National Cheng Kung University

About: National Cheng Kung University is a education organization based out in Tainan City, Taiwan. It is known for research contribution in the topics: Population & Thin film. The organization has 49723 authors who have published 69799 publications receiving 1437420 citations. The organization is also known as: NCKU.

Gold Nanorods in Photodynamic Therapy, as Hyperthermia Agents, and in Near-Infrared Optical Imaging

Abstract: Decreasing the size of a material to the nanometer scale makes it sensitive to a further decrease in size or a change in shape. Among the nanomaterials that are currently being developed, gold nanoparticles are extensively exploited in organisms because of their good stability and biocompatibility. However, in biomedical applications that require a considerably deeper penetration of near-infrared (NIR) light, in which both blood and soft tissues are highly penetrable, a different type of gold nanostructure is required. Surface plasmon resonance (SPR) is a phenomenon in which free electrons in the nanostructures collectively oscillate and scatter or absorb the incident electromagnetic wave. Previous studies have demonstrated various methods of shifting the SPR of gold nanomaterials to the NIR region and shown their potential in biological applications. In the NIR region, tissue transmission is optimal owing to low scattering and energy absorption, thus providing maximum irradiation penetration through tissue and minimizing the autofluorescence of the non-target tissue. There are many applications for NIR-absorbing gold nanostructures in biology, and in particular gold nanorods. For example, gold nanorods can be applied in plasmon resonance light scattering, Rayleigh elastic scattering, surface-enhanced Raman inelastic scattering, optical coherent tomography scattering, twophoton luminescent non-linear imaging, and photothermal therapy. Gold nanorods have also received significant attention for their emerging potential in photothermal therapy. However, little attention has been paid to the use of nanorods combined with photosensitizers in photodynamic therapy (PDT), which is the destruction of cancer cells by the highly reactive singlet oxygen of the reactive oxygen species (ROS) produced by a photosensitizing compound and light of an appropriate wavelength. Gold nanorods couple a hydrophilic and anionic photosensitizer, indocyanine green (ICG) (Supporting Information, Figure S1), with light from an NIR laser emitting in the NIR region on the surface of the nanorods to produce PDT. Furthermore, the excitation and emission maxima of ICG are similar to NIR wavelengths, thus enabling ICG-conjugated gold nanorods to be utilized as an effective contrast agent in biomedical imaging. Practical applications in the early detection and destruction of cancer cells using nanomaterials have emerged in recent years, and the development of multifunctional nanomaterials is currently being pursued. Herein, we propose a medical diagnosis method that uses a lethal photochemical destruction reaction and shows that multifunctional ICGconjugated gold nanorods can simultaneously serve as photodynamic and photothermal therapeutic agents to destroy cancer cells. Furthermore, combined PDT and hyperthermia can more efficiently extinguish cancer cells than PDT or hyperthermia treatment alone, and the system can also serve as an effective bioimaging probe in the NIR region. Gold nanorods with a cetyltrimethylammonium bromide (CTAB) surfactant coating were synthesized using the seedless growth method. To conjugate ICG on the surface, CTAB was coated on the nanorods with poly(styrene-altmaleic acid) (PSMA) and ICG in sequence by an electrostatic interaction. A TEM image (Figure 1) depicts gold nanorods with an aspect ratio of approximately 3.8 (length: 35 nm, width: 9.3 nm). Owing to CTAB, the surface charge of the nanorods revealed a zeta potential of approximately 39.2 mV. PSMA polymer was then first hydrolyzed by NaOH to expose the carboxyl group and then adsorbed on the nanorods by electrostatic interactions (Supporting Information, Figure S2). Figure 1 b shows Au-PSMA nanorods with negatively charged PSMA; the Au-PSMA nanorods have a surface charge of approximately 10.7 mV. By the p–p stacking

A new fabrication process for ultra-thick microfluidic microstructures utilizing SU-8 photoresist

Abstract: In this paper we describe a new process for fabricating ultra-thick microfluidic devices utilizing SU-8 50 negative photoresist (PR) by standard UV lithography. Instead of using a conventional spin coater, a simple 'constant-volume-injection' method is used to create a thick SU-8 PR film up to 1.5 mm with a single coating. The SU-8 PR is self-planarized during the modified soft-baking process and forms a highly-uniform surface without any edge bead effect, which commonly occurs while using a spin coater. Photomasks can be in close contact with the PR and a better lithographic image can be generated. Experimental data show that the average thickness is 494.32 ± 17.13 μm for a 500 μm thick film (n = 7) and the uniformity is less than 3.1% over a 10 × 10 cm2 area. In this study, the temperatures for the soft-baking process and post-exposure baking are 120 °C and 60 °C, respectively. These proved to be capable of reducing the processing time and of obtaining a better pattern definition of the SU-8 structures. We also report on an innovative photomask design for fabricating ultra-deep trenches, which prevents the structures from cracking and distorting during developing and hard-baking processes. In this paper, two microfluidic structures have been demonstrated using the developed novel methods, including a micronozzle for thruster applications and a microfluidic device with micropost arrays for bioanalytical applications.

Reverse logistics system planning for recycling electrical appliances and computers in Taiwan

Abstract: Since the disposition of end-of-life home appliances has caused tremendous attention, Taiwan recently promulgated a Scrap Home Appliances and Computers Recycling Regulation that mandates manufacturers and importers to take back their products. Reverse logistics system planning shall become vital as the take-back rate increases and the service area expands in the future. This study utilizes a mixed integer programming model to optimize the infrastructure design and the reverse network flow. The proposed model attempts to minimize the total cost, which consists of transportation cost, operating cost, fixed cost for new facilities, final disposal cost and landfill cost, as well as the sale revenue of reclaimed materials. Results for various scenarios that consider various take-back rates and operating conditions are presented.