Quantum dots and nanoparticles for photodynamic and radiation therapies of cancer

Abstract

Semiconductor quantum dots and nanoparticles composed of metals, lipids or polymers have emerged with promising applications for early detection and therapy of cancer. Quantum dots with unique optical properties are commonly composed of cadmium contained semiconductors. Cadmium is potentially hazardous, and toxicity of such quantum dots to living cells, and humans, is not yet systematically investigated. Therefore, search for less toxic materials with similar targeting and optical properties is of further interest. Whereas, the investigation of luminescence nanoparticles as light sources for cancer therapy is very interesting. Despite advances in neurosurgery and radiotherapy the prognosis for patients with malignant gliomas has changed little for the last decades. Cancer treatment requires high accuracy in delivering ionizing radiation to reduce toxicity to surrounding tissues. Recently some research has been focused in developing photosensitizing quantum dots for production of radicals upon absorption of visible light. In spite of the fact that visible light is safe, this approach is suitable to treat only superficial tumours. Ionizing radiation (X-rays and gamma rays) penetrate much deeper thus offering a big advantage in treating patients with tumours in internal organs. Such concept of using quantum dots and nanoparticles to yield electrons and radicals in photodynamic and radiation therapies as well their combination is reviewed in this article.

Nanodrug applications in photodynamic therapy

“…Quantum dots are semiconductor nanoparticles, which have several characteristics that make them a potentially new class of photosensitizers [104]. These small nanoparticles of the size range of 1-6 nm posses high photoluminescence quantum yield, high photostability, high molar extinction coefficient and have a constant composition.…”

“…More importantly, quantum dots can be used to deliver ionizing radiation in a more localized fashion to the place of action. Thus, ionizing radiation can be used for cancer treatment with circumvents the low tissue penetration of light activated PS [104]. Thus, ultimately radiosensitization will complement photosensitization for treatment.…”

Diffusivity of adatoms on plasma-exposed surfaces determined from the ionization energy approximation and ionic polarizability

“…Equations (12) and (13) imply that when the applied electric field gradient, ∂ E app /∂r is large, then ǫ e and D S are also large. Any increment in dimensionless energy,ǭ e implies an increased surface diffusivity, D S because large ǫ e reduces the effect of ǫ d as follows from Eq.…”

“…Plasma-based nanofabrication techniques possess pronounced advantages to produce uniform QDs in terms of distributions of QD sizes, as well as the distances between QDs [11]. This uniformity is extremely important for applications in different fields, for example, in DNA-single electron transistors (nanoelectronics) [12], in photodynamic and radiation therapies (medicine) [13], in nanophotonics (quantum information) [14,15,16,17] and nano-optics [18,19,20,21].…”

Aqueous phase synthesis of CdTe quantum dots for biophotonics

“…Cancer sensing and imaging is another promising application of QDs [71]. For example, Weng et al synthesized CdTe QDs conjugated with either plant lectin or antibody anti-von Willebrand factors as biological labels for targeted cancer cell imaging [72].…”