What Are Nanoparticles, and What Are Their Examples? Nanotechnology in Cancer Diagnosis

In our first article on nanotechnology, we discussed its definition and applications and introduced nanotechnology in cancer. Nanotechnology is a new scientific field using particles (nanoparticles) measuring 1 – 100 nanometers, with broad applications in medicine, biomedicine, physics, chemistry, electronics, and energy production.

In medicine, nanotechnology and nanoparticles (NTs); are used to provide more sensitive analyses, as a type of biological marker (biomarker), for molecular imaging in radiological fields such as magnetic resonance, ultrasound, and computed tomography, and for drug development systems, targeted treatment, and vaccine development. NTs can be attached to address-labeled biological molecules capable of targeted movement to direct them to specific locations in the body or even specific organelles inside cells. They can even be programmed to track various proteins or RNA molecules in living cells. These address labels are monoclonal antibodies, small molecules, or peptides. These targeted agents are ideally attached to NTs through covalent bonds (chemical bonds characterized by sharing one or more electrons between two atoms). Special methods can place NTs inside red blood cells, enabling them to hide from the immune system.

Nanoparticle Platforms

NTs can be produced from numerous inorganic and organic materials. Inorganic means nonorganic. In biology, these are compounds such as water, minerals, acids, bases, and salts found in living organisms but not alive or produced by an organism. They are obtained directly from nature, and producing inorganic substances is not possible. The word organic has various meanings today. Its original meaning describes something that is part of or derived from a living thing.

The best-known inorganic NTs are iron oxide NTs. Because of their distinctive properties, inorganic NTs are frequently used in diagnostic procedures.

Organic NTs are often formulated with biocompatible substances such as lipids, polymeric micelles (drug delivery systems that solubilize poorly soluble substances), nucleic acids, and peptides. Because of their biocompatibility, organic NTs are primarily used therapeutically. Polymeric micelles often consist of a hydrophilic surface and hydrophobic core. A form of a chemotherapy drug containing paclitaxel, used since the early 1970s, was approved for cancer treatment in 2005. Called nab-paclitaxel, it has contributed positively to breast, lung, and pancreatic cancer treatment.

NTs can be coated with long-chain polymers, also called stimulus-responsive or smart polymers, that respond to environmental stimuli by swelling or shrinking. Anticancer drugs are loaded into these polymers, and cancer cell-specific ligands (an atom, ion, or molecule binding to a central metal) are attached to the surface to target the desired tissue. When the particles reach the targeted tissue, an externally applied magnetic field increases tissue temperature to release the drug trapped inside the polymer, aiming to treat cancerous tissue without harming healthy tissue. These nanoparticles can be injected intravenously and travel through the blood to tumor sites. Through an applied electromagnetic field, these supermagnetic particles release the therapeutic drug they carry into the diseased area. Like radio waves, these magnetic waves pass through the body harmlessly and heat only the nanoparticles. The particles also make cancer cells more readily visible with magnetic resonance (MR) devices.

Nanotechnology in Imaging and Diagnosis

Nanotechnology has made major contributions to medical imaging and diagnosis. Iron oxide NTs can be used particularly to detect suspected lymph node metastases (metastasis: cancer cells spreading beyond their original tissue to other regions directly or through blood or lymphatic vessels) . A study in prostate cancer patients showed that, compared with conventional magnetic resonance imaging (MRI) , MRI using iron oxide NTs detected lymph node metastases much better.

Exploiting NTs' selective accumulation in metastatic lymph nodes (lymphotropic NTs) has opened the way to more successful treatments for head and neck, breast, and anal cancers, in which radiotherapy is used extensively. Identifying lymph nodes at risk of metastasis is critical for planning radiation therapy. Until now, these nodes were mostly identified through computed tomography (CT) imaging. Studies in prostate cancer patients compared CT and MR imaging using NTs to identify at-risk lymph nodes. Biopsies confirmed that NT-MRI detected metastatic lymph nodes more accurately and also found, contrary to previous knowledge, that metastatic lymph nodes were around blood vessels rather than bones.

Nanotechnology has also begun contributing to conventional radiography (X-ray) . Carbon nanotubes have been used as electron emitters in X-ray imaging. This method provides higher resolution, lower radiation, and smaller equipment. 

Related Topic:

- The first nanoparticle cancer drug nab-paclitaxel, radiosensitizers, and nanotherapeutics