Flow Cytometry

Flow cytometry is a widely used technique for individually characterising cells by their light scattering properties with a range of fluorescently labelled markers. Flow cytometry allows cells to be counted, characterised and sorted. It has applications in many fields in life science and medicine, including diagnostics, haematology, virology and molecular biology. 

CPN-510 showing strong labelling of the 50% subpopulation of CD-4 positive cells in flow cytometry.

Conjugated Polymer Nanoparticles (CPNs) have a number of features that make them particularly useful as fluorescent probes for use in flow cytometry. The intense fluorescent signal from the CPNs allows cellular markers expressed at low levels to be readily detected, enabling the study of low abundance surface antigens. The range of CPNs with unique excitation and emission spectra enables their use with additional channels in existing detection panels. This includes CPNs that can be excited by 808nm lasers and emit in the infrared range (900nm or 1130nm). The CPNs can label cells that require challenging or prolonged isolation techniques and storage conditions, as the CPNs are resistant to photobleaching, extreme temperatures or pH and fixation methods. Additionally, the CPNs’ magnetic cell populations can be magnetically isolated prior to flow cytometry, enriching the specific cellular subpopulation to enhance the detection of rare cell types for diagnosis.

CPNs have been used in a number of flow cytometry paradigms, either loaded directly into cells by endocytosis or attached to antibodies to label cell surface markers such as CD-3, CD-4 or CD-44. The range of CPNs allows for multiple targets to be labelled simultaneously and in conjunction with other fluorophores. Individual CPNs can also be resolved using flow cytometry enabling their use as calibration beads. The figure shows CPN510, linked via streptavidin/biotin to an anti-CD4 antibody labelling the CD4+ cell subpopulation.