Exploiting the Versatility of Polydopamine-Coated Nanoparticles to Deliver Nitric Oxide and Combat Bacterial Biofilm.
Adnan Nik Nik M,Sadrearhami Zahra,Bagheri Ali,Nguyen Thuy-Khanh,Wong Edgar H H,Ho Kitty K K,Lim May,Kumar Naresh,Boyer Cyrille
Macromolecular rapid communications
In this study, an antimicrobial platform in the form of nitric oxide (NO) gas-releasing polydopamine (PDA)-coated iron oxide nanoparticles (IONPs) is developed for combating bacterial biofilms. NO is bound to the PDA-coated IONPs via the reaction between NO and the secondary amine moieties on PDA to form N-diazeniumdiolate (NONOate) functionality. To impart colloidal stability to the nanoparticles in aqueous solutions (e.g., phosphate buffered saline (PBS) and bacteria cell culture media M9), a polymer bearing hydrophilic and amine pendant groups, P(OEGMA)-b-P(ABA), is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization and is subsequently grafted onto the PDA-coated IONPs by employing the Schiff base/Michael addition reaction between o-quinone and a primary amine. These nanoparticles are able to effectively disperse Pseudomonas aeruginosa biofilms (up to 79% dispersal) at submicromolar NO concentrations. In addition, the nanoparticles demonstrate excellent bactericidal activity toward P. aeruginosa planktonic and biofilm cells (up to 5-log reduction).
10.1002/marc.201800159
Folate-Conjugated Polyphosphoester with Reversible Cross-Linkage and Reduction Sensitivity for Drug Delivery.
Cao Youwen,He Jinlin,Liu Jie,Zhang Mingzu,Ni Peihong
ACS applied materials & interfaces
To improve the therapeutic efficacy and circulation stability in vivo, we synthesized a new kind of drug delivery carrier based on folic acid conjugated polyphosphoester via the combined reactions of Michael addition polymerization and esterification. The produced amphiphilic polymer, abbreviated as P(EAEP-AP)-LA-FA, could self-assemble into nanoparticles (NPs) with core-shell structure in water and reversible core cross-linked by lipoyl groups. Using the core cross-linked FA-conjugated nanoparticles (CCL-FA NPs) to encapsulate hydrophobic anticancer drug doxorubicin (DOX), we studied the stability of NPs, in vitro drug release, cellular uptake, and targeting intracellular release compared with both un-cross-linked FA-conjugated nanoparticles (UCL-FA NPs) and core cross-linked nanoparticles without FA conjugation (CCL NPs). The results showed that under the condition of pH 7.4, the DOX-loaded CCL-FA NPs could maintain stable over 72 h, and only a little DOX release (∼15%) was observed. However, under the reductive condition (pH 7.4 containing 10 mM GSH), the disulfide-cross-linked core would be broken up and resulted in 90% of DOX release at the same incubation period. The study of methyl thiazolyl tetrazolium (MTT) assay indicated that the DOX-loaded CCL-FA NPs exhibited higher cytotoxicity (IC: 0.33 mg L) against HeLa cells than the DOX-loaded CCL NPs without FA. These results indicate that the core cross-linked FA-conjugated nanoparticles have unique stability and targetability.
10.1021/acsami.7b18887
Facile and efficient fabrication of photoresponsive microgels via thiol-Michael addition.
Zhang Hui-Juan,Xin Yan,Yan Qiang,Zhou Li-Lin,Peng Liao,Yuan Jin-Ying
Macromolecular rapid communications
A photoresponsive microgel is designed by the combination of a noncovalent assembly strategy with a covalent cross-linking method. End-functionalized poly(ethylene glycol) with azobenzene [(PEG-(Azo)(2))] was mixed with acrylate-modified β-CD (β-CD-MAA) to form photoresponsive inclusion complex through host-guest interaction. The above photoresponsive complex was cross-linked by thiol-functionalized PEG (PEG-dithiol) via Michael addition click reaction. The photoreversibility of resulted microgel was studied by TEM, UV-Vis spectroscopy, and (1)H NMR measurements. The characterization results indicated that the reversible size changes of the microgel could be achieved by alternative UV-Vis irradiations with good repeatability.
10.1002/marc.201200439
A programmable chemical switch based on triggerable Michael acceptors.
Chemical science
Developing an engineerable chemical reaction that is triggerable for simultaneous chemical bond formation and cleavage by external cues offers tunability and orthogonality which is highly desired in many biological and materials applications. Here, we present a chemical switch that concurrently captures these features in response to chemically and biologically abundant and important cues, , thiols and amines. This thiol/amine-triggerable chemical switch is based on a Triggerable Michael Acceptor (TMAc) which bears good leaving groups at its β-position. The acceptor undergoes a "trigger-to-release" process where thiol/amine addition triggers cascaded release of leaving groups and generates a less activated acceptor. The newly generated TMAc can be further reversed to liberate the original thiol/amine by a second nucleophile trigger through a "trigger-to-reverse" process. Within the small molecular volume of the switch, we have shown five locations that can be engineered to achieve tunable "trigger-to-release" kinetics and tailored reversibility. The potential of the engineerable bonding/debonding capability of the chemical switch is demonstrated by applications in cysteine-selective and reversible protein modification, universal self-immolative linkers, and orthogonally addressable hydrogels.
10.1039/c9sc05841a
A reversible coumarin-based sensor for intracellular monitoring cysteine level changes during Cu-induced redox imbalance.
Chao Jianbin,Zhao Jiamin,Jia Jinping,Zhang Yongbin,Huo Fangjun,Yin Caixia
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy
Biological thiols are crucial small molecule amino acids widely existing in cells, which play indispensable roles in maintaining redox homeostasis of living systems. Owing to their abnormal levels have close relation with many diseases, thus, developing more convenient, rapid and practical in-vivo detection tools is imminent. Herein, a reversible coumarin-based probe (HNA) was successfully constructed through a simple two-step synthesis. HNA can detect Cys/Hcy with high response speed and desirable selectivity based on Michael addition recognition mechanism. Free HNA has an orange emission at 580 nm, but after addition of Cys/Hcy, the conjugated structure of probe HNA was destroyed by the attack of sulfhydryl, resulting in a new green emission at 507 nm. Further, HNA has been applied to monitor Cys/Hcy in HeLa cells and zebrafish. Notably, HNA has also been successfully applied for real-time tracing Cys levels changes in living cells and zebrafish during the imbalance in redox status caused by copper (II). This provides a new strategy for studying the process of oxidative stress in cells.
10.1016/j.saa.2021.120173
From irreversible to reversible covalent inhibitors: Harnessing the andrographolide scaffold for anti-inflammatory action.
Tran Quy T N,Tan Daniel W S,Wong W S Fred,Chai Christina L L
European journal of medicinal chemistry
Covalent drugs with prolonged actions often show superior potency, yet integrated strategies for optimizing their structural and electronic features are lacking. Herein, we present our effort directed towards understanding the contribution of chemical reactivity to biological potency to rationally design new covalent inhibitors based on the ent-ladane andrographolide scaffold for anti-inflammatory action. Specifically, a series of andrographolide derivatives comprising various Michael acceptors was developed and their thiol reactivity was assayed under various chemical and biological conditions. The cell-based SAR studies permitted the assessment of the inhibitor efficacy in more complex systems, which were often limited in traditional covalent drug development using isolated proteins or peptides. Our in vitro study identified enone 17 as the most promising candidate which demonstrated potent anti-inflammatory activity and superior safety profiles as compared to the lead compound andrographolide. Its reversibility following a Michael addition reaction with biological thiols resulted in more predictable pharmacological responses. In addition, 17 exhibited good in vivo efficacy at doses as low as 0.3 mg/kg when tested in LPS-induced acute lung injury model. Given a good balance of chemical reactivity and biological potency, enone 17 potentially offers a new therapeutic option based on natural product chemistry for the management of inflammatory conditions.
10.1016/j.ejmech.2020.112481
Michael addition-based probes for ratiometric fluorescence imaging of protein -depalmitoylases in live cells and tissues.
Beck Michael W,Kathayat Rahul S,Cham Candace M,Chang Eugene B,Dickinson Bryan C
Chemical science
The reversible modification of cysteine residues through thioester formation with palmitate (protein -palmitoylation) is a prevalent chemical modification that regulates the function, localization, and stability of many proteins. Current methods for monitoring the "erasers" of -palmitoylation, acyl-protein thioesterases (APTs), rely on destructive proteomic methods or "turn-on" probes, precluding deployment in heterogeneous samples such as primary tissues. To address these challenges, we present the design, synthesis, and biological evaluation of Ratiometric Depalmitoylation Probes (RDPs). RDPs respond to APTs with a robust ratiometric change in fluorescent signal both and in live cells. Moreover, RDPs can monitor endogenous APT activities in heterogeneous primary human tissues such as colon organoids, presaging the utility of these molecules in uncovering novel roles for APTs in metabolic regulation.
10.1039/c7sc02805a
Conjugated Covalent Organic Frameworks via Michael Addition-Elimination.
Rao M Rajeswara,Fang Yuan,De Feyter Steven,Perepichka Dmitrii F
Journal of the American Chemical Society
Dynamic covalent chemistry enables self-assembly of reactive building blocks into structurally complex yet robust materials, such as covalent organic frameworks (COFs). However, the synthetic toolbox used to prepare such materials, and thus the spectrum of attainable properties, is very limited. For π-conjugated COFs, the Schiff base condensation of aldehydes and amines is the only general dynamic reaction, but the resulting imine-linked COFs display only a moderate electron delocalization and are susceptible to hydrolysis, particularly in acidic conditions. Here we report a new dynamic polymerization based on Michael addition-elimination reaction of structurally diverse β-ketoenols with amines, and use it to prepare novel two-dimensional (2D) π-conjugated COFs, as crystalline powders and exfoliated micron-size sheets. π-Conjugation is manifested in these COFs in significantly reduced band gap (1.8-2.2 eV), solid state luminescence and reversible electrochemical doping creating midgap (NIR absorbing) polaronic states. The β-ketoenamine moiety enables protonation control of electron delocalization through the 2D COF sheets. It also gives rise to direct sensing of triacetone triperoxide (TATP) explosive through fluorescence quenching.
10.1021/jacs.6b12005
Rapid and Reversible Reaction-Based Ratiometric Fluorescent Probe for Imaging of Different Glutathione Levels in Living Cells.
Tian Ming,Yang Mian,Liu Yi,Jiang Feng-Lei
ACS applied bio materials
Glutathione (GSH) serves many cellular functions, within the range of 1-10 mM in mammalian cells, abnormal levels of which have been related to many pathological processes. Until now, many researches have been devoted to qualitative sensing of intracellular GSH. However, it is still quite difficult to determine the dynamic GSH levels in living cells. To solve this problem, we designed and synthesized a ratiometric fluorescent probe for the detection of different GSH levels based on a reversible Michael addition reaction. The Michael addition product was characterized by ESI-MS. The reversibility and kinetics of the reaction of with GSH were studied by spectroscopic methods. According to the concentration dependence of the ratio / ( and are the fluorescence intensities at 505 and 571 nm when in the presence of GSH was excited at 405 and 488 nm, respectively), GSH in the range of 0.1-50 mM could be detected by a very low concentration of 2.5 μM in the PBS buffer, indicating that the interference of to the biological system in living cell imaging would be minimized. Simultaneously, the dissociation constant () was obtained as 4.89 mM, suggesting its capability to accurately quantify the GSH concentration in the range of 1-10 mM in cells. Moreover, to improve the cell permeability, we converted with a carboxylic acid group into with an acetoxymethyl ester group. It is noteworthy that the rapid cell uptake rate of the made it very promising because the living cells were efficiently stained with high brightness after incubation with for only 1 min. Furthermore, the successful ratio imaging (merged image of 405 channel and 488 channel) of different GSH levels by in living cells demonstrated the further development and utilization in the future.
10.1021/acsabm.9b00642
Rational molecular design of a reversible BODIPY-Based fluorescent probe for real-time imaging of GSH dynamics in living cells.
Zhang Yushi,Zhang Junqing,Su Meihui,Li Changhua
Biosensors & bioelectronics
Marring the reversible covalent chemistry with BODIPY dye, which is a superfamily of fluorophores with striking photophysical performances, would enable a panel of diverse dynamic fluorescent probes for biomedical applications. Herein we show that structural manipulation of BODIPY allows rational tuning of α-site or meso-site activation as well as the spectral response toward nucleophiles. By rational molecular design, we have obtained a highly specific and reversible GSH probe, BD-GSH, which exhibits a tremendously fast and dynamic fluorescence response within the wide physiological GSH concentration range of 0-8 mM. We successfully applied BD-GSH to real-time imaging of intracellular GSH dynamics in different cell lines. In light of the remarkable photophysical properties and synthesis flexibility of BODIPY dyes, the current findings will help to design more reversible BODIPY-based fluorescent probes targeting various bio-species.
10.1016/j.bios.2020.112866
Heat- and Light-Responsive Materials Through Pairing Dynamic Thiol-Michael and Coumarin Chemistry.
Chakma Progyateg,Wanasinghe Shiwanka V,Morley Colleen N,Francesconi Sebastian C,Saito Kei,Sparks Jessica L,Konkolewicz Dominik
Macromolecular rapid communications
Covalent adaptable networks (CANs) based on the thiol-Michael (TM) linkages can be thermal and pH responsive. Here, a new vinyl-sulfone-based thiol-Michael crosslinker is synthesized and incorporated into acrylate-based CANs to achieve stable materials with dynamic properties. Because of the reversible TM linkages, excellent temperature-responsive re-healing and malleability properties are achieved. In addition, for the first time, a photoresponsive coumarin moiety is incorporated with TM-based CANs to introduce light-mediated reconfigureability and postpolymerization crosslinking. Overall, these materials can be on demand dynamic in response to heat and light but can retain mechanical stability at ambient condition.
10.1002/marc.202100070
Efficient Synthesis of Polymer Prodrug by Thiol-Acrylate Michael Addition Reaction and Fabrication of pH-Responsive Prodrug Nanoparticles.
Xu Chao-Ran,Qiu Liang,Pan Cai-Yuan,Hong Chun-Yan,Hao Zong-Yao
Bioconjugate chemistry
In this study, an efficient method is proposed for the synthesis of polymer prodrug with acid-liable linkage via thiol-acrylate Michael addition reaction of the camptothecin with tethering acrylate group and polymer scaffold containing multiple thiol groups. The polymer scaffold P(HEOMA)- b-P(HEMA-DHLA) is prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization of the methacrylate of lipoic acid (HEMA-LA) using poly(2-(2-hydroethoxy) ethyl methacrylate) (PHEOMA) as macro-RAFT agent followed by reduction of the disulfides in lipoic acid (LA) groups to give polymer scaffold with dihydrolipoic acid (DHLA) pendent groups. Acrylate-tethering camptothecin (ACPT) is connected to P(HEOMA)- b-P(HEMA-DHLA) via Michael addition reaction between thiol and acrylate with a high coupling efficiency (95%). Amphiphilic polymer prodrug P(HEOMA)- b-P(HEMA-DHLA-CPT) spontaneously self-assembles into nanoparticles in an aqueous solution and exhibits a CPT loading content as high as 40.1%. The prodrug nanoparticles with the acid-liable β-thiopropionate linkages can release CPT under acidic conditions, and the prodrug nanoparticles show similar cytotoxicity to HeLa cells as free CPT. Overall, the prodrug nanoparticles with high drug loading contents and acid-liable linkages are promising for pH-responsive anticancer therapy.
10.1021/acs.bioconjchem.8b00531
Kinetics and Thermodynamics of Reversible Thiol Additions to Mono- and Diactivated Michael Acceptors: Implications for the Design of Drugs That Bind Covalently to Cysteines.
Krenske Elizabeth H,Petter Russell C,Houk K N
The Journal of organic chemistry
Additions of cysteine thiols to Michael acceptors underpin the mechanism of action of several covalent drugs (e.g., afatinib, osimertinib, ibrutinib, neratinib, and CC-292). Reversible Michael acceptors have been reported in which an additional electron-withdrawing group was added at the α-carbon of a Michael acceptor. We have performed density functional theory calculations to determine why thiol additions to these Michael acceptors are reversible. The α-EWG group stabilizes the anionic transition state and intermediate of the Michael addition, but less intuitively, it destabilizes the neutral adduct. This makes the reverse reaction (elimination) both faster and more thermodynamically favorable. For thiol addition to be reversible, the Michael acceptor must also contain a suitable substituent on the β-carbon, such as an aryl or branched alkyl group. Computations explain how these structural elements contribute to reversibility and the ability to tune the binding affinities and the residence times of covalent inhibitors.
10.1021/acs.joc.6b02188
Total Synthesis of (±)-Spiroaxillarone A via a Reversible Sulfa-Michael Addition.
Long Xianwen,Zhang Min,Yang Xiaodong,Deng Jun
Organic letters
A bioinspired strategy is described for the total synthesis of spiroaxillarone A, which exhibited significant antimalarial activity against resistant (IC = 2.32 μM). The key steps include an intermolecular ethanethiol Michael addition, -quinone Michael addition, and subsequent β-ethanethiol elimination. This synthetic sequence provides a potential biosynthetic pathway of spiroaxillarone A.
10.1021/acs.orglett.1c04282
In Situ Observation of Thiol Michael Addition to a Reversible Covalent Drug in a Crystalline Sponge.
Duplan Vincent,Hoshino Manabu,Li Wei,Honda Tadashi,Fujita Makoto
Angewandte Chemie (International ed. in English)
A reversible Michael addition reaction between thiol nucleophiles and cyanoenones has been previously postulated to be the mechanism-of-action of a new family of reversible covalent drugs. However, the hypothetical Michael adducts in this mechanism have only been detected by spectroscopic methods in solution. Herein, the crystallographic observation of reversible Michael addition with a potent cyanoenone drug candidate by means of the crystalline-sponge method is reported. After inclusion of the cyanoenone substrate, the sponge crystal was treated with a thiol solution. Subsequent crystallographic analysis confirmed the single-crystal-to-single-crystal transformation of the substrate into the impermanent Michael adduct.
10.1002/anie.201509801