Recaptured photobleached liposomes display a response identical to a non-fluorescent (photobleached) liposome. Partial photobleaching of particles is also possible. When a partially photobleached particle is recaptured, the fluorescence intensity resumes the photobleaching trend where it left off in the previous multipassing (Figure ). Additionally, since the fluorescence response is approximately proportional to the particle size, it is possible to estimate rL from the fluorescence alone. An example of multipassing 100 nm and 50 nm nominal radius fluorescent PS nanoparticles in the same solution can be found in the Supporting Information that further demonstrates the correlation between particle size and fluorescence intensity (Figure ). In future work, we plan to implement anti-fading agents (e.g., triplet state quenchers, oxygen scavenging systems) which have been shown to significantly increase photostability. Characterization of fluorescent and non-fluorescent liposomes. A significant advantage of simultaneous multipass resistive-pulse sensing and fluorescence imaging is the ability to distinguish between liposomes with and without fluorescent markers. For example, Figure shows the simultaneous characterization of a completely photobleached, non-fluorescent liposome and a fluorescent liposome. This smaller, 70.3 ± 0.7 nm, liposome is non-fluorescent due to prolonged exposure to the excitation light inside of the nanopipette, resulting in complete photobleaching. This liposome originated from the inside of the nanopipette as indicated by its first resistive pulse corresponding to a particle leaving the nanopipette orifice at 1.0 V (Figure ). The second, larger, 95.4 ± 0.3 nm, fluorescent liposome originated from the external electrolyte solution (its first resistive pulse corresponds to a particle entering the nanopipette orifice at -1.0 V) has not been photobleached in the interior of the nanopipette and exhibits typical liposome fluorescence. Additional examples of particle photobleaching can be found in the Supporting Information (Figure ). The qualitative detection of particle fluorescence will be useful in future studies of biologically relevant particles to probe specific surface markers with fluorescent labeling.