Nanoplastics and 'forever chemicals' disrupt molecular structures, functionality

Researchers at The University of Texas at El Paso have made significant inroads in understanding how nanoplastics and per- and polyfluoroalkyl substances (PFAS) -- commonly known as forever chemicals -- disrupt biomolecular structure and function. The work shows that the compounds can alter proteins found in human breast milk and infant formulas -- potentially causing developmental issues downstream.

Nanoplastics and forever chemicals are manmade compounds present throughout the environment; a series of recent studies have linked them to numerous negative health outcomes. While nanoplastics originate primarily as a result of the degradation of larger plastic materials, like water bottles and food packaging, forever chemicals are found in various products like cookware and clothing.

The UTEP research team focused on the compounds' impact on three proteins critical to human development and function: beta-lactoglobulin, alpha-lactalbumin and myoglobin. Their findings, which provide an atomic-level insight into the detrimental effects of nanoplastics and PFAS on human health, are described in two recent articles in the Journal of the American Chemical Society and ACS Applied Materials and Interfaces.

"By understanding the molecular mechanisms of how nanoplastics and forever chemicals disrupt cellular functions, scientists can develop safer alternatives to these materials," said Mahesh Narayan, Ph.D., a professor, fellow of the Royal Society of Chemistry and chief of the Division of Biochemistry in UTEP's Department of Chemistry and Biochemistry, who oversaw the two studies. "The insights gained from this research have far-reaching implications."

Narayan said that, most importantly, their research revealed that nanoplastics and PFAS completely "dissolved" a region of proteins known as the alpha helix, converting them into structures called beta sheets.

"We weren't expecting them all to have this similar impact on the alpha helix," Narayan said. "It was a complete coincidence." The team observed that this alteration also occurs in amyloid proteins, which can cause neurodegeneration and neurotoxic outcomes if the synthetic chemicals reach the brain.

Additional key findings of the studies are described below.

Milk Protein: Beta-Lactoglobulin (BLG)

BLG is a protein found in the milk of sheep and cows and is commonly used as an ingredient in infant formula. The protein binds to retinol (vitamin A) and fatty acids and is crucial for vision and brain development in infants.

The research team discovered that the binding efficiency of BLG to retinol and fatty acids decreases upon exposure to nanoplastics and PFAS. This decrease, modeled by Lela Vukovic, Ph.D., associate professor in the Department of Chemistry and Biochemistry, can lead to significant developmental issues in neonatal infants, the team said.

Additionally, for the first time ever, the team observed that PFAS binds to the milk protein, turning it into a carrier for these compounds.

Human Breast Milk: Alpha-Lactalbumin

Alpha-lactalbumin is found in human breast milk, participates in lactose synthesis and is ingested by infants to help meet nutritional needs. UTEP researchers found that nanoplastics and PFAS corrupt the structure of alpha-lactalbumin protein, thereby potentially compromising lactose formation. The team said the disruption can lead to downstream developmental defects in neonatal infants, such as compromised immunity and reduced mineral absorption.

Oxygen Storage: Myoglobin

Myoglobin, found in the blood and muscle tissue of most mammals, is crucial for storing oxygen. The UTEP research team found that nanoplastics and PFAS compromise the functionality of the myoglobin protein, disrupting its ability to store oxygen. This disruption could lead to health issues such as breathlessness and anemia.

Additional experiments by the team demonstrated that exposure to nanoplastics impairs locomotion in worms, with effects comparable to paraquat -- an herbicide that has been tied to causing Parkinson's disease.

"This work has the potential to significantly impact public health and environmental policies, highlighting the vital role of scientific research in addressing global challenges," said Robert Kirken, Ph.D., dean of the College of Science. "I am proud of the groundbreaking research conducted by Dr. Narayan, Dr. Vukovic and their teams. Their innovative approach to understanding how these manmade materials disrupt biomolecular functions is a prime example of the transformative work UTEP researchers do on a regular basis."

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Every breath you take: Study models the journey of inhaled plastic particle pollution

With recent studies having established the presence of nano and microplastic particles in the respiratory systems of both human and bird populations, a new University of Technology Sydney (UTS) study has modelled what happens when people breathe in different kinds of plastic particles and where they end up.

Led by Senior Lecturer of Mechanical Engineering Dr Suvash Saha, the UTS research team has used computational fluid-particle dynamics (CFPD) to study the transfer and deposition of particles of different sizes and shapes depending on the rate of breathing.

The results of the modelling, published in the journal Environmental Advances, have pinpointed hotspots in the human respiratory system where plastic particles can accumulate, from the nasal cavity and larynx and into the lungs.

Dr Saha said evidence was mounting on the significant impact of nano and microplastics on respiratory health and the UTS study would provide essential insights for the development of targeted strategies to mitigate potential risks and ensure effective health interventions.

"Experimental evidence has strongly suggested that these plastic particles amplify human susceptibility to a spectrum of lung disorders, including chronic obstructive pulmonary disease, fibrosis, dyspnea (shortness of breath), asthma, and the formation of what are called frosted glass nodules," Dr Saha said.

"Plastic particle air pollution is now pervasive and inhalation ranks as the second most likely pathway for human exposure.

"The primary types are intentionally manufactured, including a wide array of cosmetics and personal care products such as toothpaste.

"The secondary ones are fragments derived from the degradation of larger plastic products, such as water bottles, food containers and clothes.

"Extensive investigations have identified synthetic textiles as a principal source of indoor airborne plastic particles, while the outdoor environment presents a multitude of sources encompassing contaminated aerosols from the ocean to particles originating from wastewater treatment."

Dr Saha said the UTS team's modelling found that breathing rate along with particle size and shape determined where in the respiratory system plastic particles would be deposited.

"Faster breathing rates led to heightened deposition in the upper respiratory tract, particularly for larger microplastics, whereas slower breathing facilitated deeper penetration and deposition of smaller nanoplastic particles," he said.

"Particle shape was another factor, with non-spherical microplastic particles showing a propensity for deeper lung penetration compared to spherical microplastics and nanoplastics, potentially leading to different health outcomes.

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Nanoplastics promote conditions for Parkinson's across various lab models

Nanoplastics interact with a particular protein that is naturally found in the brain, creating changes linked to Parkinson's disease and some types of dementia.

In a Duke-led study appearing Nov. 17 in Science Advances, the researchers report that the findings create a foundation for a new area of investigation, fueled by the timely impact of environmental factors on human biology.

"Parkinson's disease has been called the fastest growing neurological disorder in the world," said principal investigator, Andrew West, Ph.D., professor in the Department of Pharmacology and Cancer Biology at Duke University School of Medicine. "Numerous lines of data suggest environmental factors might play a prominent role in Parkinson's disease, but such factors have for the most part not been identified."

Improperly disposed plastics have been shown to break into very small pieces and accumulate in water and food supplies, and were found in the blood of most adults in a recent study.

"Our study suggests that the emergence of micro and nanoplastics in the environment might represent a new toxin challenge with respect to Parkinson's disease risk and progression," West said. "This is especially concerning given the predicted increase in concentrations of these contaminants in our water and food supplies."

West and colleagues in Duke's Nicholas School of the Environment and the Department of Chemistry at Trinity College of Arts and Sciences found that nanoparticles of the plastic polystyrene -- typically found in single use items such as disposable drinking cups and cutlery -- attract the accumulation of the protein known as alpha-synuclein. West said the study's most surprising findings are the tight bonds formed between the plastic and the protein within the area of the neuron where these accumulations are congregating, the lysosome.

Researchers said the plastic-protein accumulations happened across three different models performed in the study -- in test tubes, cultured neurons, and mouse models of Parkinson's disease. West said questions remain about how such interactions might be happening within humans and whether the type of plastic might play a role.

"While microplastic and nanoplastic contaminants are being closely evaluated for their potential impact in cancer and autoimmune diseases, the striking nature of the interactions we could observe in our models suggest a need for evaluating increasing nanoplastic contaminants on Parkinson's disease and dementia risk and progression," West said.

"The technology needed to monitor nanoplastics is still at the earliest possible stages and not ready yet to answer all the questions we have," he said. "But hopefully efforts in this area will increase rapidly, as we see what these particles can do in our models. If we know what to look out for, we can take the necessary steps to protect ourselves, without compromising all the benefits we reap every day from plastics."

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Automated analysis of microplastic concentrations

How high are concentrations of microplastics in the environment, in our drinking water or in foods? Researchers at the Technical University of Munich (TUM) have developed an automated analysis method for the identification and quantification of particles.

Microplastics are everywhere in the environment. The tiny particles, with diameters of less than 5 millimeters, can also absorb and transport contaminants and toxins. “We urgently need analytical techniques to learn about the size, concentration and composition of these particles,” says Dr. Natalia Ivleva at the Chair of Analytical Chemistry and Water Chemistry at TUM. Together with her team, the scientist has developed a new process.

To be able to detect microplastic particles, the researchers had several hurdles to overcome: The first was the problem of low concentrations. River water, for example, contains massive amounts of suspended solids and fine sand, with plastic accounting for less than 1 percent of the particles. These particles must first be isolated before their concentrations and ultimately their chemical composition are determined. Previous methods have relied on the analysis of the residues that are released when the samples are heated. With that approach, however, it is not possible to determine the number, size and shape of the plastic particles.

Plastics can be identified through light scattering

“Our approach is fundamentally different,” says Dr. Ivleva: “It is particle-based. That means that instead of destroying the particles, we analyze them directly.” To do this, the researchers use a method known as Raman microspectroscopy. It works by shining a monochromatic laser source onto a sample and detecting the light scattered by the molecules. Comparing the scattered light against the laser source provides information on the substance under investigation. To analyze plastic particles with a diameter greater than 1 µm (micrometer), they must first be filtered out of the aqueous solution, detected under the microscope and then illuminated with laser light. Because plastics such as polyethylene, polystyrene and polyvinyl chloride scatter the photons in characteristic ways, they each generate signals as unique as a fingerprint.

Automation instead of manual measurements

It took years to develop the tracing process: “When we started, we still had to make manual measurements,” recalls the chemist. “It took us months to investigate a few thousand particles.” In the meantime the team has succeeded in automating the detection of microplastics. A single analysis no longer takes weeks, but only a matter of hours. Although the tiny particles still have to be filtered out of the aqueous solution, followed by placement of the filter under the Raman microspectroscope, all remaining steps are carried out by the software developed by the team. The plastic particles are first localized with a light microscope, photographed and measured, and the particles are distinguished from fibers. The software uses these data to compute the number of particles and fibers and to select the image sections needed for a statistically significant result in the subsequent Raman spectroscopy.

In the next step, the laser is directed onto the sample and the scattering is detected and analyzed. This allows quick and reliable analysis of the number, size, shape and composition of the microplastics. The open-source TUM-Particle Typer 2 software is now available to researchers around the world.

Nanoplastics require special detection processes

To investigate nanoparticles with diameters of less than 1 µm, however, Dr. Ivleva’s team is already working on a modified process. “Nanoparticles like these are difficult or even impossible to discern under a light microscope. To detect them, we first have to carry out size fractionation and then identify them,” explains the researcher.

For this purpose, a field flow fractionation (FFF) system is used. This creates a water flow that captures the particles – depending on their size – and separates them by transporting them at varying speeds. A specially developed device, combined with Raman spectroscopy, permits the chemical characterization of different types of nanoplastics.

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