Particle morphology: an important factor affecting drug delivery by nanocarriers into solid tumors

ABSTRACT

Introduction: Efficient delivery of drugs by nanoparticles deep into solid tumors is the precondition of valid cancer therapy. Despite profound understanding of the delivery of spherical nanoparticles into solid tumor attained, insufficient attention was paid to anisotropic particles. Actually, owing to their structural asymmetry, some non-spherical particles exhibit significant advantages over their spherical counterparts.

Areas covered: This review will focus on particles with different shapes (discoidal particle, nanorod, filamentous particle, single-walled carbon nanotube) and the influence of their morphological characteristics (size, aspect ratio, rigidity) on the process of drug delivery to solid tumor in view of systemic circulation, transport from circulation system to tumor tissue, intratumoral transport and uptake by tumor cells, on the basis of introduction of challenges for drug delivery to solid tumor. In addition, the morphological characteristics will be briefly introduced to provide an understanding of anisotropic particle morphology.

Expert opinion: Anisotropic particles exhibit desirable properties such as enhanced circulation time and efficient tumor penetration that could serve as an enlightenment in the exploitation of novel non-spherical nanocarriers to clinical therapy. Yet, current understanding of how anisotropic particles interact with organism is insufficient, which restricts the biomedical application of anisotropic particles. Further work is desired for the development of practical fabrication of anisotropic particles, quantitative analysis of particle morphology, as well as profound understanding of new targeting mechanism and intratumoral penetration of anisotropic particles.

KEYWORDS:

• Anisotropic particles
• drug delivery
• intratumoral transport
• morphological characteristics

Article highlights

• Morphological characteristics such as size, aspect ratio and rigidity play a key role in, and affect the influence of other particle properties on, the in vivo fate of anisotropic particles.

• Tumor environment develops several physiological barriers hindering the delivery of anticancer agents into solid tumor.

• Discoidal particles are likely to drift laterally in tumor vascular and therefore easily target to solid tumor.

• Nanorods readily transport within porous tumor tissue and are efficiently taken up by tumor cells owing to their elongated structures.

• Filamentous particles tend to persistently circulate in blood vessels.

• Single-wall carbon nanotubes are able to undergo renal elimination and tend to exhibit high diffusion rate in tumor cell spheroids.

This box summarizes key points contained in the article.

Declaration of Interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Peer reviewers on this manuscript have no relevant financial or other relationships to disclose

Additional information

Funding

This work was supported by National Science and Technology Major Project under Grant [No. 2017YFA0205400] and the National Science Foundation Grant of China under Grant [No. 81503005]; the Natural Science Foundation of Jiangsu Province under Grant [No. BK20140669]; the Priority Academic Program Development of Jiangsu Higher Education Institutions.