A new study has shown that nanomaterials in consumer and healthcare products can easily pass from the bloodstream into the brain of a blood-brain barrier model. This could have potential neurological effects.Scientists discovered that nanomaterials made of metals, such as zinc oxide and silver, can be used to cross the in vitro 'blood brain barrier (BBB). This is because both particles as well as dissolved ions are present. This adversely affects the health of astrocytes which regulate neurological responses.Researchers also believe their discovery will lead to safer nanomaterials, which could allow for new methods of treating brain diseases in difficult-to-reach areas.A team of international researchers published their findings in PNAS today. They discovered that metallic nanomaterials' physiochemical properties can influence their ability to penetrate the blood brain barrier in vitro and how toxic they could be in the brain.Zinc oxide and silver nanomaterials in higher concentrations may cause cell death and impair cell growth. This can also lead to increased BBB permeability, which can allow brain access to these compounds.The BBB is vital for brain health as it prevents the entry of foreign and chemical compounds from the blood vessels surrounding the brain.A compromised BBB integrity can lead to a decline in the health and function of the central nervous systems. In turn, increased permeability to foreign substances could eventually lead to brain damage (neurotoxicity).Iseult Lynch (Professor of Environmental Nanosciences at University of Birmingham) commented that the study co-authors found that both silver and zinc oxide nanomaterials were passed through the in vitro BBB model in the form of particles and dissolvedions."Nanomaterials can be impacted by variations in their shape, size, and chemical composition. This is crucial for medical applications of nanomaterials that are tailored to specific needs, such as bioimaging, targeted delivery systems and assessment of potential risks.The BBB is a physical barrier made up of tightly packed endothelial cells that surround the brain. It allows for the transfer of essential nutrients and oxygen, but prevents most molecules from getting in.Recent research has shown that nanomaterials like zinc oxide can build up on the brain side in vitro BBB. This can lead to altered brain activity and brain health. Nanomaterials that are inhaled, ingested or applied dermally can be absorbed into the bloodstream. A small amount may cross the BBB, which could have an impact on the central nervous systems.Researchers synthesized a variety of metallic nanomaterials in a variety of sizes and compositions. They then evaluated their ability to penetrate BBB with an in vitro BBB Model. Then, they assessed their behavior and fate within and beyond the model BBB.Zhiling Guo (a Research Fellow at University of Birmingham) commented that understanding the behavior of these materials once they have passed the blood brain barrier is crucial for evaluating neurological effects from accidental entry into the brain. Because of the way they are made, neurotoxicity can be greater in certain materials than in others.Researchers tested various sizes of iron oxide and cerium oxide as well as zinc oxide. They also tested four shapes of silver: spherical, disc-like (Ag. ND), rod-shaped and rod-shaped (Ag. NR).The in vitro BBB allowed zinc oxide to pass through with ease. Researchers discovered that spherical and disc-like nanomaterials of silver were subject to different dissolution regimes. This allowed them to gradually transform into silver-sulfur compounds within BBBs, creating easier entry routes.Zinc oxide can be used as both a bulking agent or a colorant. It is also used in over-the-counter drugs as a skin protector and sunscreen. This UV radiation scatters and reflect sun rays to reduce sunburns and premature skin aging. Anti-aging creams and cosmetics that use silver are made with it.###Tony Moran, International Communications Manager, can be reached at +44 (0)782-783 2312 for more information and interviews. Call +44 (0)7789 921 165.Notes for editors* The University of Birmingham is one of the top 100 universities in the world. Its work attracts people from all over the globe to Birmingham, including teachers, researchers, and 6,500 students from more than 150 countries.* "Biotransformation modulates penetration of metallic nanomaterials through the blood brain barrier" - Zhiling Guio, Peng Zhang and Swaroop Chakraborty are published by PNAS.
