A Supramolecular-Based Dual-Wavelength Phototherapeutic Agent with Broad-Spectrum Antimicrobial Activity Against Drug-Resistant Bacteria.

With the ever-increasing threat posed by the multi-drug resistance of bacteria, the development of non-antibiotic agents for the broad-spectrum eradication of clinically prevalent superbugs remains a global challenge. Here, we demonstrate the simple supramolecular self-assembly of structurally defined graphene nanoribbons (GNRs) with a cationic porphyrin (Pp4N) to afford unique one-dimensional wire-like GNR superstructures coated with Pp4N nanoparticles. This Pp4N/GNR nanocomposite displays excellent dual-modal properties with significant reactive-oxygen-species (ROS) production (in photodynamic therapy) and temperature elevation (in photothermal therapy) upon light irradiation at 660 and 808 nm, respectively. This combined approach proved synergistic, providing an impressive antimicrobial effect that led to the complete annihilation of a wide spectrum of Gram-positive, Gram-negative, and drug-resistant bacteria both in vitro and in vivo. The study also unveils the promise of GNRs as a new platform to develop dual-modal antimicrobial agents that are able to overcome antibiotic resistance.

Polydiacetylene-based colorimetric and fluorescent chemosensor for the detection of carbon dioxide.

We developed a colorimetric and fluorescent turn-on carbon dioxide sensor that relies on a polydiacetylene, PDA-1, functionalized with amines and imidazolium groups. The pendant amines react with CO2 under basic conditions to form carbamoate anions, which partially neutralize the polymer's positive charges, inducing a phase transition. PDA-1 allows for the selective sensing of CO2 with high sensitivity, down to atmospheric concentrations. Naked-eye detection of CO2 is accomplished either in water solutions of PDA-1 or in the solid state with electrospun coatings of PDA-1 nanofibers.

Recent progress in fluorescent and colorimetric chemosensors for detection of amino acids.

Due to the biological importance of amino acids, the development of optical probes for these molecules has been an active research area in recent years. This tutorial review focuses on recent contributions since the year 2000 concerning the fluorescent or colorimetric sensors for amino acids, and is organized according to their structural classification and reaction types. For reaction based chemosensors, the works are classified according to the mechanisms between sensors and amino acids, including imine formation, Michael addition, thiazinane or thiazolidine formation, cleavage of a sulfonate ester, cleavage of disulfide, metal complexes-displace coordination and others.

Biosensors and chemosensors based on the optical responses of polydiacetylenes.

Polydiacetylenes (PDAs), a family of conjugated polymers, have very unique electrical and optical properties. Upon environmental stimulation, such as by viruses, proteins, DNAs, metal ions, organic molecules etc., the blue PDAs can undergo a colorimetric transition from blue to red, which is accompanied by a fluorescence enhancement. Since the first report on polymerized diacetylene molecules as sensors of influenza virus, the development of efficient sensory systems based on PDAs continues to be of great interest. This tutorial review highlights the recent advances in bio- and chemo-sensors derived from polydiacetylenes.

Polydiacetylene-based electrospun fibers for detection of HCl gas.

Polydiacetylenes (PDAs), a family of conjugated polymers, are very intriguing materials in several aspects. Especially, the stimulus-induced apparent blue-to-red transition of the PDAs has led to the development of a variety of PDA-based chemosensors. In the current work, we synthesized PDA monomers bearing trimethyl amine (PCDA-DMEDA) and incorporated them with Poly(ethylene oxide) (PEO) into electrospun fibers. For the first time, we successfully demonstrated that PDA-based electrospun fibers can be used for the naked-eye detection of HCl gas by simple color change (blue to red).

Recent progress on polymer-based fluorescent and colorimetric chemosensors.

Recently, fluorescent or colorimetric chemosensors based on polymers have attracted great attention due to several important advantages, such as their simplicity of use, signal amplification, easy fabrication into devices, and combination of different outputs, etc. This tutorial review will cover polymer-based optical chemosensors from 2007 to 2010.

A dual colorimetric and fluorometric sensor for lead ion based on conjugated polydiacetylenes.

A PDA based sensor, derived from a di-(2-picolyl) amine (DPA) substituted diacetylene monomer, displayed a selective colorimetric change and a large fluorescence enhancement in the presence of lead ions. The lead selective PDA-based chemosensor enabled easy detection of the presence of lead in 100% aqueous solution by the naked-eye.

Highly Efficient Aggregation-Induced Red-Emissive Organic Thermally Activated Delayed Fluorescence Materials with Prolonged Fluorescence Lifetime for Time-Resolved Luminescence Bioimaging.

Organic thermally activated delayed fluorescence (TADF) materials are emerging as potential candidates for time-resolved fluorescence imaging in biological systems. However, the development of purely organic TADF materials with bright aggregated-state emissions in the red/near-infrared (NIR) region remains challenging. Here, we report three donor-acceptor-type TADF molecules as promising candidates for time-resolved fluorescence imaging, which are engineered by direct connection of electron-donating moieties (phenoxazine or phenothiazine) and an electron-acceptor 1,8-naphthalimide (NI). Theoretically and experimentally, we elucidate that three TADF materials possessed remarkably small ΔEST to promote the occurrence of reverse intersystem crossing (RISC). Moreover, they all exhibit aggregation-induced red emissions and long delayed fluorescence lifetimes without the influence of molecular oxygen. More importantly, these long-lived and biocompatible TADF materials, especially the phenoxazine-substituted NI fluorophores, show great potential for high-contrast fluorescence lifetime imaging in living cells. This study provides further a molecular design strategy for purely organic TADF materials and expands the versatile biological application of long-lived fluorescence research in time-resolved luminescence imaging.

Colorimetric and fluorometric detection of cationic surfactants based on conjugated polydiacetylene supramolecules.

The polydiacetylenes derived from a hydroxybenzaldehyde substituted diacetylene monomer display a unique colorimetric change (blue to red) and large fluorescent enhancement in the presence of cetyl trimethylammonium salt.

Supramolecular Antibacterial Materials for Combatting Antibiotic Resistance.

Antibiotic-resistant bacteria have emerged as a severe threat to human health. As effective antibacterial therapies, supramolecular materials display unprecedented advantages because of the flexible and tunable nature of their noncovalent interactions with biomolecules and the ability to incorporate various active agents in their platforms. Herein, supramolecular antibacterial materials are discussed using a format that focuses on their fundamental active elements and on recent advances including material selection, fabrication methods, structural characterization, and activity performance.

Recent progress in stimuli-induced polydiacetylenes for sensing temperature, chemical and biological targets.

Polydiacetylenes (PDAs) have received increasing attention as smart materials owing to their unique properties. Upon addition of various stimuli, blue PDAs can undergo a colorimetric transition from blue to red along with a change from non-fluorescent to fluorescent. The optical changes can be readily detected by the naked eye and by using absorption and fluorescence spectrometers. These properties make PDAs excellent materials for use in platforms for sensing chemical or biological targets. In recent years, a number of biosensors and chemosensors based on the optical responses of polydiacetylenes have been reported. In this review, recent advances made in this area were discussed following a format based on different cognizing targets, including temperature, metal ions, anions, surfactants, amines, water, gas, sugars, hydrocarbons, neomycin, heparin, virus, enzymes, bacteria, and cancers. Emphasis is given to the methods used to prepare PDA sensing systems as well as their sensing performance.

Sensing and antibacterial activity of imidazolium-based conjugated polydiacetylenes.

In the current study, we report the first example of polydiacetylenes (PDAs), where our PDA-based system acts as both a sensing probe and killer for bacteria. The contact of imidazolium and imidazole-derived PDA with various bacterial strains including MRSA (methicillin-resistant Staphylococcus aureus) and ESBL-EC (extended-spectrum ß-lactamase-producing Escherichia coli) results in a distinct blue-to-red colorimetric change of the solution as well as a rapid disruption of the bacterial membrane, which is demonstrated by transmission electron microscopy and confocal microscopy. Zeta potential analysis supports that antibacterial activity of the PDA solution originates from an electrostatic interaction between the negatively charged bacterial cell surface and the positively charged polymers. These results suggest that the PDA has a great potential to carry out the dual roles of a probe and killer for bacteria.

Polydiacetylenes bearing boronic acid groups as colorimetric and fluorescence sensors for cationic surfactants.

A new polydiacetylene oxyphenylboronic acid (PDA-OPBA-1) bearing group was synthesized and showed diverse colorimetric changes, such as yellow, orange, and red, upon the addition of cationic surfactants at pH 7.4. On the other hand, anionic surfactants and simple ammonium salts did not show any color change. Specifically, color changes to yellow for cetyl trimethylammonium chloride (CTAC), red for dodecyl trimethylammonium bromide (DTAB), orange for benzylcetyldimethylammonium chloride (BCDA), and dark orange for hexadecylpyridium bromide (HDPB) are observed, respectively. Different head groups and alkyl chain lengths of cationic surfactants can be intelligently distinguished via a unique penetration process.

Colorimetric and fluorometric assays based on conjugated polydiacetylene supramolecules for screening acetylcholinesterase and its inhibitors.

Polydiacetylene supramolecules (PDAs) are unique sensing materials. Upon environmental stimulation, blue PDAs can undergo a colorimetric transition from blue to red accompanied by fluorescence enhancement. In this paper, we report a new PDA system polymerized from a mixed liposome comprising 2-(2-(2-hydroxyethoxy)ethoxy)ethyl pentacosa-10,12-diynoate and pentacosa-10,12-diynoic acid at a 3:7 ratio. The PDA system provided new colorimetric and fluorometric assay methods for screening acetylcholinesterase and its inhibitors through three processes. First, myristoylcholine reacted with PDAs, which then underwent colorimetric and fluorometric transition. Second, acetylcholinesterase catalyzed the hydrolysis of myristoylcholine into tetradecanoic acid, which reduced the myristoylcholine concentration and led to faded color and fluorescence. Third and last, acetylcholinesterase inhibitors retarded the activity of acetylcholinesterase, thereby inducing the recovery of color and fluorescence.

A dual-polymer electrochromic device with high coloration efficiency and fast response time: poly(3,4-(1,4-butylene-(2-ene)dioxy)thiophene)-polyaniline ECD.

A new dual-polymer electrochromic device (ECD) composed of poly(3,4-(1,4-butylene-(2-ene)dioxy)thiophene) (PBueDOT) and polyaniline (PANI) with a hydrophobic molten salt electrolyte has been developed. To build this system, an alkylenedioxy ring in the BueDOT backbone was expanded to include a strongly electron-donating alkylenedioxy bridge, and the thickness and surface morphology of the corresponding PBueDOT film were controlled systematically. Not only the dual-electrochromic-polymer-electrode system, but also the expanded alkylenedioxy ring in the BueDOT backbone, synergistically improved the electrochromic performance. From the coloration efficiency (CE) value calculations, we found that the CE was enhanced up to 930 cm(2) C(-1). Furthermore, these ECDs showed an extremely fast response time of less than 80 ms.