Xiaoyuan Chen

Bio: Xiaoyuan Chen is an academic researcher from National University of Singapore. The author has contributed to research in topics: Physics & Photothermal therapy. The author has an hindex of 149, co-authored 994 publications receiving 89870 citations. Previous affiliations of Xiaoyuan Chen include Brown University & University of Southern California.

Functional Micro-/Nanomaterials for Multiplexed Biodetection.

Abstract: When analyzing biological phenomena and processes, multiplexed biodetection has many advantages over single-factor biodetection and is highly relevant to both human health issues and advancements in the life sciences. However, many key problems with current multiplexed biodetection strategies remain unresolved. Herein, the main issues are analyzed and summarized: 1) generating sufficient signal to label targets, 2) improving the signal-to-noise ratio to ensure total detection sensitivity, and 3) simplifying the detection process to reduce the time and labor costs of multiple target detection. Then, available solutions made possible by designing and controlling the properties of micro- and nanomaterials are introduced. The aim is to emphasize the role that micro-/nanomaterials can play in the improvement of multiplexed biodetection strategies. Through analyzing existing problems, introducing state-of-the-art developments regarding relevant materials, and discussing future directions of the field, it is hopeful to help promote necessary developments in multiplexed biodetection and associated scientific research.

Ultrasound‐Mediated Diagnosis and Therapy based on Ultrasound Contrast Agents

Abstract: Ultrasound-mediated diagnosis techniques have consistently attracted worldwide attention. Compared with other medical-diagnosis methods, relatively distinguished features of ultrasound being readily accessible, swift, inexpensive, and safe make it routinely used for diverse purposes. With the development of ultrasound-imaging devices, the recent advent of ultrasound contrast agents (UCAs) has expanded the sphere of ultrasound's influence to therapy. UCAs, which are generally gas-filled and microsized bubbles, have been grafted onto multifunctional particles or molecules to selectively detect various diseases and effectively treat them. Additionally, nanosized bubbles as well as microsized bubbles have lately received a lot of attention since the phase-transition behavior of the bubbles is observed under certain conditions. The focus here is an introduction to and the preparation of therapeutic and multimodal UCAs. Also, high-intensity focused ultrasound (HIFU), among the ultrasound-mediated techniques, which enables researchers and health-care providers to overcome existing approaches, is described in depth. To close, the future and challenges of diagnosis and therapy with ultrasound are reviewed.

PEGylated Exendin-4, a Modified GLP-1 Analog Exhibits More Potent Cardioprotection than Its Unmodified Parent Molecule on a Dose to Dose Basis in a Murine Model of Myocardial Infarction

Abstract: A Site-specifically PEGylated exendin-4 (denoted as PEG-Ex4) is an exendin-4 (denoted as Ex4) analog we developed by site-specific PEGylation of exendin-4 with a high molecular weight trimeric poly(ethylene glycol) (tPEG). It has been shown to possess prolonged half-life in vivo with similar receptor binding affinity compared to unmodified exendin-4 by our previous work. This study is sought to test whether PEG-Ex4 is suitable for treating myocardial infarction (MI). In the MI model, PEG-Ex4 was administered every 3 days while equivalent amount of Ex4 was administered every 3 days or twice daily. Animal survival rate, heart function, remodeling and neoangiogenesis were evaluated and compared. Tube formation was examined in endothelial cells. In addition, Western blotting and histology were performed to determine the markers of cardiac hypertrophy and angiogenesis and to explore the possible molecular mechanism involved. PEG-Ex4 and Ex4 showed comparable binding affinity to GLP-1 receptor. In MI mice, PEG-Ex4 given at 3 days interval achieved similar extent of protection as Ex4 given twice daily, while Ex4 given at 3 days interval failed to produce protection. PEG-Ex4 elevated endothelial tube formation in vitro and capillary density in the border area of MI. PEG-Ex4 increased Akt activity and VEGF production in a GLP-1R dependent manner in endothelial cells and antagonism of GLP-1R, Akt or VEGF abolished the protection of PEG-Ex4 in the MI model. PEG-Ex4 is a potent long-acting GLP-1 receptor agonist for the treatment of chronic heart disease. Its protection might be attributed to enhanced angiogenesis mediated by the activation of Akt and VEGF.

New Generation of Gold Nanoshell-Coated Esophageal Stent: Preparation and Biomedical Applications

Abstract: Esophageal cancer is one of the six most common cancers in the world, constituting ∼7% of the gastrointestinal cancers. Esophageal stents can be inserted into the esophagus to open the pathway as a palliative treatment for advanced esophageal cancer. For the treatment of esophageal cancer, a series of anticancer drug-loaded stents such as paclitaxel or 5-fluorouracil/esophageal stent combinations have been prepared by covering a nitinol stent with a polymer or hydrogel shell. For the first time, we developed a gold nanoshell (AuNS)-coated stent with high photothermal efficiency and used in the repetitive photothermal therapy of esophageal cancer. The functionalized stent was prepared by using surface-coated polydopamine as the Au3+ anchor and template. The thickness of the AuNS can be easily adjusted by controlling the reaction time and amount of Au3+. The AuNS-coated stent efficiently increased the temperature of pork and porcine intestines irradiated with a near-infrared (NIR) laser. The deep penetratio...

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Chemistry and properties of nanocrystals of different shapes.

Abstract: The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102