Nano and biology

Nanomedicine as a research field

Nanomedicine is the name given to research that applies nanoscale materials and devices to questions in medicine and biology. This page describes it as a field of study: the kinds of structures researchers work with, the questions they ask, and how public agencies organise research in the area. It makes no claims about treatments, and nothing on it is medical advice.

What the field covers

The Wikipedia article on nanomedicine describes it as the medical application of nanotechnology, ranging from uses of nanomaterials and biological devices to nanoelectronic biosensors and possible future applications of molecular nanotechnology. It notes that nanomaterials are similar in size to many biological molecules and structures, which is why they are of interest for research both inside and outside living systems, and it lists research tools such as diagnostic devices, contrast agents, analytical tools and delivery vehicles among the directions pursued. The same article is candid that current problems for the field include understanding the toxicity and environmental impact of nanoscale materials, the subject of the nanotoxicology page.

The structures researchers study

Dendrimers. The Wikipedia article on dendrimers describes them as highly ordered, branched polymer molecules, usually symmetric about a core and often roughly spherical. The article records that the first dendrimers were made by divergent synthesis, building outward from a core, by several groups between 1978 and 1985. Their defined size and the large number of chemical groups at their surface made them an early model system for chemists interested in carrying molecules at the nanoscale.

Liposomes. According to the Wikipedia article on liposomes, a liposome is a small artificial vesicle, spherical in shape, with at least one lipid bilayer. The article records that liposomes were first described by Alec Douglas Bangham in 1961 at the Babraham Institute in Cambridge, with the findings published in 1964, and that the discovery came while testing a new electron microscope. Because their bilayer resembles a cell membrane, liposomes have been studied for decades as model membranes and as carriers.

Lipid-based nanoparticles. The Wikipedia article on lipid-based nanoparticles describes them as very small spherical particles made of lipids, studied as a pharmaceutical delivery system, and distinguishes hollow liposomes, whose interior is watery, from solid lipid nanoparticles, whose interior is a lipid core with a single outer layer.

Delivery as a research problem

Much nanomedicine research is framed around delivery. The Wikipedia article on drug delivery describes the field as the methods and technologies for transporting pharmaceutical compounds to where they act, involving questions of preparation, route of administration, targeting, metabolism and toxicity, and notes that a key goal is to change how a compound is distributed in the body by combining it with carriers and other materials. Nanoscale carriers are one family of approaches studied under that heading. What happens to a carrier after it enters the body turns out to be a research question in its own right, and two parts of that question have large literatures of their own.

The protein corona

A nanoparticle placed in a biological fluid does not stay bare for long. The Wikipedia article on the protein corona describes a dynamic coating of biomolecules, mostly proteins, that forms spontaneously on a nanoparticle's surface on exposure to biological media. Its pattern depends on the particle's size, shape, composition, charge and surface groups, and on conditions such as temperature and pH. The article distinguishes a "hard" corona of tightly bound proteins from a "soft" corona of more loosely and reversibly bound ones.

In a 2021 critical review, Kopac surveys what is known about corona formation. The abstract identifies particle size, surface chemistry and charge as critical factors in the corona's behaviour, states that corona composition affects how particles are taken up by cells, and notes that protein–nanoparticle interactions have been studied extensively in connection with the potential use of nanoparticles as carriers. It calls for further study of variables such as particle size, surface modifier, temperature and pH, including their bearing on the toxicity of new nanoparticles. The practical lesson for a reader is that the particle a cell encounters is the particle plus its corona, which may behave quite differently from the particle characterised in a clean buffer.

Why size matters

Size is the other recurring variable. A 2022 review by Mellor and Uchegbu focuses on gold nanoparticles and examines how particle size affects optical properties, coating by blood proteins, uptake into cells, clearance through the kidneys, distribution in the body, accumulation in tissues and toxicity. It also reviews an approach its authors call ultrasmall-in-nano, which aims to combine properties from both ends of the size range, and describes results of such constructs in laboratory and animal studies. Reviews of this kind are useful because they gather many separate studies into one comparison, but they also show how much depends on the exact particle and coating tested.

How agencies organise the research

In the United States, several agencies run programmes in this area. The Food and Drug Administration's nanotechnology programmes page describes staff activities intended to build regulatory science knowledge, to support collaboration, and to establish a product-focused, science-based approach to regulating products that involve nanomaterials, and notes that the agency is a member of the National Nanotechnology Initiative. The National Cancer Institute's Division of Cancer Treatment and Diagnosis describes its support for research on nanotechnology methods, and mentions a Nanotechnology Characterization Laboratory run jointly by NCI, FDA and NIST that provides preclinical characterisation and safety testing of nanoparticles.

Reading nanomedicine papers

Papers in this area range from basic chemistry to animal studies, and it is worth being clear which kind you are reading. A result obtained in cells in a dish, or in a small number of animals, is a research finding, not evidence that anything works in people. Look for what was actually measured, in what system, and against what control. Look also for the caveats the authors themselves give, which are often in the last paragraph. For peptides and self-assembled nanostructures in particular, see peptides at the nanoscale.