Volume 1, Issue 2

Photodynamic therapy (PDT) uses the combination of nontoxic dyes and harmless visible light to produce reactive oxygen species that can kill cancer cells and infectious microorganisms. Due to the tendency of most photosensitizers (PS) to be poorly soluble and to form nonphotoactive aggregates, drug-delivery vehicles have become of high importance. The nanotechnology revolution has provided many examples of nanoscale drug-delivery platforms that have been applied to PDT. These include liposomes, lipoplexes, nanoemulsions, micelles, polymer nanoparticles (degradable and nondegradable), and silica nanoparticles. In some cases (fullerenes and quantum dots), the actual nanoparticle itself is the PS. Targeting ligands such as antibodies and peptides can be used to increase specificity. Gold and silver nanoparticles can provide plasmonic enhancement of PDT. Two-photon excitation or optical upconversion can be used instead of one-photon excitation to increase tissue penetration at longer wavelengths. Finally, after sections on in vivo studies and nanotoxicology, we attempt to answer the title question, “can nanotechnology potentiate PDT?”

The unique chemical and physical properties of nanoscale materials have led to important roles in several scientific and technological fields. Environmental chemistry processes have benefited from the enhanced reactivity of nanoscale particles relative to their bulk counterparts with contaminants. Here, we describe recent advances in the synthesis and characterization of metallic and bimetallic nanoparticles that have been effective toward degrading toxic organohalide contaminants. We then review the degradation mechanisms involved in the reactions of nanoscale particles with organohalides via reduction pathways. We also discuss an emerging area – the degradation of organohalides via multi-electron transfer pathways.

Sonodynamic therapy (SDT) is a newly developed anticancer treatment where ultrasound is used to trigger the cytotoxic effect of chemical compounds, known as sonosensitizers. Although SDT is similar to photodynamic therapy (PDT), SDT activates the chemical compounds through energy transfer using ultrasound rather than light. Moreover, SDT can focus the ultrasound energy onto malignant sites situa\xadted deeply within tissues, thus overcoming the main drawback linked to the use of PDT. Several physical and chemical mechanisms underlying ultrasound bioeffects and anticancer SDT take advantage of the non-thermal effect of acoustic cavitation generated by selected pulsed or continuous ultrasound. As the physical-chemical structure of the sonosentizer is essential for the success of SDT, we believe that the different aspects related to nanotechnology in medicine might well be able to improve the triggering effect ultrasound has on sonosensitizing agents. Therefore, the aim of this review is to focus on how nanotechnology might improve this innovative anticancer therapeutic approach.

Reasons abound for assessing the potential advances of nanoscale manipulation with much optimism. This was even more so on the eve of the creation of the 2003 21st Century Nanotechnology Research and Development Act. At a certain level of logic there seemed to be no option then but to forge ahead. The voices helping to frame the initiative heralded the new wave of nanoscience as the key to future competitiveness and human happiness. In this commentary, my emphasis is on bringing to awareness other counterbalancing perspectives regarding the societal implications of R&D activity. I underscore the repercussions that the incorporation and naturalization of nanotechnology within society perforce starts to have in the midst of human life and organization. I summarize (i) how the top policy, although limited and internally contradictory with regards to engaging R&D pluralistically and socio-technically, provides outlets for reckoning with the inevitable repercussions of the social deployment of nanotechnology; (ii) what some of the societal challenges with which nanotechnology is confronting us are; and (iii) what current research is being carried out that provides models for subsequent nanoscience-related policy development in the right socio-technical direction.

To the extent that the USPTO issues a proliferation of broad and potentially overlapping nanotechnology patents, the development of a nanotechnology patent thicket could impede the licensing process required for further innovation. If the contractor refuses the federal agency’s request, the agency can grant a license to the applicant itself if “the contractor or assignee has not taken, or is not expected to take within a reasonable time, effective steps to achieve practical application of the subject invention in such field of use” or if “action is necessary to meet requirements for public use specified by Federal regulations and such requirements are not reasonably satisfied by the contractor, assignee, or licensees.” Theoretically, the march-in right demonstrates the power of the government to prevent the nonuse of patents in the context of patent hoarding or blocking patents used to stifle competition. These university-based nanotechnology research centers are in a prime position to secure bids for significant shares of the new funding from the Nanotechnology Act; ultimately, they should have an augmented government license defense in order to carry out incremental and innovative research effectively without becoming unduly encumbered by a nanotechnology patent thicket.

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