| Convection |
Transfer of mass due to the bulk movement of molecules within fluids utilized for several intracellular delivery techniques as a driving force for transporting macromolecules. For convective intracellular delivery, an external force is required for the internalization of a cargo. |
| Delivery (transfection) efficiency |
A ratio (%) of cells with successful cargo delivery to total cells. In intracellular delivery, this parameter is used for evaluating the performance of the technique. |
| Dextran |
A complex branched glucan (polysaccharide) commercially available in diverse sizes, usually labeled with fluorescence. In intracellular delivery, dextran is extensively used as a characterization cargo, identifying the intracellular delivery performance of a method. |
| Diffusion |
The process by which molecules and small particles move from one location to another by random and thermally driven motion. For membrane disruption‐mediated methods, diffusive transport facilitates small cargo delivery but is limited in transporting macromolecules. |
| Endocytosis |
The cellular process in which proteins and other soluble small molecules in the extracellular milieu are internalized by being engulfed with a segment of the plasma membrane. In the intracellular delivery assay, cells subjected to endocytosis are often considered a negative control group. |
| Immortalized cell line |
The population of cells derived from a plant or animal (human) capable of dividing indefinitely in culture. |
| Messenger RNA (mRNA) |
RNA that specifies the order of amino acids in a protein (i.e., the primary structure). In intracellular delivery, mRNA is widely used for transient transfection. |
| Microfluidics/nanofluidics |
Manipulation, control of fluids, or study of flow behaviors that are confined within micro/nanometer‐scale channels. |
| Plasmid DNA (pDNA) |
A circular double‐stranded DNA molecule that can be replicated independently and used extensively as a vector carrying specific genes for cellular engineering by transformation. In intracellular delivery, a high level of delivery of plasmid DNA is regarded as one of the challenging tasks. |
| Primary cell |
A cell isolated directly from plant or animal (human) tissue with limited growth potential in culture. Most primary cells are known to be more challenging to transfect compared with immortalized cell lines, regardless of the delivery method of choice. |
| Reynolds number (Re) |
A nondimensional number given by Re = ρuL
c/η, where u is the mean velocity of the flow, L
c is the characteristic length, ρ is the fluid density, and η is the fluid dynamic viscosity. The physical representation of the Reynolds number is that it is a measure of the ratio between inertial forces and viscous forces in a particular flow. In microfluidics and nanofluidics, the associated Reynolds number reaches close to zero due to small scale and low flow velocity, resulting in linear and predictable Stokes flow. |
| Transfection |
The process of delivering nucleic acids (e.g., DNA or RNA) into eukaryotic cells for modulation of gene expression. |
