternative mean to measure ion channel can be promoted extensively. Storing lipid bilayer precursor frozen with ion channels will automatically drive membrane formation and ion channels will subsequently be incorporated. This system as a whole can be automated, leading to fully labor free experiment that can be carried out in any place, increasing the accessibility to bilayer measurements This golden technique can finally provide applications for nanobio sensors, drug screening, and DNA sequencing.

Human can discriminate numerous odors with combinatorial olfactory receptor codes among odorant molecules. In the case of some odorant molecules, even same odorant smells differently depending on its concentration. In this study, we have verified that this concentrationdependent perception is caused by the change in the combination of activated receptors. The receptor activation was monitored by measuring the calcium signal in HEK-293 cells expressing various human olfactory receptors. Indole and amyl butyrate were used as model odorant molecules. The indole is the odorant which smells differently depending on the concentration, while the amyl butyrate is the odorant which smells similarly even with the different concentration. The combination of the activated receptors was changed with the concentration of indole, while it was barely changed with the concentration of amyl butyrate. From this experiment, we could verify the cause of concentration-dependent changes of odor perception.

A higher level of homocysteine (Hcy) than 15 μM known as hyperhomocysteinemia is an implication of cardiovascular disease as well as Alzheimer’s disease, pregnancy complications and osteoporosis. Currently, there are growing interests in the development of simple and reliable assay for Hcy. Herein, the new Hcy assay employing two E. coli auxotrophs immobilized within respective wells of a 96-well plate was established to quantitatively determine Hcy. By transformation of bioluminescent reporter gene into these auxotrophs, termed Met5 and MetB auxotrophs which grew only in the presence of methionine (Met) and both Met and Hcy, respectively, facile measurement of the cell growth was easily performed. To determine Hcy concentration in unknown sample, the luminescent value corresponding to the Met concentration determined by Met5 auxotroph was subtracted from the total value corresponding to both Hcy and Met concentrations determined by MetB auxotroph. The analytical characteristics of this method, such as selectivity, sensitivity, and precision, and its diagnostic utility, were successfully investigated. We suggest that this assay would become a powerful alternative for rapid, convenient and cost-saving diagnosis of hyperhomocysteinemia, also provide great benefit to be applicable to medical and clinical areas demanding high-throughput Hcy determination of biological fluids.

A neural stem cell has been investigated intensively for the treatment of neurological disorders such as Alzheimer disease and PD. A neuronal stem cell is sensitive to the changes of its circumstances, which cause severe genetic mutations or cellular damages, critical for stem cell differentiation. However, the effects of environmental toxins on a neuronal stem cell has been limitedly investigated so far. In this study, we developed a neuronal stem cell-based assay to detect the effects of environmental toxins on the stem cell electrochemically. A nanopatterened peptide layer was firstly developed on an electrode surface to enhance the cellular adhesion. After cell immobilization on the substrate, cell viability was monitored electrochmeically with increasing the concentration of enivronmental toxins. The peptide-nanopatterned electrode showed stronger quasi-reversible signals from neuronal stem cells, compared to a bare gold electrode and peptide monolayer coated electrode. The electrochemical signals from neuronal stem cells on the electrode were found to decreae with increasing the concentrations of enivronmental toixns. The electrochemcial experimental data were validated by MTT assay. Our newly developed neuronal stem cell-based electrochemical system can be used to determine stem cell viability easily. Acknowledgments: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (2010-0000845) and by the Nano/Bio science & Technology Program (M10536090001-05N3609-00110) of the Ministry of Education, Science and Technology (MEST) and by Seoul R&BD Program (10816).

GABA(γ-amino butyric acid) is one of the major inhibitory neurotransmitters in CNS(central nervous system). Imbalance of GABA and excitatory neurotransmitter can trigger nervous system disorders. Among the nervous system disorders, Parkinson’s disease which slows down the activity of nerve cells is related to GABA. For this reason, highly sensitive and label free sensor was produced for the detection of GABA as biomarker of Parkinson’s disease. First, by using UV nano imprint lithography, 100 nm wide silicon nanowire was fabricated and verified by SEM (Scanning Electron Microscopy). Second, the electrical sensing capability of the fabricated silicon nanowire was confirmed by semiconductor parameter analyzer. Third, the antibody against GABA was immobilized on silicon nanowire by self assembly method. Finally, GABA was applied for the detection ; the conductance change of the silicon nanowire sensor was measured through semiconductor parameter analyzer. Consequently, proposed system could be applied to develop the highly sensitive and selective biosensor and biochips.

Development of artificial tongue is important for quality control in the food and beverage industry. However, artificial tongue using inorganic synthetic materials as sensing elements, so called ‘Electronic tongues’, still have problems in terms of sensitivity and selectivity. Bioelectorinc tongue using biological taste receptor proteins as sensing elements is expected to overcome limitations of electronic tongue. In this study, nano-vesicles containing sweet taste receptor, heterodimer composed of hTAS1R2 and hTAS1R3, derived from artificial sweet taste cells were constructed. We created each artificial sweet taste cells stably expressing hTAS1R2 and hTAS1R3 and then the cells were transfected to express both receptor proteins. The artificial cells expressing sweet taste receptors were treated with cytochalasin B to obtain nano-vesicles budded out form the cells. The diameter of the nano-vesicles was nanometer scale which is suitable for applying to nano-material-based sensor platform to detect specific tastant binding to receptors. This nano-vesicle production method is useful for development of receptor protein-based bioelectronic tongue. Furthermore, this work also offers useful tool for basic research on taste receptors and opens up opportunities for many industrial applications.

Surface enhanced Raman scattering (SERS) sensing has attracted considerable attention for ultrasensitive, highly specific and multiplex biomolecular assays. Here we demonstrated the SERS-active nanostructures to highly sensitive detect SERS signals. In order to fabricate the SERS-active substrate, densely packed, 200 nm diameter, metal nanotube arrays were made using an anodized alumina nanoporous membrane as a template for shadow evaporation. The nanotubes on SERS-active PDMS substrate are well ordered with uniform packing and an average diameter of 200 nm. We explore the use of two kinds of SERS-active metal nanotube substrates: a single layer Au structure and a multilayer Au/Ag/Au structure. The latter multilayer structure was designed to in order to take advantage of the greater SERS enhancement offered by the silver while maintaining the biocompatibility and chemical reactivity characteristics (for immobilization of the capture aptamer) offered by the gold outer layer. We also demonstrate a facile assembly technique by which the metallic substrates can be integrated with an all PDMS microfluidic chip.

We suggest an approach to investigate the kinetic and thermodynamic properties of the peptide-receptor interaction, by measuring its adhesion force by using atomic force microscopy (AFM). As a model system, Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm) is a potent neutrophil chemoattractant. Ever since it has been known as an agonist for formyl peptide receptor (FPR), its high affinity to FPR was proven by investigating their kinetic and physiological behaviors with conventional methods. However, the adhesion force of WKYMVm-FPR has never been investigated. In this research, we measured the adhesion force of WKYMVm-FPR by using AFM. Kinetic parameters obtained from the relationship between the adhesion force and loading rate could be used to characterize thermodynamic properties of the WKYMVm-hFPR binding.

A simple colorimetric method for single nucleotide polymorphisms (SNPs) detection is described using gold nanoparticles (AuNPs) and allele-specific polymerase chain reaction (ASPCR) products. The current strategy is based on the employment of forward primers with thiol group at 5’ end which after PCR can successfully discriminate the type of target in a simple AuNPs assay. In the case of wild type target DNA, thiolated amplicon is generated by PCR, which upon mixing with AuNPs solution, bind to the surface of nanoparticles (due to the strong gold- thiol interaction) and prevent salt-induced aggregation of particles exhibiting red color to the solution. On the contrary, when the target DNA has single base mutation, PCR cannot be performed, resulting in the absence of thiolated amplicon. Adding this solution to AuNPs followed by NaCl shows blue colored solution suggesting salt-induced aggregation of AuNPs. Applicability of this strategy was successfully demonstrated by detecting single base mutations in breast cancer susceptibility gene BRCA1. This new method enables simple and reliable detection of SNPs without any specialized equipment.

Single-walled carbon nanotubes (SWNTs) have attracted considerable attention as a platform material for manufacturing miniaturized label-free biosensors.1 Here, we developed the network density-modulated SWNT sensor for the label-free DNA detection.2 The nanotube networks with various densities are fabricated via vacuum filtration method and incorporated with two-terminal resistor. The SWNT network-based devices exhibit linear I-V characteristics, resulting in the network density over the percolation threshold. We found that SWNT films having low network densities giving the conductance of 0.74 × 10-7 < Gbare < 2.00 × 10-7 allow detection of DNA hybridization with higher sensitivities compared with the high density networks. This study show the capability of label-free detection based on the SWNT networks showing metallic like electrical behavior. [This research was supported by WCU program through the Korea Science and Engineering Foundation funded by the Ministry of Education, Science and Technology (R32-2008-000-10142-0)].

Outstanding optical property of noble metal nanostructures, localized surface plasmon resonance (LSPR), is a powerful phenomenon used in many chemical and biological. This report described two types of goldcapped nanostructures: nanoparticle and porous anodic alumina (PAA) which reveal the strong excitation of LSPR spectra in the UV-visible region. The silica nanoparticles layer formed by chemical reaction [1] and PAA-fabricated by two-step anodizing process [2] could be used as the bases in gold-capped nanoparticle and PAA structures. After gold deposition on the surface, nanostructures of nanoparticle and PAA are obviously expressed the optical absorbance of LSPR spectra. Interestingly, depending on the nanostructures, gold-capped nanoparticle structure provides a single peak for its absorbance at 540 nm, however, the gold-capped PAA structure enables to observed many fringes in a wide range of wavelengths due to the coupling of LSPR and interferometry. We demonstrated that all two types of nanostructures have high potential to develop the extra-sensitive protein sensors with the molecular interface functionalizations. [This work was supported in part by the IT Leading R&D Support Project from the Ministry of Knowledge Economy through KEIT].

Enzyme-based biosensor that can selectively detect biological events is one of the powerful tools for the diagnostics of diabetes, detection of environmental hazards and biological warfare agents [1,2]. Of various detection techniques developed, electrochemical methods have been considerable attention for biosensors owing to their high sensitivity, fast response, inexpensive and easy miniaturization [2,3]. Herein, we demonstrated the fabrication of glucose sensor based on glucose oxidase immobilized on the self-assembled peptide with single-walled carbon nanotubes (SAP/SWNT) for the detection of glucose. The morphology of the SAP/SWNT-coated electrode was investigated by TEM images. The electrochemical properties of prepared-SAP/SWNT sensor for glucose detection were characterized by cyclic voltammetry and amperometric measurements.

Intense requirement has grown in developing enzyme-based electrochemical biosensor possessing favorable analytical performance due to its widespread applications on biotechnology. In this regard, diverse nanostructured matrices synthesized in recent years have been widely employed as electrode due to their superior characteristics such as large surface area, controlled nano-scale structures, and inherent conductivity; however, natural enzymes are inevitably denaturated by their weakly folded structures. Thus the development of more stable artificial enzyme mimics is substantially important to improve the performance of biosensor particularly by grafting on excellent nanostructures. Among them, Fe3O4 magnetic nanoparticles was recently reported to show intrinsic and more stable peroxidase activity than native one. Along with these lines, herein, we first demonstrate the potential of ordered m esoporous carbon, an attractive m aterial for enzyme immobilization by its unique characteristics of large pore volume to enable high loading capacity along with superior electrical conductivity, to efficiently utilize magnetic nanoparticles as next-generation peroxidase alternatives for efficient electrochemical biosensing platform possessing excellent compatibility with other enzymatic system. To this purpose, conductive multi-catalyst system consisting of magnetic nanoparticles and glucose oxidase simultaneously entrapped in the mesopore of the carbon matrix was developed.

The immobilized enzyme is necessary for the development of biofuel cells which can be applied to power source of implantable devices. The carbon nanotube has been focused on applying to electrode in electrical devices because it’s nanostructure with conducting properties enables tiny signals to be detected and transmitted, leading to the detection of target molecules at extremely low levels. Here, we explored the immobilization of glucose oxidase (GOx) on the surfaces of carboxylated multiwalled carbon tube (MWCNT) by covalent attachment using 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Characterization of GOx-immobilized MWCNT was performed by FT-IR analysis and the formation of gluconic acid produced by enzyme reaction was analyzed by TLC analysis. The newly formed amide bond between GOx and MWCNT was identified by the characteristic C=O stretching of 1634 cm-1 in FT-IR spectra. The spot of gluconic acid was observed in the reaction mixture containing immobilized GOx whereas it was not observed in the reaction mixture containing MWCNT. This result indicates that GOx was successfully immobilized on MWCNT by covalent attachment.

ZnO (Zinc Oxide) is a unique material that exhibits semiconducting, piezoelectric, and pyroelectric multiple properties. Recently, a various of new research shows that ZnO nanostructures are suitable for electrochemical biosensors. The enzyme used for glucose detection, glucose oxidase, was attached to ZnO nanocombs which resulted in a biosensor that exhibits a high affinity, high sensitivity, and fast response for glucose detection. This simple method of fabricating a ZnO based biosensor can be extended to immobilize other enzymes and other bioactive molecules on various 1D metal oxide nanostructures, and form versatile electrodes for biosensor studies.

By the development of nanotechonology, many researchers are interested in fusion technology between NT and BT. A three-dimensional structure fabricated by nano-imprinting, called nano-pillar, has a potential to be applied in this fusion technology. We studied about fabrication of DNA chip using nano-pillar structure for improving sensitivity. Also we fabricated different morphologies of three dimensional structures. The dense and long nano-pillar structure increased an actual immobilization amount of a probe and the sensitivity by providing high surface density. In this experiment, we immobilized a partial sequence of 5s rRNA of Legionella pnuemophila as a probe and measured fluorescence intensity with various concentration of cy3 tagged target. The maximum of fluorescence intensity of nano-pillar substrate exhibited 4.5 times higher than that of planar substrate. In addition, we examined specificity of the chip using mismatched sequence of the probe as well as sensitivity. These results showed a possibility of nano-pillar structure as a sensitive platform of biosensors.

Detection of heavy metal ions in aqueous system including human blood plasma is an important issue because of their adverse effects on human health and the environments. Among them, Pb2+, and Hg2+ are the major elements requiring a critical caution because of the severe health effects. While various detection methods have been developed, the heavy metal specific oligonucleotides such as metal dependent DNAzyme and Hg2+ aptamers have led to significant improvement for the detection sensitivity and specificity. However, further improvement for the detecting sensitivity and feasibility are still open. Specially, no scheme is reported to detect Pb2+ and Hg2+ simultaneously. In case of heavy metal dependent DNAzymes, there should be a false positive signal change because of the nearly similar sequences of the substrate oligonucleotides. For the dual detection, a fluorescence signal change is more suitable rather than color change in the presence of the metal ions. However, the conformation of the reported Hg2+ aptamers deforms in a signal decrease way which should be less sensitive to the metal ion than fluorescence-on based methods. Therefore, we devised a scheme to generate fluorescence signal combining the DNAzyme and aptamer on gold nanoparticles which act as a super quencher for two different fluorophores ;,one is linked to the substrate and the other is linked to aptamer. In the presence of the metal ions, the fluorescence signal can be turned on because of the enzymatic cleavages of the substrate by DNAzymes for Pb2+ and the conformational change for Hg2+ whereas the nanoparticles are in latent in the absence of the metal ions. Until now up to 5 nM of Pb2+ is detectable within 20 minutes. Detection sensitivity for Hg2+ and specificity for the two metal ions will be presented in the conference.

Planar bilayer lipid membranes (BLMs) are important tools in studying ion channels and their engineered applications. Montal and Mueller methods are typically used but this method has shortcomings of labor intensive and lack of stability that make it inefficient. For this reason Montal and Mueller method has been substituted by patch clamp method, another gold standard method to study ion channels. However, this method has a critical drawback as this method require intensive labor and live cells. Consequently, methods to ameliorate Montal and Mueller methods has been studied in terms of increasing stability, reducing intensive labor and decreasing degree of skill required. First, using 2:8 mixture of n-decane and hexadecane, which freezes at ~14°C, was spread over a small aperture and froze before its spontaneous self-assembly process to a bilayer membrane. This membrane precursor can be stored frozen, enabling transportation. This membrane precursor can be transported to other place and thawed when a membrane is needed. However, this method has a low success rate (~30%) and various thinning out time, requiring a controlled volume of deposition. To resolve the problem pin tool is used for exact volume control. Despite increased precision of deposition, several problems remained. The success rate of reconstitution of BLMs was low and when gasket’s condition or aperture was changed, we had to use a different pin tool. As a result we used PDMS gasket instead of conventional hydrophobic films. PDMS is typically known to extract organic solvent, facilitating lipid bilayer formation. This property fostered optimization and at the same time reduced the membrane formation time to ~30 minutes. Membranes were created timely in a controlled manner (Lipid bilayer has different initiation time when change PDMS’s and lipid solution’s composition.) Combined with automated machinery, an array of lipid bilayer membrane can be created for the potential use of high-throughput ion channel screening. To demonstrate high-throughput measurement of ion channels we devised an analog switch, enabling sequential measurement of each membrane using just one amplifier. Membranes measured using this switch were shown identical to those in the conventional system. We will show a number of potential applications using our membrane system. BLMs are used for drug screening.

Recently, various novel biosensors have been widely studied and developed for early diagnostics of various diseases. Dopamine is one of the large of number of neurotransmitters which plays a role as the excitement transmission in a brain cell. Development of neurotransmitter sensor using Fluorescence Resonance Energy Transfer (FRET) is expected to diagnosis or medical treatment for a disease related to the brain such as Alzheimer’s disease, Parkinsonism and High blood pressure in an aging society due to possibility for measurement of low concentration and brain pressure of the brain trouble. FRET is a physical phenomenon between two fluorophores which transfers emission energy from donor to acceptor for excitation. In this paper, FRET between carboxyl quantum dots and Alexa Fluor has been investigated and the effect of FRET efficiency depending on dopamine concentration has been studied. Quantum Dots 525 (QDs 525) as a donor has been immobilized on surface of well plate which is modified functional group, and conjugated protein A with anti-dopamine labeled by Alexa Fluor 546 (AF 546). AF 546 is used as an acceptor. The fluorescent excitation and emission scans for two fluorophores have been obtained using photoluminescence spectroscopy (PL). The FRET efficiency was obtained from intensity ratio of the fluorescent spectra with and without acceptor group. The dependence of FRET efficiency on dopamine concentration shows that dopamine can be detected by monitoring the FRET phenomena between two fluorescent dyes. Neurotransmitter sensor will be able to establish the system which is possible to diagnosis and medical treatment

Dopamine is a potent neuromodulator in the brain, influencing a variety of motivated behaviors and involved in several neurological diseases. In this present study, antibody-conjugated gold nanoparticles have been used for the surface enhanced raman scattering (SERS) detection of neurotransmitter release in human neuronal stem cells. Also, the specific interaction between the dopamine and immobilized dopamine antibody was studied by surface plasmon resonance (SPR). This study demonstrated the potential feasibility of using antibody-conjugated gold nanoparticles as highly sensitive and homogeneous sensing probes for biological monitoring of neurotransmitters in neuronal stem cells. Also, the biosensor for dopamine was designed with a dopamine antibody as a recognition element. The self-assembled monolayer was constructed by the immobilization of the dopamine antibody onto a gold surface. Based on the principle of direct competitive inhibition, the biosensor could detect dopamine in a linear range from 1 to 100 nM. The immunosensor based on dopamine antibody offers the advantages of being highly sensitive, easy, and rapid to prepare, and also realizes a short assay time.

Recently, QD-based fluorescence resonance energy transfer (FRET) probe as a DNA nanosensor has been studied [1]. In this experiment, PDMS-based microfluidic chips using QD-DNA probe have been fabricated for the detection of p53 gene related to genetic disease. The PDMS microfluidic chip with a weir structure has been utilized for trapping microbeads, sample injection to wells, and fluorescence detection. Carboxylated QDs (Em: 605 nm) have been linked to microbeads of polystyrene/divinyl benzene via EDC/NHS crosslinking reaction. After hybridization with target gene, Borate buffer with DNA intercalating dye has been loaded to the micro-channel. Fluorescence spectra have been observed from the hybridized DNA at the channel of weir structure. The FRET efficiency between QD and dye has been measured by photoluminescence spectroscopy. This experiment shows the possibility of rapid detection of DNA via bead-QD complex on microfluidic system.

The development of biological molecule interacting to inorganic material is an application without chemical modification of surface. The peptide molecule with specificity and selectivity to surface material was identified by the phage display technique. The phage display is a selective assay with high affinity using bacteriophage displaying 7 or 12 mer-sized peptide sequence. The phage pool bound to material is collected and amplified through repeated binding and amplification cycles and the peptide motif of individual clone is identified by DNA sequencing. In this approach, the gold foil (0.5mm thickness) in duplicate was incubated with 1 x 1011 pfu/ml of random phage libraries and unbound phage was washed away. The bound phage was eluted and amplified by infecting E.coli ER2738 and infected plaque was counted. This cycle was repeated three times increasing the affinity against target and DNA was sequenced from the final eluate. The identified two different 7 mer – sized peptide sequences were HGVVHHL and HRADMHF. For further specificity analysis, chemical conjugation of peptide to a report enzyme or solid surface will be required. It is anticipated that peptide molecule identified phage display could be a physical linkage on the biosensor with bi-functional affinity, one end for surface material and the other for biomolecule.

Taste receptors belong to the subfamily of G-protein-coupled receptors (GPCR). When the GPCR binds to the ligand, recruitment of β-arrestin (β-arr) to agonist-stimulated receptor occurs. In this study, HEK-293 cells which coexpress the taste receptor T2R38 and β-arr2 was established, and we observed that the recruitment of β-arr2 to the C-terminus of receptor was stimulated by the specific ligand. The monitoring method was based on the fluorescence resonance energy transfer (FRET) from GFP to DsRed, which were attached to the c-terminals of β-arr2 and T2R38, respectively. The fluorescence of GFP and DsRed excited at 485nm was monitored at 535nm and 590nm, respectively. Agonist-induced signals were measured by the DsRed/GFP emission ratio. Mammalian cell-derived nanovesicles containing taste receptor and β-arr2 were formed by treating the HEK-293 cells with cytochalasin B. The taste receptor and β-arr2 imbedded in the nanovesicles were confirmed by the fluorescence image using confocal microscopy. This methodology would be very effective for the development of GPCR-based biosensor, which can be used for ligand screening.

Label-free electrochemical method for the detection of human α-thrombin using a water-soluble, ferrocene-functionalized gold nanoparticles and a single-stranded oligonucleotide aptamer probe is described. Au nanoparticles coated with ω-ferrocenyl hexanethiolate ligand and polyethylene glycol, with average composition Au140(ω-ferrocenyl hexanethiolate)39 which has about 1~2 nm size range, exhibit a unique combination of adsorption properties to the major grooves of DNA by electrostatic interactions. The ferrocene molecules of the adsorbed gold nanoparticles can be robustly oxidized and reduced upon the aptamer molecule and there exhibit stable ferrocene voltammetry over long periods of time. It can be a direct method in which the recorded current decreases upon addition of the targeted protein. The interacrions between thrombin aptamer and ferrocene coated gold nanoparticles are characterized through cyclic voltammogram, differntial pulse voltammogram and SPR phenomena on the gold electride surface.

Aptamers are ssDNA or RNA oligonucleotides with high affinity and high specificity to their targets. SELEX (Systematic Evolution of Ligands by EXponential enrichment) is an in vitro selection and amplification technique used for selecting aptamers. There are several studies showing that Nampt, as one of adipokines, is secreted from all adipose tissue, and Nampt (visfatin/PBEF) is known to be related to various diseases such as type 2 diabetes, chronic kidney dysfunction, inflammation and cancer. Hence, aptamers binding to Nampt are expected to provide fast and sensitive diagnosis for these related diseases. A modified SELEX, FluMag-SELEX from random DNA library composed of approximately 1.2 x 1014 DNA molecules was used in this experiment. We have successfully screened ssDNA aptamers binding to the Nampt specifically.

In order to enhance detected signal without an additional step in a gold nanoparticle (AuNP)-based lateral flow immunoassay (LFA), a new and simple method utilizing two AuNP- conjugates was developed. The 1st conjugate was the AuNP immobilized with an biotinylated anti-Human IL-5 antibody and blocked with bovine serum albumin (BSA), and the 2nd conjugate was the AuNP immobilized with an streptavidin and blocked with bovine serum albumin (BSA). The two conjugates were respectively encapsulated in different pads. A scheme of the LFA system is described in first figure. The size of the two conjugates was very critical in the detection sensitivity of IL-5. When 10nm for the 1st and 40nm for the 2nd were used. As compared to the conventional LFA, the detection sensitivity sucessfully increased. We could detect as low as 0.01 ng/mL IL-5 in 10 min using the dual AuNP conjugate-based LFA.

Mycosporine-like amino acids(MAAs), particularly many exist in Marine plant, are known to indicate high UV absorbance ability because of its characteristic structures. Phorphyra-334, a representative material of MAAs, absorbs most amount of UV at 334nm wavelength. And other MAAs materials also absorb UV in UV-A range. That is why MAAs are expected as natural materials for functional cosmetics and UV screening. This study shows that Porphyra tenera of red algae having high amount of MAAs can be used in sunscreen. First, extracts are optimized through various extract methods, purification and separation. These are measured by UV-vis spectrometer. This experiment can be established the extract concentration and effect. Then, sunscreen made from Porphyra tenera extract is compared with Homosalate sunscreen. Its SPF value is measured by SPF Analyzer. With this, Porphyra tenera's UV screening effect is verificated in-vitro.

Astaxanthin is a natural color cartenoid that has strong anti-oxidation effect. It is widely distributed in foods such as shrimp, crab, salmon etc. Haematococcus pluvialis is the abundant source of natural astaxanthin and is cultivated at industrial scale. It is reported that anti-oxidation effect of astaxanthin is 500 to 1000 times greater than alpha-tocopherol. And diverse range of its physiological functions have been studied intensively. In this study, we optimized the supercritical fluid extraction condition such as pressure and temperature to get the higher yield of astaxanthin. Astaxanthin content is analyzed by HPLC and antioxidative activies of astaxanthin were examined by DPPH free radical scavanging activites. Liposomal encapsulation of astaxanthin was prepared by microfludizer. Size of liposome was measured by dynamic light scattering system.

Robusta contributes about 30% of the world coffee production, and Vietnam is the No1 country for exporting Robusta. Therefore a chemical profile of this coffee is very useful for researchers and manufacturers related to coffee. The objective of this work is to determine the composition of fatty acids, tocopherols, diterpenes and sterols in coffee oil of Vietnamese Robusta green beans and roasted beans. This work also tests the capacities for whitening, anti-oxidation and UV light protection of these coffee oils in order to provide subsidiary information for applying coffee oil in cosmetic. Coffee oil was extracted by supercritical carnon dioxide. Fatty acids were analysed as methyl esters by GC system while tocopherols, diterpenes and sterols were determined by HPLC analyses. Whitening, anti-oxidation and UV protected capacities of coffee oil was tested through Tyrosinase, DPPH assay and SPF values respectively.