Porphyrin-loaded nanoparticles for cancer theranostics

Abstract

Porphyrins have been used as pioneering theranostic agents not only for the photodynamic therapy, sonodynamic therapy and radiotherapy of cancer, but also for diagnostic fluorescence imaging, magnetic resonance imaging and photoacoustic imaging. A variety of porphyrins have been developed but very few of them have actually been employed in clinical trials due to their poor selectivity to tumorous tissue and high accumulation rates in the skin. In addition, most porphyrin molecules are hydrophobic and form aggregates in aqueous media. Nevertheless, the use of nanoparticles as porphyrin carriers shows great promise to overcome these shortcomings. Encapsulating or attaching porphyrins to nanoparticles makes them more suitable for tissue delivery because we can create materials with a conveniently specific tissue lifetime, specific targeting, immune tolerance, and hydrophilicity as well as other characteristics through rational design. In addition, various functional components (e.g. for targeting, imaging or therapeutic functions) can be easily introduced into a single nanoparticle platform for cancer theranostics. This review presents the current state of knowledge on porphyrin-loaded nanoparticles for the interwined imaging and therapy of cancer. The future trends and limitations of prophyrin-loaded nanoparticles are also outlined.

A versatile, stimulus-responsive nanoparticle-based platform for use in both sonodynamic and photodynamic cancer therapy

“…While no statistically-significant difference was observed between nanoparticle-treated cells in the presence of either light or ultrasound, a significant decrease in viability was noted when the viability of cells treated with either stimulus alone was compared with cells treated with the combined stimuli. It was interesting to note that when cells were 14 treated with either nanoparticles alone or the combined stimuli in the absence of nanoparticles no significant effect on cell viability was detected and this will be discussed below.…”

“…Although its use as a sensitiser for SDT would be clinically acceptable, since it is a natural prophyrin and indeed derivatives of this are currently used clinically for PDT (Photofrin), its direct clinical exploitation is hindered by its limited solubility in aqueous media and its adverse biodistribution characteristics which result in prolonged skin photosensitization [12,13]. Since it has been suggested that nanotechnology could play a very significant role in the clinical exploitation of porphyrins [14], primarily because it could resolve issues associated with limited solubility and impact favorably on biodistribution, we decided to explore the possibility of using HP as a sensitiser payload in a nanoparticle-based platform. Poly(DL-lactic-co-glycolic acid) (PLGA) was used as a platform polymer because it is biocompatible, biodegradable and is approved by the United States Food and Drug Administration for use in humans [15].…”

Cancer, Photodynamic Therapy and Porphyrin-Type Derivatives

“…These compounds have low solubility in aqueous media, which difficult their biodistribution (Zhou et al 2016). So, it's factual that the development of drug delivery strategies that can carry these PSs to cancer cells is a research area of enormous importance.…”

“…In fact, the development of PS drug delivery systems based on nanotechnology is an emerging approach to PDT. Liposomes, cyclodextrins (CDs) dendrimers, polymeric and metallic nanoparticles, porphyssomes, quantum dots and carbon nanotubes are examples of formulations that can be used as multifunctional platforms for in cancer photodynamic therapy (Bae et al 2014, Zhou et al 2016. CD is a macrocyclic oligo sugar with wide commercial availability and easy modification.…”

“…One of the approaches to reach selectivity to malignant cells is based on the synthesis of porphyrins bearing targeting moieties, like carbohydrate moieties (Zheng and Pandey 2008, Aksenova et al 2003, Abrahamse and Hamblin 2016. The preparation of porphyrin-carbohydrate conjugates and the investigation of their ability to target carbohydrate -recognized proteins, which are known for their high expression in certain tumors, might be of great significance (Zhou et al 2016, Hilf 2007, Wöhrle et al 1998, Zheng and Pandey 2008. In fact, the conjugation of carbohydrates to porphyrin derivatives can increase their water solubility and bring better hydrophilic/hydrophobic ratios.…”