Tan Yen Nee
Email Address
chmtanyn@nus.edu.sg
4 results
Publication Search Results
Now showing 1 - 4 of 4
Publication Decoupling the CO-reduction protocol to generate luminescent Au22(SR)18 nanocluster(American Chemical Society, 2015) Yu Yong; Li Jingguo; Chen Tiankai; Tan Yen Nee; Xie Jianping; CHEMICAL & BIOMOLECULAR ENGINEERINGPublication Nucleotide-derived theranostic nanodots with intrinsic fluorescence and singlet oxygen generation for bioimaging and photodynamic therapy(Royal Society of Chemistry, 2019) Zheng, X.T.; Lai, Y.C.; Tan, Y.N.; CHEMISTRYNucleic acids are important molecules of life and have recently emerged as important functional materials to synthesize, organize and assemble inorganic nanoparticles for various technological applications. In this study, we have systematically investigated the four basic nucleotides of DNA as precursors to form fluorescent nucleotide derived biodots (N-dots) with unique singlet oxygen generation properties by one-pot hydrothermal synthesis. It has been discovered for the first time that the nitrogenous base adenine accounts for the bright fluorescence, while the sugar and phosphate groups of the nucleotide endow the N-dots with good photo-stability. Among the N-dots synthesized in this study, adenosine triphosphate (ATP)-dots were found to exhibit the highest fluorescence quantum yield (QY) of 13.9%, whereas adenosine diphosphate (ADP)-dots exhibited the best photo-stability maintaining 97.6% photoluminescence intensity after continuous UV excitation for 30 min. Overall, deoxyadenosine monophosphate (dAMP)-dots display both high fluorescence QY (12.4%) and good photo-stability (91.9%). Most critically, dAMP-dots show the highest singlet oxygen generation with a remarkable singlet oxygen (1O2) quantum yield of 1.20 surpassing the 1O2 quantum yield of the conventional photosensitizer Rose Bengal (0.75). Further cellular experiments reveal that dAMP-dots possess excellent cellular uptake ability for successful fluorescent labeling with the ability to kill >60% HeLa cancer cells under white light treatment within 10 minutes. Additionally, N-dots possess excellent stability against both UV irradiation and DNase enzymatic action. These results demonstrate the unique physiochemical properties of N-dots, including an ultra-small size for cellular uptake, tunable photoluminescence for bioimaging, excellent aqueous solubility, high chemical stability and photo-stability as well as excellent singlet oxygen quantum yield with inherent biocompatibility for photodynamic therapy, which are important factors contributing to the promising theranostic applications in future personalized nanomedicine. © 2019 The Royal Society of Chemistry.Publication Poly(ferrocenylsilane) electrolytes as a gold nanoparticle foundry: "two-in-one" redox synthesis and electrosteric stabilization, and sensing applications(Royal Society of Chemistry, 2017) Song, J; Tan, Y.N; Ja?czewski, D; Hempenius, M.A; Xu, J.W; Tan, H.R; Vancso, G.J; CHEMISTRYGold nanoparticles (AuNPs) coated with responsive polymers gained considerable interest due to their controllable size, good stability, and fast environmental response suitable for biological applications and sensing. Here we report on a simple and efficient method for the synthesis of stable and redox responsive AuNPs using organometallic polyelectrolytes in aqueous solutions of HAuCl4. In the redox reaction, positively or negatively charged poly(ferrocenylsilanes) (PFS+/PFS-) served as reducing agents, and also as stabilizing polymers. Due to their unique tunable electrostatic and electrosteric protection, AuNPs coated with PFS-, (PFS+)@AuNPs, possess high redox sensitivity, with reversible, repetitive, sustainable color switching between the assembled (purple color) and disassembled (red color) states as evidenced by UV-Vis absorption and TEM measurements. Feasibility studies reported here indicate that the particles described can be applied as a colorimetric probe for the detection of redox molecules, e.g. vitamin C, in a controlled and facile manner. © 2017 The Royal Society of Chemistry.Publication DNA-Directed Assembly of Nanogold Dimers: A Unique Dynamic Light Scattering Sensing Probe for Transcription Factor Detection(NATURE PUBLISHING GROUP, 2015-12-18) Seow, Nianjia; Tan, Yen Nee; Yung, Lin-Yue Lanry; Su, Xiaodi; Assoc Prof Yung Lin Yue; CHEMISTRY; CHEMICAL & BIOMOLECULAR ENGINEERINGWe have developed a unique DNA-assembled gold nanoparticles (AuNPs) dimer for dynamic light scattering (DLS) sensing of transcription factors, exemplified by estrogen receptor (ER) that binds specifically to a double-stranded (ds) DNA sequence containing estrogen response element (ERE). Here, ERE sequence is incorporated into the DNA linkers to bridge the AuNPs dimer for ER binding. Coupled with DLS, this AuNP dimer-based DLS detection system gave distinct readout of a single â € complex peakâ €™ in the presence of the target molecule (i.e., ER). This unique signature marked the first time that such nanostructures can be used to study transcription factor-DNA interactions, which DLS alone cannot do. This was also unlike previously reported AuNP-DLS assays that gave random and broad distribution of particles size upon target binding. In addition, the ERE-containing AuNP dimers could also suppress the light-scattering signal from the unbound proteins and other interfering factors (e.g., buffer background), and has potential for sensitive detection of target proteins in complex biological samples such as cell lysates. In short, the as-developed AuNP dimer probe coupled with DLS is a simple (mix and test), rapid (readout in ∼5 min) and sensitive (low nM levels of ER) platform to detect sequence-specific protein-DNA binding event.