Imperial College London

Dr Jing Sheng Pang

Central FacultyEnterprise

Industry Partnerships & Commercialisation Executive (FoE)
 
 
 
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Contact

 

+44 (0)20 7594 1014j.pang Website

 
 
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Location

 

Faculty BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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16 results found

Pang JS, Theodorou IG, Centeno A, Petrov PK, Alford NM, Ryan MP, Xie Fet al., 2019, Tunable three-dimensional plasmonic arrays for large near-infrared fluorescence enhancement, ACS Applied Materials and Interfaces, Vol: 11, Pages: 23083-23092, ISSN: 1944-8244

Metal-enhanced fluorescence (MEF), resulting from the near-field interaction of fluorophores with metallic nanostructures, has emerged as a powerful tool for dramatically improving the performance of fluorescence-based biomedical applications. Allowing for lower autofluorescence and minimal photoinduced damage, the development of multifunctional and multiplexed MEF platforms in the near-infrared (NIR) windows is particularly desirable. Here, a low-cost fabrication method based on nanosphere lithography is applied to produce tunable three-dimensional (3D) gold (Au) nanohole–disc arrays (Au-NHDAs). The arrays consist of nanoscale glass pillars atop nanoholes in a Au thin film: the top surfaces of the pillars are Au-covered (effectively nanodiscs), and small Au nanoparticles (nanodots) are located on the sidewalls of the pillars. This 3D hole–disc (and possibly nanodot) construct is critical to the properties of the device. The versatility of our approach is illustrated through the production of uniform and highly reproducible Au-NHDAs with controlled structural properties and tunable optical features in the NIR windows. Au-NHDAs allow for a very large NIR fluorescence enhancement (more than 400 times), which is attributed to the 3D plasmonic structure of the arrays that allows strong surface plasmon polariton and localized surface plasmon resonance coupling through glass nanogaps. By considering arrays with the same resonance peak and the same nanodisc separation distance, we show that the enhancement factor varies with nanodisc diameter. Using computational electromagnetic modeling, the electric field enhancement at 790 nm was calculated to provide insights into excitation enhancement, which occurs due to an increase in the intensity of the electric field. Fluorescence lifetime measurements indicate that the total fluorescence enhancement may depend on controlling excitation enhancement and therefore the array morphology. Our findings provide important in

Journal article

Wang T, Centeno A, Darvill D, Pang J, Ryan MP, Xie Fet al., 2018, Tuneable fluorescence enhancement over nanostructured ZnO arrays with controlled morphology, Physical Chemistry Chemical Physics, Vol: 21, Pages: 14828-14834, ISSN: 1463-9076

Zinc oxide (ZnO) nanorods (NRs) have been demonstrated as a promising platform for enhanced fluorescence-based sensing. It is, however, desirable to achieve a tuneable fluorescence enhancement with these platforms so that the fluorescence output can be adjusted based on the real need. Here we show that the fluorescence enhancement can be tuned by changing the diameter of the ZnO nanorods, simply controlled by potassium chloride (KCl) concentration during synthesis, using arrays of previously developed aligned NRs (a.k.a. aligned NR forests) and nanoflowers (NFs). Combining the experimental results obtained from ZnO nanostructures with controlled morphology and computer-aided verification, we show that the fluorescence enhancement factor increases when ZnO NRs become thicker. The fluorescence enhancement factor of NF arrays is shown to have a much stronger dependency on the rod diameter than that of aligned NR arrays. We prove that the morphology of nanostructures, which can be controlled, can be an important factor for fluorescence enhancement. Our (i) effort towards understanding the structure–property relationships of ZnO nanostructured arrays and (ii) demonstration on tuneable fluorescence enhancement by nanostructure engineering can provide some guidance towards the rational design of future fluorescence amplification platforms potentially for bio-sensing.

Journal article

Pang J, Theodorou I, Centeno A, Petrov P, Alford N, Ryan M, Xie Fet al., 2016, Gold nanodisc arrays as near infrared metal-enhanced fluorescence platforms with tuneable enhancement factors, Journal of Materials Chemistry C, Vol: 5, Pages: 917-925, ISSN: 2050-7534

Metal enhanced fluorescence (MEF) is a physical effect through which the near-field interaction of fluorophores with metallic nanoparticles can lead to large fluorescence enhancement. MEF can be exploited in many fluorescence-based biomedical applications, with potentially significant improvement in detection sensitivity and contrast enhancement. Offering lower autofluorescence and minimal photoinduced damage, the development of effective and multifunctional MEF platforms in the near-infrared (NIR) region, is particularly desirable. In this work, the enhancement of NIR fluorescence caused by interaction with regular arrays of cylindrical gold (Au) nanoparticles (nanodiscs), fabricated through nanosphere lithography, is reported. Significant MEF of up to 235 times is obtained, with tuneable enhancement factors. The effect of array structure on fluorescence enhancement is investigated by semi-quantitatively de-convoluting excitation enhancement from emission enhancement, and modelling the local electric field enhancement. By considering arrays of Au nanodiscs with the same extinction maximum, it is shown that the excitation enhancement, due to increased electric field, is not significantly different for the particle sizes and separation distances considered. Rather, it is seen that the emission from the fluorophore is strongly enhanced, and is dependent on the topography, in particular particle size. The results show that the structural characteristics of Au nanodisc arrays can be manipulated to tune their enhancement factor, and hence their sensitivity.

Journal article

Wang T, Costan J, Centeno A, Pang J, Price D, Ryan M, Xie Fet al., 2015, Broadband enhanced fluorescence using Zinc-Oxide nanoflower arrays, Journal of Materials Chemistry C, Vol: 3, Pages: 2656-2663, ISSN: 2050-7534

ZnO nanostructures were fabricated into flower-like nanoscale arrays by the hydrothermal growth of ZnO nanowires onto a self-assembled monolayer of polystyrene spheres on a glass substrate. Fluorescent molecules conjugated with streptavidin were incubated on glass with 3-(glycidoxypropyl) trimethoxysilane (GPTS) modified and biotinylated bovine serum albumin (bBSA) attached (GPTS–bBSA), aligned ZnO nanorod arrays and ZnO nanoflower arrays, respectively. An enhancement factor of up to 45 was obtained from ZnO nanoflower arrays, compared to less than 10 for the aligned nanorods. More importantly, using the same substrate, we observed a broadband fluorescence enhancement. The level of enhancement obtained from the nanoflower arrays is comparable with that from Metal Enhanced Fluorescence. The broadband nature of this process makes it an attractive alternative for fluorescent based device development.

Journal article

Donchev E, Gammon PM, Pang JS, Petrov PK, Alford NMet al., 2014, Systematic study of metal-insulator-metaldiodes with a native oxide, Conference on Thin Films for Solar and Energy Technology VI, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X

Conference paper

Gammon PM, Perez-Tomas A, Shah VA, Vavasour O, Donchev E, Pang JS, Myronov M, Fisher CA, Jennings MR, Leadley DR, Mawby PAet al., 2013, Modelling the inhomogeneous SiC Schottky interface, JOURNAL OF APPLIED PHYSICS, Vol: 114, ISSN: 0021-8979

Journal article

Xie F, Pang J, Centeno A, Ryan M, Riley J, Alford Net al., 2013, Nanoscale control of Ag nanostructures for plasmonic fluorescence enhancement of near-infrared dyes, Nano Research, Vol: 6, Pages: 495-510, ISSN: 1998-0124

Potential utilization of proteins for early detection and diagnosis of various diseases has drawn considerable interest in the development of protein-based detection techniques. Metal induced fluorescence enhancement offers the possibility of increasing the sensitivity of protein detection in clinical applications. We report the use of tunable plasmonic silver nanostructures for the fluorescence enhancement of a near-infrared (NIR) dye (Alexa Fluor 790). Extensive fluorescence enhancement of ∼2 orders of magnitude is obtained by the nanoscale control of the Ag nanostructure dimensions and interparticle distance. These Ag nanostructures also enhanced fluorescence from a dye with very high quantum yield (7.8 fold for Alexa Fluor 488, quantum efficiency (Qy) = 0.92). A combination of greatly enhanced excitation and an increased radiative decay rate, leading to an associated enhancement of the quantum efficiency leads to the large enhancement. These results show the potential of Ag nanostructures as metal induced fluorescence enhancement (MIFE) substrates for dyes in the NIR “biological window” as well as the visible region. Ag nanostructured arrays fabricated by colloidal lithography thus show great potential for NIR dye-based biosensing applications.

Journal article

Pang JS, Xie F, Centeno A, Petrov PK, Ryan MP, Alford Net al., 2012, Optical absorption of metal nanoparticle arrays

A study into the enhanced optical absorption due to metal nanoparticle arrays fabricated by nanosphere lithography. Prediction and measurement has been undertaken. Implementation to improve the efficiency of PV solar cells is discussed. © 2012 OSA.

Conference paper

Pang JS, Xie F, Centeno A, Petrov PK, Ryan MP, Alford Net al., 2012, Optical absorption of metal nanoparticle arrays

A study into the enhanced optical absorption due to metal nanoparticle arrays fabricated by nanosphere lithography. Prediction and measurement has been undertaken. Implementation to improve the efficiency of PV solar cells is discussed. © 2012 OSA.

Conference paper

Pang JS, Xie F, Centeno A, Petrov PK, Ryan MP, Alford Net al., 2012, Optical absorption of metal nanoparticle arrays

A study into the enhanced optical absorption due to metal nanoparticle arrays fabricated by nanosphere lithography. Prediction and measurement has been undertaken. Implementation to improve the efficiency of PV solar cells is discussed. © 2012 OSA.

Conference paper

Gammon PM, Donchev E, Perez-Tomas A, Shah VA, Pang JS, Petrov PK, Jennings MR, Fisher CA, Mawby PA, Leadley DR, Alford NMet al., 2012, A study of temperature-related non-linearity at the metal-silicon interface, JOURNAL OF APPLIED PHYSICS, Vol: 112, ISSN: 0021-8979

Journal article

Pang JS, Xie F, Centeno A, Petrov PK, Ryan MP, Alford Net al., 2012, Optical absorption of metal nanoparticle arrays

A study into the enhanced optical absorption due to metal nanoparticle arrays fabricated by nanosphere lithography. Prediction and measurement has been undertaken. Implementation to improve the efficiency of PV solar cells is discussed. © 2012 OSA.

Conference paper

Pang JS, Xie F, Centeno A, Petrov PK, Ryan MP, Alford Net al., 2012, Optical absorption of metal nanoparticle arrays

A study into the enhanced optical absorption due to metal nanoparticle arrays fabricated by nanosphere lithography. Prediction and measurement has been undertaken. Implementation to improve the efficiency of PV solar cells is discussed.

Conference paper

Pang JS, Xie F, Centeno A, Petrov PK, Ryan MP, Alford Net al., 2012, Optical absorption of metal nanoparticle arrays

© 2012 OSA. A study into the enhanced optical absorption due to metal nanoparticle arrays fabricated by nanosphere lithography. Prediction and measurement has been undertaken. Implementation to improve the efficiency of PV solar cells is discussed.

Conference paper

Pang JS, Xie F, Centeno A, Petrov PK, Ryan MP, Alford Net al., 2012, Optical absorption of metal nanoparticle arrays

A study into the enhanced optical absorption due to metal nanoparticle arrays fabricated by nanosphere lithography. Prediction and measurement has been undertaken. Implementation to improve the efficiency of PV solar cells is discussed. © 2012 OSA.

Conference paper

Knaapila M, Garamus VM, Almásy L, Pang JS, Forster M, Gutacker A, Scherf U, Monkman APet al., 2008, Fractal aggregates of polyfluorene-polyaniline triblock copolymer in solution state, Journal of Physical Chemistry B, Vol: 112, Pages: 16415-16421, ISSN: 1520-6106

We report on the aggregate structure of a symmetrical A-B-A 9,9-dialkylfluorene/2-alkylaniline "coil-rod-coil" triblock copolymer (or PF/PANI11112-b-PANI11)-consisting of 2-dodecylanilines as A blocks and 9,9-di(3,7,11-trimethyldodecyl)fluorene)s as B blocks-mixed in deuterated toluene, chloroform, and methylcy-clohexane. These mixtures contain micrometer scale aggregates. Small-angle neutron scattering data indicate that the interface between the aggregates and solvents manifests surface fractal-like structure. The upper and lower limit length scales which show fractal character are of the order of > 100 and 15 nm. The surface fractal dimension D s varies from 2.2 to 2.8. The data show that stiff polyfluorene (PF) segments (persistence length ≥9.5 nm, diameter ~ 2 nm) of PF/PANI11112-b-PANI11 are dissolved down to the molecular level. Photoluminescence data indicate that most PF units are isolated from both polyaniline (PANi) units and each others. Together with the scattering data, this implies that the disordered interface consists of stiff isolated PF blocks linked together via domains of associated PANi blocks. © 2008 American Chemical Society.

Journal article

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