Volume 5, Issue 3

Photodynamic therapy (PDT) employs the combination of non-toxic photosensitizers (PS) together with harmless visible light of the appropriate wavelength to produce reactive oxygen species that kill unwanted cells. Because many PS are hydrophobic molecules prone to aggregation, numerous drug delivery vehicles have been tested to solubilize these molecules, render them biocompatible and enhance the ease of administration after intravenous injection. The recent rise in nanotechnology has markedly expanded the range of these nanoparticulate delivery vehicles beyond the well-established liposomes and micelles. Self-assembled nanoparticles are formed by judicious choice of monomer building blocks that spontaneously form a well-oriented 3-dimensional structure that incorporates the PS when subjected to the appropriate conditions. This self-assembly process is governed by a subtle interplay of forces on the molecular level. This review will cover the state of the art in the preparation and use of self-assembled liposomal nanoparticles within the context of PDT.

Carbon nanomaterials have unique physicochemical properties based solely on their small size, which makes them ideal for nano-oncology. While there have been tremendous advances in the current treatment of high-risk cancers, conventional treatment still causes harm to the surrounding healthy tissue. Carbon nanomaterials such as carbon nanotubes, carbon nanohorns, and graphenes have been increasingly used in the field of cancer photothermal therapy. Through surface functionalization, carbon nanomaterials can be specifically targeted to the tumorous tissue allowing for an increase in therapeutic potential. The unique photo-electron transfer features of carbon nanomaterials coupled with functional moieties, is proving useful for their use in the photothermolysis of cancer cells.

Intracellular delivery of promising therapeutic agents as well as nanocarriers presents a unique challenge. However, with the discovery of the cell-penetrating peptides (CPPs), overcoming this obstacle seems more plausible. In many cases, CPPs conjugated with therapeutic agent or therapeutic agent loaded-nanoparticles have shown promising results via increased cellular uptake. In this review, the current status of CPPs for the intracellular delivery of not just potential therapeutic small molecules but also large molecules like peptides, nucleic acids and nanocarriers is discussed. In addition, the design of ‘smart stimuli-sensitive nanocarrier’ to overcome the non-target-specificity of CPPs is also described.

The present report describes the improved ocular retention and aqueous humoral drug availability of ganciclovir (GCV) when administered via topical instillation of different kind of nanoparticles onto the rabbit eye. GCV was loaded into PLGA nanoparticles, chitosan-coated nanoparticles and chitosan-coated niosomal nanoparticles. All three formulations contained nanoparticles equally round in shape with a mean particle size in the range of 180–200 nm. The ocular corneal retention property was evaluated by gamma scintigraphy, revealing that the clearance was slowest in the case of the chitosan-containing formulations. GCV in chitosan-coated PLGA nanoparticles and chitosan-coated niosomal nanoparticles showed approx. 6-fold higher aqueous humor drug availability as compared to a GCV solution and nearly 2.5-fold higher as compared to the chitosan-lacking GCV-PLGA nanoparticles. The results indicate that the use of a mucoadhesive chitosan coating can improve the ocular residence time and aqueous humoral availability of GCV when administered topically in nanoparticles.