Nanomaterials influence their ability to cross the blood-brain barrier

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A new study reveals that nanomaterials found in consumer and healthcare products can pass from the bloodstream to the brain of a blood-brain barrier model with varying ease depending on their shape, creating possible neurological impacts that could be both positive as negatives.

Scientists found that metal-based nanomaterials such as silver and zinc oxide can cross an in vitro model of(BBB) ​​as dissolved particles and ions, which negatively affect the health of astrocyte cells, which control neurological responses.

But researchers also believe their discovery will help design safer nanomaterials and could open up new ways to target hard-to-reach places when treating brain diseases.

Posting your results today at PNAS, an international team of researchers found that the physicochemical properties of metallic nanomaterials influence their effectiveness in penetrating the in vitro model of the blood-brain barrier and their potential levels of brain toxicity.

A higher concentration of certain forms of silver and zinc oxide nanomaterials can affect cell growth and lead to increased BBB permeability, which can lead to BBB allowing easier brain access to these compounds.

The BBB plays a vital role in brain health by restricting the passage of various chemicals and foreign molecules to the brain from the surrounding blood vessels.

Impaired BBB integrity compromises the health of the central nervous system and increased permeability to foreign substances can end up causing brain damage (neurotoxicity).

The co-author of the study, Iseult Lynch, a professor of environmental nanosciences at the University of Birmingham, commented: “We found that silver and zinc oxide nanomaterials, which are widely used in various daily products for the consumer and the health, they went through our in vitro BBB model, in the form of particles and dissolved ions.

“Variation in shape, size, and chemical composition can dramatically influence the penetration of nanomaterials across the blood-brain barrier (in vitro). This is of great importance for the custom-made medical application of nanomaterials, e.g. , targeted delivery systems, bioimaging and assessment of possible risks associated with each type of metal . “

The BBB is a physical barrier made up of a layer of endothelial cells that surrounds the brain and separates blood from the cerebrospinal fluid that allows the transfer of oxygen and essential nutrients, but prevents access to most molecules.

Recent studies have found that nanomaterials such as zinc oxide can accumulate on the brain side of the BBB in vitro in altered states that can affect neurological activity and brain health. Inhaled, ingested, and dermally applied nanomaterials can reach the bloodstream and a small fraction of these can cross the BBB, affecting the central nervous system.

The researchers synthesized a library of metallic nanomaterials with different compositions, sizes, and particle shapes, assessing their ability to penetrate the BBB using an in vitro BBB model, followed by evaluation of their behavior and fate inside and outside. of the BBB model.

Co-author Zhiling Guo, a researcher at the University of Birmingham, commented: “” Understanding the behavior of these materials once past the blood-brain barrier is vital to assess the neurological effects of their involuntary entry into the . The potential for neurotoxicity is greater in some materials than in others, due to the different ways in which their shapes allow them to move and be transported. “

The research team tested various sizes of cerium oxide and iron oxide along with and four different shapes of silver: spherical (Ag NS), disk-shaped (Ag ND), rod-shaped (Ag NR), and nanowires (Ag NW).

Zinc oxide slipped through the BBB in vitro with the greatest ease. The researchers found that spherical, disk-shaped silver nanomaterials were subjected to different dissolution regimes, gradually transforming into silver-sulfur compounds within the BBB, creating easier entry pathways.

Zinc is used as an accumulating agent and dye. In over-the-counter pharmaceuticals, it is used as a skin protector and sunscreen, reflecting and dispersing UV radiation to help reduce or prevent sunburn and premature skin aging. Silver is used in cosmetics and skin care products, such as anti-aging creams.


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More information:
Zhiling Guo et al., “Biotransformation modulates the penetration of metal nanomaterials through an artificial blood-brain barrier model.” PNAS (2021). www.pnas.org/cgi/doi/10.1073/pnas.2105245118

Citation: The shape and form of nanomaterials influence their ability to cross the blood-brain barrier (2021, July 5) recovered on July 5, 2021 at https://medicalxpress.com/news/2021-07-nanomaterials-ability -blood-brain-barrier.html

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