Fluorescent liposomal nanoparticles containing oxidized [5]CPP-nanohoop aggregates

Carbon Nanomaterial Fluorescent Probes and Their Biological Applications

“…Although nanohoops emerged theoretically in 1954, their synthesis was not feasible until 2008, when Jasti, Bertozzi, and colleagues synthesized [9], [12], and [18]-cycloparaphenylenes ([ n ]-CPPs) . This groundbreaking CNHs synthesis has been followed up by various innovative approaches leveraging transition metals to execute reductive eliminations for formation of highly strained CPP macrocycles. − Unlike many other π-conjugated CNMs, nanohoops have radially oriented π-systems yielding unique optical, electronic, and charge transport properties, making them attractive for select bioimaging applications. , In terms of optical properties, smaller CNHs demonstrate red-shifted fluorescence due to the narrowing of the HOMO–LUMO (highest occupied molecular orbital–lowest unoccupied molecular orbital) gap . In addition to size, electron donating and accepting rings also change fluorescent emission properties via solvent-molecule interactions and improve quantum yields …”

“…The newest and smallest class of fluorescent CNMs, carbon nanohoops, have also been leveraged for cell imaging studies. Although numerous studies and reviews have noted the promise of carbon nanohoops as biological imaging agents, applications of these materials have been slow to emerge owing to low solubility in aqueous mediums, but encouraging advances have been made to ameliorate this . A seminal study by White and co-workers has achieved water solubility through the synthesis of sulfonate-functionalized carbon nanohoops .…”

“…1009 Other studies have similarly sought to improve solubility of CPPs. Park and co-workers developed a water-soluble oxidized- [5]CPP (Oxi-[5]CPP) by exposing [5]CPP to air at room temperature for 24 h. 1010 These Oxi- [5]CPPs were then packaged into liposomal nanoparticles via thin-film hydration and subsequently applied to HeLa cells (excitation: 335 nm, emission: 446 nm). Internalized Oxi- [5]CPP-liposomes efficiently labeled the cytosol, and no reduction in cell viability was observed at concentrations of up to 40 μM.…”

“…79−86 Unlike many other π-conjugated CNMs, nanohoops have radially oriented π-systems yielding unique optical, electronic, and charge transport properties, 87 making them attractive for select bioimaging applications. 88,89 In terms of optical properties, smaller CNHs demonstrate redshifted fluorescence due to the narrowing of the HOMO− LUMO (highest occupied molecular orbital−lowest unoccupied molecular orbital) gap. 90 In addition to size, electron donating and accepting rings also change fluorescent emission properties via solvent-molecule interactions and improve quantum yields.…”

“…Although numerous studies and reviews have noted the promise of carbon nanohoops as biological imaging agents, 428 applications of these materials have been slow to emerge owing to low solubility in aqueous mediums, but encouraging advances have been made to ameliorate this. 1007 A seminal study by White and co-workers has achieved water solubility through the synthesis of sulfonate-functionalized carbon nanohoops. 1008 Their disulfonate- [8]CPP (excitation: 328 nm, emission: 510 nm) showed no cytotoxicity at concentrations of up to 10 μM and good cell permeability when used for live cell staining and imaging in HeLa cells (Figure 21).…”