Cheng-An J. Lin

Synthesis and surface modification of highly fluorescent gold nanoclusters and their exploitation for cellular labeling

We introduce a general approach to make colorful fluorescent gold nanoclusters which are protected by dihydrolipoic acid, mercaptoundecanoic acid and polyethylenimine. The fluorescent gold nanoclusters can perform a variety of bioconjugation processes such as PEGylation, biotinylation as well as forming complex nanobioconjugates with streptavidins. The brightening effects under proper surface modification are also reported. The clusters have a decent quantum yield, high colloidal stability, and can be readily conjugated with biological molecules. Nonspecific uptake by human aortic endothelial cells is demonstrated.

Impact of dihydrolipoic acid on mouse embryonic stem cells and related regulatory mechanisms

α‐Lipoic acid (LA) is a thiol with antioxidant properties that protects against oxidative stress‐induced apoptosis. LA is absorbed from the diet, taken up by cells and tissues, and subsequently reduced to dihydrolipoic acid (DHLA). Recently, DHLA has been used as the hydrophilic nanomaterial preparations, and therefore, determination of its bio‐safety profile is essential. In this article, we show that DHLA (50–100 μM) induces apoptotic processes in mouse embryonic stem cells (ESC‐B5), but exerts no injury effects at treatment dosages below 50 μM. Higher concentrations of DHLA (50–100 μM) directly increased the reactive oxygen species (ROS) content in ESC‐B5 cells, along with a significant increase in cytoplasmic free calcium and nitric oxide (NO) levels, loss of mitochondrial membrane potential (MMP), activation of caspases‐9 and −3, and cell death. Pretreatment with NO scavengers suppressed the apoptotic biochemical changes induced by 100 μM DHLA and promoted the gene expression levels of p53 and p21 involved in apoptotic signaling. Our results collectively indicate that DHLA at concentrations of 50–100 μM triggers apoptosis of ESC‐B5 cells, which involves both ROS and NO. Importantly, at doses of less than 50 μM (0–25 μM), DHLA does not exert hazardous effects on ESC‐B5 cell properties, including viability, development and differentiation. These results provide important information in terms of dosage safety and biocompatibility of DHLA to facilitate its further use as a precursor for biomaterial preparation.

Fluorescent Gold Nanoclusters for Biomedical Applications

Synthesis, characterization, and bioconjugation of fluorescent gold nanoclusters (FGNCs) are reported. The gold nanocluster is synthesized by etching gold nanoparticle. When the gold nanocluster is capped with reduced dipoic acid (DHLA, dihydrolipoic acid) that the nanocluster has the fluorescent property. The fluorescent gold nanoclusters have the emission in the range of 600 800 nm that is suitable for cell labeling, and its size and hydrodynamic radius are around 1.8 nm and 1.8 3.4 nm. The FGNCs can also be conjugated with desired biomolecules, such as biotin-PEG and avidin. In the preliminary data, the FGNCs can be taken nonspecifically by human aortic endothelial cells and the FGNCs conjugated with avidin can label specifically endogenous biotin within human hepatoma cells. Compare the FGNCs with semiconductor quantum dots and conventional organic dyes, the FGNCs are more biocompatible than quantum dots and more stable than organic dyes. So we believe that the FGNCs have great potential for biomedical applications.

Non-Toxic Gold Nanoclusters for Solution-Processed White Light-Emitting Diodes

Solution-processed optoelectronic devices are attractive because of the potential low-cost fabrication and the compatibility with flexible substrate. However, the utilization of toxic elements such as lead and cadmium in current optoelectronic devices on the basis of colloidal quantum dots raises environmental concerns. Here we demonstrate that white-light-emitting diodes can be achieved by utilizing non-toxic and environment-friendly gold nanoclusters. Yellow-light-emitting gold nanoclusters were synthesized and capped with trioctylphosphine. These gold nanoclusters were then blended with the blue-light-emitting organic host materials to form the emissive layer. A current efficiency of 0.13u2009cd/A was achieved. The Commission Internationale de l’Eclairage chromaticity coordinates of (0.27, 0.33) were obtained from our experimental analysis, which is quite close to the ideal pure white emission coordinates (0.33, 0.33). Potential applications include innovative lighting devices and monitor backlight.

Template-based formation of ultrasound microbubble contrast agents

Precisely controlling microbubble size is critical for medical ultrasound imaging, where large microbubble contrast agents may lead to pulmonary microvascular embolization. In this study, we reported a facile method to fabricate the laminated ultrasound contrast agents with narrow size distribution. First, we prepared monodisperse silica particles (∼1.0 μm in diameter) as a core template. Then an amphiphilic shell was coated on the SiO2 particles surface via amine–anhydride modification. After etching the SiO2 cores by HF, the formed hollow structured particles were further PEGylated with free carboxylate residues. After dialysis and freeze-drying, the as-prepared microbubbles showed a narrow size distribution (diameter = 1.1 μm, PDI = 0.36). The microbubbles showed excellent stability for enhanced ultrasound contrast imaging for at least 20 minutes, resulting from the observed firm-shelling through electron microscopy. The laminated shells of the microbubbles have an average thickness of 100 nm composed of multiple aliphatic composites that efficiently reduce the leakage of inert gas. Further, these microbubbles also showed good biocompatibility when co-culturing with BNL CL2 cells in vitro. Based on the above evidence, this improved method for fabricating uniform ultrasound contrast agents can further translate into many biomedical applications.

Single Functionalized of Different Size Nanoparticles Effect

Nanomaterials is one of the areas most highly concerned about medical technology nowadays.Such as metal nanoparticles,nanorods,and so on.

Dark-Field Hyperspectral System for Monitoring the Nanoparticles Interaction with the Cells

Nanomaterials are commonly used in biomedical research, mostly in cancer diagnosis and therapy. In this study, we used dark-field hyperspectral systems to investigate nanomaterials for the biological interaction of the opsonized or pegylated nanomaterials. Gold nanoparticles have good biocompatibility and exhibit strong light scattering behavior under the dark-field microscope. Those properties make it feasible to study the interaction between the surface functionalized nanomaterials and cellular micro-environments multi-dimensionally.

Synthesis of Gadolinium-doped Fluorescent Au/Ag Nanoclusters as Bimodal MRI Contrast Agents

In this presentation synthesized the T1 contrast agent, combinations of MRI and optical imaging modalities will be introduced. Using bovine serum albumin conjugated with gadolinium and fluorescence gold or silver nanoclusters (Fluorescence gold /silver protein). An average of 34 Gd-DTPA chelates were covalently conjugated to bovin serum albumin. The T1 relaxivity of BSA-Gd-DTPA was 163.27mM− 1sec− 1. The experimental results shows a new dual-modal imaging agent of fluorescent gold/silver protein with a paramagnetic in vitro and in vivo, which can be hold many potential applications in medical diagnostics and therapy.

Synthesis and optical properties of shaped gold nanomaterials under dark-field microscope

Nanophotonics has raised a great attention because detection limit can easily go down to the molecular level. Herein, we present a dark-field integrated Light-eye Technology (iLeyeT) system for monitoring of polarization-dependent surface plasmons of single shaped nanomaterials. Single shaped gold nanomaterial such as gold nanorod present both longitudinal and transverse surface plasmonic resonance under dark-field microscope. The orientation of single nanomaterials significantly tunes the direction of polarized light. We introduce a programmable light source into the dark-field microscope and image the relative peak intensities of the transverse and longitudinal surface plasmon via fast tuning wavelength. The signals from single nanomaterials can be visualized and detected by the dark-field iLeyeT system.