transfection

Transfection is the process of deliberately introducing nucleic acids into eukaryotic cells. It is a fundamental technique in molecular biology used to study gene function, regulate gene expression, or produce cells that express a desired gene product. In common usage, transfection refers to non-viral delivery of DNA or RNA; delivery by viral vectors is typically described as transduction.

A wide range of methods exists to achieve transfection. Non-viral approaches include chemical reagents that form complexes with nucleic acids, such as cationic lipid–DNA complexes used in lipofection and polymer-based carriers. Physical methods include electroporation, microinjection, and biolistic delivery (gene gun). Calcium phosphate precipitation is an older chemical method. Newer techniques such as magnetofection employ magnetic nanoparticles to enhance delivery. Each method varies in efficiency and impact on cell viability and is selected based on cell type and experimental goals.

Nucleic acids delivered by transfection can be plasmid DNA, synthetic messenger RNA, or molecules such as antisense oligonucleotides or small interfering RNA. Transfection can yield transient expression, lasting for hours to days, or stable expression when the construct integrates into the genome and is maintained with selection.

Applications are widespread, including basic research on gene function, overexpression or knockdown studies, screening approaches, and production of recombinant proteins for experimentation. Transfection also provides a platform for delivering genome-editing tools, such as CRISPR components, into cells. Considerations include efficiency, cell health, potential off-target effects, and adherence to appropriate biosafety guidelines.