Project highlights

  • Exploratory research on how microplastics and nanoplastics (MNPLs) impact on human health
  • Study of how MNPLs affect long diseases by assessing their influence on smooth muscle and epithelial bacterial cells
  • A multidisciplinary supervisory team to facilitate the student with wide-ranging skills.


Macroscale plastic waste polluting the earth is now a well-known issue, triggering policies that aim to limit the production and use of plastic bags and bottles, and increase of recycling. However, plastics at much smaller scale, namely, microplastics (particles < 5 mm) and nanoplastics (particles < 1  mm), can have insidious effects, which raise growing awareness and concern. These particles are produced from a variety of sources, such as breakdown of larger plastic debris into smaller pieces, synthetic clothing fibres, dust from tyres, and even from chewing gums and toothpastes. MNPLs are ubiquitous in the marine environment, which are now found inside living organisms, and can have diverse impact on marine ecosystems and humans through physical damage and chemical transfer of toxicants.

Humans are extensively and inevitably exposed to environmental MNPLs, mainly through inhalation and ingestion.1-3 MNPLs are now ubiquitous in our daily life; for example, a recent analysis of tap water samples from around the world found that a high proportion (>80%) of drinking water is contaminated with MNPLs. MNPLs can cause oxidative stress, inflammatory lesions, increased internalization or translocation through tissues. Once internalized, MNPLs can release toxic compounds added during manufacture to enhance the polymers’ performance. Additionally, MNPLs can adsorb and facilitate the transport of other environmental contaminants and pathogens into living organisms, in the way of a Trojan horse. Microplastics have recently been detected in human lungs, phlegm and bloodstream; and studies suggest that exposure to MNPLs contributes to respiratory problems in certain groups of workers.4-6 Experiments in rodents support a detrimental role of MNPLs in lung health, e.g., via changes in the epithelial cells that line the airways, increased inflammation, and airway tissue thickening (termed “fibrosis”).7,8

This project will study the effects of MNPLs on airway smooth muscle (ASM) and epithelial cells that surround the airways in fibres/bundles, which are important as they help maintain the airway calibre in health and can become dysfunctional in respiratory disease that contributes to breathing difficulties. The lung microbial community also plays a major role in respiratory health and disease, which will be influenced by MNPLs and will be explored.

Image of microplastics being looked at through magnifying glass

Figure 1: Microplastics had already been spotted in oceans, air and food – now researchers have found it in human blood [Source:].


University of Leicester


  • Climate and Environmental Sustainability
  • Organisms and Ecosystems


Project investigator

Dr Shengfu Yang, University of Leicester ([email protected])



How to apply


MNPLs ranging between 50nm to 100µm will be investigated. We will also embed photoluminescent nanoparticles into MNPLs to track MNPLs in cells. Whether MNPLs can adhere to and/or be internalised by ASM and epithelial cells will be studied by optical microscopy and atomic force microscopy. Key changes in response to the dysfunction of ASM and epithelial cells, such as contraction, production of inflammatory substances, and the number or size of cells surrounding the airway, will be assessed using various in vitro ASM and epithelial cell-based assays routinely available in the laboratory. This will include assays to measure levels of contraction-related proteins, contraction per se, migration, proliferation, viability, size and production of inflammation-causing substances. We will also study how the concentration, size, and type of MNPLs affect the bacterial interaction with epithelial and ASM cells by assessing cell viability and structure using microbiology and advanced imaging technologies.

Training and skills

Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.

The student will receive wide-ranging training in this project, including synthesis and characterization of different types of MNPLs across a wide range of sizes, the use of advanced microscopy techniques, the culture of ASM and epithelial cells from human lungs, various assays to assess the behaviour and phenotype of these ASM and epithelial cells, as well as bacterial interactions. This interdisciplinary project will facilitate the student with skills in chemistry, molecular microbiology, tissue cell culture, and advanced imaging microscopy techniques, and will also significantly enhance the student’s ability to communicate with experts across different fields of research.

Partners and collaboration

One of the supervisory team, Dr Ruth Saunders, is from University Hospitals of Leicester NHS Trust. We also have collaborations with several industrial partners in relevant areas such as polymer degradation under UV radiation (with Polymateria). This project will elucidate how MNPLs influence human health, which might have strong indication for the usage of plastic-related products such as chewing gums, toothpaste formulas and toothbrushes. We intend to cultivate this interest to generate commercial sponsorship and to explore converting the project to a future CASE studentship.

Further details

Potential applicants are welcome to discuss the project informally and obtain further information from the project supervisors:

Dr Shengfu Yang, School of Chemistry, University of Leicester; [email protected].

Dr Ruth Saunders, Department of Respiratory Sciences, University Hospitals of Leicester NHS Trust; [email protected].

Prof. Julie Morrissey; Department of Genetics and Genome Biology, University of Leicester; [email protected].

If you wish to apply to the project, applications should include:

  • A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)

Applications to be received by the end of the day on Wednesday 11th January 2023. 

Possible timeline

Year 1

Synthesise plastic particles with good control over size and shape. Meantime, the student will be involved the preparation of fluorescent nanoparticles which will be embedded in MNPLs to enhance the visibility of plastic particles. The student will also undertake training activities offered by CENTA.

Year 2

Conduct early experiments with ASM cells to study the behaviour and phenotype of ASM cells in presence of MNPLs. The transport behaviour of MNPLs will be monitored by the use of photoluminescent nanoparticles embedded in MNPLs.

Year 3

Study the impact of MNPLs on bacterial interaction with epithelial and smooth muscle cells; assess cell viability and structure using microbiology and advanced imaging technologies on the chemical environment in the biological systems.

Further reading

  1. Vethaak, A. D., Legler, (2021) Microplastics and human health Knowledge gaps should be addressed to ascertain the health risks of microplastics, Science, Feb. 12; 371:6530. doi: 10.1126/science.abe5041.
  2. Prata, J.C., da Costa, J.P, Lopes, I., Duarte, A.C., Rocha-Santos, T. (2020) Environmental exposure to microplastics: An overview on possible human health effects, Sci Total Environ, Feb 1;702:134455. doi: 10.1016/j.scitotenv.2019.134455
  3. Liang, B., Zhong, Y., Huang, Y., Lin, X., Liu, J., Lin, L., et al. (2021) Underestimated health risks: polystyrene micro- and nanoplastics jointly induce intestinal barrier dysfunction by ROS-mediated epithelial cell apoptosis, Part Fibre Toxicol, Jun 7;18(1):20. doi: 10.1186/s12989-021-00414-1.
  4. Amato-Lourenço, L.F., Carvalho-Oliveira, R., Júnior, G.R., Dos Santos Galvão, L., Ando, R.A., Mauad, T. (2021) Presence of airborne microplastics in human lung tissue, J Hazard Mater, Aug 15;416:126124. doi: 10.1016/j.jhazmat.2021.126124.
  5. Huang, S., Huan, X., Bi, R., Guo, Q., Yu, X., Zeng, Q., et al. (2022) Detection and Analysis of Microplastics in Human Sputum, Environ Sci Technol, Feb 15;56(4):2476-2486. doi: 10.1021/acs.est.1c03859.
  6. Leslie, H.A., van Velzen, M.J.M., Brandsma, S.H., Vethaak, A.D., Garcia-Vallejo, J.J., Lamoree, M.H. (2022) Discovery and quantification of plastic particle pollution in human blood, Environ Int, May;163:107199. doi: 10.1016/j.envint.2022.107199.
  7. Lu, K., Lai, K.P., Stoeger, T., Ji, S., Lin, Z., Lin, X., et al. (2021) Detrimental effects of microplastic exposure on normal and asthmatic pulmonary physiology, J Hazard Mater, Aug 15;416:126069. doi: 10.1016/j.jhazmat.2021.126069.
  8. Xu, M., Halimu, G., Zhang, Q., Song, Y., Fu, X., Li, Y., et al. (2019) Internalization and toxicity: A preliminary study of effects of nanoplastic particles on human lung epithelial cell, Sci Total Environ, Dec 1;694:133794. doi: 10.1016/j.scitotenv.2019.133794.


The preparation of MNPLs will be performed at the School of Chemistry and the cell-related experiments will be performed at the University Hospital of Leicester. We have frozen stocks of ASM and epithelial bacterial cells which can be used to perform the project. University of Leicester has developed well-established protocols to enable time-restricted work to continue during the pandemic.