A population of nanoparticles, comprising: a plurality of core/shell nanocrystals, each including, a semiconductor core, an intermediate semiconductor shell layer disposed over the semiconductor core, an external semiconductor shell layer disposed over the intermediate semiconductor shell layer, and a hydrophilic organic layer in direct contact with the external semiconductor shell layer, characterised in that, the hydrophilic organic layer includes a plurality of hydrophilic ligands, wherein the hydrophilic ligands are selected from dipeptides, thiols and functionalized phosphinates, said thiols being tridentate thiols of Formula I, II, III, IV, V, or VI: or wherein R 1, R 2, R 3 are independently H, halo, hydroxyl, (-(C=O)-C 1 -C 22, -(C=O)CF 3) alkanoyl, C 1 -C 22 alkyl, C 1 -C 22 heteroalkyl, ( OC 1 -C 22) alkylcarbonato, alkylthio (C 1 -C 22) or (- NH(C 1 -C 20) or - N(C 1 -C 20) 2) alkylcarbamoyl, wherein R 1, R 2 and R 3 are different or the same; wherein R 4 and R 5 are independently H, C 1 -C 20 alkyl, C 6 -C 18 aryl, C 1 -C 22 heteroalkyl, or C 1 -C 22 heteroaryl, wherein R 4 and R 5 are different or the same; wherein R 6 is a polyethylene glycol based moiety of Formula VII: wherein R 7 is -NH 2, -N 3, -NHBoc, -NHFmoc, -NHCbz, -COOH, -COOt-Bu, -COOMe, iodoaryl, hydroxyl, alkyne, boronic acid, allylic alcohol carbonate, -NHBiotin, - NHNHBoc, - NHNHFmoc, or -OMe, n is an integer from 1 to 100; and wherein the population of nanoparticles is capable of undergoing a Fluorescence Resonance Energy Transfer, FRET, with donor moieties or acceptor moieties, whichhas a FRET efficiency of greater than 20%. a plurality of core/shell nanocrystals, each including, a semiconductor core, an intermediate semiconductor shell layer disposed over the semiconductor core, an external semiconductor shell layer disposed over the intermediate semiconductor shell layer, and a hydrophilic organic layer in direct contact with the external semiconductor shell layer, characterised in that, the hydrophilic organic layer includes a plurality of hydrophilic ligands, wherein the hydrophilic ligands are selected from dipeptides, thiols and functionalized phosphinates, said thiols being tridentate thiols of Formula I, II, III, IV, V, or VI: or wherein R 1, R 2, R 3 are independently H, halo, hydroxyl, (-(C=O)-C 1 -C 22, -(C=O)CF 3) alkanoyl, C 1 -C 22 alkyl, C 1 -C 22 heteroalkyl, ( OC 1 -C 22) alkylcarbonato, alkylthio (C 1 -C 22) or (- NH(C 1 -C 20) or - N(C 1 -C 20) 2) alkylcarbamoyl, wherein R 1, R 2 and R 3 are different or the same; wherein R 4 and R 5 are independently H, C 1 -C 20 alkyl, C 6 -C 18 aryl, C 1 -C 22 heteroalkyl, or C 1 -C 22 heteroaryl, wherein R 4 and R 5 are different or the same; wherein R 6 is a polyethylene glycol based moiety of Formula VII: wherein R 7 is -NH 2, -N 3, -NHBoc, -NHFmoc, -NHCbz, -COOH, -COOt-Bu, -COOMe, iodoaryl, hydroxyl, alkyne, boronic acid, allylic alcohol carbonate, -NHBiotin, - NHNHBoc, - NHNHFmoc, or -OMe, n is an integer from 1 to 100; and wherein the population of nanoparticles is capable of undergoing a Fluorescence Resonance Energy Transfer, FRET, with donor moieties or acceptor moieties, whichhas a FRET efficiency of greater than 20%. a semiconductor core, an intermediate semiconductor shell layer disposed over the semiconductor core, an external semiconductor shell layer disposed over the intermediate semiconductor shell layer, and a hydrophilic organic layer in direct contact with the external semiconductor shell layer, characterised in that, the hydrophilic organic layer includes a plurality of hydrophilic ligands, wherein the hydrophilic ligands are selected from dipeptides, thiols and functionalized phosphinates, said thiols being tridentate thiols of Formula I, II, III, IV, V, or VI: or wherein R 1, R 2, R 3 are independently H, halo, hydroxyl, (-(C=O)-C 1 -C 22, -(C=O)CF 3) alkanoyl, C 1 -C 22 alkyl, C 1 -C 22 heteroalkyl, ( OC 1 -C 22) alkylcarbonato, alkylthio (C 1 -C 22) or (- NH(C 1 -C 20) or - N(C 1 -C 20) 2) alkylcarbamoyl, wherein R 1, R 2 and R 3 are different or the same; wherein R 4 and R 5 are independently H, C 1 -C 20 alkyl, C 6 -C 18 aryl, C 1 -C 22 heteroalkyl, or C 1 -C 22 heteroaryl, wherein R 4 and R 5 are different or the same; wherein R 6 is a polyethylene glycol based moiety of Formula VII: wherein R 7 is -NH 2, -N 3, -NHBoc, -NHFmoc, -NHCbz, -COOH, -COOt-Bu, -COOMe, iodoaryl, hydroxyl, alkyne, boronic acid, allylic alcohol carbonate, -NHBiotin, - NHNHBoc, - NHNHFmoc, or -OMe, n is an integer from 1 to 100; and wherein the population of nanoparticles is capable of undergoing a Fluorescence Resonance Energy Transfer, FRET, with donor moieties or acceptor moieties, whichhas a FRET efficiency of greater than 20%. wherein R 1, R 2, R 3 are independently H, halo, hydroxyl, (-(C=O)-C 1 -C 22, -(C=O)CF 3) alkanoyl, C 1 -C 22 alkyl, C 1 -C 22 heteroalkyl, ( OC 1 -C 22) alkylcarbonato, alkylthio (C 1 -C 22) or (- NH(C 1 -C 20) or - N(C 1 -C 20) 2) alkylcarbamoyl, wherein R 1, R 2 and R 3 are different or the same; wherein R 4 and R 5 are independently H, C 1 -C 20 alkyl, C 6 -C 18 aryl, C 1 -C 22 heteroalkyl, or C 1 -C 22 heteroaryl, wherein R 4 and R 5 are different or the same; wherein R 6 is a polyethylene glycol based moiety of Formula VII: wherein R 7 is -NH 2, -N 3, -NHBoc, -NHFmoc, -NHCbz, -COOH, -COOt-Bu, -COOMe, iodoaryl, hydroxyl, alkyne, boronic acid, allylic alcohol carbonate, -NHBiotin, - NHNHBoc, - NHNHFmoc, or -OMe, n is an integer from 1 to 100; and wherein the population of nanoparticles is capable of undergoing a Fluorescence Resonance Energy Transfer, FRET, with donor moieties or acceptor moieties, whichhas a FRET efficiency of greater than 20%.