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

Label-Free Ratiometric Upconversion Nanoprobe for Spatiotemporal pH Mapping in Living Cells

Sensing and imaging pH inside living cells are of paramount importance for better penetrating cellular functions and disease diagnostics. Herein, we engineered an original pH sensor by a simple one-step self-assembly of poly(ethylene glycol) (PEG)ylated phospholipid (DSPE-PEG) and a phenol red small molecule on the surface of upconversion nanoparticles (UCNPs) to form a phospholipid monolayer for sensing and imaging the change of intracellular pH. The sensor showed excellent reversibility and rapid response to the pH variations. Furthermore, this pH sensing system could measure spatial and temporal pH changes during endocytosis and interrogate the pH fluctuations inside cells under external stimuli. Our experimental results revealed that the pH sensor was able to map spatial and temporal pH fluctuations inside living cells, showing its potential application in diagnostics and pH-related study of cell biology.

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

The fabrication of stable fluorescent copper nanoclusters (CuNCs) in aqueous media is still challenging, despite the low price and potential biomedical applications. Herein, we report a facile and efficient strategy for assembling CuNCs using multifunctional thiolated copolymers with pH and thermoresponsive features. The new nanohybrids are formed via a simple one-pot approach through the reduction of a copper salt with hydrazine in the presence of a multithiolated polymer, which provides a template during nanocluster assembly and further efficient protection against oxidation and aggregation. Furthermore, the thermo- and pH-responsive properties of the pristine copolymers endow the nanohybrids with these stimuli-responsive features. The thiol content and the macromolecular size of the polymer ligands exert strong influences on the final photophysical properties of these new hybrid luminescent nanoclusters. The existence of stable bright greenish-yellow emission in water over long periods of time, the high photostability under UV irradiation and the strong oxidation resistance toward hydrogen peroxide of the hybrid CuNCs suggest that they have great promise for nanomedicine, bioassay and nanosensor use. Furthermore, the polymeric CuNCs obtained have been successfully tested as optical switch-off sensors for the sensitive and highly selective detection of Hg2+ in the presence of other metal ions in liquid and solid states. Finally, we demonstrate the practical application of the new hybrid to Hg2+ detection in human urine.

In situ fabrication of a luminescent copper nanocluster/eggshell membrane composite and its application in visual detection of Ag+ ions, light-emitting diodes and surface patterning

In this work, we report a novel strategy for fabricating a luminescent 2D nanocomposite at room temperature by in situ generation of luminescent copper nanoclusters (Cu NCs) embedded in natural monolithic eggshell membrane (ESM) using dithiothreitol as the reducing and capping agent. The established fabrication is facile, cost-effective and viable. The as-prepared Cu NC/ESM nanocomposite exhibited excellent photoluminescence performance, improved chemical, thermal and photo stability, convenient tailoring and flexibility. Significantly, the nanocomposites could be employed as test strips for the visual detection of Ag⁺ ions based on the luminescence quenching phenomenon and as color conversion layers in light-emitting diodes. Furthermore, application of the proposed strategy for surface luminescence patterning was well demonstrated, indicating great potential in biomass based anti-counterfeiting, information encryption and security paper or sheets.

PHEMA hydrogel films crosslinked with dynamic disulfide bonds: synthesis, swelling-induced mechanical instability and self-healing

Undesired swelling-induced instability patterns on substrate-attached hydrogel films can be self-healed by the introduction of dynamic covalent bonds.

Cleavable and thermo-responsive hybrid nanoparticles for on-demand drug delivery

By combining the photothermal ability of copper sulphide nanoparticles (NPs) upon excitation with Near Infrared (NIR) Light and the thermo-responsive properties of the homemade oligo (ethylene glycol) methyl ether methacrylate copolymer we have obtained fragmentable nanocomposites able to release a carried drug on-demand after NIR-light triggering. A complete physico-chemical characterization of the resulting nanoparticles has been carried out and their degradation assessed at different temperatures. Herein, we have also evaluated the drug loading capacity of those nanoparticles and the temperature dependence in their drug release kinetics using bupivacaine hydrochloride as a model drug. For those hybrid nanoparticles, subcytotoxic doses on four different cell lines and their potential interference in cell metabolism, induction of apoptosis, and cell cycle have been evaluated by Alamar Blue fluorometry and flow cytometry.

QDs decorated with thiol-monomer ligands as new multicrosslinkers for the synthesis of smart luminescent nanogels and hydrogels

QDs decorated with thiol-monomer ligands as new multicrosslinkers for the synthesis of smart (photoluminescent and pH/temperature sensitive) nanogels and hydrogels.

Multiamino polymeric capping of fluorescent silver nanodots as an effective protective, amphiphilic and pH/thermo-responsive coating

New multiamino thermosensitive polymers based on MEO₂MA have been described and used to the in situ synthesis of polymeric capped silver nanodots. The new highly luminescent hybrids show amphiphilic and pH/thermo-responsiveness.

Synergism at the Nanoscale

Photoactive nanoparticles are smart systems that exhibit unique optical properties. In general, their intrinsic properties are size dependent. The degree and type of response to size are both related to their composition. Nanoparticles usually require to be capped with organic ligands in order to be dispersible in an aqueous or organic media, thus leading to nanoparticle colloidal dispersions and enhancing the processability of the material. The organic ligand also plays a key role in their preparation. In addition, the high surface-to-volume ratio of the nanoparticles combined with the affinity of the ligands for the nanoparticle surface can be used to place a large number of functional molecules at their periphery. The purpose of this chapter is to understand the synergism between nanoparticles and organic ligands with regard to their preparation, performance, and applicability.

Dynamism of Stimuli-Responsive Nanohybrids: Environmental Implications

Nanomaterial science and design have shifted from generating single passive nanoparticles to more complex and adaptive multi-component nanohybrids. These adaptive nanohybrids (ANHs) are designed to simultaneously perform multiple functions, while actively responding to the surrounding environment. ANHs are engineered for use as drug delivery carriers, in tissue-engineered templates and scaffolds, adaptive clothing, smart surface coatings, electrical switches and in platforms for diversified functional applications. Such ANHs are composed of carbonaceous, metallic or polymeric materials with stimuli-responsive soft-layer coatings that enable them to perform such switchable functions. Since ANHs are engineered to dynamically transform under different exposure environments, evaluating their environmental behavior will likely require new approaches. Literature on polymer science has established a knowledge core on stimuli-responsive materials. However, translation of such knowledge to environmental health and safety (EHS) of these ANHs has not yet been realized. It is critical to investigate and categorize the potential hazards of ANHs, because exposure in an unintended or shifting environment could present uncertainty in EHS. This article presents a perspective on EHS evaluation of ANHs, proposes a principle to facilitate their identification for environmental evaluation, outlines a stimuli-based classification for ANHs and discusses emerging properties and dynamic aspects for systematic EHS evaluation.

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

Thiol-bearing microgels have been synthesised from copolymerisation of 2-(acetylthio)ethylacrylate and 2-hydroxyethylmethacrylate, and subsequent deprotection using sodium thiomethoxide.