A Supramolecular Naphthalene Diimide Radical Anion with Efficient NIR-II Photothermal Conversion for E. coli-Responsive Photothermal Therapy

An Immediate Bacterial-Responsive Supramolecular Thio-Naphthalene Diimide: A Real-Time NIR-II Photothermal Anti-Bacterial

A new kind of supramolecular thio-naphthalene diimide (SNDI) which can be immediately reduced as supramolecular radical anion by bacteria is reported. The introduction of thiocarbonyl effectively elevates the reduction potential of SNDI, largely increasing the bacteria-response speed in hypoxia. It selectively distinguishes the bacteria with high and low reduction ability in real time. The host-guest complexation of SNDI and cucurbit[7]uril can enhance radical anion quantum yield, ensuring intense NIR-II absorption and realizing high photothermal conversion. The real-time NIR-II photothermal anti-bacteria is successfully carried out. This development will enrich the design of bio-responsive agent with promising future towards actual application.

Photoinduced Stable Circularly Polarized Luminescent Radicals From a Triphenylamine-Attached Planar Chiral Pillar[5]Arene

Photoinduced organic radicals with unique luminescent properties are highly sought-after due to their important prospects in synthetic chemistry and materials science. However, the current development of organic free radicals, including photoinduced ones, is significantly limited and faces challenges related to stability and poor luminescence behavior. Taking advantage of the photoelectric activity of triarylamine, we herein describe an unusual luminescent radical, which can be rapidly generated by UV irradiation of a solid-state triarylamine-functionalized π-conjugated pillar[5]arene (EtP5NN) in air, accompanied by luminescent color switching from bluish-violet to sky-blue. The persistent radicals within EtP5NN with a half-life of 12.7 h suggest that the pillar[5]arene skeleton straightforwardly improves the stability of radicals. The sterically bulky triarylamine groups inhibit the racemization of planar chiral pillar[5]arene and allow the optical resolution of this system. The enhancement of circularly polarized luminescence (CPL) is triggered by UV irradiation of the enantiomers (pS/pR-EtP5NN) in the solid state.

A Dynamic Metal-Organic Radical Emission System

Developing new organic radical emission systems and regulating their luminescence properties presents a significant challenge. Herein, we build dynamic and multi-emission band radical luminescence systems by co-assembling inorganic metal salts with carbonyl compounds in ionic liquids. After the assembling, dual-band, and excitation wavelength-dependent emission was observed upon ultraviolet light irradiation, one emission band originates from carbonyl radical after light irradiation, the other band from the ligand-metal charge transfer (LMCT) state, which benefits from the charge transfer from the radicals to the metal salts. The dual emission centers also introduce excitation wavelength-dependent properties for the molecules. In addition, three-band emission covering the visible and near-infrared regions can be shown when two or three kinds of metal ions are simultaneously doped into the radical system driven by the ligand-metal-metal charge transfer (LMMCT). Interestingly, visible light can quickly quench the radical emission of systems, thus realizing a dynamic luminescence. The LMMCT effect and strong supramolecular interactions significantly improve the photoluminescence quantum yield by up to 67.2 %. Moreover, such materials can be successfully used for detecting radioactive metal ions and information encryption. This study develops a platform for manufacturing various metal-organic radical emission systems with diverse properties.

From X- To J-Aggregation: Subtly Managing Intermolecular Interactions for Superior Phototheranostics with Precise 1064 nm Excitation

The stacking mode in aggregate state results from a delicate balance of supramolecular interactions, which closely affects the optoelectronic properties of organic π-conjugated systems. Then, managing these interactions is crucial for advancing phototheranostics, yet remains challenging. A subtle strategy involving peripheral phenyl groups is debuted herein to transform X-aggregated SQ-H into J-aggregated SQ-Ph, reorienting intermolecular dipole interactions while rationally modulating π-π interactions. Co-assembled with liposomes (DSPE-PEG2000), SQ-Ph nanoparticles (NPs) exhibit low toxicity, superior biocompatibility, and a bathochromic shift to the 1064 nm match-excited NIR-II region, with a fluorescence brightness (ε1064 nm ΦNIR-II) of 4129 M-1 cm-1 and a photothermal conversion efficiency (PCE) of 48.3%. Preliminary in vivo experiments demonstrate that SQ-Ph NPs achieve a signal-to-background ratio (SBR) of up to 14.29 in NIR-II fluorescence imaging (FLI), enabling highly efficient photothermal therapy (PTT) of tumors guided by combined photoacoustic imaging (PAI). This study not only enriches the J-aggregation library but also provides a paradigm for optimizing photosensitizers at the supramolecular level.

A supramolecular diazapyrene radical assembly with NIR absorption for selective photothermal antibacterial activity

A supramolecular radical assembly that can be induced in situ by facultative anaerobic bacteria has been reported and used for selective near-infrared (NIR) photothermal antibacterial action. Herein, we report the synthesis of a water-soluble diazapyrene derivative (DAPNP), which could be in situ initiated into the corresponding radicals by facultative anaerobic bacteria, such as E. coli or S. aureus. The introduction of cucurbit[10]uril (CB[10]) alters the stacking mode of the diazapyrene radical cations, resulting in a redshift of their characteristic absorption peak from the visible region to the NIR region. Under 660 nm laser irradiation, the in situ-induced supramolecular radical assembly exhibits great photothermal conversion properties and achieves highly efficient antibacterial activity (up to 98%). In contrast, with the aerobic B. subtilis it is difficult to induce the formation of diazapyrene radical cations in situ and maintain good activity under light irradiation. In addition, DAPNP@CB[10] exhibits excellent biocompatibility and has great potential as an intelligent photothermal material for antibacterial applications.

Molecular engineering charge transfer and triplet exciton formation in donor-acceptor cocrystals

Organic donor-acceptor (D-A) cocrystals are gaining attention for their potential applications in optoelectronic devices. This study explores the dynamics of charge transfer (CT) and triplet exciton formation in various D-A cocrystals. By examining a series of D-A cocrystals composed of coronene (COR), peri-xanthenoxanthene (PXX), and perylene (PER) donors paired with N,N-bis(3'-pentyl)perylene-3,4:9,10-bis(dicarboximide) (PDI), naphthalene-1,4:5,8-tetracarboxy-dianhydride (NDA), or pyrene-4,5,9,10-tetraone (PTO) acceptors, using transient absorption microscopy and time-resolved electron paramagnetic resonance spectroscopy, we find that the strength of the CT interaction influences the nature and yield of triplet excitons produced by CT state recombination. In particular, in the PER-PDI, COR-PTO, and PER-PTO cocrystals, localized triplet excitons are lower in energy than the CT state. By contrast, no localized triplet excitons are available to the CT states of the PXX-NDA, PER-NDA, and PXX-PTO cocrystals, and as a result, the CT states rapidly decay to ground state with no triplet formation. Moreover, density functional theory calculations show that the transition between delocalized CT states to a triplet state localized to a single donor or acceptor unit provides the source of spin-orbit coupling necessary when the triplet states are energetically accessible. These findings provide insights into the design of molecular materials with tailored exciton properties for optoelectronic applications.

Cell-Penetrating Peptide Induced Superstructures Triggering Highly Efficient Antibacterial Activity

To endow non-antibacterial molecules with highly efficient bactericide activity is an important but challenging issue. Herein, a kind of cell-penetrating peptide octa-arginine (R8) is found to be effective in activating antibacterial ability when assembling with anionic surfactant sodium dodecyl sulfate (SDS), while individual R8 or SDS shows poor or no antibacterial ability. By combined electrostatic, hydrogen bond, and hydrophobic interactions, R8 and SDS associate into wormlike micelle and lamellar structure by forming supramolecular self-assembling units, depending on their charge ratio (CR). The lamellar aggregates show particularly high antibacterial activities against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Interestingly, E. coli and S. aureus are killed by membrane-disrupting and membrane-penetrating mechanisms, respectively. Furthermore, in vivo experiments evidence that the R8/SDS lamellar aggregates accelerate the recovery of bacteria-infected wounds, wherein the reduced inflammation and promoted angiogenesis are clearly presented. This study proves that highly efficient bactericidal activity is triggered by the synergistic action of penetrating peptide and anionic amphiphiles, thus providing a new strategy to realize highly efficient and targetable antibacterial application.

A guanidiniocarbonyl-pyrrole functionalized cucurbit[7]uril derivative as a cytomembrane disruptor for synergistic antibacterial therapy

The antibiotic resistance of bacterial membranes poses a significant threat to global public health, highlighting the urgent need for novel therapeutic agents and strategies to combat bacterial membranes. In response, we have developed a novel macrocyclic host molecule (GCPCB) based on guanidiniocarbonyl-pyrrole (GCP) functionalized cucurbit[7]uril with an aggregation-induced luminescence effect. GCPCB exhibits high antimicrobial potency against bacterial membranes, particularly demonstrating strong antibacterial activity against Gram-positive strains of S. aureus and Gram-negative strains of E. coli. Significantly, due to the strong binding between GCP and the bacterial membrane, GCPCB can effectively eradicate the bacteria encapsulated within. Furthermore, the formation of a host-guest complex between GCPCB and berberine hydrochloride (BH) not only enhances synergistic destructive activity against both species of bacteria but also provides a potential supramolecular platform for effective bacterial membrane destruction.

A NIR-II Organic Dendrimer with Superb Photothermal Performance Based on Electron-Donor Iteration for Photothermal Immunotherapy

Organic photothermal materials have attracted extensive attention due to their designable molecular structure, tunable excited-state properties, and excellent biocompatibility, however, the development of near-infrared II (NIR-II) absorbing organic photothermal materials with high photothermal conversion efficiency (PTCE) and molar extinction coefficient (ɛ) remains challenging. Herein, a novel "electron-donor iteration" strategy is proposed to construct organic photothermal dendrimers (CR-DPA-T, CR-(DPA)2-T and CR-(DPA)3-T) with donor-π-acceptor-π-donor (D-π-A-π-D) features and diradical characteristics. Owing to the enhanced D-A effect and intramolecular motions, their absorption and photothermal capacity increase as the generation grows. Surprisingly, an excellent photothermal performance (ɛ1064 × PTCE1064) with a superb value of 2.85 × 104 in the NIR-II region is achieved for CR-(DPA)3-T nanoparticles (CR-(DPA)3-T NPs) compared to most reported counterparts. Besides, CR-(DPA)3-T NPs exhibit superior antitumor efficacy by the synergistic effect of photothermal therapy (PTT) and immunotherapy, efficiently inhibiting the growth of both primary and distant tumors. To the best knowledge, organic photothermal dendrimer is for the first time reported, and a universal donor engineering strategy is offered to develop NIR-II-absorbing organic photothermal materials for photothermal immunotherapy.

Regulation of Cell Membrane Potential through Supramolecular System for Activating Calcium Ion Channels

The regulation of the cell membrane potential plays a crucial role in governing the transmembrane transport of various ions and cellular life processes. However, in situ and on-demand modulation of cell membrane potential for ion channel regulation is challenging. Herein, we have constructed a supramolecular assembly system based on water-soluble cationic oligo(phenylenevinylene) (OPV) and cucurbit[7]uril (CB[7]). The controllable disassembly of OPV/4CB[7] combined with the subsequent click reaction provides a step-by-step adjustable surface positive potential. These processes can be employed in situ on the plasma membrane to modulate the membrane potential on-demand for precisely controlling the activation of the transient receptor potential vanilloid 1 (TRPV1) ion channel and up-regulating exogenous calcium-responsive gene expression. Compared with typical optogenetics, electrogenetics, and mechanogenetics, our strategy provides a perspective supramolecular genetics toolbox for the regulation of membrane potential and downstream intracellular gene regulation events.

Construction of a supramolecular antibacterial material based on water-soluble pillar[5]arene and a zwitterionic guest molecule

A new antibacterial system (HG) based on the host-guest chemistry between pillar[5]arene and a zwitterionic guest was fabricated. The HG complex displayed excellent antibacterial and biofilm formation inhibition and dispersal activities against E. coli, S. aureus and MRSA.

A supramolecular naphthalenediimide radical anion through host-guest interactions for photooxidation of alkylarenes to carbonyls

A supramolecular naphthalenediimide radical anion was developed through host-guest interactions between NDI and cucurbit[7]uril (CB[7]), which can be greatly promoted in the presence of chloride ions to obtain Cl˙ and NDI-2CB[7]˙-. Under the synergistic action of Cl˙ as a hydrogen atom transfer (HAT) agent and NDI-2CB[7]˙- transferring electrons to O2 to produce O2˙-, the photocatalytic oxidation reactions of alkylarenes to carbonyls can be realized with universal applicability.

An ion synergism fluorescence probe via Cu2+ triggered competition interaction to detect glyphosate

The widespread use of glyphosate (Gly) poses significant risks to environmental and human health, underscoring the urgent need for its sensitive and rapid detection. In this work, we innovated by developing a novel material, ionic liquids, which formed the ionic probe "[P66614]2[2,3-DHN]-Cu2+ (PDHN-Cu2+)" through coordination with Cu2+. This probe capitalized on the distinctive fluorescence quenching properties of ionic liquids in the presence of Cu2+, driven by synergistic interactions between anions and cations. Glyphosate disrupted the PDHN-Cu2+ coordination structure due to its stronger affinity for Cu2+, triggering a "turn-on" fluorescence response. Impressively, PDHN-Cu2+ enabled the sensitive detection of glyphosate within just one minute, achieving a detection limit as low as 71.4 nM and excellent recovery rates of 97-103% in diverse samples. This groundbreaking approach, utilizing ionic probes, lays a robust foundation for the accurate and real-time monitoring of pesticides, employing a strategy based on synergism and competitive coordination.

Thermal-Responsive Gel-Based Overheat Limiter Enabled Intelligent Photothermal Therapy

Uncontrolled and excessive photothermal heating in photothermal therapy (PTT) inevitably causes thermal damage to surrounding normal tissues, severely limiting the universality and safety of PTT. To address this issue, an intelligent cooling thermal-responsive (ICTR) gel containing poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAM-AM))microgel is applied onto the skin to realize intelligent PTT, which can avoid excessive heating and accidental injury. The high near-infrared (NIR) light transmittance (> 95%) of the ICTR gel ensures effective light delivery at low temperatures, while the refractive index of the P(NIPAM-AM) microgel increases remarkably when the temperature exceeds a predetermined threshold, resulting in progressively enhanced light scattering and weakened photothermal conversion. In animal studies, the negative feedback regulation of ICTR gel on light transmittance and photothermal heating allows the photothermal temperature in the lesion site to be stabilized within the effective therapeutic range (45 °C) while ensuring that the skin surface temperature does not exceed 35 °C. Compared with the severe skin thermal damage found in the histological staining of mice skin receiving conventional PTT, the mice skin receiving the ICTR gel-enabled intelligent PTT remains in good condition. This study establishes an intelligent and universal paradigm for PTT thermal regulation, which is of great significance for achieving safe and effective PTT.

Cucurbit[7]uril as the host of adamantane-modified dyes for fluorescence enhancement in aqueous environments

Taking advantage of the excellent host-guest complexation ability between an auxochrome (adamantane group) and CB[7], the fluorescence emission performance of dyes in water was effectively improved with the addition of two equivalents of CB[7], which provided an efficient method for increasing fluorescence intensity in aqueous environments. Furthermore, these dyes with the host were successfully used in cell imaging.

Boron Cluster Renders Organic Radicals Water-Stable for Photothermal Anti-Infections

Water-stable organic radicals are promising photothermal conversion candidates for photothermal therapy (PTT). However, organic radicals are usually unstable in biological environments, which greatly hinders their wide application. Here, we have developed a chaotropic effect-based and photoinduced water-stable supramolecular radical (MB12-2) for efficient antibacterial PTT. The supramolecular radical precursor MB12-1 was constructed by the chaotropic effect between closo-dodecaborate cluster (B12H122-) and N,N'-dimethylated dipyridinium thiazolo [5,4-d] thiazole (MPT2+). Subsequently, with triethanolamine (TEOA) serving as an electron donor, MB12-1 could transform to its radical form MB12-2 through photoinduced electron transfer (PET) under 435-nm laser irradiation. The N2 adsorption-desorption analysis confirmed that MB12-2 was tightly packed through the introduction of B12H122-, which effectively enhanced its stability via a spatial site-blocked effect. Moreover, the half-life of MB12-2 in water was calculated through ultraviolet-visible light (UV-vis) absorption spectra results for periods as long as 20 days. In addition, in the skin infection model, MB12-2, as a wound dressing, showed remarkable photothermal antibacterial activity (>97%) under 660-nm laser irradiation and promoted wound healing. This study presents a simple method for designing long-term water-stable supramolecular radicals, offering a novel avenue for noncontact treatments for bacterial infections.

Supramolecularly modulated carbon-centered radicals: toward selective oxidation from benzyl alcohol to aldehyde

The reactivity of ketyl radicals and benzoyl radicals, two key intermediates of photo-induced oxidation of benzyl alcohol, can be stabilized by the host-guest interaction of the radicals with cucurbit[7]uril. As a result, the selectivity of photo-induced oxidation from benzyl alcohol to aldehyde is significantly improved by diminishing side reactions and inhibiting the generation of carboxylic acid products. This work presents a new route to modulate the reactivity of radical intermediates, enriching the chemistry of supramolecular intermediates and the toolbox of supramolecular catalysis.

A Nanographene-Porphyrin Hybrid for Near-Infrared-Ii Phototheranostics

Photoacoustic imaging (PAI)-guided photothermal therapy (PTT) in the second near-infrared (NIR-II, 1000-1700 nm) window has been attracting attention as a promising cancer theranostic platform. Here, it is reported that the π-extended porphyrins fused with one or two nanographene units (NGP-1 and NGP-2) can serve as a new class of NIR-responsive organic agents, displaying absorption extending to ≈1000 and ≈1400 nm in the NIR-I and NIR-II windows, respectively. NGP-1 and NGP-2 are dispersed in water through encapsulation into self-assembled nanoparticles (NPs), achieving high photothermal conversion efficiency of 60% and 69%, respectively, under 808 and 1064 nm laser irradiation. Moreover, the NIR-II-active NGP-2-NPs demonstrated promising photoacoustic responses, along with high photostability and biocompatibility, enabling PAI and efficient NIR-II PTT of cancer in vivo.

Chaotropic Effect-Induced Sol-Gel Transition and Radical Stabilization for Bacterially Sensitive Near-Infrared Photothermal Therapy

Deep-seated bacterial infections (DBIs) are stubborn and deeply penetrate tissues. Eliminating deep-seated bacteria and promoting tissue regeneration remain great challenges. Here, a novel radical-containing hydrogel (SFT-B Gel) cross-linked by a chaotropic effect was designed for the sensing of DBIs and near-infrared photothermal therapy (NIR-II PTT). A silk fibroin solution stained with 4,4',4″-(1,3,5-triazine-2,4,6-triyl)tris(1-methylpyridin-1-ium) (TPT3+) was employed as the backbone, which could be cross-linked by a closo-dodecaborate cluster (B12H122-) through a chaotropic effect to form the SFT-B Gel. More interestingly, the SFT-B Gel exhibited the ability to sense DBIs, which could generate a TPT2+• radical with obvious color changes in the presence of bacteria. The radical-containing SFT-B Gel (SFT-B★ Gel) possessed strong NIR-II absorption and a remarkable photothermal effect, thus demonstrating excellent NIR-II PTT antibacterial activity for the treatment of DBIs. This work provides a new approach for the construction of intelligent hydrogels with unique properties using a chaotropic effect.

Tuning Shortwave-Infrared J-aggregates of Aromatic Ring-Fused Aza-BODIPYs by Peripheral Substituents for Combined Photothermal and Photodynamic Therapies at Ultralow Laser Power

Achieving photothermal therapy (PTT) at ultralow laser power density is crucial for minimizing photo-damage and allowing for higher maximum permissible skin exposure. However, this requires photothermal agents to possess not just superior photothermal conversion efficiency (PCE), but also exceptional near-infrared (NIR) absorptivity. J-aggregates, exhibit a significant redshift and narrower absorption peak with a higher extinction coefficient. Nevertheless, achieving predictable J-aggregates through molecular design remains a challenge. In this study, we successfully induced desirable J-aggregation (λabs max : 968 nm, ϵ: 2.96×105  M-1  cm-1 , λem max : 972 nm, ΦFL : 6.2 %) by tuning electrostatic interactions between π-conjugated molecular planes through manipulating molecular surface electrostatic potential of aromatic ring-fused aza-BODIPY dyes. Notably, by controlling the preparation method for encapsulating dyes into F-127 polymer, we were able to selectively generate H-/J-aggregates, respectively. Furthermore, the J-aggregates exhibited two controllable morphologies: nanospheres and nanowires. Importantly, the shortwave-infrared J-aggregated nanoparticles with impressive PCE of 72.9 % effectively destroyed cancer cells and mice-tumors at an ultralow power density of 0.27 W cm-2 (915 nm). This phototherapeutic nano-platform, which generates predictable J-aggregation behavior, and can controllably form J-/H-aggregates and selectable J-aggregate morphology, is a valuable paradigm for developing photothermal agents for tumor-treatment at ultralow laser power density.