Deterministic encapsulation of particles and cells through viscoelastic ordering in microfluidic devices

New techniques which afford the rapid screening of cells to determine the presence of diseases are essential to provide efficient and effective future treatments and to improve patient health outcomes across a broad spectrum of disease states. In the last 30 years, the introduction of micro electro mechanical systems (MEMS) has prompted substantial research to develop miniaturised disease screening equipment based on microfluidic technologies. Such technologies aim to enhance point of care (POC) diagnosis, as a rapid clinical alternative to biopsy or blood tests (results typically between 2-10 days).

The encapsulation of cells together with expensive functionalised particles, called Drop-seq, is currently regarded as the most effective existing single diagnostic platform approach to derive the genome of cells affected by a variety of diseases down to the single-cell level. Although this Drop-seq technology represents the current state of the art, it suffers from a serious drawback as only approximately 10% of the cells involved are encapsulated together with a single functionalised expensive particle. This loss of over 90% of cells and expensive particles in the sensing process is a serious limitation for the screening of rare cells such as circulating tumour cells of which there are only 1/1000 in a typical blood sample. Earlier and more accurate detection of potentially fatal diseases would represent a remarkable advance in healthcare, with substantive reductions in the ongoing health cost burden and significant improvements to the quality of life of each affected individual.

The research proposed aims to exploit advances in viscoelastic flow technology to increase the efficiency of the Drop-seq technique to an unprecedented 100%. To achieve this transformative result the planned work will establish a means to ensure the equal-spacing of cells and functionalised particles before they approach the encapsulation area. This ensures that a single cell is encapsulated with a single particle, in a single droplet (a process referred to herein as deterministic encapsulation). Thus, the Drop-seq becomes deterministic when the frequency of droplet formation is synchronised with the frequency of particles and cells approaching the encapsulation area. Henceforth, the efficiency of the Drop-seq technology becomes 100%, rather than the mere 10% currently obtained.

The project will be carried out in conjunction with an industry partner that is recognised as the world leader in the design and manufacture of pioneering microfluidic products.

The objectives of the research are as follows:

(1) Achieving cell ordering in straight channel; (2) Achieving continuous formation of viscoelastic droplets with uniform sizes and shapes; (3) Encapsulation of single particles in viscoelastic droplets with uniform size distribution; (4) Encapsulation of single cells in viscoelastic droplets.

The research, which will achieve unprecedented disease detection capability, has substantive potential impacts, both in terms of healthcare outcomes and economic benefits. It will provide a basis for transforming the accuracy of detection for diseases such as lung, prostate, breast and bowel cancers, which currently account for more than half the types of cancer and lead to premature death. Beneficiaries will therefore include patients and healthcare professionals. Specifically, the POC testing approach has special relevance to healthcare professional working in remote locations. Examples include GP surgeries, clinics in remote locations or even within pharmacies. Our project partner is well placed to drive the research outputs to commercialisation and economic gain- on a global basis. Furthermore, widespread technical benefits in diverse fields including Process Engineering and Advanced Manufacturing may be anticipated to arise from enhanced knowledge of the innovative uses of viscoelastic flows within microfluidic settings.

The project targets the establishment of a viable microfluidic prototype for point-of-care (POC) applications based on the deterministic encapsulation of particles and cells suspended in viscoelastic polymer solution flowing in microfluidic devices. The prototype will be developed and commercialised in conjunction with an industry partner that is recognised as the World leader in the design and manufacture of pioneering microfluidic products.
Health Impact -The eventual availability of a new healthcare product will orchestrate marked benefits for patients and healthcare professionals. Early diagnosis of disease is critical to achieve effective patient care and improve health outcomes. Obtaining a blood sample takes several minutes, blood analysis can take significantly longer. To expedite clinical tests, for point-of-care, tools based on microfluidic devices have been developed. These include so called 'lab-on-a-chip' devices that analyse blood in relation to common clinical parameters including white blood cell count, platelet count and haemoglobin.
The proposed research will extend existing capabilities and significantly improve the analysis of single cells with lab-on-a-chip technologies, allowing highly efficient screening of blood diseases (analysing both white and red blood cells), for a wider range of disorders. For instance, the encapsulation of red blood cells with functionalised particles can be used for the genome identification of the cells, allowing the screening of a variety of gene-related diseases (Drop-seq technology). Notably, currently commercialised products offer an efficiency of only 10%. The presented research will establish a novel technique based on the use of polymer solutions to boost the efficiency close to 100% - resulting in a superior commercialised product.
Patients will benefit from very detailed diagnosis of diseases (single-cell analysis). Healthcare professionals will be advantaged by the ability to deliver more accurate and efficient point-of-care duties. The product could be utilised by Health Boards (UK and international) and will be pertinent to medicine in unconventional or remote locations - military bases; field hospitals, submarines, ships; oil and gas rigs; rural healthcare centres and international Embassies.
Economic Impact -The development and commercialisation of the prototype microfluidic device will realise significant financial benefits for the industry partner, as it will financially gain from a new product with unprecedented efficiency. Subsequently, the industry partner will profit from the (probable) high sales figures associated with widespread demand for a technically superior diagnostic device.
Other potential financial beneficiaries are end users - i.e NHS; Government bodies, responsible for military medicine - who will be advantaged from a technically advanced device in comparison to less accurate and less flexible alternative existing products.
Public Engagement -The use of chemical engineering to create a new healthcare product, involving the innovative application of polymer solutions (typically associated with plastics and negative environmental impact) promises to stimulate public interest and lead to knowledge enhancement. Beneficiaries include School children (supporting an interest in STEM); healthcare support groups and patient support organisations.