Nucleic acids induced peptide-based AIE nanoparticles for fast cell imaging

Herein, we utilized nucleic acids induced peptide co-assembly strategy to develop novel nucleic acids induced peptide-based AIE (NIP-AIE) nanoparticles. Strong fluorescent of AIE could be observed when a little amount of nucleic acids was added into the peptide solution, and the intensity could be regulated by the concentration of nucleic acids. This AIE nanoparticle with good biocompatibility could achieve fast cell imaging. It is also proved that the fluorescence intensity of AIE decreased with time, which indicates that the reducible cross-linkers of Wpc peptide by GSH and nanoparticles gradually disintegrate in cell. Based on the different of AIE fluorescence signals which regulated by the formation and disintegration of nanoparticles, this AIE system is expected to be used for real-time monitoring of drug release from peptide-based nano carriers in vivo or in vitro, and may provide a new platform for the construction of other organic AIE nanoparticles.     

Unprecedented tunable hydrophobic effect and anion recognition triggered by AIE with Hofmeister series in water

An unprecedented tunable hydrophobic effect in self-assembly of a small cationic organic fluorophore(NI-TPy~+)-based with aggregation-induced emission(AIE) property was realized in aqueous solution.The amplification of hydrophobicity was found to be significantly dependent upon the increasing aggregate s of NI-TPy~+,which enable d the study of the hydrophobic binding of chaotropic anions with the Hofmeister series.     

Bioactivated in vivo assembly(BIVA) peptide-tetraphenylethylene(TPE) probe with controllable assembled nanostructure for cell imaging

The emergence of fluorescent light-up molecular probe, which can specifically turn on their fluorescent in the presence of stimulation factors, has open up a new opportunity to advance biosensing and bioimaging. In this work, we designed and synthesized a peptide-AIE conjugate probe for cell imaging with controlled in situ assembled nanostructures. The modular designed probe is consisted of a selfassembled peptide-tetraphenylethene(TPE) motif, a fibroblast activation protein alpha(FAP-α)responsive motif, a hydrophilic motif and a targeting motif. The probe exhibits typically turn-on fluorescence property specifically triggered by FAP-α, which is a significant overexpressed membrane protein on pancreatic tumor cells. Interestingly, the peptide modified the TPE dramatically impacts the assembled nanostructure, which can be modulated by peptide sequences. As a result, the peptide FF(PhePhe) modification of TPE as the self-assembled motif provides a suitable balance of the probe with lightup property and nanofiber assembled structure in situ. Finally, our probe could effectively detect the FAP-α on tumor cells with high specificity. Meantime, the nanofibers in situ assembled on the surface of CAFs enhanced the probe accumulation and prolonged the retention for cell imaging. We envision that this study may inspire new insights into the design of nanostructure controlled AIE light-up bio-probe.     

Flash nanoprecipitation with Gd(III)‐based metallosurfactants to fabricate polylactic acid nanoparticles as highly efficient contrast agents for magnetic resonance imaging

Polylactic acid (PLA) nanoparticles coated with Gd(III)‐based metallosurfactants (MS) are prepared using a simple and rapid one‐step method, flash nanoprecipitation (FNP), for magnetic resonance imaging (MRI) applications. By co‐assembling the Gd(III)‐based MS and an amphiphilic polymer, methoxy poly(ethylene glycol)‐b‐poly(?‐caprolactone) (mPEG‐b‐PCL), PLA cores were rapidly encapsulated to form biocompatible T₁ contrast agents with tunable particle size and narrow size distribution. The hydrophobic property of Gd(III)‐based MS were finely tuned to achieve their high loading efficiency. The size of the nanoparticles was easily controlled by tuning the stream velocity, Reynolds number and the amount of the amphiphilic block copolymer during the FNP process. Under the optimized condition, the relaxivity of the nanoparticles was achieved up to 35.39 mM^?1 s^?1 (at 1.5 T), which is over 8 times of clinically used MRI contrast agents, demonstrating the potential application for MR imaging.     

An AIE probe for long-term plasma membrane imaging and membrane-targeted photodynamic therapy

Two red-emissive luminogens (TPTH and TPTB) with typical aggregation-induced emission characteristics were developed. By introducing the heavy atom of Br at the end of alkyl chain, TPTB exhibited higher reactive oxygen species generation efficiency through both types I and II pathways. Due to its excellent biocompatibility and proper lipophilicity, TPTB could be used for long-term cell membrane staining and this staining ability was independent of the change of plasma membrane potential. Furthermore, TPTB could ablate the cancer cells through cell membrane-targeted photodynamic therapy.     

Side-Chain Type Polysulfates: Their Synthesis,AIE Properties and Applications for p-Nitrophenol Detection in Water

Two small molecular monomers, ph-TPE and ph-TPE-CN, and their homopolymers Poly (ph-TPE) and Poly (ph-TPE-CN) containing tetra phenylethylene and sulfate structures, were synthesized by a sulfur (VI) fluorine exchange click reaction (SuFEx) and radical polymerization. All the monomers and polymers exhibit a typical aggregation-induced emission (AIE) effect both in the solid state and aggregated state. Moreover, based on the intermolecular charge transfer (ICT) effect between the tetra phenylethylene chromophore and p-nitrophenol, both polymers could be used for the selective detection of p-nitrophenol. The detection limit and reactivity coefficient of Poly (ph-TPE) are 0.081 μM and 5.15×10⁴ M⁻¹, respectively, whereas the detection limit and reactivity coefficient of Poly (ph-TPE-CN) are 0.077 μM and 1.81×10⁴ M⁻¹, respectively. This can be attributed to the greater sensitivity of Poly (ph-TPE-CN) to p-nitrophenol than that of Poly (ph-TPE). This work provides a new methodology for the preparation and broadening application of side-chain type AIE-active polysulfate fluorescent probes.     

A benzothizole-based fluorescent probe for Hg2+ recognition utilizing ESIPT coupled AIE characteristics

A new benzothizole-based fluorescent probe 1 for Hg²⁺ recognition utilizing “ESIPT+AIE” strategy has been developed. In THF/H₂O (1:1, v/v, PBS 20 mM, pH = 8.5) mixed solution, probe 1 displays rapid fluorescence responses to Hg²⁺ ions with high selectivity and sensitivity through Hg²⁺-triggered releasing of a compound possessing “ESIPT+AIE” characteristics. Cell imaging investigations indicate that probe 1 is cell permeable with low toxicity to MCF-7 cells, and applicable to detect Hg²⁺ ions in living MCF-7 cells.     

Donor-Acceptor Typed AIE Luminogens with Near-infrared Emission for Super-resolution Imaging

Aggregation-induced emission(AIE)luminogens(AIEgens)with high brightness in aggregates exhibit great potentials in biological imaging,but these AIEgens are seldom applied in super-resolution biological imaging,especially in the imaging by using the structural illumination microscope(SIM).Based on this consideration,we synthesized the donor-acceptor typed AIEgen of DTPA-BTN,which not only owns high brightness in the near-infrared(NIR)emission region from 600 nm to 1000 nm(photoluminescence quantum yield,PLQYs=11.35%),but also displays excellent photo-stability.In addition,AIE nanoparticles based on 4,7-ditriphenylamine-[1,2,5]-thiadiazolo[3,4-c]pyridine(DTPA-BTN)were also prepared with highly emissive features and excellent biocompatibility.Finally,the developed DTPA-BTN-based AIE nanoparticles were applied in the super-resolution cellular imaging via SIM,where much smaller full width at half-maximum values and high signal to noise ratios were obtained,indicating the superior imaging resolution.The results here imply that highly emissive AIEgens or AIE nanoparticles can be promising imaging agents for super-resolution imaging via SIM.     

Preparation of hybrid fluorescent-magnetic nanoparticles for application to cellular imaging by self-assembly

A unique fluorescent-magnetic hybrid bimodal nanocomposite was prepared by the layer-by-layer self-assembly (LbL) technique fabrication of water-soluble conjugated polymers (CPs) onto the CoFe₂O₄@SiO₂ core-shell nanoparticles (NPs). First, magnetic CoFe₂O₄ nanoparticles were prepared as the magnetic core and coated with a SiO₂ shell to obtain a good dispersion in aqueous solution. Then the polyelectrolytes and cationic conjugated polymer PFV was assembled onto the surface of core-shell nanoparticles by the LbL technique. The prepared nanocomposites were magnetically responsive and fluorescent, simultaneously. Finally, the biomacromolecule heparin sodium (HS) was then assembled on the outer layer of the nanocomposite to provide a cytocompatible surface. The nanocomposites show monodispersity, good fluorescence and good biocompatibility that are useful for efficient cellular imaging. Moreover, the colloidal stability and the cellular uptake ability of the nanocomposition with HS layer were efficiently improved.     

喹喔啉酮类JNK3抗肿瘤抑制剂的绿色合成——推荐一个综合化学实验

介绍了一个荧光光谱方面新的实验项目:以苝和六苯基噻咯作为发光物质的特征分子,通过测定其不同聚集状态下的荧光光谱,观察聚集荧光淬灭ACQ(aggregation-causedquenching)和聚集诱导发光AIE(aggregationinduced emission)两种不同的发光现象;利用晶体学数据库CCDC (Cambridge Crystallographic Data Centre)检索特征分子的晶体结构,从分子晶体结构层面分析AIE和ACQ发光现象产生的原因,在此基础上探讨不同发光机制和分子状态的关系。论文详细描述了实验的设计思想、实验内容和实验结论,并结合教学过程,分析了该实验在开阔学生视野、提高认知水平及培养科研素养等方面所取得的教学效果。     

Dendritic polyaniline nanoparticles synthesized by carboxymethyl chitin templating

Dendritic polyaniline (PANI) nanoparticles were synthesized via oxidative polymerization of aniline, using ammoniumperoxodisulfate as an oxidant, and CM-chitin as a template. The reaction was performed under acidic conditions and the template was removed after the polymerization was completed. Molecular characterization (including UV-vis, FTIR, TGA, and XRD) suggests that the structure of the synthesized dendritic PANI nanoparticles is identical to that of the emeraldine form of PANI, synthesized by the conventional route (without the addition of the CM-chitin template). SEM images reveal that the dendritic PANI nanoparticles have an average diameter in the nanometer range, and are globular in shape, with radially oriented PANI dendrites; in contrast, irregularly-shaped aggregates of PANI are obtained using the conventional synthesis. It was further found that the size of the dendritic PANI nanoparticles is dependent on the CM-chitin content. The higher the CM-chitin concentration, the smaller is the size of the dendritic PANI nanoparticles obtained. An interpretation of these observations and a possible formation mechanism are proposed based on self-assembly between the CM-chitin chains and the aniline monomer.     

Fluorescent AIE dots encapsulated organically modified silica (ORMOSIL) nanoparticles for two-photon cellular imaging

2,3-Bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TPE-TPA-FN or TTF), which possesses aggregation-induced emission (AIE) characteristic, is doped in organically modified silica (ORMOSIL) nanoparticles. By increasing the weight ratio of TTF to the precursor of silica nanoparticles (the quantities of the precursors were kept the same), the fluorescence intensity of nanoparticles increased correspondingly, due to the formation of larger AIE dots in the cores of ORMOSIL nanoparticles. The fluorescent and biocompatible nanoprobes were then utilized for in vitro imaging of HeLa cells. Two-photon fluorescence microscopy clearly illustrated that the nanoparticles have the capacity of nucleus permeability, as well as cytoplasm staining towards tumor cells. Our experimental results may offer a promising method for fast and bright fluorescence imaging, as well as bio-molecule/drug delivery to cell nucleus.     

A Novel L-Shaped Fluorescent Probe for AIE Sensing of Zinc (II) Ion by a DR/NIR Response

In the field of optical sensors, small molecules responsive to metal cations are of current interest. Probes displaying aggregation-induced emission (AIE) can solve the problems due to the aggregation-caused quenching (ACQ) molecules, scarcely emissive as aggregates in aqueous media and in tissues. The addition of a metal cation to an AIE ligand dissolved in solution can cause a “turn-on” of the fluorescence emission. Half-cruciform-shaped molecules can be a winning strategy to build specific AIE probes. Herein, we report the synthesis and characterization of a novel L-shaped fluorophore containing a benzofuran core condensed with 3-hydroxy-2-naphthaldehyde crossed with a nitrobenzene moiety. The novel AIE probe produces a fast colorimetric and fluorescence response toward zinc (II) in both in neutral and basic conditions. Acting as a tridentate ligand, it produces a complex with enhanced and red-shifted emission in the DR/NIR spectral range. The AIE nature of both compounds was examined on the basis of X-ray crystallography and DFT analysis.     

Preparation of cotton fabric based non-invasive colorimetric sensor for instant detection of ketones

Cotton based colorimetric sensing offers great potential for the detection of desired analytes due to their easy naked-eye sensing, ease in fabrication, cost effectiveness, rapid recognition, high sensitivity and selectivity. Poly (2-(dimethylamino ethyl) methacrylate) (pDMAEMA) and sodium nitroprusside (SNP) were deposited alternatively on a treated cotton fabric for non invasive calorimetric sensing of ketones. Physical and chemical characterizations such as FESEM, EDS, XRD, UV–vis, FTIR and XPS of the treated cotton based sensor were carried out. Standard colour chart of the targeted ketones is prepared by dissolving appropriate amount of them with distilled water to get down to the final concentration as 80 mM and 10 µL of each solution of analyte was dropped on the surface of treated cotton fabric. The fabricated sensor is also tested for its practicability by analyzing the targeted ketones in human urine and the results obtained were compared with the standard colour chart. The results shows consistency in colours thereby making it a quick, efficient, eco-friendly and reliable monitoring tool to detect various ketones.     

Preparation of a fixed-tetraphenylethylene motif bridged ditopic benzo-21-crown-7 and its application for constructing AIE supramolecular polymers

Benzo-21-crown-7(B21 C7) is one of the most important crown ethers,which not only shows excellent physicochemical properties but also exhibits promising binding capability with dialkylammonium salts.In this paper,we designed and synthesized a fixed-tetraphenylethylene(FTPE) motif bridged ditopic benzo-21-crown-7 molecule(H).The fixed tetraphenylethylene motif endows H with aggregation induced emission(AIE) prope rty.In the presence of a ditopic dialkylammonium salt guest molecule(G),a fluorescent supramolecular polymer with golden luminescent property could be fabricated.This B21 C7-based host-guest supramolecular polymer with golden fluorescence may have potential application in dynamic luminescent materials.     

Development of a gold nanoparticles based chemiluminescence imaging assay and its application

In this paper, a novel gold nanoparticles based protein immobilization method was designed. Biocomposites of gold nanoparticles and proteins were successfully coated on poly(methyl methacrylate) (PMMA) plates and polystyrene microtiter plates. The proteins could be immobilized on solid materials with high density and better bioactivity. Based on above design, chemiluminescence (CL) imaging assay for determination of H₂O₂ and recombinant human interleukin-6 (rHu IL-6) was developed. The linear range and the loading capability were greatly improved when compared with imaging assay performed with direct proteins immobilization. Under the selected experimental conditions, a linear relationship was obtained between the CL intensity and the concentration of H₂O₂ in the range of 1.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol L⁻¹, and rHu IL-6 in the range of 2.0-312.0 pg mL⁻¹. The detection limits were 2 × 10⁻⁷ mol L⁻¹ (3σ) for H₂O₂ and 0.5 pg mL⁻¹ for rHu IL-6 with relative standard deviation of 3.8% for 3.0 × 10⁻⁵ mol L⁻¹ H₂O₂, and 4.4% for 39.0 pg mL⁻¹ rHu IL-6. This method has been applied to the determination of rHu IL-6 in human serum with satisfactory results.     

Synthesis of a cationic poly(p-phenylenevinylene) derivative for lysosome-specific and long-term imaging

A cationic poly(p-phenylenevinylene) derivative (PPV) is designed and synthesized to bear quaternized N-methyl-imidazole groups, which is successfully utilized in lysosome-specific and long-term imaging.     

Melanin-based nanoparticles in biomedical applications: From molecular imaging to treatment of diseases

The melanin-based nanoparticles preparation methods were summarized here. Biomedical applications of melanin-based nanoparticles were also reviewed, including molecular imaging (magnetic resonance, positron emission tomography, and photoacoustic imaging) and treatment of diseases (drug delivery, photothermal therapy, antioxidant therapy, and iron overload therapy).     

Facile synthesis of metal-polyphenol-formaldehyde coordination polymer colloidal nanoparticles with sub-50 nm for T_1-weighted magnetic resonance imaging

Plant polyphenol-based coordination polymers(CPs) with ultra-small particle size and tailorable compositions are highly desired in biomedical applicatio ns,but their synthesis is still challenging due to the sophisticated coordination assembly process and unavoidable self-oxidation polymerization of polyphenol. He rein,a general ligand covalent-modification mediated coordination assembly strategy is proposed for the synthesis of water-dispersible CPs with tunable metal species(e.g., Gd,Cu,Ni,Zn,Fe)and ultra-small diameter(8.6-37.8 nm) using nontoxic plant polyphenol(e.g..tannic acid,gallic acid) as a polymerizable ligand.Polyphenol molecules react with formaldehyde firstly,which can effectively retard the oxidation induced self-polymerization of polyphenol and lead to the formation of metal ions containing CPs colloidal nanoparticles.These ultrafine nanoparticles with stably chelated metal io ns are highly water dispersible and thus advantageous for bioimaging.As an example,ultra-small Gd contained CPs exhibit higher longitudinal relaxivity(r_1=25.5 L mmol ~1 s ~1) value with low r_2/r_1(1.19) than clinically used Magnevist(Gd-DTPA,r_1=3.7 L mmol ~1 s ~1).Due to the enhanced permeability and retention effect,they can be further used as a positive contrast agent for T_1-weighted MR imaging of tumour.     

TICT based fluorescent probe with excellent photostability for real-time and long-term imaging of lipid droplets

Lipid droplets (LDs) are dynamic organelles and involve in various physiological processes by regulation of the storage and metabolism of lipid molecules. The real-time and long-term imaging of LDs’ distribution and movement is critical for investigation of their biological functions. However, current LDs-targeted fluorescent probes suffer from low photostability and high background noise. To tackle these challenges, we herein reported that the red-emissive fluorescent probe DCQTB with twisted intramolecular charge transfer (TICT) characteristics can be used for wash-free imaging of LDs with advantages of fast cell penetration ability, high specificity, excellent photostability, and low phototoxicity. This LDs-specific fluorescent probe is thus promising for investigation of the biological functions of LDs.