Optical methods are promising to address the ever‐increasing demands for chirality analysis in drug discovery and related fields because they are amenable to high‐throughput screening. Circular ...dichroism‐based chiroptical sensing using host‐guest chemistry is especially appealing due to the fast equilibrium kinetics, wide substrate scope, and potential for sustainable development. In this Minireview, we give an overview on this emerging field. General aspects of molecular recognition and chirality transfer are analyzed. Chirality sensors are discussed by dividing them into three classes according to their structural features. Applications of these chirality sensors for chirality analysis of the products of asymmetric reactions and for the real‐time monitoring of reaction kinetics are demonstrated with selected examples. Moreover, challenges and research directions in this field are also highlighted.
Chiroptical sensing based on noncovalent recognition using synthetic hosts and circular dichroism spectroscopy is discussed in this Minireview. The synthetic hosts used as the chirality sensors are divided into three classes according to their structural features. Applications of the chirality sensors are demonstrated with selected examples together with the challenges.
Selective molecular recognition in water is the foundation of numerous biological functions but is a challenge for most synthetic hosts. We employ the concept of endo‐functionalized cavity and the ...strategy of simultaneous construction to address this issue. The concept and the strategy were demonstrated in the construction of a biomimetic host for selectively recognizing quinones in water. The host was synthesized by joining two pieces of bent anthracene dimer through amide bond formation, affording a deep hydrophobic cavity and inward‐directing hydrogen bonding sites. The host can recognize quinones over their close analogues in water, and its association affinity to p‐benzoquinone is the highest among all the known hosts and is even comparable to that of the bioreceptor. The binding with an anthraquinone reaches nanomolar affinity. Shielded hydrogen bonding, C−H⋅⋅⋅π, and charge transfer interactions, and the hydrophobic effect are responsible for the high binding affinity and selectivity.
A new biomimetic host with anthracene sidewalls was constructed based on the concept of endo‐functionalized cavity and by employing the synthetic strategy of simultaneous construction. This host is able to effectively bind quinones with high selectivity by employing shielded noncovalent interactions and the hydrophobic effect.
Highlights
Recent advances in bacterial theranostics using antimicrobial photo/sonodynamic therapy (aPDT/SDT) are summarized in this review.
The inherent optical characteristics of ...photo/sonosensitizers facilely enable imaging diagnosis of bacterial infections.
Reactive oxygen species as the killing effector of aPDT/SDT cause broad-spectrum damage for sterilization with no concern about antibiotic resistance.
Rapid evolution and propagation of multidrug resistance among bacterial pathogens are outpacing the development of new antibiotics, but antimicrobial photodynamic therapy (aPDT) provides an excellent alternative. This treatment depends on the interaction between light and photoactivated sensitizer to generate reactive oxygen species (ROS), which are highly cytotoxic to induce apoptosis in virtually all microorganisms without resistance concern. When replacing light with low-frequency ultrasonic wave to activate sensitizer, a novel ultrasound-driven treatment emerges as antimicrobial sonodynamic therapy (aSDT). Recent advances in aPDT and aSDT reveal golden opportunities for the management of multidrug resistant bacterial infections, especially in the theranostic application where imaging diagnosis can be accomplished facilely with the inherent optical characteristics of sensitizers, and the generated ROS by aPDT/SDT cause broad-spectrum oxidative damage for sterilization. In this review, we systemically outline the mechanisms, targets, and current progress of aPDT/SDT for bacterial theranostic application. Furthermore, potential limitations and future perspectives are also highlighted.
Abstract
The clinical applications of magnetic hyperthermia therapy (MHT) have been largely hindered by the poor magnetic-to-thermal conversion efficiency of MHT agents. Herein, we develop a facile ...and efficient strategy for engineering encapsulin-produced magnetic iron oxide nanocomposites (eMIONs) via a green biomineralization procedure. We demonstrate that eMIONs have excellent magnetic saturation and remnant magnetization properties, featuring superior magnetic-to-thermal conversion efficiency with an ultrahigh specific absorption rate of 2390 W/g to overcome the critical issues of MHT. We also show that eMIONs act as a nanozyme and have enhanced catalase-like activity in the presence of an alternative magnetic field, leading to tumor angiogenesis inhibition with a corresponding sharp decrease in the expression of HIF-1α. The inherent excellent magnetic-heat capability, coupled with catalysis-triggered tumor suppression, allows eMIONs to provide an MRI-guided magneto-catalytic combination therapy, which may open up a new avenue for bench-to-bed translational research of MHT.
Antibiotic‐free methods hold particular promise for preventing and controlling multidrug‐resistant (MDR) bacterial infection via eradiation of bacteria and their pathogenic virulence. A facile and ...bioinspired strategy is presented for bridging antibacterial sonodynamic therapy and antivirulence immunotherapy. As a proof‐of‐concept, an antibody which neutralizes alpha‐toxin of methicillin‐resistant Staphylococcus aureus (MRSA) is genetically engineered on to the surface of cell membrane nanovesicles, which then undergo sonosensitizer encapsulation. Compared with conventional passive virulence absorption using natural red blood membrane, the highly active antibody–toxin interaction enables the nanovesicles to capture virulence more potently in vitro. Upon ultrasound activation, the sonosensitizers efficiently generate reactive oxygen species to kill bacteria and accelerate the virulence clearance. In vivo optical imaging shows that the antibody‐piloted nanocapturer can successfully locate MRSA infection and accurately distinguish the foci from sterile inflammation. In situ magnetic resonance imaging and oxyhemoglobin saturation detection visualize the treatment progression, revealing a complete sono‐immunotherapeutic eradication of MRSA myositis in mice. The first combination of antibacterial sonodynamic therapy and antivirulence immunotherapy, which promises a new way for antibiotic‐free nanotheranostics to robustly combat MDR bacterial infections, is presented.
A two‐birds‐with‐one‐stone nanocapturer is presented for bridging antibacterial sonodynamic therapy and antivirulence immunotherapy. A genetically engineered antibody on cell membrane nanovesicles (ANVs) potently reduces MRSA virulence. Upon ultrasound activation, sonosensitizers in the ANVs generate reactive oxygen species to kill bacteria and accelerate virulence clearance. Specific MRSA infection diagnosis is realized via fluorescence imaging and photoacoustic imaging.
Pure aluminum powder was successfully sprayed on AZ31B extrusion flat and round coupons at low temperature. The corrosion and corrosion fatigue behavior of the coated and uncoated samples were ...examined by performing accelerated corrosion tests. The corrosion resistance of AZ31B samples with and without coating was investigated based on ASTM B117 standard salt spray with a concentration of 5% NaCl at 36°C, 100% relative humidity. The corrosion fatigue of bare and coated round samples was examined by producing a thin film of 3.5% NaCl solution on the surface of the fatigue samples via integrating a corrosion chamber into a rotating bending fatigue testing machine. Pure Al coating provided significant corrosion protection for AZ31B in 5% NaCl fog environment by improving its corrosion resistance from 90% average weight loss in 33days for bare samples to <10% average weight loss in 90days of continuous corrosion cycles. However, pure Al coating did not improve the corrosion fatigue strength of magnesium and samples with and without coating showed similar corrosion fatigue trends. Test results in salt solution showed fatigue life reduction of 88% when compared with test results in air. The microstructure examination of samples failed under cyclic load showed early cracking of Al coat which allowed the electrolyte penetration into Mg substrate creating a localized corrosion and premature failure. The early cracking was attributed to the lower fatigue strength of pure Al compared to AZ31B.
•Comprehensive study on corrosion behavior and mechanisms of CS-coated and bulk AZ31B based on ASTM117 salt spray.•The corrosion rate of CS-coated samples are reduced by two orders of magnitudes compared to bulk magnesium.•In-situ corrosion fatigue of coated and bulk samples and their underlying fracture mechanisms.•CS-coated samples in presence of fatigue load in corrosive environment show coating early cracking and premature failure.
Ultrasound (US)-driven sonodynamic therapy (SDT) has demonstrated wide application prospects in the eradication of deep-seated bacterial infections due to its noninvasiveness, site-confined ...irradiation, and high-tissue-penetrating capability. However, the ineffective accumulation of sonosensitizers at the infection site, the hypoxic microenvironment, as well as rapid depletion of oxygen during SDT greatly hamper the therapeutic efficacy of SDT. Herein, an US-switchable nanozyme system was proposed for the controllable generation of catalytic oxygen and sonosensitizer-mediated reactive oxygen species during ultrasound activation, thereby alleviating the hypoxia-associated barrier and augmenting SDT efficacy. This nanoplatform (Pd@Pt-T790) was easily prepared by bridging enzyme-catalytic Pd@Pt nanoplates with the organic sonosensitizer meso-tetra(4-carboxyphenyl)porphine (T790). It was really interesting to find that the modification of T790 onto Pd@Pt could significantly block the catalase-like activity of Pd@Pt, whereas upon US irradiation, the nanozyme activity was effectively recovered to catalyze the decomposition of endogenous H2O2 into O2. Such “blocking and activating” enzyme activity was particularly important for decreasing the potential toxicity and side effects of nanozymes on normal tissues and has potential to realize active, controllable, and disease-loci-specific nanozyme catalytic behavior. Taking advantage of this US-switchable enzyme activity, outstanding accumulation in infection sites, as well as excellent biocompatibility, the Pd@Pt-T790-based SDT nanosystem was successfully applied to eradicate methicillin-resistant Staphylococcus aureus (MRSA)-induced myositis, and the sonodynamic therapeutic progression was noninvasively monitored by photoacoustic imaging and magnetic resonance imaging. The developed US-switchable nanoenzyme system provides a promising strategy for augmenting sonodynamic eradication of deep-seated bacterial infection actively, controllably, and precisely.
The strategy of combining a vaccine with immune checkpoint inhibitors has been widely investigated in cancer management, but the complete response rate for this strategy is still unresolved. We ...describe a genetically engineered cell membrane nanovesicle that integrates antigen self-presentation and immunosuppression reversal (ASPIRE) for cancer immunotherapy. The ASPIRE nanovaccine is derived from recombinant adenovirus-infected dendritic cells in which specific peptide-major histocompatibility complex class I (pMHC-I), anti-PD1 antibody and B7 co-stimulatory molecules are simultaneously anchored by a programmed process. ASPIRE can markedly improve antigen delivery to lymphoid organs and generate broad-spectrum T-cell responses that eliminate established tumours. This work presents a powerful vaccine formula that can directly activate both native T cells and exhausted T cells, and suggests a general strategy for personalized cancer immunotherapy.
Although ultrasound‐based therapeutic strategies have achieved great success in the battle against antibiotic‐resistant bacterial infections, various sonodynamic treatments still suffer from poor ...therapeutic efficiency, failing to completely eradicate infections. Thus, more potent strategies are urgently required. Herein, a novel ultrasound‐driven treatment modality, sonoactivated chemodynamic therapy (SCDT), is proposed, which shows a robust generation of superoxide anion and destructive hydroxyl radical via sonotriggered catalytic reactions. This SCDT platform is prepared by grafting Fe3+ onto polyethylenimine‐modified bismuth oxybromide (BiOBr) nanoplates. During sonocatalysis, the introduction of Fe3+ can effectively separate the holes (h+) and electrons (e‐) of BiOBr NPs and shorten their transport path of valence electrons, resulting in the activation of multioxygen reduction and Fenton reaction to generate abundant reactive oxygen species against methicillin‐resistant Staphylococcus aureus (MRSA) infection. More importantly, Fe3+ can also serve as a magnetic resonance imaging (MRI) contrast agent to achieve the accurate diagnosis of bacterial infection. The SCDT‐mediated bactericidal outcome can be monitored by in situ monitoring through MRI technique, revealing a complete elimination of MRSA myositis in mice. Collectively, its deep tissue penetration, high therapeutic efficacy, and noninvasive properties make SCDT a promising therapeutic modality for combating multidrug‐resistant bacterial infection.
A novel ultrasound‐driven treatment is developed, featuring a robust generation of superoxide anions and hydroxyl radicals via sonocatalysis. Grating Fe3+ on the surface of bismuth oxybromide nanoplates effectively separates the holes and electrons, shortening the transport path of valence electrons. As a result, multi‐oxygen reduction and Fenton reactions is activated facilely to generate abundant reactive oxygen species against bacteria.
PDF
