Effect of TEOA on the Process of Photopolymerization at 532 nm and Properties of Nanogels.

Nanogel is an important kind of biomaterials applied for wound dressings, drug delivery, medical diagnostics and biosensors. The properties of nanogels closely depend on the density of the crosslinking network. In this study, the role of triethanolamine (TEOA) in the effect on the crosslinking degree of nanogels based on poly(ethylene glycol) diacrylate (PEGDA) was investigated and illustrated. The effect of TEOA on the process of photopolymerization at 532 nm and properties of the nanogels was systematically investigated by using UV-vis spectroscopy, FT-IR spectroscopy, 1 H NMR, DLS, SEM, AFM and DSC. In brief, the double-bond conversion of photopolymerization and the crosslinking degree of nanogels can be effectively regulated by TEOA.

Rapid preparation of nanogels by photopolymerization at 532 nm.

The strategy of laser beam expansion was used to rapidly prepare nanogels by photopolymerization at 532 nm under low monomer concentration. According to the unique micellar morphology formed by amphiphilic polyethylene glycol diacrylate (PEGDA) in water, the monomer concentration was largely decreased to increase the distance of micellar aggregates. In this case, the photo-crosslinking could prefer to occur inside the micelles instead of crosslinking between the micellar aggregates. The variations of double bond content with reaction time in different beam expansion experiments were investigated. Finally, nanogels with uniform size could be rapidly prepared by regulating the reaction parameters, including monomer concentration, reaction time and power density.

Preparation of ultrasmall nanogels by facile emulsion-free photopolymerization at 532 nm.

Nanogels have been widely prepared and characterized in recent years due to their unique advantages. Here, an effective, original, and facile method of emulsion-free photopolymerization at 532 nm without surfactant was developed to prepare nanogels based on poly(ethylene glycol) diacrylate (PEGDA). The 532 nm continuous laser with symmetrical energy distribution like a three-dimensional shape of a straw hat was used to control the reaction region. The self-emulsification of PEGDA in water was studied and PEGDA micelles were directly cross-linked by controlling the laser energy. The number of micelles participating in the microreaction region and the double bond crosslinking between micellar aggregates and inside micelles were reasonably regulated. The size of the nanogels could be effectively modulated by controlling reaction parameters including laser power, monomer concentration, initiator concentration, and reaction time. Finally, ultrasmall nanogels with around 30 nm in size were prepared by balancing double bond crosslinking between micellar aggregates and inside micelles.

Upconversion Nanoparticle-Assisted Photopolymerization.

Near-infrared (NIR) laser has deeper penetration and lower thermal effect compared with ultraviolet-visible (UV/vis) laser. NIR laser can stimulate upconversion nanoparticles (UCNPs) to emit UV/vis light efficiently. Therefore, the UCNPs become an important kind of materials to produce upconversion luminescence through NIR laser. Compared with photopolymerization induced with UV/vis laser, the UV/vis light from UCNP-assisted photopolymerization presents some unique characters. This review focuses on the research progress of UCNP-assisted photopolymerization and its potential applications. We will discuss the influencing factors of UCNP-assisted polymerization, illustrate the relation between the gel size and monomer concentration and propose the development prospects of UCNP-assisted polymerization in the biological field.

A novel cross-linked nanoparticle with aggregation-induced emission properties for cancer cell imaging.

Fluorescent probes have been widely used in bioimaging as an efficient and convenient analytical tool. From the initial inorganic nanoparticles and small organic molecules to polymeric nanoparticles, scientific researchers have been trying to develop a probe with strong fluorescence and excellent biocompatibility. In this study, a tetraphenylethylene derivative with AIE properties and hyaluronic acid modified by methacrylic anhydride were combined to prepare a novel nanoparticle (HA-Ac-Pha-C) as a fluorescent probe by a photochemical cross-linking reaction. The fluorescence intensity and size of the nanoparticles were characterized by different techniques. It was confirmed that cross-linked nanoparticles not only showed stronger fluorescence, but also had better photostability while still maintaining 85.9% of the initial intensity after seven days. Moreover, cells and zebrafish imaging experiments also demonstrated that nanoparticles show specific fluorescence labeling for cancer cells and excellent biocompatibility in living organisms.

Hyaluronic Acid-Modified Fluorescent Probe for Dual Color Imaging of Living Cell.

Nanoprobes with biocompatibility and strong fluorescence have unique advantages in tumor detection and diagnosis. A nanoparticle with dual fluorescent signals for detecting and imaging of tumor cells was prepared, in which the outer layer of the particle is a hyaluronic acid-modified molecule with aggregation-induced emission properties, and the inner content is the boron-dipyrromethene (BODIPY) derivative. This nanoparticle has low critical micelle concentration, small size, and high fluorescence intensity. Cell imaging experiments showed that it is capable of stable cell imaging with a red and blue fluorescence conversion in response to cancer cells. Furthermore, the zebrafish experiment confirmed that it can be used for biological imaging. Nanoparticles with dual fluorescence response properties of the coated structure provide an effective way for detecting cancer cells.