4 January 2017:
CNBP researchers (Liuen Liang pictured), report on the deployment of upconversion nanoparticles to enhance the treatment depth of the fluorescent protein KillerRed in photodynamic therapy.
The work was published in the journal ‘Acta Biomaterialia’ and is accessible online.
Journal: Acta Biomaterialia.
Title: Deep-penetrating photodynamic therapy with KillerRed mediated by upconversion nanoparticles.
Authors: Liuen Liang, Yiqing Lu, Run Zhang, Andrew Care, Tiago A. Orteg, Sergey M. Deyev, Yi Qian, Andrei V. Zvyagina.
Abstract: The fluorescent protein KillerRed, a new type of biological photosensitizer, is considered as a promising substitute for current synthetic photosensitizes used in photodynamic therapy (PDT). However, broad application of this photosensitiser in treating deep-seated lesions is challenging due to the limited tissue penetration of the excitation light with the wavelength falling in the visible spectral range. To overcome this challenge, we employ upconversion nanoparticles (UCNPs) that are able to convert deep-penetrating near infrared (NIR) light to green light to excite KillerRed locally, followed by the generation of reactive oxygen species (ROS) to kill tumour cells under centimetre-thick tissue. The photosensitizing bio-nanohybrids, KillerRed-UCNPs, are fabricated through covalent conjugation of KillerRed and UCNPs. The resulting KillerRed-UCNPs exhibit excellent colloidal stability in biological buffers and low cytotoxicity in the dark. Cross-comparison between the conventional KillerRed and UCNP-mediated KillerRed PDT demonstrated superiority of KillerRed-UCNPs photosensitizing by NIR irradiation, manifested by the fact that ∼70% PDT efficacy was achieved at 1-cm tissue depth, whereas that of the conventional KillerRed dropped to ∼7%.
25 February 2016:
CNBP researchers have published a paper in the journal Analytical Chemistry titled, “High-contrast visualization of upconversion luminescence in mice using timegating approach.”
Authors: Xianlin Zheng, Xingjun Zhu, Yiqing Lu, Jiangbo Zhao, Wei Feng, Guohua Jia, Fan Wang, Fuyou Li and Dayong Jin.
Abstract: Optical imaging through the near-infrared (NIR) window provides deep penetration of light up to several centimetres into biological tissues. Capable of emitting 800-nm luminescence under 980-nm illumination, the recently-developed upconversion nanoparticles (UCNPs) suggest a promising optical contrast agent for in vivo bioimaging. However, presently they require high-power lasers to excite when applied to small animals, leading to significant scattering background that limits the detection sensitivity as well as detrimental thermal effect. In this work, we show that the time-gating approach implementing pulsed illumination from a NIR diode laser and time-delayed imaging synchronized via an optical chopper offers detection sensitivity more than one order of magnitude higher than the conventional approach using optical band-pass filters (S/N: 47321/6353 vs. 5339/58), when imaging UNCPs injected into Kunming mice. The pulsed laser illumination (70μs ON in 200 μs period) also reduces the overall thermal accumulation to 35% of that under the continuous-wave mode. Technical details are given on setting up the time-gating unit comprising an optical chopper, a pinhole and a microscopy eyepiece. Being generally compatible with any cameras, this provides a convenient and low cost solution to NIR animal imaging using UCNPs as well as other luminescent probes.
The full paper is accessible online.
27 June 2015:
Associate Investigator Dr Yiqing Lu and PhD student Mr Xianlin Zheng were CNBP attendees at CYTO 2015 – the 30th Congress of the International Society for Advancement of Cytometry held in Glasgow, June 26-30, 2015.
Oral presentations were given by both – ‘A Multifunction Workstation Underpinning Lanthanide-Based Luminescence Techniques’ by Dr Lu and ‘Precise Pinpointing of Luminescent Targets Empowers Quantitative Scanning Cytometry’ by Mr Zheng.
Dr Lu was also on the program committee.
While in the UK, both researchers took the time to visit CNBP Partner Prof Tong Sun at City University London, as well as Prof Klaus Suhling at King’s College London and Prof Peter Sadler at the University of Warwick.