Hsin-Yi Hsieh

Effective enhancement of fluorescence detection efficiency in protein microarray assays: application of a highly fluorinated organosilane as the blocking agent on the background surface by a facile vapor-phase deposition process.

Protein microarrays are emerging as an important enabling technology for the simultaneous investigation of complicated interactions among thousands of proteins. The solution-based blocking protocols commonly used in protein microarray assays often cause cross-contamination among probes and diminution of protein binding efficiency because of the spreading of blocking solution and the obstruction formed by the blocking molecules. In this paper, an alternative blocking process for protein microarray assays is proposed to obtain better performance by employing a vapor-phase deposition method to form self-assembled surface coatings using a highly fluorinated organosilane as the blocking agent on the background surfaces. Compared to conventional solution-based blocking processes, our experimental results showed that this vapor-phase process could shorten the blocking time from hours to less than 10 min, enhance the binding efficiency by up to 6 times, reduce the background noise by up to 16 times, and improve the S/N ratio by up to 64 times. This facile blocking process is compatible with current microarray assays using silica-based substrates and can be performed on many types of silane-modified surfaces.

Dynamics of hydrogen nanobubbles in KLH protein solution studied with in situ wet-TEM

Although the stability of the nanobubble remains a controversial issue that is subject to the classical predictions of high Laplace pressure, we demonstrate that a hydrogen nanobubble can be generated and stabilized in an aqueous solution of Keyhole limpet hemocyanin (KLH) protein via an electron radiolysis process. The hydrogen gas inside the nanobubble is in a “dense gas” phase that is characterized by a Knudsen number and number density of hydrogen molecules. The dynamics of nanobubbles are analyzed using time-series electron microscopy images. The growth of small nanobubbles will be affected by the largest neighboring nanobubble; however, a diffusive shielding effect for small nanobubbles is observed. Locally, anti-Ostwald ripening of nanobubbles can be observed; however, the global growth behavior among the nanobubbles is randomly correlated because the characteristic diffusion length of the hydrogen molecules is considerably greater than the average spacing among the nanobubbles.

A UV-sensitive hydrogel based combinatory drug delivery chip (UV gel-Drug Chip) for cancer cocktail drug screening

The effective and efficient treatment of diseases, such as HIV, cancer or hereditary diseases, requires accurate and precise control of the combinatorial drug-dosage and their release. Herein, we introduce a simple photosensitive poly(ethylene glycol) diacrylate (PEGDA) hydrogel based platform for high dynamic range testing of combinatorial cocktail drug screening using three chemical and two protein drug treatments for colon cancer. UV cross linked PEGDA hydrogel droplet arrays on a Teflon patterned glass substrate enable a rapid yet accurate selection and dosage assignment of the drugs. Precisely loaded cocktails of the anticancer drugs were simultaneously released in-parallel with the PEGDA hydrogel chips into 2D or 3D cultured HCT-8 colon cancer cells for combinatorial drug screening. We demonstrate the functionality of our UV gel-Drug Chips 1000 fold range of concentrations for each of the five drugs in 30 seconds to find the optimized drug cocktail using a fractional factorial control system. Our device has low drug consumption, requiring only 12 nL per screening run per droplet. In addition, our UV gel-Drug Chips were employed for find the optimized drug cocktail using a fractional search algorithm. Our cocktail drug response results for both 2D (cell viability is 7.3%) and 3D (cell viability is 10.8%) colon cancer cells were analogous to those found by conventional method (6.8 and 9.3 respectively). In contrast to conventional method, our approach is faster, more effective, less time consuming and requires a lower amounts of drug volume.

Spontaneous motion of a water droplet on hydrophilic and curvature gradient conical-shaped surfaces

This paper reports the study on spontaneous and fast motion for a microliter water droplet on nanotextured glass capillary surfaces with a wide range of curvature gradients. The surface is highly related to the surface tension gradient that is mainly formed by three distinct driving forces, including surface hydrophilicity gradents, chemically patterned nanotexture, and curvature gradient capillaries. In the experiments, the droplet velocity shows a dependency to the droplet position on the conical capillary curvature surface and moves toward the more wettable part of the gradient. The speed of the droplet on the oxygen plasma treated nanotextured glass capillary is up to 238.5 mm/s with more than two times of that, 101.7 mm/s, on the untreated surface. Therefore, we can conclude that a gradual variation of wettability property governs the droplet motion.

Dual faced SERS nanoparticles equipped with tri-functions for target drug delivering into single cell

We reports an approach to fabricate dual-faced polystyrene beads (DFPSBs) with tri-functions of tumor cell recognition, drug delivery, and real-time Raman sensing. Onestep oxygen-plasma treatment process was used to etch commercially available fluorescent polystyrene beads into a corrugated upper hemisphere and simultaneously change the entire surface with carboxylic groups. After depositing gold onto the corrugated hemisphere for surface enhanced Raman scattering (SERS) while leaving the other smooth and clean hemisphere for fluorescence detection, the DFPSBs are formed with dual-surfaces of plasmonic gold semishells on the top and fluorescent carboxylated polystyrene at the bottom. Sulfo-NHS-SS-biotin disulfide linkers and anti-CD44 antibodies can be modified and added onto the top gold surfaces and the bottom carboxyl groups through Au-S and peptide bonds, respectively. Then, the surface-modified DFPSB suspension can be employed to target overexpressive glycoproteins (CD44) on the surfaces of cancer cells and release their loads via the cleavage of disulfide bonds in the cytoplasm environment. These anti-CD44-modified DFPSBs exhibit a 12-fold cancer targeting ability on HeLa cells when compared to a normal chondrocyte cell.

Gold-coated polystyrene bead array and the investigation of their plasmon coupling abilities

Many of SERS nanoparticles took advantage of the surface roughness for the significant improvement of their Raman sensing ability. Nevertheless, few papers analyzed the characteristics of surface roughness nanostructures that contribute to the SERS. Thus, this paper investigates the characteristics of the corrugated polystyrene bead (PSB) array etched by a series of oxygen plasma etching time for giving a criterion to fabricate appropriate SERS-active nanoparticles. Three factors were considered in this paper: (1) the effect of plasma coupling among neighboring particles, (2) the vertical surface roughness of nanocorrugations, and (3) the pitch size, the lateral surface roughness, of nanocorrugations. By the analysis of SEM and AFM images, those factors were quantifiable. The correlation coefficient between each factor and SERS Raman enhancement was also investigated to verify that the pitch size of nanocorrugations (ranging from ~6 nm to ~12 nm on the surface of PSBs) dominates the SERS enhancement. Therefore, the maximum improvement of Raman intensity that derives from surface roughness treatment is 12 times compared to smooth surface. Moreover, it has a high enhancement factor of ~106.

Enhanced gold SERS signals on HSR surface extrutions generated on carboxyl-rich polystyrene beads

This paper reports the employment of carboxyl groups on polystyrene beads surface to generate high aspect ratio (HSR) nano-extrutions by plasma etching for enhancing SERS signal. We investigate the detail mechanism of the surface corrugation formation on PSBs and propose a novel method to produce HSR surface nano-extrutions on carboxyl-rich PSBs surface. By understanding the mechanism of the surface corrugation formation, we can control the HSR. Therefore, a 4-fold Raman signal enhancement was achieved when compared to the result by previous method, using oxygen plasma to generate corrugation surface on PSBs without carboxyl groups.