@article{qian_he_2010, title={Polymeric macroinitiators for signal amplification in AGET ATRP-based DNA detection}, volume={150}, ISSN={["0925-4005"]}, DOI={10.1016/j.snb.2010.08.034}, abstractNote={We report here the use of polylysine (PLL) as a carrier to bring multiple polymerization reaction initiators to surface-affixed PNA/DNA duplexes for signal amplification in polymerization-based DNA detection. Two primary benefits of the described approach have been demonstrated in this report: (1) positively charged PLL as the initiator carrier binds to PNA/DNA duplexes electrostatically; thus eliminates the need for chemical modification of each individual DNA probes prior to detection and provides a universal DNA detection scheme. (2) Furthermore, each PLL molecule brings multiple polymerization reaction initiators to each hybridization event, which leads to significantly improved detection sensitivity. Systematic investigation shows the use of longer PLL (∼215 lysine residues per chain) has yielded thicker polymer films in comparison to that of a shorter PLL (∼27 lysine residues per chain). An optimal percentage of lysine moieties modified on each PLL molecule has been determined that allowed maximum polymer growth from each modified lysine group without compromising vital electrostatic binding between unmodified amino groups and negatively charged DNA. Quantitative DNA detection has been demonstrated where the detection limit has been improved for approximately 60 times compared to the previously reported value in single-initiator-tagged DNA detection.}, number={2}, journal={SENSORS AND ACTUATORS B-CHEMICAL}, author={Qian, Hong and He, Lin}, year={2010}, month={Oct}, pages={594–600} }
 @article{qian_he_2009, title={Detection of Protein Binding Using Activator Generated by Electron Transfer for Atom Transfer Radical Polymerization}, volume={81}, ISSN={["1520-6882"]}, DOI={10.1021/ac900959v}, abstractNote={A purge-free controlled living polymerization method, activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP), is used to amplify the occurrence of protein binding events. Detection of ovalbumin is demonstrated where binding of femtomole protein is differentiable from the background using ellipsometry. Moreover, binding of subpicomole protein leads to visually distinguishable spots on the sensor surface within 15 min, which signifies its potential in future development of point-of-need devices.}, number={23}, journal={ANALYTICAL CHEMISTRY}, author={Qian, Hong and He, Lin}, year={2009}, month={Dec}, pages={9824–9827} }
 @article{qian_he_2009, title={Surface-Initiated Activators Generated by Electron Transfer for Atom Transfer Radical Polymerization in Detection of DNA Point Mutation}, volume={81}, ISSN={["1520-6882"]}, DOI={10.1021/ac900401m}, abstractNote={Amplification-by-Polymerization reportedly offers a sensitive and detector-free approach for DNA detection. However, the requirement for an oxygen-free environment when classic radical polymerization reactions are used in signal amplification significantly limits the mobility of this approach for point-of-need applications. We report here the employment of a purge-free controlled/"living" polymerization reaction, activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP), to achieve signal amplification upon DNA hybridization. Its aptitude in simplifying assay procedure and shortening assay turn-around has been demonstrated in this report, which substantiates the feasibility of using Amplification-by-Polymerization for high throughput or portable screening of genetic mutations. In addition, employment of water-soluble ascorbic acid as the reducing agent has overcome the hurdles encountered by heterogeneous AGET ATRP reactions. Optimization of AGET ATRP in the presence of oligonucleotides has been conducted where tris[(2-pyridyl)methyl]amine (TPMA) was selected as the catalyst ligand for its mild reaction rate. Effective polymer growth has been achieved when the concentration of the Cu(II) catalyst was controlled at 20 mM and ascorbic acid at 18 mM. The propagation and termination reaction constants have been derived, purporting the speculated controlled growth kinetics during polymer grafting. A linear relationship between the grafted polymer film thickness and the amount of captured DNA target sequences has been established, which provides the quantification basis during DNA detection. Detection of DNA sequences with single-point mutations has been successful regardless of the mutation site.}, number={11}, journal={ANALYTICAL CHEMISTRY}, author={Qian, Hong and He, Lin}, year={2009}, month={Jun}, pages={4536–4542} }