Redox-responsive ferrocene-containing poly(ionic liquid)s for antibacterial applications

Tracing the Antibacterial Performance of Bis-Imidazolium-based Ionic Liquid Derivatives

Ionic liquid (IL) cationic species have recently captivated the attention of pharmacists, biochemists, and biomedical scientists as promising antibacterial agents to deal with the multidrug resistance bacteria crisis. The structure and functional groups of ILs influence their physiochemical properties and biological activities. However, a comprehensive study is required to fully understand the details of the antibacterial activity of ILs carrying various functional groups. Herein, dicationic ILs (DCILs) are reported based on imidazolium rings as efficient antibacterial agents. The DCILs carried various functionalities such as 2-hydroxybutyl (DCIL-1), 2-hydroxy-3-isopropoxypropyl (DCIL-2), 2-hydroxy-3-(methacryloyloxy)propyl (DCIL-3), 2-hydroxy-2-phenylethyl (DCIL-4), and 2-hydroxy-3-phenoxypropyl (DCIL-5). The structure-antibacterial activity relationships of the DCILs against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) were comprehensively studied through antibacterial tests, morphology analysis, and adhesion tests. The experimental assays revealed an antibacterial efficacy order of DCIL-5 > DCIL-1 > DCIL-4 > DCIL-2 > DCIL-3. The all-atom molecular dynamics (MD) simulation showed a deep permeation of the hydrophobic -OPh functional group of DCIL-5 through the E. coli membrane model in agreement with the experimental observations. Current findings assist scientists in designing new task-specific DCILs for effective interactions with biological membranes for different applications.

A Comprehensive Review on Imperative Role of Ionic Liquids in Pharmaceutical Sciences

Ionic liquids (ILs) are poorly-coordinated ionic salts that can exist as a liquid at room temperatures (or <100 °C). ILs are also referred to as "designer solvents" because so many of them have been created to solve particular synthetic issues. ILs are regarded as "green solvents" because they have several distinctive qualities, including better ionic conduction, recyclability, improved solvation ability, low volatility, and thermal stability. These have been at the forefront of the most innovative fields of science and technology during the past few years. ILs may be employed in new drug formulation development and drug design in the field of pharmacy for various functions such as improvement of solubility, targeted drug delivery, stabilizer, permeability enhancer, or improvement of bioavailability in the development of pharmaceutical or vaccine dosage formulations. Ionic liquids have become a key component in various areas such as synthetic and catalytic chemistry, extraction, analytics, biotechnology, etc., due to their superior abilities along with highly modifiable potential. This study concentrates on the usage of ILs in various pharmaceutical applications enlisting their numerous purposes from the delivery of drugs to pharmaceutical synthesis. To better comprehend cuttingedge technologies in IL-based drug delivery systems, highly focused mechanistic studies regarding the synthesis/preparation of ILs and their biocompatibility along with the ecotoxicological and biological effects need to be studied. The use of IL techniques can address key issues regarding pharmaceutical preparations such as lower solubility and bioavailability which plays a key role in the lack of effectiveness of significant commercially available drugs.

Photoacidolysis-Mediated Iridium(III) Complex for Photoactive Antibacterial Therapy

Photoactive antibacterial therapy is one of the novel therapeutic methods that has great application potential and prospects for curbing bacterial infections. In this work, a photoactivated iridium complex (Ir-Cl) is synthesized for photoactive antibacterial research. Ir-Cl exhibits photoacidolysis, which can generate H⁺ and be converted into a photolysis product Ir-OH under blue light irradiation. At the meantime, this process is accompanied by ¹O₂ generation. Notably, Ir-Cl can selectively permeate S. aureus and exhibit excellent photoactive antibacterial activity. Mechanism studies show that Ir-Cl can ablate bacterial membranes and biofilms under light irradiation. Metabolomics analysis proves that Ir-Cl with light exposure mainly disturbs some amino acids' degradation (e.g., valine, leucine, isoleucine, arginine) and pyrimidine metabolism, which indirectly causes the ablation of biofilms and ultimately produces irreversible damage to S. aureus. This work provides guidance for metal complexes in antibacterial application.

Conductive Mediators in Oxidation Based on Ferrocene Functionalized Phosphonium Ionic Liquids

Herein, the synthesis of ferrocene-containing salts is presented. Acylation of ferrocene (Fc) according to the Friedel-Crafts method led to ω-bromoacyl ferrocenes. The ω-bromoacyl ferrocenes were subsequently introduced to quaternization reaction with tri-tert-butyl phosphine, which resulted in phosphonium salts. Obtained phosphonium salts were characterized by physical methods. The electrochemical properties of phosphonium salts were studied by cyclic voltammetry (CV). It was found that the replacement of n-butyl fragments at the phosphorus atom by tert-butyl leads to a more anodic potential shift. In contrast to isolobal structures Fc-C(O)(CH₂)_nP⁺(n-Bu)₃X^- and Fc-(CH₂)_n+1P⁺(n-Bu)₃X^-, the CV curves of Fc-C(O)(CH₂)_nP⁺(t-Bu)₃X^- and Fc-(CH₂)_n+1P⁺(t-Bu)₃X^- did not show a large discrepancy between forward and reverse currents. The transformation of the C=O groups to CH₂ fragments had a significant effect on the electrochemical properties of ferrocene salts, the oxidation potential of which is close to that of pure ferrocene.

Advanced Formulations Based on Poly(ionic liquid) Materials for Additive Manufacturing

Innovation in materials specially formulated for additive manufacturing is of great interest and can generate new opportunities for designing cost-effective smart materials for next-generation devices and engineering applications. Nevertheless, advanced molecular and nanostructured systems are frequently not possible to integrate into 3D printable materials, thus limiting their technological transferability. In some cases, this challenge can be overcome using polymeric macromolecules of ionic nature, such as polymeric ionic liquids (PILs). Due to their tuneability, wide variety in molecular composition, and macromolecular architecture, they show a remarkable ability to stabilize molecular and nanostructured materials. The technology resulting from 3D-printable PIL-based formulations represents an untapped array of potential applications, including optoelectronic, antimicrobial, catalysis, photoactive, conductive, and redox applications.

Nano-assemblies of phosphonium-functionalized diblock copolymers with fabulous antibacterial properties and relationships of structure-activity

As a novel antimicrobial material, quaternary phosphonium salts (QPSs) have been drawing close attention because of their excellent antimicrobial capacity with high activity and low bacterial survivability. Polymeric QPSs (PQPSs) also exhibit selectivity and long-term stability, however the polymerization of QPSs is severely challenged by low controllability and narrow selectivity of cation type. In this study, high-conversion RAFT polymerization is employed to prepare innovative phosphonium-functionalized diblock copolymers (PFDCs) with desired molecular weights and particle sizes. The excellent antibacterial activity of the PFDCs achieves lowest MIC values of 40 and 60 μg mL^-1 (i.e., 1.4 and 2.2 μmol L^-1) against E. coli and S. aureus, respectively. Mixing with an ink, dye, and latex coating does not weaken the antibacterial activity of the PFDCs, which inhibited 99.9% E. coli, showing broad applicability in different media. The effects of the cation type, synthesis medium, crosslinking content, and particle size on the morphology and antibacterial activity are studied. In summary, the RAFT polymerization of QPSs through the versatile design of ionic liquid monomers and the polymerization-induced self-assembly (PISA) method for constructing nano-assemblies with various micromorphology and particle size provides an exceedingly efficient way to build up multifunctional and multi-morphological polymeric nano-objects that open up vast possibilities in the fields of antibiotics, drug delivery, templated synthesis, and catalysis.

Biomedical polymers: synthesis, properties, and applications

Biomedical polymers have been extensively developed for promising applications in a lot of biomedical fields, such as therapeutic medicine delivery, disease detection and diagnosis, biosensing, regenerative medicine, and disease treatment. In this review, we summarize the most recent advances in the synthesis and application of biomedical polymers, and discuss the comprehensive understanding of their property-function relationship for corresponding biomedical applications. In particular, a few burgeoning bioactive polymers, such as peptide/biomembrane/microorganism/cell-based biomedical polymers, are also introduced and highlighted as the emerging biomaterials for cancer precision therapy. Furthermore, the foreseeable challenges and outlook of the development of more efficient, healthier and safer biomedical polymers are discussed. We wish this systemic and comprehensive review on highlighting frontier progress of biomedical polymers could inspire and promote new breakthrough in fundamental research and clinical translation.

Recent Advances in Ionic Liquids in Biomedicine

The use of ionic liquids and deep eutectic solvents in biomedical applications has grown dramatically in recent years due to their unique properties and their inherent tunability. This review will introduce ionic liquids and deep eutectics and discuss their biomedical applications, namely solubilization of drugs, creation of active pharmaceutical ingredients, delivery of pharmaceuticals through biological barriers, stabilization of proteins and other nucleic acids, antibacterial agents, and development of new biosensors. Current challenges and future outlooks are discussed, including biocompatibility, the potential impact of the presence of impurities, and the importance of understanding the microscopic interactions in ionic liquids in order to design task-specific solvents.

Membrane-disruptive peptides/peptidomimetics-based therapeutics: Promising systems to combat bacteria and cancer in the drug-resistant era

Membrane-disruptive peptides/peptidomimetics (MDPs) are antimicrobials or anticarcinogens that present a general killing mechanism through the physical disruption of cell membranes, in contrast to conventional chemotherapeutic drugs, which act on precise targets such as DNA or specific enzymes. Owing to their rapid action, broad-spectrum activity, and mechanisms of action that potentially hinder the development of resistance, MDPs have been increasingly considered as future therapeutics in the drug-resistant era. Recently, growing experimental evidence has demonstrated that MDPs can also be utilized as adjuvants to enhance the therapeutic effects of other agents. In this review, we evaluate the literature around the broad-spectrum antimicrobial properties and anticancer activity of MDPs, and summarize the current development and mechanisms of MDPs alone or in combination with other agents. Notably, this review highlights recent advances in the design of various MDP-based drug delivery systems that can improve the therapeutic effect of MDPs, minimize side effects, and promote the co-delivery of multiple chemotherapeutics, for more efficient antimicrobial and anticancer therapy.

More is less: Creation of pathogenic microbe-related theranostic oriented AIEgens

Theranostic agents based on photo-dynamic therapy exhibited the properties of the noninvasive feature, spatial-temporal control and be free of drug resistance. Herein, based on the principle of "More is Less", a multifunctional nanoprobe for selective lighting-up of fungi and targeted anti-microbes was designed and achieved. The introducing of the hydroxyl groups and alkaline diethylamino moiety facilitate the probe with well aggregation-induced emission feature, good selectivity towards fungi and acid responsiveness. This probe could only light-up fungi with bright fluorescence, and exhibited diversity anti-microbe behavior towards different microbes. Moreover, the in vitro and in vivo eradication of the supergerm of methicillin resistant staphylococcus aureus was achieved by the treatment of the probe. Confidently, this well-designed nanoprobe is anticipated to have great potential in infective theranostic applications in clinic.

Ultrastable radical-doped coordination compounds with antimicrobial activity against antibiotic-resistant bacteria

In the present work, we have introduced a series of stable radical-doped coordination compounds composed of donor-acceptor structures and shown to produce organic radicals in situ as a result of unconventional lone pair-π interactions in ambient conditions. Inconspicuous lone pair-π and C-Hπ interactions were shown to play a key role in self-assembly as well as the charge transfer process, resulting in a long-lived charge-separated state able to generate organic radicals. The resultant species displayed broad-spectrum antimicrobial activity, including against multi-drug-resistant bacteria. This study unveiled the promise of reactive organic radical-doped materials as a new platform for developing antimicrobial agents that can overcome antibiotic resistance.

Fluorescent Imidazolium-Type Poly(ionic liquid)s for Bacterial Imaging and Biofilm Inhibition

Fluorescent imidazolium-type poly(ionic liquid)s (PIL)s were synthesized by anion exchange of bromide (Br^-) in poly(3-butyl-1-vinylimidazolium bromide) (PIL-Br) with a fluorescent anion, namely, 3-(4-(1,2,2-triphenylvinyl)phenoxy)propane-1-sulfonate (TPESO₃^-). Such an anion exchange provided antibacterial PILs with aggregation-induced emission (AIE) properties that simultaneously kill and image bacteria. These fluorescence and antibacterial properties could be regulated by controlling the Br^-/TPESO₃^- ratio. The fluorescence intensity increases as this ratio increases, while the antibacterial property exhibits an opposite trend. Moreover, the AIE-type PILs are useful for fluorescently imaging dead bacteria (macroscopically and microscopically) and could effectively inhibit biofilm growth. This study provided a convenient method to obtain fluorescent PILs with adjustable antibacterial and imaging properties.