19 June 2018:
Researchers from CNBP have developed an X-ray-induced photodynamic therapy (PDT) system where nanoparticles incorporating a photosensitizer, verteporfin, were triggered by X-ray radiation to generate cytotoxic singlet oxygen. This system offers the possibility of enhancing the radiation therapy commonly prescribed for the treatment of cancer by simultaneous PDT.
Lead author on the paper was Dr Sandhya Clement (pictured).
Journal: International Journal of Nanomedicine.
Publication title: X-ray radiation-induced and targeted photodynamic therapy with folic acid-conjugated biodegradable nanoconstructs.
Authors: Sandhya Clement, Wenjie Chen, Wei Deng, Ewa M Goldys.
Introduction: The depth limitation of conventional photodynamic therapy (PDT) with visible electromagnetic radiation represents a challenge for the treatment of deep-seated tumors. Materials and methods: To overcome this issue, we developed an X-ray-induced PDT system where poly(lactide-co-glycolide) (PLGA) polymeric nanoparticles (NPs) incorporating a photosensitizer (PS), verteporfin (VP), were triggered by 6 MeV X-ray radiation to generate cytotoxic singlet oxygen. The X-ray radiation used in this study allows this system to breakthrough the PDT depth barrier due to excellent penetration of 6 MeV X-ray radiation through biological tissue. In addition, the conjugation of our NPs with folic acid moieties enables specific targeting of HCT116 cancer cells that overexpress the folate receptors. We carried out physiochemical characterization of PLGA NPs, such as size distribution, zeta potential, morphology and in vitro release of VP. Cellular uptake activity and cell-killing effect of these NPs were also evaluated. Results and discussion: Our results indicate that our nanoconstructs triggered by 6 MeV X-ray radiation yield enhanced PDT efficacy compared with the radiation alone. We attributed the X-ray-induced singlet oxygen generation from the PS, VP, to photoexcitation by Cherenkov radiation and/or reactive oxygen species generation facilitated by energetic secondary electrons produced in the tissue. Conclusion: The cytotoxic effect caused by VP offers the possibility of enhancing the radiation therapy commonly prescribed for the treatment of cancer by simultaneous PDT.
21 April 2017:
A new paper from CNBP researchers (lead author Wenjie Chen pictured) reports on the design of a new light-triggerable liposome. The work has just been published in the journal ‘Molecular Therapy: Nucleic Acid’ and is accessible online.
Journal: Molecular Therapy: Nucleic Acid.
Title: Light-triggerable liposomes for enhanced endo/lysosomal escape and gene silencing in PC12 cells.
Authors: Wenjie Chen, Wei Deng, Ewa M. Goldys.
Abstract: Liposomes are an effective gene/drug delivery system, widely used in biomedical applications including gene therapy and chemotherapy. Here we designed a photo-responsive liposome (lipVP) loaded with a photosensitizer verteporfin (VP). This photosensitizer is clinically approved for photodynamic therapy (PDT). LipVP was employed as a DNA carrier for pituitary adenylyl cyclase-activating polypeptide (PACAP) receptor 1 (PAC1R) gene knockdown in PC12 cells. This has been done by incorporating PAC1R antisense oligonucleotides inside the lipVP cavity. Cells which have taken up the lipVP were exposed to light from a UV light source. As a result of this exposure, reactive oxygen species (ROS) were generated from VP, destabilising the endo/lysosomal membranes and enhancing the liposomal release of antisense DNA into the cytoplasm. Endo/lysosomal escape of DNA was documented at different time points based on quantitative analysis of colocalization between fluorescently labelled DNA and endo/lysosomes. The released antisense oligonucleotides were found to silence PAC1R mRNA. The efficiency of this photo-induced gene silencing was demonstrated by a 74 ± 5% decrease in PAC1R fluorescence intensity. Following the light-induced DNA transfer into cells, cell differentiation with exposure to two kinds of PACAP peptides was observed to determine the cell phenotypic change after PAC1R gene knockdown.
22 March 2017:
A new publication from CNBP researchers (lead author Sandhya Clement pictured) reports on a more effective and less harmful gold-based nano-agent for bioimaging and photodynamic therapy treatment for deep tissue tumors.
The work has just been reported in the journal ‘Microchimica Acta ’ and is accessible online.
Journal: Microchimica Acta.
Title: Verteprofin conjugated to gold nanoparticles for fluorescent cellular bioimaging and X-ray mediated photodynamic therapy.
Authors: Sandhya Clement, Wenjie Chen, Ayad G. Anwer & Ewa M. Goldys.
Abstract: Photodynamic therapy (PDT) uses photosensitizers, light and molecular oxygen to generate cytotoxic reactive oxygen species. Its effectiveness is limited to <1 cm due to the limited penetration depth of light. The present study compares the PDT effectivity of the photosensitizer verteporfin (VP) conjugated to gold nanoparticles (AuNPs) (a) by using deeply penetrating X-rays administered in standard radiotherapy doses, and (b) by using red light (690 nm). VP was conjugated to AuNPs of around 12 nm size to enhance the interaction of ionizing radiation with PS. For comparison, VP also was directly exposed to X-rays. It is found that VP alone is stimulated by X-rays to generate singlet oxygen. The conjugate to AuNPs also generated a significant amount of singlet oxygen on irradiation with X-rays in comparison to illumination with 690-nm light. It is also found that the rate of singlet oxygen generation is amplified in case of AuNP-conjugated VP compared to VP alone. The performance of the AuNP-VP conjugate and of the VP alone was tested in Panc 1 cells. Their viability was impaired much more in these two scenarios than with the X-ray radiation only. This suggests excellent perspectives for PDT based on VP and with X-ray stimulation, both as a stand-alone photosensitizer and in Au-NP conjugates. Moreover, both VP and AuNP-VP conjugates show bright fluorescence in physiological media for excitation/emission wavelengths in the range of 405/690 nm; hence they can also be used for simultaneous bioimaging.
17 April 2015:
Last week Macquarie node welcomed two new PhD students who joined Ewa Goldys’ group.
Kashif Islam (left) hails from Pakistan. His project is concerned with expanding the range of fluorophores that can be non-invasively quantified in cells and tissues. This work will have components of hardware development, photochemistry and photobiology. Kashif will be part of the hyperspectral team working with Martin Gosnell, Ayad Anwer, Biju Cletus, Saabah Mahbub and Aziz Rehman and external partners. We hope he will be able to observe tryptophan, kyneurenine and collagen, which will open up exciting options for CNBP.
Wenjie Jason Chen (right) came from China. He is developing specialised nanoparticles which will be targeted to receptors of interest and deliver their cargo following a trigger. He will be working with Wei Deng and external partners working towards translational medical objectives.
We are excited to have Jason and Kashif here and looking forward to seeing their results soon.