Carboxyl FRET Quantum Dots QFH is a group of water soluble CdSe/ZnS core/shell quantum dots with poly (ethylene glycol)-appended dihydrolipoic acid (DHLA-PEG) coating, which offer high fluorescence with great long-term colloidal stability over a broad pH range (5-10) and accessible to simple and efficient bioconjugation techniques. Our conjugate design combines the use of mixed ligand exchange strategy: capping QDs with a mixture of a desired reactive ligand and an inert ligand. The mixed ligands strategy allows the introduction of a small but controlled fraction of terminal amines on the QD surface to modulate the number of bound molecules. Unlike encapsulation strategy, the hydrophilic nanoparticles provided here by ligand exchange are compact in size, reactive with target dyes/molecules and suitable for use in biosensing applications (e.g., via Förster Resonance Energy Transfer (FRET)). *Other size QDs with different terminal functional groups are available upon request. Product Name Description Pricing QFH-620 Compact CdSe/ZnS Quantum Dots w/Carboxylic Acid, 620 nm Pricing QFH-535 Compact CdSe/ZnS Quantum Dots w/Carboxylic Acid, 535 nm Pricing QFH-570 Compact CdSe/ZnS Quantum Dots w/Carboxylic Acid, 570 nm Pricing