One-Pot Production of Fluorescent Surface-Labeled Polymeric Nanoparticles via Miniemulsion Polymerization with Bodipy Surfmers

Bright and Stable Nanomaterials for Imaging and Sensing

This review covers strategies to prepare high-performance emissive polymer nanomaterials, combining very high brightness and photostability, to respond to the drive for better imaging quality and lower detection limits in fluorescence imaging and sensing applications. The more common approaches to obtaining high-brightness nanomaterials consist of designing polymer nanomaterials carrying a large number of fluorescent dyes, either by attaching the dyes to individual polymer chains or by encapsulating the dyes in nanoparticles. In both cases, the dyes can be covalently linked to the polymer during polymerization (by using monomers functionalized with fluorescent groups), or they can be incorporated post-synthesis, using polymers with reactive groups, or encapsulating the unmodified dyes. Silica nanoparticles in particular, obtained by the condensation polymerization of silicon alcoxides, provide highly crosslinked environments that protect the dyes from photodegradation and offer excellent chemical modification flexibility. An alternative and less explored strategy is to increase the brightness of each individual dye. This can be achieved by using nanostructures that couple dyes to plasmonic nanoparticles so that the plasmon resonance can act as an electromagnetic field concentrator to increase the dye excitation efficiency and/or interact with the dye to increase its emission quantum yield.

Fluorescent detection of emerging virus based on nanoparticles: From synthesis to application

The spread of COVID-19 has caused huge economic losses and irreversible social impact. Therefore, to successfully prevent the spread of the virus and solve public health problems, it is urgent to develop detection methods with high sensitivity and accuracy. However, existing detection methods are time-consuming, rely on instruments, and require skilled operators, making rapid detection challenging to implement. Biosensors based on fluorescent nanoparticles have attracted interest in the field of detection because of their advantages, such as high sensitivity, low detection limit, and simple result readout. In this review, we systematically describe the synthesis, intrinsic advantages, and applications of organic dye-doped fluorescent nanoparticles, metal nanoclusters, up-conversion particles, quantum dots, carbon dots, and others for virus detection. Furthermore, future research initiatives are highlighted, including green production of fluorescent nanoparticles with high quantum yield, speedy signal reading by integrating with intelligent information, and error reduction by coupling with numerous fluorescent nanoparticles.

Unadulterated BODIPY nanoparticles as light driven antibacterial agents for treating bacterial infections and promoting wound healing

Antimicrobial photodynamic therapy (aPDT) is an effective strategy to eliminate bacteria without inducing bacterial resistance. As typical aPDT photosensitizers, most of boron-dipyrromethene (BODIPY) are hydrophobic, and nanometerization is imperative to render them dispersible in physiological media. Recently, carrier-free nanoparticles (NPs) are formed via the self-assembly of BODIPYs without the help of any surfactants or auxiliaries, arousing people's interest. So as to fabricate carrier-free NPs, BODIPYs usually need to be derived into dimers, trimers, or amphiphiles through complex reactions. Few unadulterated NPs were obtained from BODIPYs with precise structures. Herein, BNP1-BNP3 were synthesized by the self-assembly of BODIPY, which showed excellent anti-Staphylococcus aureus ability. Among them, BNP2 could effectively fight bacterial infections and promote wound healing in vivo.

Synthesis and Biological Characterization of Fluorescent Cyclipostins and Cyclophostin Analogues: New Insights for the Diagnosis of Mycobacterial-Related Diseases

Patients with cystic fibrosis (CF) have a significantly higher risk of acquiring nontuberculous mycobacteria infections, predominantly due to Mycobacterium abscessus, than the healthy population. Because M. abscessus infections are a major cause of clinical decline and morbidity in CF patients, improving treatment and the detection of this mycobacterium in the context of a polymicrobial culture represents a critical component to better manage patient care. We report here the synthesis of fluorescent Dansyl derivatives of four active cyclipostins and cyclophostin analogues (CyCs) and provide new insights regarding the CyC's lack of activity against Gram-negative and Gram-positive bacteria, and above all into their mode of action against intramacrophagic M. abscessus cells. Our results pointed out that the intracellularly active CyC accumulate in acidic compartments within macrophage cells, that this accumulation appears to be essential for their delivery to mycobacteria-containing phagosomes, and consequently, for their antimicrobial effect against intracellular replicating M. abscessus, and that modification of such intracellular localization via disruption of endolysosomal pH strongly affects the CyC accumulation and efficacy. Moreover, we discovered that these fluorescent compounds could become efficient probes to specifically label mycobacterial species with high sensitivity, including M. abscessus in the presence several other pathogens like Pseudomonas aeruginosa and Staphylococcus aureus. Collectively, all present and previous data emphasized the therapeutic potential of unlabeled CyCs and the attractiveness of the fluorescent CyC as a potential new efficient diagnostic tool to be exploited in future diagnostic developments against mycobacterial-related infections, especially against M. abscessus.

A BODIPY-O-glycoside based near-infrared fluorescent sensor for serum albumin

Highly sensitive and selective near-infrared fluorescent bioprobes for serum albumin detection and quantification are in high demand for biomedical applications. Herein, we report a near-infrared emitting BODIPY-O-glycoside dye as a turn-on emission sensor for serum albumin. To the best of our knowledge, this is the first report of NIR-emitting BODIPY dyes for serum albumin sensing. Despite the various outstanding photophysical properties of the BODIPY dyes, their insolubility in water/biological media restricts their real biomedical applications. To overcome this issue, highly stable unadulterated BODIPY-O-glycoside nanoparticles (BDP-Glu-NPs) were prepared in aqueous solution by self-assembly of amphiphilic BODIPY-O-glycoside dyes. The BDP-Glu-NPs were characterized by spectroscopic, NMR, DLS and TEM studies. The ability of the BDP-Glu-NPs for the detection and quantification of serum albumin was demonstrated. It showed a 150-fold fluorescence enhancement in the presence of serum albumin, with excellent selectivity over other amino acids, porphyrin, proteins and various inorganic salts. Detection of human serum albumin (HSA) in urine samples showed that the bioprobe is applicable to a clinically significant range of the analytes with very low detection limit. These results suggested that the BDP-Glu-NPs can act as potential bioprobe to quantify albumin in biochemical and clinical samples.

A facile fabrication of conjugated fluorescent nanoparticles and micro-scale patterned encryption via high resolution inkjet printing

Conjugated fluorescent materials are getting more and more attention in the biomedical arena due to their high fluorescence intensity, non-bleaching and good biocompatibility. However, conjugated fluorescent materials are still not widely used in the field of anti-counterfeiting and pattern encryption due to their extremely low solubility and enormous difficulties in processing. Here, we use a facile approach to fabricate conjugated polymer fluorescent nanoparticles through a classic micro-emulsion method to address these issues. The particle size, loading materials and fluorescence intensity can be tuned as demanded. Later, these particles are transformed into invisible inks for inkjet printers to achieve micro-scale pattern encryption. These patterns show an ultra-high accuracy of around 30 micrometres. They can be used as QR codes for information encryption with 3 times more information encryption and great anti-counterfeiting ability. Finally, we establish an identification recognition system to check their validity. The scenario is the patient identification system of a hospital. The results show that these tags can be read in less than 3 seconds and they can last for 12 months at least. This facile approach holds great potential and bright prospects in the field of privacy protection, information encryption and anti-counterfeiting.

Light-Regulated Natural Fluorescence of the PCC 6803@ZIF-8 Composite as an Encoded Microsphere for the Detection of Multiple Biomarkers

The use of color-encoded microspheres for a bead-based assay has attracted increasing attention for high-throughput multiplexed bioassays. A fluorescent PCC 6803@ZIF-8 composite was prepared as a bead-based assay platform by a self-assembled zeolitic imidazolate framework (ZIF-8) on the surface of inactivated PCC 6803 cells. The composite fluorescence owing to the presence of pigment proteins in PCC 6803 could be gradually bleached with the prolongation of the ultraviolet light irradiation time. The composites with different fluorescence intensities were therefore obtained as encoded microspheres for the multiplexed assay. ZIF-8 provides a stable, rigid shell and a large specific surface area for composites, which prevent the composites from breakage during use and storage, simplify the protein immobilization procedure, reduce non-specific adsorption, and enhance the detection sensitivity. The encoded composites were successfully used to detect multiple DNA insertion sequences of Mycobacterium tuberculosis. The presented strategy offers an innovative color-encoding method for high-throughput multiplexed bioassays without the need of using chemically synthesized fluorescent materials.

Boron dipyrromethene (BODIPY) in polymer chemistry

The present review provides both a summary and outlook on the exciting field of BODIPYs in polymer chemistry.

Light and latex: advances in the photochemistry of polymer colloids

Unparalleled temporal and spatial control of colloidal chemical processes introduces immense potential for the manufacturing, modification, and manipulation of latex particles.

An invisible private 2D barcode design and implementation with tunable fluorescent nanoparticles

The popularity of 2D barcodes is playing a key role in simplifying people's daily life activities, such as identification, quick payment, checking in and checking out, etc. However, relevant issues have emerged as their popularity has soared. The most urgent and representative problem is decryption, which may lead to serious information leakage and substantial damage to organizations, such as governments and international enterprises. This issue is mainly due to the visibility of 2D barcodes. In order to prevent potential privacy violation and sensitive information leakage through easy access of those visible 2D barcodes, we have designed and fabricated invisible 2D barcodes that will only be visible under UV illumination. This approach provides a promising solution to address the previous problem by transferring 2D barcodes into an invisible state. We have employed a typical micro-emulsion method to fabricate polystyrene (PS) fluorescent nanoparticles due to its simplicity. The invisible patterns can and will only be accessed and recognized under UV light illumination to protect personal private information. These invisible 2D barcodes provide a feasible solution for personal information protection and fit with a patient's privacy protection scenario very well, as we have demonstrated.

Water-soluble and highly emissive near-infrared nano-probes by co-assembly of ionic amphiphiles: towards application in cell imaging

Highly emissive near-infrared nano-emitters formed by co-assembly of ionic amphiphiles were applicable in cell imaging.

Active Ester Containing Surfmer for One-Stage Polymer Nanoparticle Surface Functionalization in Mini-Emulsion Polymerization

Functional surface active monomers (surfmers) are molecules that combine the functionalities of surface activity, polymerizability, and reactive groups. This study presents an improved pathway for the synthesis of the active ester containing surfmer p-(11-acrylamido)undecanoyloxyphenyl dimethylsulfonium methyl sulfate (AUPDS). Further, the preparation of poly(methyl methacrylate) and polystyrene nanoparticles (NPs) by mini-emulsion polymerization using AUPDS is investigated, leading to NPs with active ester groups on their surface. By systematically varying reaction parameters and reagent concentrations, it was found that AUPDS feed concentrations between 2⁻4 mol% yielded narrowly distributed and stable spherical particles with average sizes between 83 and 134 nm for non-cross-linked NPs, and up to 163 nm for cross-linked NPs. By basic hydrolysis of the active ester groups in aqueous dispersion, the positive ζ-potential (ZP) was converted into a negative ZP and charge quantities determined by polyelectrolyte titrations before and after hydrolysis were in the same range, indicating that the active ester groups were indeed accessible in aqueous suspension. Increasing cross-linker amounts over 10 mol% also led to a decrease of ZP of NPs, probably due to internalization of the AUPDS during polymerization. In conclusion, by using optimized reaction conditions, it is possible to prepare active ester functionalized NPs in one stage using AUPDS as a surfmer in mini-emulsion polymerization.

π-Conjugated Chromophore Incorporated Polystyrene Nanobeads as Single Optical Agent for Three-Channel Fluorescent Probe in Bioimaging Application

Fluorescent polystyrene (PS) nanobeads in the size range ∼70-120 nm incorporating perylene bisimide (PBI-PS) and/or oligo(p-phenylenevinylene) (OPV-PS) was developed by miniemulsion polymerization technique. A dye loading content (DLC) of <3% was sufficient to impart high fluorescence emission capability to the PS beads. OPV-PS exhibited emission in the range 400-550 nm with peak emission at 450 nm (λ_ex = 350 nm; ϕ_FL = 26%); PBI-PS showed emission from 520-650 nm with peak emission at 545 nm (λ_ex = 490 nm; ϕ_FL = 9.7%) in 1× PBS buffer, whereas OPV(PBI)-PS nanobeads incorporating both the fluorophores exhibited multicolor emission capabilities (λ_ex from 350 to 490 nm). The nanoparticles were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS) for size and zeta potential for surface charge. For bioimaging applications, the PS nanoparticles were incubated with HeLa cells. Cell viability analysis involving HeLa cells showed more than 90% cell viability confirming the biocompatibility of the PS beads. The cellular uptake of the nanoparticles was confirmed by flow cytometry analysis and confocal laser scanning microscopy (CLSM) images. The subcellular localization of the nanoparticles in the cytoplasm could be precisely established by their simultaneous multicolor emission. The PS-based single optical agent presented here that can function as three-channel fluorescent probe to meet the requirements for multicolor bioimaging is advantageous.

Fluorescent Polymer Nanoparticles Based on Dyes: Seeking Brighter Tools for Bioimaging

Speed, resolution and sensitivity of today's fluorescence bioimaging can be drastically improved by fluorescent nanoparticles (NPs) that are many-fold brighter than organic dyes and fluorescent proteins. While the field is currently dominated by inorganic NPs, notably quantum dots (QDs), fluorescent polymer NPs encapsulating large quantities of dyes (dye-loaded NPs) have emerged recently as an attractive alternative. These new nanomaterials, inspired from the fields of polymeric drug delivery vehicles and advanced fluorophores, can combine superior brightness with biodegradability and low toxicity. Here, we describe the strategies for synthesis of dye-loaded polymer NPs by emulsion polymerization and assembly of pre-formed polymers. Superior brightness requires strong dye loading without aggregation-caused quenching (ACQ). Only recently several strategies of dye design were proposed to overcome ACQ in polymer NPs: aggregation induced emission (AIE), dye modification with bulky side groups and use of bulky hydrophobic counterions. The resulting NPs now surpass the brightness of QDs by ≈10-fold for a comparable size, and have started reaching the level of the brightest conjugated polymer NPs. Other properties, notably photostability, color, blinking, as well as particle size and surface chemistry are also systematically analyzed. Finally, major and emerging applications of dye-loaded NPs for in vitro and in vivo imaging are reviewed.

Detection of λ-cyhalothrin by a core-shell spherical SiO2-based surface thin fluorescent molecularly imprinted polymer film

A fluorescent core-shell molecularly imprinted polymer based on the surface of SiO2 beads was synthesized and its application in the fluorescence detection of ultra-trace λ-cyhalothrin (LC) was investigated. The shell was prepared by copolymerization of acrylamide with allyl fluorescein in the presence of LC to form recognition sites. The experimental results showed that the thin fluorescent molecularly imprinted polymer (FMIP) film exhibited better selective recognition ability than fluorescent molecularly non-imprinted polymer (FNIP). A new nonlinear relationship between quenching rate and concentration was found in this work. In addition, the nonlinear relationship allowed a lower concentration range of 0-5.0 nM to be described by the Stern-Volmer equation with a correlation coefficient of 0.9929. The experiment results revealed that the SiO2@FMIP was satisfactory as a recognition element for determination of LC in soda water samples. Therefore this study demonstrated the potential of MIP for the recognition and detection of LC in food.

A green miniemulsion-based synthesis of polymeric aggregation-induced emission nanoparticles

A green miniemulsion-based technique for preparing polymeric aggregation-induced emission nanoparticles was described.

Dual-compartment nanofibres: separation of two highly reactive components in close vicinity

Nanofibers based on polyvinyl alcohol encapsulating epoxy and amine colloids in close vicinity as reactive compartments are investigated. Their crosslinking can be initiated upon thermal or mechanical stimuli and enables self-healing applications.

One-pot synthesis and biological imaging application of an amphiphilic fluorescent copolymer via a combination of RAFT polymerization and Schiff base reaction

A novel one-pot strategy for the fabrication of AIE-based FONs was developed via a combination of RAFT polymerization and Schiff base reaction for the first time.

Unadulterated BODIPY-dimer nanoparticles with high stability and good biocompatibility for cellular imaging

Purely organic nanoparticles based on a BODIPY dimer, BDY-NPs, have been prepared for the first time using a nanoprecipitation procedure. The fluorescent nanoparticles have high physical homogeneity, good stability in water, and low cytotoxicity, which are suitable for cell imaging.

Monodisperse boronate polymeric particles synthesized by a precipitation polymerization strategy: particle formation and glycoprotein response from the standpoint of the Flory-Huggins model

The development of a highly specific recognition system for glycoprotein capture from complex biological samples is a prerequisite to the success of mass spectra-based glycoproteomics analysis. To achieve this purpose, a one-pot precipitation polymerization (PP) strategy with a novel solvent system composed of water/ethanol (4:1, v/v) is described for preparing boronate-affinity polymeric micro/nano particles using 4-vinylphenylboronic acid (VPBA) as the functional monomer and N,N'-methylenebis(acrylamide) (MBA) alone or together with divinylbenzene (DVB) as the cross-linker(s). The proposed polymerization strategy not only affords monodisperse polymeric submicrometer particles with a smooth surface and controllable size, ranging from 300 to 700 nm, but also increases the loading capacity of boronic acid, which could hardly be achieved by other polymerization methods, thus leading to the specific recognition of glycoproteins. The effects of solvent systems and monomers on the morphology and boronate-affinity capacity of prepared materials were further investigated based on the Flory-Huggins model. It was proved that the reaction rate of various monomers during particle formation might be the key factor affecting the affinity capacity for glycoproteins. Our results demonstrated that under the theoretical guidance of the Flory-Huggins model the PP strategy with a selected monomer and solvent system might provide a good approach to prepare submicrometer polymer particles with plenty of boronic acid groups on the surface to achieve a highly selective enrichment of glycoproteins.