TECHNOLOGY FOCUS - PHARMACEUTICALS - Preferred Components: The nanoparticle further comprises at least one therapeutic agent.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The organic photovoltaic semiconductor polymer is poly(cyclopentadithiophene-alt-benzothiadiazole) (PCPDTBT), poly(acenaphthothienopyrazine-alt-benzodithiophene) (PATPBDT), poly(4,6-(dodecyl-thieno(3,4b)thiophene-2-carboxylate)-alt-2,6-(4,8-dioctoxylbenzo(1,2-b:4,5-b)dit)), poly(N-90-heptadecanyl-2,7-carbazole-alt-3,6-bis(thiophen-5-yl)-2,5-dioctyl-2,5-dihydropyrrolo (3,4) pyrrole-1,4-dione), poly(4,8-bis((2-ethylhexyl)oxy)benzo (1,2-b:4,5-b')dithiophene-2,6-diyl-alt-3-fluoro-2-(2-ethylhexyl))), or poly(2,6(4,4'bis(ethylhexyl)dithieno(3,2-b:2',3'-d)silole-alt-(1,3-(5-octyl-4H-thieno(3,4-c)pyrrole)))). The organic photovoltaic semiconductor polymer is polymers designated as SNP1, SNP2, SNP3, SNP4, or SNP5. The phospholipid is 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dinonadecanoyl-sn-glycero-3-phosphocholine, 1,2-diarachidoyl-sn-glycero-3-phosphocholine, 1,2-dibehenoyl-sn-glycero-3-phosphocholine, 1,2-dilignoceroyl-sn-glycero-3-phosphocholine, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy(polyethylene glycol)2000) (ammonium salt), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy(polyethylene glycol)-2000) (ammonium salt), 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy(polyethylene glycol)-350) (ammonium salt), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy(polyethylene glycol)-550) (ammonium salt), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy(polyethylene glycol)-3000) (ammonium salt), and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy(polyethylene glycol)-5000) (ammonium salt). The nanoparticle further comprises reactive oxygen species (ROS)-inactivated fluorophore. The fluorophore is 2-(4'-( beta -carboxyethylthio)-7'-(1",3",3"-trimethylindolenine)-3',5'-trimethyleneheptatrien-1-yl)-1,3,3-trimethyl indolenium perchlorate (IR775S). EXAMPLE - Two efficient photovoltaic semiconducting Tr-conjugated polymers (SPs) with strong absorption in near-infrared (NIR) region, poly(cyclopentadithiophene-alt-benzothiadiazole) (PCPDTBT) and poly(acenaphthothienopyrazine-alt-benzodithiophene) (PATPBDT) derivatives were used to prepare photoacoustic semiconducting polymer nanoparticles (PA SPNs). In addition diketopyrrolopyrroles were also used to generate the SNPs designated as SPN3, SPN4, and SPN5. Nanoprecipitation assisted by 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) afforded water-soluble PCPDTBT-based (SPN1) and PATPBDT-based (SPN2) nanoparticles as clear dark-green and olive-green solutions, respectively. Transmission electron microscopy (TEM) revealed that SPN1 and SPN2 had spherical morphologies with average diameters of 41 plus minus 2 and 43 plus minus 2 nm, respectively. Additionally, dynamic light scattering (DLS) confirmed their narrow size distribution with polydispersity indexes of 0.16 plus minus 0.03 and 0.19 plus minus 0.02 for SPN1 and SPN2, respectively. The zeta potentials of SPN1 and SPN2 were - 35 plus minus 2 and - 32 plus minus 3 mVin phosphate-buffered saline (pH 7.4), respectively. Such large zeta potentials were attributed to the presence of DPPC, which resulted in high SPN stability under physiologically relevant conditions with no obvious size change for both SPNs at least one week after synthesis. SPN1 and SPN2 had NIR absorptions with maxima at 660 and 700 nm, respectively. The SPNs designated SPN3, SPN4, and SPN5 had absorption peaks of 625 nm, 650 nm to 725 nm, and 750 nm.