A facile strategy for fabrication of aggregation-induced emission (AIE) active fluorescent polymeric nanoparticles (FPNs) via post modification of synthetic polymers and their cell imaging

Self-assembled nano-particles of chitosan amphiphilic derivative for formaldehyde fluorescent detection and its application in test strips

Excessive levels of formaldehyde (FA) represent serious health risks. Aiming at the detection of formaldehyde content, this paper proposes a self-assembly method of proportional nanoprobes. Spherical nanoparticles (NPs) were prepared by one-step condensation reaction between rhodamine B (RhB) and chitosan (CS). After CS was modified by RhB, the linear structure changed and self-assembled under the action of "hydrophilic/hydrophobic" to form a core-shell structure with a cavity structure. The hydrophobic small molecule probe N-Butyl-4-Hydrazo-1,8-Naphacticimide (NBHN) spontaneously entered into the hydrophobic cavity to form spherical particles Chitosan-Rhodamine B@N-Butyl-4-Hydrazo-1,8-Naphacticimide (CS-RhB@NBHN) with a size of about 60 nm. The hydroxyl groups on CS enrich formaldehyde through charge interaction, and promote the reaction of formaldehyde with NBHN, so that the probe can detect formaldehyde at a lower concentration (detection limit 87 nmol·L-1). The self-assembled CS-RhB@NBHN nanoparticles significantly increased the response speed of NBHN (from 30 min to 10 min). After the reaction of NBHN with formaldehyde, the PET effect is released, the fluorescence transition from red to yellow of CS-RhB@NBHN, and the visual fluorescence response effect to formaldehyde is significantly improved. With the help of smartphone color recognition software, we converted the color of the probe solution into RGB values to realize the quantitative and visual detection of formaldehyde. In addition, CS-RhB@NBHN was used for the detection of FA in leather and air.

A Label-Free Fluorescent Sensor Based on Si,N-Codoped Carbon Quantum Dots with Enhanced Sensitivity for the Determination of Cr(VI)

A signal shut-off probe of Si, N-codoped carbon quantum dots (Si, N-CQDs) was exploited to detect Cr(VI) by fluorescence quenching without the aid of any biomolecules or labeling materials. The sensing system prepared the precursor of diacetone acrylamide and the silane coupling agent 3-aminopropyltriethoxysilane (KH-550) by a simple hydrothermal method, and the quantum yield is as high as 75% Si, N-CQDs. The fluorescence stability and microstructure of the Si, N-CQDs were studied. The Si, N-CQDs has a high sensitivity for detecting Cr(VI) with the linear range of 0–200 μM and the detection limit of 0.995 μM. The quenching mechanism of Si, N-CQDs is attributed to FRET.

Aggregation-induced emission (AIE) from poly(1,4-dihydropyridine)s synthesized by Hantzsch polymerization and their specific detection of Fe2+ ions

As an important metal element widely existing in nature and the human body, the simple and specific detection of Fe2+ ions has always been of interest.

Catalyst-Free Spontaneous Polymerization with 100% Atom Economy: Facile Synthesis of Photoresponsive Polysulfonates with Multifunctionalities

Photoresponsive polymers have attracted extensive attention due to their tunable functionalities and advanced applications; thus, it is significant to develop facile in situ synthesis strategies, extend polymers family, and establish various applications for photoresponsive polymers. Herein, we develop a catalyst-free spontaneous polymerization of dihaloalkynes and disulfonic acids without photosensitive monomers for the in situ synthesis of photoresponsive polysulfonates at room temperature in air with 100% atom economy in high yields. The resulting polysulfonates could undergo visible photodegradation with strong photoacid generation, leading to various applications including dual-emissive or 3D photopatterning, and practical broad-spectrum antibacterial activity. The halogen-rich polysulfonates also exhibit a high and photoswitched refractive index and could undergo efficient postfunctionalizations to further expand the variety and functionality of photoresponsive heteroatom-containing polyesters.

The solvent-free one-pot multicomponent tandem polymerization of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) catalyzed by ionic-liquid@Fe3O4 NPs: the development of polyamide gels

Solvent-free MCTP via Biginelli DHPMs catalyzed by a non-toxic magnetic catalyst (IL1–2@ Fe₃O₄) in a one-pot reaction was illustrated for the development of fluorescent non-conjugated polyamide gels.

Influence factors on the critical micelle concentration determination using pyrene as a probe and a simple method of preparing samples

The critical micelle concentration (CMC) is an important parameter of widely used surfactants and needs to be measured in the application and development of surfactants. Fluorometric method is a widely used method determining CMC values owing to the advantages of highly sensitivity, fast response and wide application range. There are two common methods (I and II) of preparing samples for CMC fluorometric determination. In the process of developing CMC probes with aggregation-induced emission (AIE) characteristics, we found that methods I and II were not suitable for CMC probes with AIE charateristics and developed a new sample preparation method (III), which is not only suitable for CMC probes with AIE characteristic but also decreases operation procedures and errors owing to omitting the addition of micro amount of dyes into each sample. To ascertain if method III is also suitable for other CMC probes without AIE characteristics, the CMC values of surfactants were determined by fluorometric method using widely used pyrene without AIE charateristic as probe and methods I-III to prepare samples. The obtained experimental results proved that method III not only was suitable for preparation of samples for CMC determination of surfactants using pyrene as probe but also led to the least average deviation (methods I-III led to ±0.13, ±0.34 and ±0.05 mM deviation for the CMC determination of sodium dodecyl sulfate (SDS), respectively). The CMC determination using pyrene as probe is based on its change in the ratio (I FIII/I FI) of its emission peaks I and III with surfactant concentration. Unexpectedly, it was found that the I FIII/I FI value of pyrene in surfactant solutions is sensitive to the measurement conditions changing exciting light energy, such as slit widths and sample-measured number. In addition, it was found that surfactant SDS or cetrimonium bromide from different suppliers not only has significantly different CMC values but also leads to very different I FIII/I FI values of pyrene in a certain concentration of surfactant, which can be used as a simple method to distinguish the same surfactant with different CMC values.

Advances of Nano-Structured Extended-Release Local Anesthetics

Extended-release local anesthetics (LAs) have drawn increasing attention with their promising role in improving analgesia and reducing adverse events of LAs. Nano-structured carriers such as liposomes and polymersomes optimally meet the demands of/for extended-release, and have been utilized in drug delivery over decades and showed satisfactory results with extended-release. Based on mature technology of liposomes, EXPAREL, the first approved liposomal LA loaded with bupivacaine, has seen its success in an extended-release form. At the same time, polymersomes has advances over liposomes with complementary profiles, which inspires the emergence of hybrid carriers. This article summarized the recent research successes on nano-structured extended-release LAs, of which liposomal and polymeric are mainstream systems. Furthermore, with continual optimization, drug delivery systems carry properties beyond simple transportation, such as specificity and responsiveness. In the near future, we may achieve targeted delivery and controlled-release properties to satisfy various analgesic requirements.

Three dimensional (3D) printed polylactic acid with nano-hydroxyapatite doped with europium(III) ions (nHAp/PLLA@Eu3+) composite for osteochondral defect regeneration and theranostics

In the current research previously developed composites composed from poly (l-lactide) (PLLA) and nano-hydroxyapatite (10 wt% nHAp/PLLA) were functionalized with different concentrations of europium (III) (Eu³⁺). The aim of this study was to determine whether Eu³⁺ ions doped within the 10 wt% nHAp/PLLA scaffolds will improve the bioactivity of composites. Therefore, first set of experiments was designed to evaluate the effect of Eu³⁺ ions on morphology, viability, proliferation and metabolism of progenitor cells isolated from adipose tissue (hASC). Three different concentration were tested i.e. 1 mol%, 3 mol% and 5%mol. We identified the 10 wt% nHAp/PLLA@3 mol% Eu³⁺ scaffolds as the most cytocompatible. Further, we investigated the influence of the composites doped with 3 mol% Eu³⁺ ions on differentiation of hASC toward bone and cartilage forming cells. Our results showed that 10 wt% nHAp/PLLA@3 mol% Eu³⁺ scaffolds promotes osteogenesis and chondrogenesis of hASCs what was associated with improved synthesis and secretion of extracellular matrix proteins specific for bone and articular cartilage tissue. We also proved that obtained biomaterials have bio-imaging function and their integration with bone can be monitored using micro computed tomography (μCT).

Complexation and fluorescence behavior of proflavin with chemically engineered amine capped carbon nanodots and its subsequent release into DNA environments

Amine capped carbon dots are prepared by pyrolysis of citric acid. Probable excited-state interactions between PF and CNDs have been studied. A controlled release of PF into ctDNA by CNDs shows their utility as an efficient drug delivery agent.

Ultrasound-assisted catalyst-free thiol-yne click reaction in chitosan chemistry: Antibacterial and transfection activity of novel cationic chitosan derivatives and their based nanoparticles

In this work, we demonstrate that the thiol-yne click reaction could be efficiently mediated by ultrasonic irradiation and implement the ultrasound-assisted thiol-yne click reaction to chitosan chemistry as a polymer-analogous transformation. We optimize power and frequency of ultrasound to preserve selectivity of the click reaction and avoid ultrasonic degradation of the chitosan polymer chain. Thus, we obtain a new water-soluble betaine. Using ionic gelation of the obtained betaine derivatives of chitosan, we prepare nanoparticles with a unimodal size distribution. Furthermore, we present results of antibacterial and transfection activity tests for the chitosan derivatives and their based nanoparticles. The derivative with a medium molecular weight and a high degree of substitution demonstrated the best antibacterial effect. It derived nanoparticles with a size of ca. 100 nm and ζ-potential of ca. +69 mV revealed even higher antibacterial activity, slightly superior to commercial antibiotics ampicillin and gentamicin. On the contrary, the obtained polymers possess a much more pronounced transfection activity as compared with their based nanoparticles and species with a low degree of substitution acts as the most efficient transfecting agent. Moreover, the obtained betaine chitosan derivatives as well as their derived nanoparticles are non-toxic.

Polymer Microfibers Incorporated with Silver Nanoparticles: a New Platform for Optical Sensing

The enhanced sensitivity of up-conversion luminescence is imperative for the application of up-conversion nanoparticles (UCNPs). In this study, microfibers were fabricated after co-doping UCNPs with polymethylmethacrylate (PMMA) and silver (Ag) solutions. Transmission losses and sensitivities of UCNPs (tetrogonal-LiYF4:Yb3+/Er3+) in the presence and absence of Ag were investigated. Sensitivity of up-conversion luminescence with Ag (LiYF4:Yb3+/Er3+/Ag) is 0.0095 K-1 and reduced to (LiYF4:Yb3+/Er3+) 0.0065 K-1 without Ag at 303 K under laser source (980 nm). The UCNP microfibers with Ag showed lower transmission losses and higher sensitivity than without Ag and could serve as promising candidate for optical applications. This is the first observation of Ag-doped microfiber via facile method.

Polymer/nanodiamond composites - a comprehensive review from synthesis and fabrication to properties and applications

Nanodiamond (ND) is an allotrope of carbon nanomaterials which exhibits many outstanding physical, mechanical, thermal, optical and biocompatibility characteristics. Meanwhile, ND particles possess unique spherical shape containing diamond-like structure at the core with graphitic carbon outer shell which intuitively contains many oxygen-containing functional groups at the outer surface. Such superior properties and unique structural morphology of NDs are essentially attractive to develop polymer composites with multifunctional properties. However, despite a long history from the discovery of NDs, which is dated back to the1960s, this nanoparticle has been less explored in the field of polymer (nano)composites compared with other carbon nanomaterials, e.g. carbon nanotube (CNT) and graphene. However, open literature indicates that research works in the field of polymer/ND (PND) composites have gained great momentum in the past half a decade. The present article provides a comprehensive review on recent achievements in ND based polymer composites. This review covers a very broad aspect from the synthesis, purification and functionalization of NDs to dispersion, preparation and fabrication of polymer/ND (PND) composites with a look in their recent applications for both structural and functional basis. Therefore, the review would be useful to pave the way for researchers to take some advancing steps in this respect.

Emulsion and miniemulsion techniques in preparation of polymer nanoparticles with versatile characteristics

In recent years, polymer nanoparticles (PNPs) have found their ways into numerous applications extending from electronics to photonics, conducting materials to sensors and medicine to biotechnology. Physical properties and surface morphology of PNPs are the most important parameters that significantly affect on their exploitations and can be controlled through the synthesis process. Emulsion and miniemulsion techniques are among the most efficient and wide-spread methods for preparation of PNPs. The objective of this review is to present and highlight the recent developments in the advanced PNPs with specific properties that are produced through emulsion and miniemulsion processes.

A fluorescent sensor based on aggregation-induced emission: highly sensitive detection of hydrazine and its application in living cell imaging

Aggregation-induced emission (AIE) molecules eliminate the aggregation-caused quenching (ACQ) phenomenon effectively and exhibit excellent properties of a fluorescent sensor in the aggregated state. In this paper, an allochroic fluorescent sensor based on AIE molecules with a diphenylacrylonitrile structure was prepared in high yield by a simple procedure. This molecule possessed good AIE properties and exhibited a sensitive sensor ability for aliphatic amines with an obvious color change from orange to blue-green. The detailed investigation on the detection of hydrazine suggested that the detection limit for hydrazine was 3.67 × 10-6 M, and the highly sensitive sensor for hydrazine was not influenced by other species. The sensor mechanism was confirmed by using 1H NMR and MS spectra. The sensor for hydrazine was successfully applied in a test paper, exhibiting good practical application potential for detecting hydrazine. The experiment of living cell imaging suggested that this sensor showed superior bioimaging performance and presented sensitive detection for hydrazine with an obvious color change from orange to blue-green.

Photoactivation of Aggregation-Induced Emission Molecules for Fast and Efficient Synthesis of Highly Fluorescent Single-Chain Nanoparticles

Single-chain nanoparticles (SCNPs) are ultrasmall soft nanomaterials constructed via intrachain cross-linking of individual precursor polymer chains, with promising prospects for nanomedicine, catalysis, and sensing, among other different fields. SCNPs are versatile building blocks for the construction of new fluorescent probes with ultrasmall size, higher brightness, and better photostability than previous particle-based systems. Herein, we report on a new, fast, and efficient method to produce SCNPs with intense fluorescence emission in solution which is based on the photoactivation of appropriate aggregation-induced emission (AIE) cross-linking molecules containing azide functional groups. Remarkably, the presence of the azide moiety-that can be transformed to highly reactive nitrene species upon UV irradiation-was found to be essential for the SCNPs to display intense fluorescence emission. We attribute the fluorescence properties of the SCNPs to the immobilization of the initially nonfluorescent AIE molecules via intrachain cross-linking upon photoactivation. Such cross-linking-induced immobilization process activates the AIE mechanism and, hence, leads to fluorescent SCNPs in both solution and solid state.

Phytocosmeceutical formulation development, characterization and its in-vivo investigations

Several plants found rich in flavonoid, polyphenols, and antioxidants reported antiaging, oppose inflammation and carcinogenic properties but have rarely been applied in dermatology. The present study was an active attempt to formulate a stable phytocosmetic emulsion system loaded with 2% pre-concentrated Prosopis cineraria bark extract, aiming to revive facial skin properties. In order to obtain potent therapeutic activities, we first prepared extracts of stem, leaves, and bark and screen them on basis of phenolic, flavonoids contents and antioxidant, antibacterial, lipoxygenase and tyrosinase inhibition activities. Furthermore, cytocompatibility of the extract was also determined prior starting in vivo investigations. Then the in vivo performance of 2% bark extract loaded emulsion formulation was determined by using non-invasive probe cutometer and elastometer with comparison to base formulation. The preliminary experiment showed that bark extract has a significant amount of phenolic and flavonoid compounds with eminent antioxidant potential. Furthermore, indicated an efficient antibacterial, lipoxygenase, and tyrosinase enzyme inhibition activities. Importantly, the bark extract did not induce any toxicity or apoptosis, when incubated with HaCat cells. Moreover, the in vivo results showed the formulation (size 3 μm) decreased the skin melanin, erythema and sebum contents up to 2.1-,2.7-and 79%, while increased the skin hydration and elasticity up to 2-folds and 22% as compared to the base, respectively. Owing to enhanced therapeutic effects the phytocosmetic formulation proved to be a potential skin whitening, moisturizer, anti-acne, anti-wrinkle, anti-aging therapy and could actively induce skin rejuvenation and resurfacing.

In vitro and in vivo toxicity evaluation of halloysite nanotubes

Because of their outstanding properties, increasing numbers of research studies and emerging applications for manufacturing products are currently in progress for halloysite nanotubes (HNTs). Therefore, the impact of HNTs on the environment and human health should be taken into consideration. In order to clearly show the cell uptake of HNTs and the biodistribution of HNTs in zebrafish, HNTs are labeled with fluorescein isothiocyanate (FITC-HNTs). The cytotoxicity assays showed that the cell viabilities of human umbilical vein endothelial cells (HUVECs) and human breast adenocarcinoma (MCF-7) cells were above 60% after being treated with different concentrations of HNTs (2.5-200 μg mL^-1) for 72 h. Confocal laser scanning microscopy (CLSM) results showed the uptake of HNTs by HUVECs and MCF-7 cells. The in vivo toxicity of HNTs was then investigated in the early development of zebrafish embryos. The percent survival of zebrafish embryos and larvae showed no significant changes at different developmental stages (24, 48, 72, 96, and 120 hpf) when treated with various concentrations of HNTs (0.25-10 mg mL^-1). Besides, HNTs could promote the hatchability of zebrafish embryos and did not affect the morphological development of zebrafish at a concentration of ≤25 mg mL^-1. HNTs could also be ingested by zebrafish larvae and accumulated predominantly in the gastrointestinal tract. The fluorescence intensity of FITC-HNTs decreased gradually with time, which suggested that HNTs could be excreted by zebrafish larvae through the gastrointestinal metabolism. Therefore, it can be concluded that HNTs are relatively biocompatible nanomaterials, which can be utilized in many fields.

A “Turn-On” fluorescent probe for sensitive and selective detection of fluoride ions based on aggregation-induced emission

Based on the fluorophore of 2-(2′-hydroxyphenyl)benzothiazole (HBT) with aggregation-induced emission (AIE) properties, a highly selective and sensitive fluorescent probe PBT towards F⁻ was investigated. “Turn-On” fluorescence type signaling was realized by employing fluoride-selective cleavage of the latent thiophosphinated probe in mixed aqueous media. The probe is designed in such a way that the excited state intramolecular proton transfer (ESIPT) of the HBT moiety becomes blocked. The chemodosimetric approach of F⁻ to the probe results in the recovery of the ESIPT by removal of a free AIE-active HBT moiety through a subsequent hydrolysis process. The F⁻ detection limit of the probe was 3.8 nM in the dynamic range of 0.5 μM to 10 μM. In addition, the proposed probe has been used to detect F⁻ in water samples and toothpaste samples with satisfying results.

A “Turn-On” fluorescent probe PBT for sensitive and selective detection of fluoride ions based on aggregation-induced emission.

A biomimetic fluorescent chemosensor for highly sensitive zinc(ii) detection and its application for cell imaging

To fabricate a novel biomimetic fluorescent chemosensor, PSaAEMA-co-PMPC was synthesized via atom transfer radical polymerization, and this copolymer could be used for the detection of zinc(ii) and cell imaging. A series tests with various metal ions verified the specific fluorescence response behavior. This novel biomimetic fluorescent chemosensor exhibits excellent selectivity for Zn²⁺ ions over a wide range of tested metal ions in an aqueous solution. Moreover, cytotoxicity and bio-imaging tests were conducted to study the potential bio-application of the chemosensor. Owing to the biomimetic portion (phosphorylcholine), this copolymer possesses outstanding biocompatibility and could clearly image cells. The results indicated that PSaAEMA-co-PMPC has great potential for application in zinc(ii) detection and cell imaging.

To fabricate a novel biomimetic fluorescent chemosensor, PSaAEMA-co-PMPC was synthesized via atom transfer radical polymerization, and this copolymer could be used for the detection of zinc(ii) and cell imaging.