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Fabricating antibacterial hydrogels with antimicrobial drugs and synthetic biocompatible biomimetic hydrogels is a promising strategy for practical medical applications. Here, we report a bicomponent hydrogel composed of a biomimetic polyisocyanopetide (PIC) hydrogel and a photodynamic antibacterial membrane-intercalating conjugated oligoelectrolyte (COE). The aggregation behavior and aggregate size of the COEs in water can be regulated using the PIC hydrogel, which could induce COEs with higher reactive oxygen species (ROS) production efficiency and increased association of COEs toward bacteria, therefore enhancing the antibacterial efficiency. This strategy provides a facile method for developing biomimetic hydrogels with high antibacterial capability.

Utilizing solar energy for hydrogen production by combining light-activated materials and biocatalysts has become a promising alternative to fossil fuels. Herein, a feasible and simple bio-hybrid complex based on water-soluble oligofluorene (OF), polythiophene (PTP) and Rhodopseudomonas palustris (R. palustris), one kind of photosynthetic bacteria, was constructed for enhancing photocatalytic hydrogen production. Under the irradiation of visible light, there was fluorescence resonance energy transfer (FRET) between OF and PTP, which amplified photoelectron signals and transferred electrons via PTP to methyl viologen (MV2+), an electron mediator that established electron transfer pathways between organic materials and R. palustris. Hydrogen production involving R. palustris was catalyzed by nitrogenase. It is noteworthy that MV2+ was reduced to MV+˙ and transferred electrons to nitrogenase in R. palustris, converting protons and electrons to molecular hydrogen. Besides, triethanolamine (TEOA) was added as an electron donor to provide electrons to PTP. The proposed OF/PTP/MV2+/TEOA/R. palustris system provided a feasible strategy for photocatalytic hydrogen production with low-cost and easily implemented techniques.

Hybrid biomimetic hydrogels with enhanced reactive oxygen species (ROS)-generation efficiency under 600 nm light show high antibacterial activity. The hybrid gels are composed of helical tri(ethylene glycol)-functionalized polyisocyanides (PICs) and a conformation-sensitive conjugated polythiophene, poly(3-(3 '-N,N,N-triethylammonium-1 '-propyloxy)-4-methyl-2,5-thiophene chloride) (PMNT). The PIC polymer serves as a scaffold to trap and align the PMNT backbone into a highly ordered conformation, resulting in redshifted, new sharp bands in the absorption and fluorescence spectra. Similar to PIC, the hybrid closely mimics the mechanical properties of biological gels, such as collagen and fibrin, including the strain stiffening properties at low stresses. Moreover, the PMNT/PIC hybrids show much higher ROS production efficiency under red light than PMNT only, leading to an efficient photodynamic antimicrobial effect towards various pathogenic bacteria.

CO2-controlled assembly of conjugated polymer and boron nitride (BN) was fabricated via electrostatic and hydrophobic interactions between the BN fiber and conjugated polymer of PFBT containing fluorene units and 2,1,3-benzothiadiazole units. CO2, an effective and green stimulus for regulating the assembly of PFBT and BN fibers, leads to an obvious fluorescence variation. Moreover, PFBT enables the assembly with the signal amplification and light-harvesting properties. This work provides a new triggering method to construct intelligent conjugated polymer-based platform, and offers fluorescence monitoring strategy for carbon dioxide capture.

Both of carbon dioxide (CO2) and near-infrared (NIR) light as triggers for non-invasive remotely control are attracting wide attentions due to their good biocompatibility and easy operation. Here, CO2/NIR light dual controlled nanoparticles are proposed to remotely regulate the unzipping of dsDNA by using imidazole functionalized conjugated polymer nanoparticles (imidazole-CPNs). The dsDNA successfully coats on the shell of imidazole-CPNs to form imidazole-CPNs/dsDNA assembly due to intensively electrostatic interaction triggered by CO2. Furthermore, the unzipping process of dsDNA is remotely controlled by NIR light based on the photothermal effect, and it can be readily monitored by the fluorescence intensity of ethidium bromide (EB) and CD spectra of dsDNA. Thus, dual stimulation responsive imidazole-CPNs effectively control dsDNA unzipping under CO2 stimulus and NIR light, promising a new direction in the biological applications of DNA, such as the treatments of diseases caused by gene duplication abnormality.

Herein, we have developed a composite antibacterial hydrogel with photodynamic therapy (PDT) and photothermal therapy (PTT) antibacterial capabilities, triggered by white light and NIR light irradiation. A water-insoluble conjugated polymer (PDPP) with photothermal ability was prepared into nanoparticles by the nanoprecipitation method, and the cell-penetrating peptide TAT was grafted on the surface of the nanoparticles. Based on our previous work that developed a hybrid hydrogel with an enhanced PDT effect from polyisocyanide (PIC) hydrogel and cationic conjugated polythiophene (PMNT), PDPP nanoparticles (CPNs-TAT) with photothermal ability are introduced to realize the synergistic antibacterial effect of PDT and PTT. Using the PIC hydrogel to combine PIC and CPNs-TAT has the following advantages. First, the PIC hydrogel can regulate the aggregation state of PMNT, making it better dispersed and improving its capacity of reactive oxygen species (ROS) production. Second, CPNs-TAT can be uniformly dispersed in the PIC hybrid, thereby avoiding the toxicity caused by too high local concentration, achieving a uniform increase in system temperature, and enhancing the therapeutic effect of PTT. Third, the PIC hybrid has the synergistic treatment effect of PDT and PTT. The PIC hybrid intelligently regulates its antibacterial ability through white light and NIR light, which can be used in the white light and NIR light areas. When irradiated with white light and NIR light sequentially, synergistic PDT and PTT exhibit stronger antibacterial ability than PDT or PTT alone. The combination of two antibacterial methods realizes the dual-control antibacterial hydrogel of PDT and PTT and provides an antibacterial mode based on PIC hybrids. Therefore, the PIC hybrids are promising as an antibacterial excipient for clinical wounds.

By coating photosynthetic bacteria of Rhodopseudomonas palustris with conjugated polymers nanoparticles modified with positively charged peptide TAT (CPNs-TAT), a bio-optical hybrid composite of R....

Calmodulin (CaM), as a calcium binding protein involved in the signal pathways of many life activities such as cell proliferation and apoptosis, can be regulated with the near-infrared (NIR) light-based photothermal conversion. Here, we build a conjugated polymer nanoparticle (CPNs-C) by assembling polypyrrole dione and dipalmitoyl phosphatidylethanolamine-polyethylene glycol-maleimide with a calmodulin antibody modified on the surface, which is NIR light-responsive for photothermally inducing apoptosis of cancer cells. Under near-infrared light irradiation, protein kinase B (Akt) and phosphatidylinositol 3-kinase, which bind to CaM, reduce the degree of phosphorylation due to the photothermal effect of CPNs-C, thus inhibiting the recruitment of Akt on the cell membrane. Therefore, the phosphorylation of GSK-3β downstream of the signaling pathway is reduced, and the phosphorylation of FoxO3a is enhanced, which can promote apoptosis of cancer cells. Compared with the photothermal effect of traditional CPNs, CPNs-C exhibits higher efficiency to regulate signaling pathways to promote cancer cells toward apoptosis. This strategy of utilizing NIR light to regulate the tumor apoptotic signaling pathway provides an effective way to enhance cancer cell apoptosis with high efficiency.

Excess aggregation of amyloid β peptide (Aβ) is a fatal cause of Alzheimer's disease (AD), which leads to physiological toxicity. Inhibiting and disaggregating the Aβ aggregates is an effective strategy to reduce physiological toxicity in neuronal cells. Herein, conjugated polymer-based thermoresponsive micelles (CPMs) were designed with an efficient thermoresponsive surface and a reactive-oxygen-species (ROS)-generating core. In this work, the CPMs exhibited a strong capability to capture the toxic Aβ aggregates at physiological temperature. Under white-light irradiation, ROS was generated in the CPMs, and the toxic Aβ aggregates were efficiently disaggregated through the oxidation of ROS, leading to appropriate Aβ homeostasis between aggregation and disaggregation and reduced the Aβ-induced cytotoxicity. Therefore, the multifunctional micelles of CPMs with both capturing shells and ROS functional cores present a promising strategy to reduce Aβ fibrillation-induced cytotoxicity.

An electrostatic complex combining anionic water-soluble conjugated polythiophene (PTP) with commercial cationic porphyrin ([5,10,15,20-tetrakis(4-(trimethylammonio)-phenyl)-21H,23H-porphine tetratosylate] (TMP)) has been designed for rapid and simple detection of bacteria infection in drinking water by applying fluorescence resonance energy transfer (FRET) strategy. There is efficient FRET from PTP to TMP for the electrostatic complex of PTP/TMP. Upon the addition of bacteria, the cationic TMP is adsorbed tightly to the negatively charged membrane surface of bacteria through electrostatic interactions, making the PTP reside in much farther proximity to TMP than that in the absence of bacteria. Therefore, much weaker FRET is observed. Interesting, the detection for bacteria based on FRET changes of PTP/TMP complex is visual in view of the color changes under ultraviolet (UV) irradiation. This assay takes advantage of the light-harvesting property of conjugated polymer and the ratiometric measurements for minimizing the nonspecific binding effect. The strategy is promising in pathogen detection in drinking water and other sources.

The conformation of calmodulin (CaM) changes from closed configuration to open one, converting to a claviform dumbbell-shaped biomolecule upon Ca2+-binding. A hybrid probe of graphene oxide (GO) cationic conjugated polymer for detection of the conformation transition of CaM by using FRET technique is demonstrated. The stronger hydrophobic interaction and weaker electrostatic repulsion leads to more CaM adsorption to the surface of GO upon binding with Ca2+ than that of CaM in the absence of Ca2+ (apoCaM), resulting in much farther proximity between poly[(9,9-bis(6-N,N,N-trimethylammonium)hexyl)-fluorenylene phenylene dibromide] (PFP) and green fluorescent protein labeled at the N-terminus of CaM and therefore much weaker FRET efficiency for PFP/Ca2+/CaM in comparison with that of PFP/apoCaM in the presence of GO. Notably, the assembly of CaM with GO is quantitatively and reversibly controlled by Ca2+ ions.

An assembly was fabricated and was revealed to be a multiple-stimulus-responsive biomimetic hybrid polymer architecture. It was constructed by the hydrophobic interactions between a conjugated polyfluorene that contained 2,1,3-benzothiadiazole units (PFBT) and a tri(ethylene glycol)-functionalized polyisocyanopeptide (3OEG-PIC). The introduction of PFBT to the polyisocyanopeptide (PIC) network allowed for the incorporation of responsiveness to multiple stimuli including temperature, CO2 , carbonic anhydrase, and nonlinear mechanics, which mimics natural processes and interactions. Furthermore, the light-harvesting and signal amplification characteristics of PFBT endowed the supramolecular assembly with the essential function of fluorescence monitoring for biological processes.

A conjugated polymer centered on fluorene and 2,1,3-benzothia-diazole (PFBT) is prepared for sensing CO2 in situ with high sensitivity and low background. Upon introducing CO2, the weaker electrostatic repulsion and stronger hydrophobic interactions between neighboring PFBT molecules enhance the interchain contacts compared to that without CO2, leading to the energy transfer from fluorene to 2,1,3-benzothia-diazole sites and the emission color shift from blue to green, which is sensitive to sensing CO2 in atmospheric air with a content of ∼400 ppm. Importantly, PFBT is employed to monitor photosynthesis and respiration upon cycling day and night in situ.

In recent years, supramolecular organization of thiophene derivatives, oligo- and polythiophene, have been developed with various designs to achieve complex functions. Here, we describe the synthesis and characterization of a conjugated polymer with thymidine side chain bases and polythiophene backbones (PTT) instead of phosphate bonds in DNA, and the PTT exhibits exceptional fluorescence quenching efficiency upon binding of Cu(2+) ions in aqueous medium, which is suggested to be electron transfer from the π* orbit at the excited state of PTT to the 3d orbit of Cu(2+) ions and subsequent Cu(2+)-mediated interpolymer π-stacking aggregation. Furthermore, Cu(2+) ions can be selectively and easily monitored by the fluorescence quenching of PTT, which can be used for detection of Cu(2+) ions with good selectivity and high sensitivity in aqueous medium. Both experimental and theoretical methods have been devoted to demonstrate the strong affinity and steric interaction of PTT toward Cu(2+). These findings will illustrate new directions for the design of nucleobase-functionalized materials with transition metals responsive activity.

A new amphiphilic conjugated polythiophene derivative (PT-Boc) is synthesized via Suzuki coupling reaction. The amphiphilic characteristic makes it form nanoaggregates in water, in which hydrophobic moieties come together to form the inner core. The polymer shows good photostability and no toxicity to human lung epithelial (A549) cells even at a high concentration (100 μg mL(-1) ). It therefore meets the crucial requirement for cellular imaging and other biological applications. The anticancer drug cisplatin is used as a model, and is linked to polythiophene to obtain a conjugate 'PT-Pt' by coordinated interactions between cisplatin and the amine groups of the polythiophene side chain. The PT-Pt can be used for monitoring the cellular distribution of cisplatin by fluorescence microscopy. The amphiphilic polythiophene provides a platform for fluorescent imaging of drugs and biological molecules in living cells.

We prepared a new conjugated polymer nanoparticle with the size of about 50 nm that is prepared by electrostatic assembly of cationic conjugated polymer PFO and anionic poly(l-glutamic acid) conjugated with anticancer drug doxorubicin (PFO/PG-Dox). The PFO exhibits good fluorescence quantum yield, photostability, and little cytotoxicity to meet the essential requests for cell imaging. In PFO/PG-Dox nanoparticles, the fluorescence of PFO is highly quenched by Dox by electron transfer mechanism, and thus the PFO is in the fluorescence "turn-off' state. After PFO/PG-Dox nanoparticles are exposed to carboxypeptidase or are taken up by cancer cells, the poly(l-glutamic acid) is hydrolysed to release the Dox, inducing the activation of PFO fluorescence to "turn-on" state. This multifunctional nanoparticle system can deliver Dox to targeted cancer cells and monitor the Dox release based on fluorescence "turn-on" signal of PFO, which concurrently images the cancer cells. The present work opens the door for new functional studies of conjugated polymer in simultaneous imaging and disease therapeutics.

A new water-soluble zwitterionic oligofluorene bearing carboxylic acid and quaternary ammonium as pendant groups (OF-1) is synthesized and characterized. It forms aggregates by intermolecular electrostatic interactions and exhibits similar light-harvesting ability as that of conjugated polymers. Efficient fluorescence resonance energy transfer (FRET) occurs from OF-1 to double-stranded DNA tagged with fluorescein (dsDNA-F1). A photoresponsive oligofluorene (OF-3) is also synthesized by protecting OF-1 with 1-(2-nitrophenyl)ethanol. Photolysis of OF-3 can produce OF-1 to result in a fluorescence "turn-on" response, thus the FRET from OF-3 to dsDNA-FI can be turned on by light irradiation. OF-3 offers the potential for remote DNA sensing.

Nuclear magnetic resonance imaging (MRI) has become a powerful technique in clinical diagnostics. In this work, a new MRI contrast agent by covalently linking Gd(III) chelates to the side chain of conjugated polymer (PF–Gd) is synthesized by Suzuki cross-coupling reaction. The PF–Gd exhibits a higher relaxivity and a pronounced enhancement in contrast than that of (NMG) 2 –Gd–DTPA widely used for clinical diagnosis. This work should be feasible to potentially lead to a new class of imaging contrast agents.

A fluorescent turn-on detection for nitric oxide in aqueous solution is developed using cationic conjugated polymers. The assay benefits from the sensitivity of optical signals from conjugated polymers and the simplicity of fluorescence measurement techniques. The assay contains three elements: a cationic conjugated polymer that contains imidazole moieties, Cu 2+ ions, and the target nitric oxide. The highly fluorescent conjugated polymer coordinates to Cu 2+ ions through weak N . . . Cu interactions, and its fluorescence is efficiently quenched by a photoinduced electron transfer process ('off' state). In the presence of nitric oxide, the transformation of the paramagnetic Cu 2+ ion into a diamagnetic Cu 1+ ion inhibits the quenching and, therefore, the fluorescence of the conjugate polymer is recovered ('on' state). Other biologically relevant reactive nitrogen species, such as NOBF 4 , NaNO 2 , and NaNO 3 don't exhibit the fluorescence recovery of the conjugated polymer under the same conditions as nitric oxide. The cationic conjugated polymer/Cu 2+ complex can thus be used as a platform to detect nitric oxide in aqueous solution with high sensitivity and selectivity.

The cationic conjugated poly[3-(3′-N,N,N-triethylamino-1′-propyloxy)-4-methyl-2,5-thiophene hydrochloride] (PMNT) has been developed for high-throughput screening of photodynamic antimicrobial chemotherapy photosensitizers (PSs). The bacterial number can be detected quantitatively by PMNT via various fluorescence quenching efficiencies. The photosensitized inactivation of bacteria is not efficient with ineffective PSs, and thus the bacteria grow exponentially and can be coated tightly by PMNT through electrostatic and hydrophobic interactions, resulting in aggregates and fluorescence quenching of PMNT, whereas, conversely, effective PSs lead to original and strong fluorescence of PMNT. This new platform of high-throughput screening is promising for discovering new PSs.

The CO2 -responsive and biocatalytic assembly based on conjugated polymers has been demonstrated by combining the signal amplification property of the polythiophene derivative (PTP) and the catalytic actions of carbonic anhydrase (CA). CO2 is applied as a new trigger mode to construct the smart assembly by controlling the electrostatic and hydrophobic interactions between the PTP molecules in aqueous solution, leading to the visible fluorescence changes. Importantly, the assembly transformation of PTP can be specifically and highly accelerated by CA based on the efficient catalytic activity of CA for the inter-conversion between CO2 and HCO3- , mimicking the CO2 -associated biological processes that occurred naturally in living organisms. Moreover, the PTP-based assembly can be applied for biomimetic CO2 sequestration with fluorescence monitoring in the presence of CA and calcium.

A new strategy has been designed for visualized detection of the conformation changes of calmodulin bound to target peptide (CaM-M13) based on the conformation sensitive property of a water-soluble conjugated polythiophene derivative (PMNT) and the electrostatic interactions of PMNT/CaM-M13. Interestingly, the direct visualized PMNT color changes under UV irradiation and the turbidity changes of samples in aqueous medium can be applied to detect the conformation changes as well as the controllable assembly of PMNT/CaM-M13 with Ca(2+) in aqueous medium. Because of the specific binding of Ca(2+), the assembly of PMNT/CaM-M13 can be applied to sense calcium as well.

A cationic polythiophene-porphyrin (PTP) dyad is shown to exhibit efficient light-activated antifungal activity. Higher singlet oxygen (¹O₂) generation efficiency can be attained from PTP upon photoexcitation due to the light-harvesting properties of the polymer backbone and efficient energy transfer from the polythiophene to the porphyrin units. PTP can be used for treating fungal infections in lower doses of irradiation light and polymer concentration.

With the increasing antibiotic resistance of microorganisms, there is a growing interest in the design and development of new materials that are effective in killing bacteria to replace conventional antibiotics. Herein, a new anionic water-soluble polythiophene (PTP) and a cationic porphyrin (TPPN) are synthesized and characterized. They can form a complex through electrostatic interactions, and efficient energy transfer from PTP to TPPN occurs upon irradiation under white light (400-800 nm). The energy of TPPN transfers to triplet by intersystem crossing, followed by sensitization of oxygen molecule to enhance the efficiency of singlet oxygen generation related to TPPN itself. The positive charges of PTP/TPPN complex promote its adsorption to the negatively charged bacteria membranes of gram-negative Escherichia coli and gram-positive Bacillus subtilis through electrostatic interactions, and the singlet oxygen effectively kills the bacteria. The photosensitized inactivation of bacteria for the PTP/TPPN complex is efficient, and about 70% reduction of bacterial viability is observed after only 5 min of irradiation with white light at a fluence rate of 90 mW x cm(-2) (27 J x cm(-2)). The technique provides a promising application in photodynamic inactivation of bacteria on the basis of enhanced energy transfer offered by light-harvesting conjugated polymers.