Polymer Micro and Nanoparticles Containing B(III) Compounds as Emissive Soft Materials for Cargo Encapsulation and Temperature-Dependent Applications.

Frederico Duarte,Mercedes Cano,Javier Fernández-Lodeiro,Cristián Cuerva,Raquel Jiménez,Carlos Fernández-Lodeiro,Carlos Lodeiro

doi:10.3390/nano11123437

Frederico Duarte, Mercedes Cano + Show 5 more

Open Access

https://doi.org/10.3390/nano11123437

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Abstract

Polymer nanoparticles doped with fluorescent molecules are widely applied for biological assays, local temperature measurements, and other bioimaging applications, overcoming several critical drawbacks, such as dye toxicity, increased water solubility, and allowing imaging of dyes/drug delivery in water. In this work, some polymethylmethacrylate (PMMA), polyvinylpyrrolidone (PVP) and poly(styrene-butadiene-styrene) (SBS) based micro and nanoparticles with an average size of about 200 nm and encapsulating B(III) compounds have been prepared via the reprecipitation method by using tetrahydrofuran as the oil phase and water. The compounds are highly hydrophobic, but their encapsulation into a polymer matrix allows obtaining stable colloidal dispersions in water (3.39 µM) that maintain the photophysical behavior of these dyes. Although thermally activated non-radiative processes occur by increasing temperature from 25 to 80 °C, the colloidal suspension of the B(III) particles continues to emit greenish light (λ = 509 nm) at high temperatures. When samples are cooling back to room temperature, the emission is restored, being reversible. A probe of concept drug delivery study was conducted using coumarin 6 as a prototype of a hydrophobic drug.

Highlights

In vivo fluorescent imaging studies, control of drug delivery success and local temperature measurements in biological and medicinal systems are critical tasks [1,2,3,4]
THF evaporation does not cause any shift in the emission band, its intensity notably changes in the three new materials
In the case of PMMA@BF14 and PVP@BF14, a decrease of the fluorescence was observed after the evaporation process, whereas an opposite behavior is found for SBS@BF14 (Figure 3a–c)

Summary

Introduction

In vivo fluorescent imaging studies, control of drug delivery success and local temperature measurements in biological and medicinal systems are critical tasks [1,2,3,4]. The results are unambiguous when the emissive molecular organic dye or fluorescent metal complex is poorly soluble in water To overcome these problems, dye-doped polymer nanoparticles can be used to prevent poor solubility, reduce the interference with the assay, control the pH-dependent analysis, prevent unexpected quenching, low absorptivity, and often maintain photostability in imaging and drug release applications [5,6,7,8]. Desbiens et al Several polystyrene (PS) nanoparticles were synthesized and doped with a luminescent europium complex, Eu(tta) phen, spanning in size from 19 to 94 nm These nanomaterials were dispersed in water through a miniemulsion polymerization approach that allowed the photophysical properties of the dye to remain unaltered, as observed in THF solution even though this compound is insoluble in water [11]. Amela-Cortes et al have demonstrated the homogeneity, stability, and the maintenance of the luminescent properties of poly(methylmethacrylate)

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