Photo‐switchable lipids are synthetic lipid molecules used in photo‐pharmacology to alter membrane lateral pressure and thus control opening and closing of mechanosensitive ion channels. The ...molecular picture of how photo‐switchable lipids interact with membranes or ion channels is poorly understood. To facilitate all‐atom simulations that could provide a molecular picture of membranes with photo‐switchable lipids, we derived force field parameters for atomistic computations of the azobenzene‐based fatty acid FAAzo‐4. We implemented a Phyton‐based algorithm to make the optimization of atomic partial charges more efficient. Overall, the parameters we derived give good description of the equilibrium structure, torsional properties, and non‐bonded interactions for the photo‐switchable lipid in its trans and cis intermediate states, and crystal lattice parameters for trans‐FAAzo‐4. These parameters can be extended to all‐atom descriptions of various photo‐switchable lipids that have an azobenzene moiety.
Photo‐switchable lipid molecules are used in photo‐pharmacology applications to control the lateral pressure of the lipid membrane with light. An azobenzene‐based lipid molecule with the central double bond in trans absorbs light, which triggers photoisomerization to cis, with altered membrane lateral pressure. The molecular picture of how photo‐switchable lipids in trans versus cis configurations interact with membranes is unclear. To enable atomistic computations of membranes with photo‐switchable lipids, here we derived CHARMM force field parameters for an azobenzene‐based molecule, implemented a protocol to validate the accuracy of the parameters, and probed the accessibility to water of the central double bond.
The ultrahigh concentration of bilirubin (BR) is recognized as a key factor leading to biliary cirrhosis and irreversible brain damage, with the efficient removal of BR from blood being an effective ...therapy against these conditions. However, the practical application of adsorbents for blood purification is often compromised by their poor regenerative performance. Therefore, by leveraging the excellent structure-function properties of stimuli-responsive materials, we developed photoregenerable nanoadsorbents (SiO2@MAzoPy–x) with excellent cyclic removal performance. We employed azobenzene macromolecule brushes as the functional ligand to enhance the adsorption performance of the nanoadsorbents and enable efficient regeneration. The best-performing nanoadsorbent exhibited BR adsorption rates of 69.71 % and 65.20 % in phosphate-buffered saline (PBS) and simulated plasma, respectively, and showed superior adsorption efficiency in patients’ serum compared to the unmodified SiO2 (≤ 5.4 %). The binding mechanism suggested that BR and the nanoadsorbent interacted through hydrophobic and electrostatic forces. Importantly, the nanoadsorbents could be photoregenerated with a recovery rate of 99 % in PBS after five regeneration experiments using a green process. Owing to their superior photoregenerative properties, the proposed nanoadsorbents show promise for clinical application.
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Azobenzene/tetraethyl ammonium photochromic ligands (ATPLs) are photoactive compounds with a large variety of photopharmacological applications such as nociception control or vision restoration. ...Absorption band maximum and lifetime of the less stable isomer are important characteristics that determine the applicability of ATPLs. Substituents allow to adjust these characteristics in a range limited by the azobenzene/tetraethyl ammonium scaffold. The aim of the current study is to find the scope and limitations for the design of ATPLs with specific spectral and kinetic properties by introducing para substituents with different electronic effects. To perform this task we synthesized ATPLs with various electron acceptor and electron donor functional groups and studied their spectral and kinetic properties using flash photolysis and conventional spectroscopy techniques as well as quantum chemical modeling. As a result, we obtained diagrams that describe correlations between spectral and kinetic properties of ATPLs (absorption maxima of
and
isomers of ATPLs, the thermal lifetime of their
form) and both the electronic effect of substituents described by Hammett constants and structural parameters obtained from quantum chemical calculations. The provided results can be used for the design of ATPLs with properties that are optimal for photopharmacological applications.
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•The selective reflection of light in the oblique helicoidal structure is tunable by the electric field.•Cholesteric mixtures were doped with rod-like, chiral, and bent-shaped ...azobenzene compounds.•Cholesterics with newly designed photosensitive molecules can be tuned by the electric field and UV light.•The tuning mechanism, reflection coefficient, and response time are related to the structure of azobenzene compounds.
The oblique helicoidal structure is formed in right-angle cholesterics under the applied electric field. The electric field changes the pitch and cone angle but preserves the single-harmonic modulation of the refractive index. As a result, in such a supramolecular system, we can tune the selective reflection of light in a broad range. Here, we report that structural colors can be tuned by simultaneously illuminating the structure with UV light and the action of an electric field. The cholesterics with the oblique helicoidal structure were doped with newly designed rod-like, chiral, and bent-shaped azo-photosensitive materials characterized by a very low rate of thermal back cis (Z) – trans (E) isomerization. The E-Z isomerization of the photo-active compounds under UV light causes the red shift of the selective light reflection in the cholesteric mixtures. We found that the molecular structure of the photosensitive materials used affects the reflection coefficient, bandwidth, response time to UV irradiation, and tuning range. The effect was explained by considering the effect of molecular matching, cis–trans isomerization, and electric field action. We investigated the dynamics of molecular changes in the oblique helicoidal structure under the influence of external factors. The designed supramolecular system has the potential application in soft matter UV detectors.
The burgeoning field of soft robotics has witnessed a surge in interest, driven by the pursuit of creating precise machines with soft actuators capable of surpassing or aiding human manufacturing ...capabilities. This work explores light-responsive shape memory actuators derived from electrospun fibers, integrating a "push-pull" azo compound into a poly(ε-caprolactone) matrix. Driven by photothermal conversion, the resulting system exhibits reversible actuation under UV light, demonstrating rapid responses and superior performance compared to film counterparts. More specifically, the significant impact of morphology on both the photothermal behavior and the actuation performance is highlighted by comparing non-woven and bulk shape memory material. The temperature variation induced by UV light in the non-woven was notably affected by scattering effects, leading to the formation of temperature gradients throughout the material. Notably, the study establishes a unique stress-responsive range for fibrous actuators, demonstrating that their porous structure contributes to higher actuation magnitudes at lower stresses compared to conventional films. This innovation holds promise for applications in micro-robotics and biomedical fields, showcasing the potential of fibrous actuators in augmenting human-friendly robotics through their lightweight, flexible, and remotely actuated features.
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•Light-responsive shape memory actuators are obtained by electrospinning.•The photothermal conversion allows reversible actuation under UV light.•Morphology impacts both the photothermal behavior and on the actuation performance.•Compared to film, the nonwoven shows higher actuation magnitudes at lower stresses.
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•The hydrogel could be self-assembled by azobenzene-based small molecule (mAzoNa).•The hydrogel exhibited a reversible gel-sol phase transition in response to green and blue light ...respectively.•The hydrogel showed good self-supporting ability.
A novel photo-responsive azobenzene-based amphiphilic small molecule (mAzoNa) with four methoxy groups located at ortho positions on azobenzene unit has been designed and synthesized. The mAzoNa molecules could self-assemble into hydrogel, which was driven mainly by hydrophobic effect and π–π stacking interaction between substituted azobenzene groups. The formed hydrogel was composed of long (∼several micrometers) lamellar ribbon structures with widths of 150 to 500 nm. The hydrogel also showed good self-supporting ability with a storage modulus (G′) higher than 104 Pa. It was more interesting that the hydrogel could undergo reversible gel-to-sol transition under 550 nm green light irradiation and the sol-to-gel transition under 450 nm blue light irradiation. This could be attributed to that the substituted four methoxy groups red-shifted the isomerization wavelengths of mAzoNa. This unique visible-light responsive behavior should make the prepared hydrogel find more potential applications in biomedical systems and smart materials without using ultraviolet light at all.
Schematic representation of the various hypoxia-responsive drug carriers used in various cancers.
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•Hypoxic conditions in TME could be used for controlled drug release.•Hypoxia active ...Prodrugs selectively target tumor cells minimizing systemic toxicity.•Azo, nitro, and N-oxide-modified polymers could serve as hypoxia-responsive carrier.•Hypoxia-responsive nanocarrier could co-deliver other chemotherapeutic drugs to TME.
Hypoxic environment-responsive nanocarriers represent a promising future in targeted drug delivery to solid tumors since hypoxia has an important role in tumor proliferation, angiogenesis, and metastasis, offering a means to overcome resistance to cancer therapy. Exploiting hypoxic conditions for cancer treatment can be achieved through two distinct approaches. Firstly, by using hypoxia-activated prodrugs (HAP) and secondly by developing nanocarriers in response to hypoxia. HAPs, such as tirapazamine, metronidazole, etc can convert into anti-cancer drugs upon hypoxic conditions, reducing the chances of side effects by eliminating non-specific targeting due to the low oxygen content and the presence of numerous bioreductive enzymes like azo, nitro-reductase. However, HAPs were unsuccessful in clinical trials due to low extravascular transport which implies the necessity of nanocarriers for their effective delivery to tumor site. Thus, precise designing of the hypoxia-responsive nanocarriers that can deliver anticancer agents or HAPs is of utmost importance for tumor-specific delivery. The current review focuses on various nano vehicles, including liposomes, micelles, hydrogel, nanogel, and dendrimers synthesized by polymeric materials to render them hypoxia-responsive properties. Here, we explain the release of chemotherapeutic drugs from the nanocarriers in the tumor cells, due to the reduction of the hypoxia-responsive functional groups. Furthermore, the limitations and potential considerations of improving hypoxia-responsive drug administration are discussed.
A series of liquid and photoliquefiable azobenzene (Azo) derivatives (Azo-Cn-Br) have been synthesized for molecular solar thermal fuels. Each of the liquid and photoliquefiable azo derivatives shows ...a high degree of isomerization, a fast isomerization rate, a long half-life, an appropriate energy storage density, and a solvent-free “charging” and “discharging” process. The photoliquefied azo derivatives can isomerize upon UV light irradiation at low temperatures to give the “UV-charged” azo ones. Therefore, the phase transition enthalpy is stored simultaneously along with the isomerization enthalpy. The “UV-charged” azo derivatives are capable of releasing heat under the manipulation of blue light.
Azobenzene is one of the most ubiquitous photoswitches in photochemistry and a prototypical model for photoisomerizing systems. Despite this, its wavelength-dependent photochemistry has puzzled ...researchers for decades. Upon excitation to the higher energy ππ* excited state instead of the dipole-forbidden nπ* state, the quantum yield of isomerization from trans- to cis-azobenzene is halved. The difficulties associated with unambiguously resolving this effect both experimentally and theoretically have contributed to lasting controversies regarding the photochemistry of azobenzene. Here, we systematically characterize the dynamic photoreaction pathways of azobenzene by performing first-principles simulations of the nonadiabatic dynamics following excitation to both the ππ* and the nπ* states. We demonstrate that ground-state recovery is mediated by two distinct S1 decay pathways: a reactive twisting pathway and an unreactive planar pathway. Increased preference for the unreactive pathway upon ππ* excitation largely accounts for the wavelength-dependent behavior observed in azobenzene.
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