Yilin Li

Aqueous Based Semiconductor Nanocrystals

This review summarizes traditional and recent nonconventional, bioinspired, methods for the aqueous synthesis of colloidal semiconductor quantum dots (QDs). The basic chemistry concepts are critically emphasized at the very beginning as these are strongly correlated with the selection of ligands and the optimal formation of aqueous QDs and their more sophisticated structures. The synergies of biomimetic and biosynthetic methods that can combine biospecific reactivity with the robust and strong optical responses of QDs have also resulted in new approaches to the synthesis of the nanoparticles themselves. A related new avenue is the recent extension of QD synthesis to form nanoparticles endowed with chiral optical properties. The optical characteristics of QD materials and their advanced forms such as core/shell heterostructures, alloys, and doped QDs are discussed: from the design considerations of optical band gap tuning, the control and reduction of the impact of surface traps, the consideration of charge carrier processes that affect emission and energy and charge transfer, to the impact and influence of lattice strain. We also describe the considerable progress in some selected QD applications such as in bioimaging and theranostics. The review concludes with future strategies and identification of key challenges that still need to be resolved in reaching very attractive, scalable, yet versatile aqueous syntheses that may widen the scope of commercial applications for semiconductor nanocrystals.

Prognostic Significance of MET Amplification and Expression in Gastric Cancer: A Systematic Review with Meta-Analysis

Background and Aims MET, the hepatocyte growth factor receptor, is a receptor tyrosine kinase overexpressed and activated in a subset of gastric cancer. Several studies investigated the relationship between MET amplification and expression with the clinical outcome in patients with gastric cancer, but yielded conflicting results. We performed a systematic review and meta-analysis to determine the influence of MET amplification and expression on prognosis in gastric cancer. Methods MEDLINE and EMBASE were searched for studies that explored the association between MET amplification and expression with survival in patients with gastric cancer up to 1 April, 2013. Data of individual hazard ratios (HRs) and 95% confidence intervals (CIs) for meta-analyses were extracted from the publications and combined in pooled HRs. Results Fourteen studies involving 2,258 patients with gastric cancer were included. It was suggested that MET overexpression had an unfavorable impact on survival of patients with gastric cancer, with HRs (95% CIs) of 2.57 (95% CI: 1.97–3.35) overall, 2.82 (95% CI: 1.86–4.27) among studies using amplification for measure scale of MET and 2.42 (95% CI: 1.66–3.54) for expression. The magnitude of association was reduced whereas remained statistically significant in high quality studies or in larger sample size studies and corresponding HRs were 2.18(1.76, 2.70) and 2.35(1.93, 2.87), respectively, without significant heterogeneity. Conclusion The findings from present study indicated that higher MET gene amplification and expression in gastric cancer was an indicator of poor prognosis.

Quantum dot-antisense oligonucleotide conjugates for multifunctional gene transfection, mRNA regulation, and tracking of biological processes

It was demonstrated that oligonucleotides, independent of their base sequence and length, could effectively induce the cellular uptake of mercapto acid-capped CdTe QDs after the oligonucleotides were covalently attached on the surface of the QDs. Following these experimental observations, a conjugate composed of covalently linked anti-survivin antisense oligonucleotides (ASON) and CdTe QDs was designed and synthesized. Then, the survivin mRNA down-regulation and the apoptosis of HeLa cells induced by ASON were studied. Systematic experimental results revealed that CdTe-ASON could effectively induce the apoptosis of HeLa cells, while CdTe QDs offered the possibility to visualize the specific intracellular localization of the CdTe-ASON probes strongly associated with their biological functions.

Establishment and characterization of patient-derived tumor xenograft using gastroscopic biopsies in gastric cancer

The patient-derived tumor xenograft (PDTX) model has become the most realistic model for preclinical studies. PDTX models of gastric cancer using surgical tissues are reported occasionally; however, the PDTX models using gastroscopic biopsies, which are best for evaluating new drugs, are unreported. In our study, a total of 185 fresh gastroscopic biopsies of gastric cancer were subcutaneously transplanted into NOD/SCID (Nonobese Diabetic/Severe Combined Immunodeficiency) mice. Sixty-three PDTX models were successfully established (34.1%, 63/185) and passaged to maintain tumors in vivo, and the mean latency period of xenografts was 65.86 ± 32.84 days (11–160 days). Biopsies of prior chemotherapy had a higher transplantation rate (52.1%, 37/71) than biopsies after chemotherapy (21.9%, 25/114; P = 0.000). No differences were found between the latency period of xenografts and characteristics of patients. The pathological and molecular features of PDTX as well as chemosensitivity were highly consistent with those of primary tumors of patients. The genetic characteristics were stable during passaging of PDTX models. In summary PDTX models using gastroscopic biopsies in gastric cancer were demonstrated for the first time, and the biological characteristics of the PDTX models were highly consistent with patients, which provided the best preclinical study platform for gastric cancer.

Surface-biofunctionalized multicore/shell CdTe@SiO 2 composite particles for immunofluorescence assay

Strongly fluorescent multicore/shell structured CdTe@SiO(2) composite particles of ∼ 50 nm were synthesized via the reverse microemulsion method by using CdTe quantum dots co-stabilized by thioglycolic acid and thioglycerol. The optical stability of the CdTe@SiO(2) composite particles in a wide pH range, under prolonged UV irradiation in pure water, or in different types of physiological buffers was systematically investigated. Towards immunofluorescence assay, both poly(ethylene glycol) (PEG) and carboxyl residues were simultaneously grafted on the surface of the silanol-terminated CdTe@SiO(2) composite particles upon further reactions with silane reagents bearing a PEG segment and carboxyl group, respectively, in order to suppress the nonspecific interactions of the silica particles with proteins and meanwhile introduce reactive moieties to the fluorescent particles. Agarose gel electrophoresis, dynamic light scattering and conventional optical spectroscopy were combined to investigate the effectiveness of the surface modifications. Via the surface carboxyl residue, various antibodies were covalently conjugated to the fluorescent particles and the resultant fluorescent probes were used in detecting cancer cells through both direct fluorescent antibody and indirect fluorescent antibody assays, respectively.

Surface-biofunctionalized multicore/shell CdTe

Strongly fluorescent multicore/shell structured CdTe@SiO(2) composite particles of ∼ 50 nm were synthesized via the reverse microemulsion method by using CdTe quantum dots co-stabilized by thioglycolic acid and thioglycerol. The optical stability of the CdTe@SiO(2) composite particles in a wide pH range, under prolonged UV irradiation in pure water, or in different types of physiological buffers was systematically investigated. Towards immunofluorescence assay, both poly(ethylene glycol) (PEG) and carboxyl residues were simultaneously grafted on the surface of the silanol-terminated CdTe@SiO(2) composite particles upon further reactions with silane reagents bearing a PEG segment and carboxyl group, respectively, in order to suppress the nonspecific interactions of the silica particles with proteins and meanwhile introduce reactive moieties to the fluorescent particles. Agarose gel electrophoresis, dynamic light scattering and conventional optical spectroscopy were combined to investigate the effectiveness of the surface modifications. Via the surface carboxyl residue, various antibodies were covalently conjugated to the fluorescent particles and the resultant fluorescent probes were used in detecting cancer cells through both direct fluorescent antibody and indirect fluorescent antibody assays, respectively.

Expression and clinical significance of c-Met in advanced esophageal squamous cell carcinoma.

Backgroundc-Met, one of current potential hot targets, has been suggested as a potential tumor marker in the development of esophageal squamous cell carcinoma (ESCC). Our aim was to investigate the expression of c-Met in advanced esophageal squamous cell carcinoma in four phase II trials who had tumor tissues from archival in our center and analyze the correlations between c-Met expression and clinical features.MethodsNinety patients with advanced ESCC who were admitted to the phase II clinical trials in the Department of Gastrointestinal Oncology, Peking University Cancer Hospital and Institute from March 2007 to March 2014 were finally eligible for present study and the corresponding tissues and clinical data were collected. The expression of c-Met in the tissue samples was detected by immunohistochemistry (IHC). c-Met overexpression was defined as ≥ the median value of H-score. Kaplan-Meier and Cox multivariate regression were conducted to evaluate the relationship between c-Met expression and ESCC survival.ResultsThe overexpression of c-Met is 43.3% in advanced ESCC. There was no statistical difference between c-Met expression and clinical features except sex and tumor location. Survival analysis documented that the overexpression of c-Met predicted a worse prognosis (OS: 253 d vs 422 d, P = 0.011). In the group treated with chemotherapy combined with anti-EGFR drugs, patients with lowexpression of c-Met had a better OS than those with overexpression of c-Met (OS: 577 d vs 232 d, P = 0.007).Conclusionsc-Met may be an independent prognostic factor in advanced ESCC. The overexpression of c-Met may predict a worse efficacy of anti-EGFR therapy.

Research on distribution of SiC particles in aluminum-alloy matrix functionally graded composite tube manufactured by centrifugal casting

chinese acad sci, inst met res, shenyang 110016, peoples r china.;qin, xh (reprint author), chinese acad sci, inst met res, shenyang 110016, peoples r china

The anti-HER3 antibody in combination with trastuzumab exerts synergistic antitumor activity in HER2-positive gastric cancer

The anti-HER2 monoclonal antibody trastuzumab is central to the treatment of HER2-positive gastric cancer (GC); however, its responses are limited. HER3 seems to be the preferred dimerization partner with HER2 and is emerging as a key target for complete blockade of downstream pathways and better clinical response. In this study, we report that novel anti-HER3 antibodies (1A5-3D4) that can neutralize multiple modes of HER3 activation, combined with trastuzumab, exhibited synergistic inhibitory effect on the cell proliferation in HER2-positive GC cell lines. Follow-up studies revealed that the combination treatment significantly inhibited phosphorylation of HER3 as well as AKT and ERK signals. In vivo experiments further showed that the anti-tumor effect of trastuzumab was enhanced by its combination with 1A5-3D4 in NCI-N87 xenograft and patient derived xenografts (PDX). Particularly in an HER2-negative whereas neuregulin1 (a ligand of HER3) positive PDX, the combination was also superior to monotherapy. 1A5-3D4 in combination with trastuzumab exhibits a synergistic inhibitory effect on tumor activity, suggesting that targeting both HER2 and HER3 resulted in an improved treatment effects on HER2-positive GC.

Detection of Epstein–Barr virus infection in cancer by using highly specific nanoprobe based on dBSA capped CdTe quantum dots

By using denatured bovine serum albumin (dBSA) molecules as multidentate ligands, surface-functionalized CdTe quantum dots (QDs) were synthesized and further evaluated for preparing fluorescent probes capable of detecting Epstein–Barr virus infection. The optical studies revealed that the dBSA coating effectively improved the optical stability of the resulting QDs (CdTe@dBSA). The interaction between CdTe@dBSA and the membrane of carcinoma cells further suggested that the nonspecific adsorption of CdTe QDs stabilized by thioglycolic acid (TGA) was significantly eliminated upon the dBSA coating. Streptavidin was covalently conjugated to CdTe@dBSA to endow the QDs with specific binding affinity in detecting the serum level of anti-Epstein–Barr virus (EBV) capsid antigen IgA (VCA-IgA) in nasopharyngeal carcinoma patients for early screening and diagnosing EBV-associated cancers.