Smart photoluminescent nanohybrids based on CdSe quantum dots capped with multidentate thiolated pH‐responsive and thermoresponsive polymers for nanosensing

Abstract

Well‐defined thermoresponsive polymers obtained by the atom transfer radical polymerization (ATRP) of short oligo(ethylene glycol) methyl ether methacrylates (MEOnMA, n = 2, 3, or 8) with small ratios of a thiolated comonomer, 2‐(acetylthio)ethylmethacrytale, can replace the hydrophobic trioctylphosphine oxide (TOPO) capping of CdSe quantum dots (QDs). After this facile ligand exchange, the mild hydrolysis of the acetylthiol group into thiol is the key to enhance the QD luminescence. However, the length of the ethylene glycol side chain is critical for the success of the functionalization; it is established that the shortest MEO2MA‐based copolymers result in a compact coating and a highest quantum yield (up to a factor of 6) when compared with that of CdSe@TOPO in dichloromethane. In addition, the amphiphilic character of the copolymer allows the CdSe@P(MEOnMA‐co‐SEMA) nanohybrids to disperse in water. On the other hand, the residual ionizable thiol groups do not get attached to the QD surface, cause that the lower critical solubility temperature of the polymer depends on pH as well. Thus, at acidic pH, an abrupt increase in the luminescence emission accompanies the polymer collapse, which establishes the promise of these hybrids as temperature/pH nanosensors and targeted drug delivery. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3087–3095

The synthesis of switch-off fluorescent water-stable copper nanocluster Hg2+ sensors via a simple one-pot approach by an in situ metal reduction strategy in the presence of a thiolated polymer ligand template

“…Furthermore, after the hydrolysis of AcSEMA and due to the acidity of the thiol group, the thermoresponsive properties become dependent on the pH; at low pH, the thiol is protonated and T cp is close to that of the p(MEO 2 MA) homopolymer, whereas in a basic medium, the thiolate anion generates a dramatic increase in the cloud point temperature. 26,27 This behavior is illustrated in Fig. S2 in the ESI † for a hydrolyzed P6-B sample.…”

“…According to our previous research involving luminescent NPs, [26][27][28][29][30][31] the polymeric shell may act as a protective coating to stabilize the CuNCs, preventing their aggregation and oxidation, keeping the size of the new nanohybrids on the nanometric scale, preserving the photophysical properties and offering, in addition, new properties with regards to water solubility, biocompatibility and even stimuli-responsivity.…”

“…1A) was carried out in benzonitrile solution at 70°C, using the monomer/initiator/ligand/ catalyst (M/I/L/C) ratios and reaction times indicated in Table 1. 27 A typical procedure for the synthesis of these statistical copolymers is described for the sample P2-C: HMTETA (0.041 g, 0.18 mmol), MEO 2 MA (4.750 g, 25.24 mmol), AcSEMA (0.250 g, 1.33 mmol), CuCl (0.017 g, 0.18 mmol) and benzonitrile (5 g) were added to a Schlenk flask, which was then immersed in an ice-water bath; after the solution was degassed via purging with nitrogen for 20 min, the initiator ethyl-2-bromoisobutyrate (EBr i B; 0.034 g, 0.177 mmol) was introduced into the flask via a nitrogen degassed syringe. The Schlenk flask was immediately immersed in an oil bath at 70°C.…”

“…Inspired by this challenge and based on our previous experience relating to the synthesis of fluorescent nanoparticles decorated with functional polymers (QDs, [26][27][28][29] UCNPs 30 and AgNPs 31 ), in this work we propose to use polymers with multithiol groups that serve as ligands and templates for the synthesis, functionalization and stabilization of CuNCs. Therefore, new multithiolated polymers, soluble in water and stimuli-responsive ( pH and temperature), have been designed and used to develop a new functionalization strategy that is simple, versatile and reproducible, allowing this type of photoluminescent nanohybrid to be obtained.…”

Synthesis of mucoadhesive thiol-bearing microgels from 2-(acetylthio)ethylacrylate and 2-hydroxyethylmethacrylate: novel drug delivery systems for chemotherapeutic agents to the bladder

“…The thioester groups could subsequently be deprotected to form a series of well-defined thiolated thermosensitive polymers, nanoparticles or hydrogels and multidentate ligands for functionalising CdSe quantum dots, or graphene. [10][11][12][13][14] These materials could, however, also have application in mucoadhesion. One potential application of mucoadhesive dosage forms is in delivery of chemotherapeutics to the bladder.…”