Nanoparticles for Biomedical Application

Dear Colleagues,

For the past three decades, the rapid development of nanotechnology has resulted in the growing implementation of nanoparticles (NP) in the field of biomedicine as vehicles for drug delivery, diagnostic imaging, and theranostic application. Clinically approved and investigational nano-based drug formulations have been applied to a variety of indications, such as cancer, infectious diseases, neurodegenerative disorders, or tissue engineering. The application of nanomedicine formulations presents several advantages when compared to conventional medicines. The unique ability of nanoparticles to improve solubility, the pharmacokinetic, and toxicological properties of active pharmaceutical ingredients, as well as the possibility to synthetically tailor them for specific tissue/organ targeting led to the great initial promise and enthusiasm in nanoparticle investigation. However, despite the growing efforts, a relatively small number of nanoparticle-based formulations is currently used in clinical practice. Challenges such as improved characterization, possible toxicity, delivery efficacy, cost-benefit considerations, and regulatory ambiguities of nanomedicines, still need to be improved and resolved. A great variety of materials has been used so far in nano-drug design and include liposomes, metals or metal oxides, synthetic and natural polymers, and nanocrystals, to mention a few. The propensity of these materials to form stable nanostructures of well-defined shape, size, and surface chemistry under physiological conditions is deemed responsible for improved drug delivery and drug efficacy. A number of important pharmacokinetic parameters such as specific tissue uptake and accumulation, biodistribution, and clearance mechanisms were found to depend on nanoparticle properties. The small size of NPs, usually between 10 and 100 nm, is exploited to avoid physiological barriers like the immune system, renal clearance, or mechanical degradation. The ability of liposomal NPs or polymer-based micelles to envelop hydrophobic drugs has been used to improve bioavailability, efficacy, and the delivery of a wide range of compounds with interesting biological properties. Additionally, the grafting of NP surfaces with polycations opened up a whole new application of NPs in combination therapy enabling the delivery of conventional chemotherapeutic agents and polynucleotides (RNA, DNA) that are the base of gene therapy. Furthermore, the surface of NPs can be modified for active tissue/cell targeting resulting in enhanced therapeutic levels at a target site. The strategy is especially used for cancer treatment where the NP surface has been decorated with a large number of ligands that selectively bind receptors overexpressed by cancer cells that leads to increased accumulation and/or cancer cell uptake. A different approach to smart NP-based drug carriers is based on the design of stimuli-sensitive NPs where external stimuli such as pH or redox conditions lead to drug release at the targeted site. On the other hand, magnetic NPs, such as superparamagnetic iron oxide NPs, rely on an external magnetic field for the controlled drug release.

Although most of the NP drug delivery systems are well characterized in vitro and exhibit improved therapeutic efficacy when compared to classical treatment with the free drug, in vivo clinical effects are not always encouraging and are often incomplete or are lacking altogether. It is, therefore, of paramount importance to systemize and present the latest developments in the field of NP in biomedical application.

In this Special Issue Nanoparticles for Biomedical Applications, including in vitro and in vivo studies, are highlighted and discussed.

It is my pleasure to invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome.

Prof. Ana R. R. Figueiras
Guest Editor

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• Nanoparticles
• Biomedical applications
• Drug delivery
• In vitro studies
• In vivo studies