Abstract: Optophoretic methods are used to determine one or more biological properties or changes in biological properties of one or more cells or cellular components. The methods use optical or photonic forces to select, identify, characterize, and/or sort whole cells or groups of cells. The methods are useful in a number of applications, including, but not limited to, drug screening applications, toxicity applications, protein expression applications, rapid clonal selection applications, biopharmaceutical monitoring and quality control applications, cell enrichment applications, viral detection, bacterial drug sensitivity screening, environmental testing, agricultural testing, food safety testing, personalized medicine applications as well as biohazard detection and analysis.