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Compact Quantum Dots for Single-molecule Imaging

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Dinámica del anillo de tiolactona en lípidos diméricos para la sintonización supramolecular conmutada por pH en

Pranay Saha¹, Parikshit Moitra², Sayan Bera¹

¹School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India.

|February 18, 2026

Abstract:

Surface functionalization of semiconductor nanocrystals with stimuli-responsive ligands provides a powerful platform for designing adaptive nanomaterials for biomedical and optoelectronic applications. In this work, we present a novel strategy for engineering quantum dot (QD) surfaces using thiolactone ring-opening and closing chemistry to enable reversible, pH-sensitive assembly. Gemini-type dimeric lipids, palmitoyl homocysteine (diPHC or GPHC), were employed as ligands that engage in dynamic thiolactone interactions with CdSe/ZnS core-shell and CuInZnS₂ (CIZS) alloyed QDs. These pH-dependent thiolactone bonds undergo intramolecular cyclization and cleavage, leading to reversible surface reorganization and tunable supramolecular self-assembly of lipidated QDs (LQDs). The resulting LQDs maintain excellent colloidal and photostability under aqueous and serum-rich conditions, with consistent fluorescence retention across pH cycles. Compared to monomeric lipid coatings, diPHC-functionalized QDs exhibit enhanced stability and responsiveness, attributed to cooperative multivalent interactions and improved membrane-like packing. Transmission electron microscopy confirms reversible aggregation without compromising nanocrystal core integrity. Dynamic light scattering validates pH-modulated size transitions. This thiolactone-mediated approach enables dynamic, modular, and environmentally responsive nanomaterials for sensing, delivery, diagnostics, and energy applications.

Palabras clave:

puntos cuánticos ligandos tiolactona pH autoensamblaje nanomateriales adaptativo química dinámico supramolecular

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