No abstract

Gold nanocrystals and nanoassemblies have attracted extensive attention for various applications, including chemical and biological sensing, solar energy harvesting, and plasmon-enhanced spectroscopies, due to their unique plasmonic properties. It is of great importance to prepare shape-controlled Au nanocrystals with high monodispersity over a large range of sizes. In this work, Au nanospheres with sizes ranging from 20 nm to 220 nm are prepared using a simple seed-mediated growth method aided with mild oxidation. As-prepared Au nanospheres are remarkably uniform in size. The resultant Au nanospheres of different sizes are ideal building blocks for constructing plasmonic nanoassemblies. Core/satellite nanostructures are assembled out of differently sized Au nanospheres with molecular linkers. The core/satellite nanostructures show a red-shifted plasmon resonance peak in comparison to that of the Au cores, which is consistent with the results calculated according to Mie theory. As predicted by fi nite-difference time-domain simulations, the assembled core/satellite nanostructures exhibit strongly enhance Raman signals. This facile growth of Au nanospheres and assembly of core/satellite nanostructures are expected to facilitate the design of new nanoassemblies with desired plasmonic properties and functions.Adv. Optical Mater. 2014, 2, 65-73 66 wileyonlinelibrary.com

The fabrication of microfluidic chips can be simplified and accelerated by three-dimensional (3D) printing. However, all of the current designs of 3D printed microchips require off-chip bulky equipment to operate, which hindered their applications in the point-of-care (POC) setting. In this work, we demonstrate a new class of movable 3D printed microfluidic chip components, including torque-actuated pump and valve, rotary valve, and pushing valve, which can be operated manually without any off-chip bulky equipment such as syringe pump and gas pressure source. By integrating these components, we developed a user-friendly 3D printed chip that can perform general colorimetric assays. Protein quantification was performed on artificial urine samples as a proof-of-concept model with a smartphone used as the imaging platform. The protein was quantified linearly and was within the physiologically relevant range for humans. We believe that the demonstrated components and designs can expand the functionalities and potential applications of 3D printed microfluidic chip and thus provoke more investigation on manufacturing lab-on-a-chip devices by 3D printers.