Plastics are highly valuable synthetic materials that benefited humanity greatly in the past six decades. During that time, both production and consumption of plastics increased tremendously, however consumerism and poor plastic waste management created so many challenges to be tackled in the near future.

Nowadays, the plastic pollution problem is increasingly recognised to be much more complex than previously thought. For a long time it was unknown that with the present biotic and abiotic influence, plastics undergo fragmentation and become much smaller in size.

Some of the smallest plastic fragments were discovered to be in the micrometer range and, quite recently - in the nanometer range [1-2]. The terms used for these small plastic fragments are microplastics and nanoplastics, ranging below 5 mm and below 1000 nm or 100 nm, respectively [3]. From various research conducted over the period of 5 years, nanoplastics are still the least explored fraction of plastic litter [4].

Recent scientific literature demonstrates that nanoplastics may be highly abundant and highly spread out due to their small size [5]. It was found that nanoplastics can easily penetrate biological barriers [6], get internalized by cells, and interact with biochemical processes in them [7]. That said, there is a great chance that nanoplastics are being transferred between organisms belonging to different trophic levels [8].

Further research shows evidence of certain toxicity events due to exposure to nanoplastics [9]. The findings listed above suggest that nanoplastic pollution needs to be carefully monitored. However, today there are no standard protocols adapted to observe tendencies of nanoplastic abundance and spreading.

Hence, the research area of nanoplastic pollution is in great need for a strong toolkit foundation to be built. Much is not known about the abundance of nanoplastics and what consequences may arise if the amount of these plastic nanoparticles continues to grow unsupervised.

Addressing difficulties with nanoplastic monitoring is a challenging task. Current attempts to investigate nanoplastic pollution are being explored at a slow pace due to the lack of adequate analytical techniques. As of 2022, only expensive optical equipment is able to provide sensitive analysis and imaging of commercial-grade plastic nanoparticles [10].

However, environmental nanoplastics can widely differ in size, shape, and surface properties [11]. Also, nanoplastics may be highly diluted in environmental samples, therefore difficulties arise when estimating relative concentrations in the samples taken [12].

The “NanoFind” project aims to combat these challenges and make the detection of nanoplastics more simple and easier to implement worldwide. The promising work of Rübsam and the colleagues (2017) inspired us to build our detection system based on peptides, which can have high, yet differentiated affinities towards different plastic materials (please read more about our system concept in the engineering section). While authors demonstrated the fundamental principles of peptide-plastic binding, we have recognized a great potential to use these principles to engineer a robust nanoplastic detection system. The mentioned research shows that a group of peptides, belonging to the family of antimicrobial peptides, have affinities to certain plastic materials, such as commonly used polystyrene and polypropylene [13]. Peptides themselves can be easily produced via microbial hosts with the additional domains needed to facilitate detection.

Two types of plastic-binding peptides were engineered during our project - peptides with additional cellulose binding domains (1) and peptides with additional fluorescent domains (2). Combining these two types of engineered peptide constructs enabled us to build the final “Nanofind” system.

The “NanoFind” system enables to drastically lower the cost of the plastic nanoparticle detection process while maintaining high accuracy results. Therefore, now and in the future, interested laboratories can achieve efficient and frequent monitoring of nanoplastics across the globe.

We hope that with the development of an easy-to-use detection tool for nanoplastics, the tendencies for this type of pollution may be better understood, and the knowledge gained may help raise awareness and encourage researchers to find ways that could help prevent nanoplastic pollution from reaching a high scale distribution across the globe and potential hazardous effects to life on earth.