The advancement in nanomaterials and nanomedicinal drugs, which consist of nanomaterial-based medicinal products, is one of the most disruptive innovations that has been introduced into the field of nanotechnology. The concept of nanomaterials, which include materials at a nanometric scale of less than 100 nm, has emerged in the last 20 years as a tool for applications such as imaging, diagnostics, and treatments within medicine.
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This innovative field is ever-evolving, solving unmet medical needs in various capacities. This article will provide an insight into nanomaterials and how radiolabeling of these key materials can be used for the efficient development of medicinal drugs.
Nanomaterials, which have become a broad field within nanotechnology itself, can offer a wide range of applications within various fields depending on their optical, magnetic, and electronic properties. The ability to tune these particles enables them to have adaptable physiochemical and pharmacokinetic characteristics for different purposes. This is a significant benefit within medicine as nanoparticles and nanomaterials can be used to target specific malignant areas which are integral for boosting therapeutic efficacy.
The use of these particles within nanoparticle drug encapsulation provides a promising prospect, with the ability of various nanoparticles being able to transport drugs to the desired area, ensuring the healthy tissue is maintained. This enhanced permeability and retention effect (EPR) can drive nanoparticles to accumulate in tumor tissue more than healthy tissue due to the leaky vasculature and decreased lymphatic drainage, which further signifies their importance within medicine.
The size of nanoscale materials allows for more natural interaction with other similar-sized cells in the body and ensures its movement across barriers which would typically be a challenge for certain drugs.
Organic and Inorganic Nanomaterials
Nanomaterials are characterized as being organic or inorganic. Organic nanomaterials consist of liposomes, protein-based or viral nanoparticles, and polymer nanomaterials. Inorganic nanomaterials include graphene or carbon-based nanomaterials, iron oxide or gold nanoparticles, or quantum dots.
The uses of these various types of nanomaterials and particles can differ, with a liposomal-based anesthetic drug being one of the first nanoparticle-based drugs that have been approved by the Food and Drug Agency (FDA) in 1989. Since then, the number of clinically approved nanomedicine drugs has grown both for drug delivery as well as imaging.
Radiolabeling
Radiolabeling, which is a form of isotopic labeling, can be used for extensive monitoring of substances such as drugs to gain more information about how it works or more insight into medical issues faced by patients.
Radiolabeled nanoparticles can be outlined as a nanomaterial structured with a radionuclide component; these may not create such a significant difference to the overall size due to being minuscule itself, however, there are some labels that can affect the nanoparticle’s physiochemical properties.
This illustrates the importance of using radiolabels that preserve the integrity of the nanoparticles without any impact on their physiochemical, biodistribution, and pharmacokinetic abilities. The selection of radionuclides used for radiolabelling nanoparticles or nanomaterials may have the ability to affect the half-life, decay mode, and biological response. This should be considered when choosing the right type of radiolabel.
Ionophore ligands can be used as radiolabels for liposomes and other vesicle-based nanoparticles, which contain a lipid bilayer membrane through forming a complex with a radiometal, which is then known as a radio-ionophore. The radio-ionophore complex releases a radiometal once inside the vesicle, which then binds to chelating molecules in the vesicle core and is trapped. Liposomal nanomedicine is one of the most widely explored in vivo drug delivery systems and uses a large diversity of radiolabeling methods, from radiolabels being held inside the vesicle core to being on the surfaces of liposomes.
However, other types of nanoparticles such as gold nanoparticles can also be used in nanomedicine, with gold nanoparticles being radiolabeled in order to gain more insight into the journey of the molecules and their affinity to malignant areas such as tumor tissue. This can be used as a targeted drug delivery mechanism that would prevent toxicity to the healthy tissue.
Radiolabeling for Drug Development
Radiolabeling can be used in many different ways, however, the five main applications include:
- Testing of new formulations and assessing its targeting ability
- Assessing clinical translation and targeting in patients for the purpose of personalized medicine
- Disease diagnosis
- Using radiolabeled nanoparticles as cell labeling agents and in vivo tracking of cells
- Radiotherapy purposes
Drug researchers use radiolabels to ascertain how a new drug is metabolized by the body as it travels through the patient.
The use of carbon isotopes as a radiolabel allows nanoparticles to be tracked more easily through imaging without changing the way it behaves or the properties of the drug.
The monitoring of drugs aids the development and testing phases, which assess the efficacy levels of a certain drug for a specific purpose. An example includes drugs that are unable to cross the blood-brain barrier due to their size, and so monitoring nanomedicinal drugs to target brain tumors would be an effective method of discovering new treatments.
Personalized nanomedicine has become a growing branch for nanomaterial and nanomaterial-based medicinal products, and radiolabeled nanomaterials can be utilized for this purpose through the assessment of target accumulation for patients who are undergoing drug treatments. Through the imaging of nanomedicinal drugs within patients, researchers can determine which patients respond to the drugs and establish the EPR-mediated uptake into tumor tissue or inflammatory sites.
The future of personalized medicine may lie within the field of nanotechnology and nanomedicine due to its wide variety of uses to aid with diagnostics and drug development. The radiolabelling of nanomaterials can assist with the development of nanomedicinal drugs which can increase the levels of efficacy of various treatments, from decreasing inflammation to targeted cancer treatment.
This can increase the quality of life of patients who will be able to retain their healthy tissue with this treatment as opposed to chemotherapy or radiotherapy which is a systemic approach affecting all cells. As patient care is the optimum priority, nanomaterial-based drug therapies and their associated development should also be a priority.
References and Further Reading
Pellico, J., Gawne, P. and T. M. de Rosales, R., 2021. Radiolabelling of nanomaterials for medical imaging and therapy. Chemical Society Reviews, 50(5), pp.3355-3423. DOI: 10.1039/D0CS00384K
Isin, E., Elmore, C., Nilsson, G., Thompson, R. and Weidolf, L., 2012. Use of Radiolabeled Compounds in Drug Metabolism and Pharmacokinetic Studies. Chemical Research in Toxicology, 25(3), pp.532-542. DOI: https://doi.org/10.1021/tx2005212
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