The design of a drug that successfully overcomes the constraints imposed by the blood−brain barrier (BBB, which acts as a gatekeeper to the entry of substances into the brain) requires an understanding of the biological firewall. It is also of utmost importance to understand the physicochemical properties of the said drug and how it engages the BBB to avoid undesired side effects. Since fewer than 5% of the tested molecules can pass through the BBB, drug development pertaining to brain-related disorders takes inordinately long to develop. Furthermore, in most cases it is also unsuccessful for allied reasons. Several drug delivery systems (DDSs) have shown excellent potential in drug delivery across the BBB while demonstrating minimal side effects. This mini-review summarizes key features of the BBB, recapitulates recent advances in our understanding of the BBB, and highlights existing strategies for the delivery of drug to the brain parenchyma.

The recent advances in applications of nanotechnology including the use of inorganic, polymeric, magnetic and carbon nanomaterials in drug delivery for treatment of neurodegenerative diseases are reported.

Schematic representation of application of Carbon Nano Onions (CNOs) in the biomedical field.

Nanobiotechnology is one of the leading research areas in biomedical science, developing rapidly worldwide. Among various types of nanoparticles, carbon nanomaterials (CNMs) have attracted a great deal of attention from the scientific community, especially with respect to their prospective application in the field of disease diagnosis and therapy. The unique features of these nanomaterials, including favorable size, high surface area, and electrical, structural, optical, and chemical properties, have provided an excellent opportunity for their utilization in theranostic systems. Carbon nanotubes, carbon quantum dots, graphene, and fullerene are the most employed CNMs in biomedical fields. They have been considered safe and efficient for non‐invasive diagnostic techniques such as fluorescence imaging, magnetic resonance imaging, and biosensors. Various functionalized CNMs exhibit a great capacity to improve cell targeting of anticancer drugs. Due to their thermal properties, they have been extensively used in cancer photothermal and photodynamic therapy assisted by laser irradiation and CNMs. CNMs also can cross the blood‐brain barrier and have the potential to treat various brain disorders, for instance, neurodegenerative diseases, by removing amyloid fibrils. This review has summarized and emphasized on biomedical application of CNMs and their recent advances in diagnosis and therapy.