Fluorescent polydopamine based molecularly imprinted sensor for ultrafast and selective detection of p-nitrophenol in drinking water

A highly effective fluorescent molecularly imprinted sensor (F-PDA-MIS) based on fluorescent polydopamine (F-PDA) was successfully synthesized for selective and ultrafast detection of p-nitrophenol (P-NP) in drinking water. F-PDA with abundant surface functional groups has been artfully modified to firstly serve as both fluorescent monomer and functional monomer in the synthesis of a uniform luminous F-PDA-MIS, which can greatly improve the detection efficiency. As expected, F-PDA-MIS had an obvious emission wavelength of 535 nm with the optimal excitation wavelength at 400 nm. Specially, F-PDA-MIS could detect P-NP in the range 100 to 1100 nM with much lower detection limit of 24.2 nM within 120 s compared with other conventional imprinted fluorescent sensors based on pure quantum dots (QDs) or dyes. This excellent test phenomenon is mainly ascribed to the rapid electron transfer between F-PDA and P-NP. Satisfactory recovery of 98.0-104% for mineral water and 98.6-106% for boiling water were obtained with relative standard deviations (RSDs) of 2.7-3.4% and 2.6-3.5% respectively. The detection reliability of F-PDA-MIS was verified by the comparison with high-performance liquid chromatography (HPLC-UV). Consequently, F-PDA as a fluorescence functional monomer has been shown to be a possible strategy to effectively improve the detection limit and shorten response time of the target determination in water..

From Synthesis to Characterization of Site-Selective PEGylated Proteins

Covalent attachment of therapeutic proteins to polyethylene glycol (PEG) is widely used for the improvement of its pharmacokinetic and pharmacological properties, as well as the reduction in reactogenicity and related side effects. This technique named PEGylation has been successfully employed in several approved drugs to treat various diseases, even cancer. Some methods have been developed to obtain PEGylated proteins, both in multiple protein sites or in a selected amino acid residue. This review focuses mainly on traditional and novel examples of chemical and enzymatic methods for site-selective PEGylation, emphasizing in N-terminal PEGylation, that make it possible to obtain products with a high degree of homogeneity and preserve bioactivity. In addition, the main assay methods that can be applied for the characterization of PEGylated molecules in complex biological samples are also summarized in this paper.

Aggregation-Caused Quenching-Type Naphthalimide Fluorophores Grafted and Ionized in a 3D Polymeric Hydrogel Network for Highly Fluorescent and Locally Tunable Emission

Polymer hydrogels with intense yet tunable fluorescence are of great research interest due to their wide potential use in biological imaging, sensing, information storage, etc. However, the conventional fluorophores such as naphthalimide and its derivatives are usually not recommended to prepare highly fluorescent hydrogels because of their aggregation-caused quenching (ACQ) nature and spontaneous tendency to undergo fluorescence self-quenching in quasi-solid-state hydrogel systems. Additionally, local regulation over fluorescent behavior of hydrogels, despite being important, still remains underdeveloped. Herein, we report highly fluorescent polymeric hydrogels based on conventional ACQ-type naphthalimide fluorophores, followed by spatial and temporal control of their fluorescent behavior. The hydrogels were prepared by one-pot radical copolymerization of naphthalimide-containing monomer and acrylamide in chitosan-acetic acid solution. Their intense emission comes from synergetic anchoring and diluting effect of the protonated naphthalimide moieties grafted on polymer chains, which result in the electrostatic repulsion among ACQ luminogens and reduced PET (photoinduced electron transfer) effect from adjacent dimethylamine groups to naphthalimide fluorophores. After being deprotonated in alkaline conditions, both PET and the ACQ effect work again to greatly quench fluorescence, endowing the hydrogels with pH-sensitive emission behavior. These properties encourage us to develop a diffusion-reaction (D-R) method to spatially and temporally control their fluorescent behavior. Based on these results, the ion-transfer-printing-assisted D-R method was further developed to fabricate many high-precision and meaningful fluorescent patterns on hydrogels. These fluorescent patterns are invisible under daylight but become vivid under specific UV light illumination, suggesting their wide potential applications in information security and transmission.

Room Temperature One-Step Conversion from Elemental Sulfur to Functional Polythioureas through Catalyst-Free Multicomponent Polymerizations

The utilization of sulfur is a global concern, considering the abundant and cheap source of sulfur from nature and petroleum industry, its limited consumption, and the safety/environmental problems caused during storage. The economic and efficient transformation of sulfur remains to be a great challenge for both academia and industry. Herein, a room temperature conversion from sulfur to functional polythioureas was reported through a catalyst-free multicomponent polymerization of sulfur, aliphatic diamines, and diisocyanides in air with 100% atom economy. The polymerization enjoys quick reaction and wide monomer scope, which affords 16 polythioureas with well-defined structures, high molecular weights ( M_ws up to 242 500 g/mol), and excellent yields (up to 95%). The polythioureas can be utilized to detect mercury pollution with high sensitivity ( K_sv = 224 900 L/mol) and high selectivity, clean Hg²⁺ with high removal efficiency (>99.99%) to achieve drinking water standard, and monitor the real-time removal process by fluorescence.

Polymerizable aggregation-induced emission dye for preparation of cross-linkable fluorescent nanoprobes with ultra-low critical micelle concentrations

In recent years, aggregation-induced emission (AIE) dyes based fluorescent organic nanoparticles (FONs) have achieved significant progress in various biomedical applications. In this work, we developed a covalent strategy to prepare biocompatible AIE-active dyes based cross-linked copolymers (MPC-POSS-PhE) via controllable reversible addition fragmentation chain transfer (RAFT) polymerization using zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC), polymerizable AIE dye (named as PhE) and 8-vinyl polyoctahedral silsesquioxanes (POSS) as monomers. Due to the existence of hydrophilic MPC and hydrophobic PhE, the resultant copolymers will self-assemble into core-shell nanoparticles in aqueous solution with ultra-low critical micelle concentration (CMC). This could effectively overcome the drawbacks of non-crosslinked micelles and show more attractive properties and better performance for biomedical applications. Furthermore, the characterization results and biological assays demonstrated that the final MPC-POSS-PhE FONs show stable aqueous stability, uniform size and morphology, high water dispersity, desirable optical properties and low cytotoxicity. These remarkable properties make the resultant AIE-active nanoprobes great potential for biomedical applications.

Recent progress and development on polymeric nanomaterials for photothermal therapy: a brief overview

This review article summarizes the recent development and progress of polymeric photothermal agents for photothermal therapy and imaging-guided photothermal therapy applications.

Thermo-responsive fluorescence of AIE-active poly(N-isopropylacrylamides) labeled with highly twisted bis(N,N-dialkylamino)arenes

A thermo-responsive fluorescent polymer materials were synthesized fromN-isopropylacrylamides with AIE-active 9,10-bis(N,N-dialkylamino)arene monomers.

Fabrication of water dispersible and biocompatible AIE-active fluorescent polymeric nanoparticles through a “one-pot” Mannich reaction

Biocompatible and water dispersible fluorescent polymeric nanoparticles with an aggregation-induced emission feature were fabricated through a facile “one-pot” Mannich reaction and utilized for biological imaging applications.

Fabrication of multifunctional fluorescent organic nanoparticles with AIE feature through photo-initiated RAFT polymerization

Novel fluorescent organic nanoparticles with AIE feature have been fabricated through a catalyst-free photo-initiated RAFT polymerization.

One-step synthesis, self-assembly and bioimaging applications of adenosine triphosphate containing amphiphilies with aggregation-induced emission feature

Amphiphilic molecules with aggregation-induced emission (AIE) characteristics have attracted intensive interest for biological imaging applications for their self-assembly into nanostructures and obvious enhanced fluorescence intensity in aqueous solution. Although many AIE-active fluorescent organic nanoparticles (FONs) have been fabricated recently, the direct linkage of hydrophilic small molecules and hydrophobic AIE dyes has rarely been reported. In this work, we reported a one-pot strategy for preparation of adenosine triphosphate (ATP) containing molecules that conjugated the amino group of ATP and aldehyde-terminated AIE dye (PhCHO) based on mercaptoacetic acid locking imine (MALI) reaction. These AIE-active ATP-PhCHO showed amphiphilic properties and could self-assemble into micelles, which displayed high water dispersibility, strong yellow fluorescence, good biocompatibility and biological imaging capability. These advantages make ATP-PhCHO FONs promising for biomedical applications.

Organic Dots Based on AIEgens for Two-Photon Fluorescence Bioimaging

Two-photon fluorescence imaging technique is a powerful bioanalytical approach in terms of high photostability, low photodamage, high spatiotemporal resolution. Recently, fluorescent organic dots comprised of organic emissive cores and a polymeric matrix are emerging as promising contrast reagents for two-photon fluorescence imaging, owing to their numerous merits of high and tunable fluorescence, good biocompatibility, strong photobleaching resistance, and multiple surface functionality. The emissive core is crucial for organic dots to get high brightness but many conventional chromophores often encounter a severe problem of fluorescence quenching when they form aggregates. To solve this problem, fluorogens featuring aggregation-induced emission (AIE) can fluoresce strongly in aggregates, and thus become ideal candidates for fluorescent organic dots. In addition, two-photon absorption property of the dots can be readily improved by just increase loading contents of AIE fluorogen (AIEgen). Hence, organic dots based on AIEgens have exhibited excellent performances in two-photon fluorescence in vitro cellular imaging, and in vivo vascular architecture visualization of mouse skin, muscle, brain and skull bone. In view of the rapid advances in this important research field, here, we highlight representative fluorescent organic dots with an emissive core of AIEgen aggregate, and discuss their great potential in bioimaging applications.

Recent developments in polydopamine: an emerging soft matter for surface modification and biomedical applications

After more than four billion years of evolution, nature has created a large number of fascinating living organisms, which show numerous peculiar structures and wonderful properties. Nature can provide sources of plentiful inspiration for scientists to create various materials and devices with special functions and uses. Since Messersmith proposed the fabrication of multifunctional coatings through mussel-inspired chemistry, this field has attracted considerable attention for its promising and exiciting applications. Polydopamine (PDA), an emerging soft matter, has been demonstrated to be a crucial component in mussel-inspired chemistry. In this review, the recent developments of PDA for mussel-inspired surface modification are summarized and discussed. The biomedical applications of PDA-based materials are also highlighted. We believe that this review can provide important and timely information regarding mussel-inspired chemistry and will be of great interest for scientists in the chemistry, materials, biology, medicine and interdisciplinary fields.

Morphology-Tailoring of a Red AIEgen from Microsized Rods to Nanospheres for Tumor-Targeted Bioimaging

Efficient morphology modulation of a red AIEgen from pristine microsized rods to nanospheres is achieved via encapsula ting QM-2 (quinolinemalononitrile-2) into hybrid micelles. This novel reagent shows great potential in tumor-targeted bioimaging because of its monodispersion in aqueous systems, the uniform diameter of ≈30 nm, enhanced fluorescence brightness with a large Stokes shift of 190 nm, and strongly increased biocompatibility and photostability.

Facile fabrication of amphiphilic AIE active glucan via formation of dynamic bonds: self assembly, stimuli responsiveness and biological imaging

A one-pot strategy has been developed for the preparation of stimuli responsive AIE active glucan through formation of a dynamic Schiff base and a phenyl borate.

Fabrication of AIE-active amphiphilic fluorescent polymeric nanoparticles through host–guest interaction

Novel polymeric luminescent nanoprobes with aggregation induced emission (AIE) properties were fabricatedviahost–guest interaction between the β-CD pendant copolymers and adamantane-terminated AIE dye.

Stimulus responsive cross-linked AIE-active polymeric nanoprobes: fabrication and biological imaging application

Stimuli responsive AIE-active polymeric luminescent nanoprobes have been fabricated through formation of dynamic bonds using AIE dye as the linker.

Di(naphthalen-2-yl)-1,2-diphenylethene-based conjugated polymers: aggregation-enhanced emission and explosive detection

Conjugated polymers with rotatable naphthalen-2-yl pendants show aggregation-enhanced emission characteristics and explosive detection potential.

Supermolecular self assembly of AIE-active nanoprobes: fabrication and bioimaging applications

AIE active luminescent polymeric nanoprobes were fabricated for the first time via formation of supermolecular complexes between an adamantane capped AIE dye and β cyclodextrin.