Multifunctional compact zwitterionic ligands for preparing robust biocompatible semiconductor quantum dots and gold...

Area of Science:

• Nanotechnology
• Materials Science
• Biomedical Engineering

Background:

• Developing biocompatible nanomaterials is crucial for advanced biological applications.
• Quantum dots (QDs) and gold nanoparticles (AuNPs) offer unique optical and physical properties but require surface functionalization for biological integration.
• Existing surface ligands often lack the optimal balance of hydrophilicity, biocompatibility, and stability.

Purpose of the Study:

• To synthesize and characterize novel compact ligands for creating hydrophilic, biocompatible quantum dots (QDs) and gold nanoparticles (AuNPs).
• To impart zwitterionic character to nanoparticles for enhanced stability and biological compatibility.
• To evaluate the performance of these functionalized nanoparticles in biological systems, including protein conjugation, cellular uptake, and in vivo applications.

Main Methods:

• Synthesis of four distinct compact ligands featuring a dihydrolipoic acid (DHLA) anchor, tertiary amines, and carboxyl/hydroxyl groups.
• Functionalization of QDs and AuNPs with the synthesized ligands.
• Comprehensive physical characterization of functionalized nanoparticles (surface charge, wettability, hydrodynamic size, pH/salt tolerance).
• Assessment of nanoparticle utility through protein conjugation, covalent coupling, Förster resonance energy transfer (FRET), cellular uptake studies, cytotoxicity assays, and in vivo monitoring.

Main Results:

• Successfully synthesized compact ligands that impart zwitterionic character and hydrophilicity to QDs and AuNPs.
• Functionalized nanoparticles exhibited excellent colloidal stability across a wide pH range and high salt concentrations.
• Ligand-coated QDs demonstrated efficient conjugation to proteins and peptides, facilitated rapid cellular uptake via cell-penetrating peptides, and showed no cytotoxicity.
• In vivo studies confirmed the biocompatibility and stability of the functionalized QDs.
• AuNPs functionalized with the same ligands displayed similar favorable colloidal properties.

Conclusions:

• The novel compact ligands effectively create hydrophilic, biocompatible, and stable QDs and AuNPs.
• These functionalized nanoparticles demonstrate significant potential for diverse biological applications, including bioimaging and drug delivery.
• The ligand design offers a versatile platform for enhancing nanoparticle performance in biological environments.
• The developed nanoparticles show promise for in vitro and in vivo applications with minimal toxicity.