Self-Immolative Difluorophenyl Ester Linker for Affinity-Based Fluorescence Turn-on Protein Detection

Spatial Control of CAR T Cell Activation Using Tumor-Homing Polymers

CAR T cell therapies often lack specificity, leading to issues ranging from inadequate antigen targeting to off-tumor toxicities. To counter that lack of specificity, we expanded tumor targeting capabilities with universal CAR and spatially defined CAR T cell engagement with targets through a combination of synthetic biology and biomaterial approaches. We developed a novel framework, called "In situ Mobilization: Polymer Activated Cell Therapies" (IMPACT) for polymer-mediated, anatomical control of IF-THEN gated CAR T cells. With IMPACT, a regulated payload such as a BiTE or tumor-targeting CAR will only be expressed after engineered cells engage a tumor-localizing polymer ("IF" condition). In this first demonstration of IMPACT, we engineered CAR T cells to respond to fluorescein that is displayed by an injectable polymer that binds to and is retained in fibrin deposits in tumor microenvironments. This interaction then drives selective and conditional expression of a protein within tumors ("THEN" condition). Here, we develop the polymer and CAR T cell infrastructure of IMPACT and demonstrate tumor-localized CAR T cell activation in a murine tumor model after the intravenous administration of polymer and engineered T cells.

Novel Endoplasmic Reticulum-Targeted Luminescent Probe for Visualization of Carbon Monoxide in Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is a major hepatic dysfunction commonly caused by hepatotoxic drug overdose, resulting in a considerable number of fatalities worldwide. Recent studies have highlighted the regulatory and hepatoprotective effects of carbon monoxide (CO) during the liver injury process. However, precisely tracking the dynamic changes in the composition of CO in DILI is still a great challenge. In this work, leveraging the innovative "quencher-insertion" strategy, a unique endoplasmic reticulum (ER)-targetable lanthanide complex-based luminescence probe, ER-ANBTTA-Eu3+/Tb3+, has been developed for the selective and accurate monitoring of CO fluxes in live cells and laboratory animals. The new probe is composed of three covalently linked functional moieties: the terpyridine polyacid-Eu3+/Tb3+-mixed chelates as the long-lived luminophore, a p-toluenesulfonamide moiety as the ER-anchoring motif, and an allyloxy-nitrobenzyl ether moiety as the CO-specific recognition unit. Upon reaction with CO in the presence of Pd2+ ions, the Tsuji-Trost reaction leads to the cleavage of the allyloxy-nitrobenzyl group from the Eu3+/Tb3+-mixed chelates, which results in the restoration of Tb3+ emission at 538 nm and the attenuation of Eu3+ emission at 688 nm, leading to a dramatic increase of the I538/I688 ratio. In addition to the exceptional response sensitivity and selectivity toward CO, ER-ANBTTA-Eu3+/Tb3+ also exhibits the outstanding ER-locating capability, which allows the probe to be used for imaging of CO in the ER of live cells. Using this probe, combined with the time-gated luminescence imaging mode, the exogenous and endogenous CO in ER of live cells were monitored without the interference of background autofluorescence. Moreover, the upregulation of hepatic CO in DILI mice was successfully visualized. The results suggested the potential of ER-ANBTTA-Eu3+/Tb3+ for deeply exploring the functions of CO in DILI pathogenesis.

Inhibitory Effects on RNA Binding and RNase H Induction Activity of Prodrug-Type Oligodeoxynucleotides Modified with a Galactosylated Self-Immolative Linker Cleavable by β-Galactosidase

Prodrug-type oligonucleotides (prodrug-ONs) are a class of oligonucleotide designed for activation under specific intracellular conditions or external stimuli. Prodrug-ONs can be activated in the target tissues or cells, thereby reducing the risk of adverse effects. In this study, we synthesized prodrug-type oligodeoxynucleotides activated by β-galactosidase, an enzyme that is overexpressed in cancer and senescent cells. These oligodeoxynucleotides (ODNs) contain a modified thymidine conjugated with galactose via a self-immolative linker at the O4-position. UV-melting analysis revealed that the modifications decreased the melting temperature (Tm) compared with that of the unmodified ODN when hybridized with complementary RNA. Furthermore, cleavage of the glycosidic bond by β-galactosidase resulted in the spontaneous removal of the linker from the nucleobase moiety, generating unmodified ODNs. Additionally, the introduction of multiple modified thymidines into ODNs completely inhibited the RNase H-mediated cleavage of complementary RNA. These findings suggest the possibility of developing prodrug-ONs, which are specifically activated in cancer cells or senescent cells with high β-galactosidase expression.

Imaging of Carbonic Anhydrase Level in Epilepsy with an Environment-Sensitive Fluorescent Probe

Carbonic anhydrases (CAs) participate in various physiological and pathological activities by catalyzing the interconversion between carbon dioxide and bicarbonate ions. Under normal circumstances, they guarantee that the relevant biological reactions in our body occur within an appropriate time scale. Abnormal expression or activity alteration of CAs is closely related to the pathogenesis of diverse diseases. This work reports an inhibitor-directed fluorescent probe FMRs-CA for the detection of CAs. Excellent selectivity, favorable biocompatibility, and desirable blood-brain barrier (BBB) penetration endow the probe with the ability to image the fluctuation of CAs in cells and mice. We achieved in situ visualization of the increased CAs in hypoxic cells with this probe. Additionally, probe FMRs-CA was mainly enriched within the liver and gradually metabolized by the liver. With the help of FMRs-CA, the increase of CAs in epileptic mouse brains was revealed first from the perspective of imaging, providing the mechanism connection between abnormal CA expressions and epilepsy.

CuxO nanorods with excellent regenerable NADH peroxidase mimics and its application for selective and sensitive fluorimetric ethanol sensing

Cu_xO nanorods with excellent NADH peroxidase mimics were synthesized by a simple hydrothermal method. The catalytic oxidation of NADH to NAD cofactor strictly follows the enzymatic kinetics with high catalytic rate and strong affinity. The catalytic mechanism of Cu_xO NRs was that in the presence of hydrogen peroxide, the catalytic oxidizing NADH to NAD ⁺ involving with O₂^.-.anion production, making it realistic to mutually convert between coenzymes. Considering that the mutual transformation of NADH/NAD cofactors plays an important role in biological function, combination of Cu_xO NRs with alcohol dehydrogenase, a highly selective method for fluorimetric detection of ethanol was established. The as-proposed sensing platform is capable of dectecting alcohol with the limit of detection of 26.7 μM (S/N = 3) and applied in practical sample with satisfied accuracy and recovery. The as-developed regenerable NADH peroxidase mimics would also cast lights in biocatalysis, synthetic biology and bioenergy.