Synthesis and bioluminescence of difluoroluciferin

Evaluation of mRNA Transfection Reagents for mRNA Delivery and Vaccine Efficacy via Intramuscular Injection in Mice

The selection of an effective delivery carrier is crucial to assessing mRNA-based vaccines and therapeutics in vivo. Although lipid nanoparticles (LNPs) are commonly used for mRNA delivery, the LNP-mRNA formulation process is laborious and time-consuming and requires a high-cost microfluidic device. Instead, mixing with commercial reagents may simplify mRNA transfection into cells. However, their potential as in vivo carriers in intramuscular vaccination in mouse models remains unclear. In this study, we used three types of commercial RNA transfection reagents, MessengerMAX (MAX; liposome), TransIT-mRNA (IT; cationic polymer), and Invivofectamine (IVF; LNP), to produce nanoparticles directly by pipetting. The particle characteristics and mRNA delivery efficacy of the mRNA-transfection reagent mixtures were analyzed. Additionally, immune responses to vaccine efficacy and protective immunity of the mRNA mixtures as vaccine antigens were evaluated in a mouse model. Although MAX and IT showed high in vitro transfection efficiencies, their in vivo performances were limited. In contrast, IVF exhibited notable particle stability and homogeneity, making it a promising delivery carrier. Intramuscular IVF injection significantly enhanced both innate and adaptive immune responses with a robust systemic protein expression. Notably, when using SARS-CoV-2 Spike mRNA, IVF showed robust humoral immune responses, including production of IgG and neutralizing antibodies, thereby resulting in complete protection against SARS-CoV-2 infection. Therefore, these findings position IVF as an accessible and efficient mRNA carrier for evaluating mRNA vaccines and therapeutic efficacy in basic research.

From imines to amides via NHC-mediated oxidation

An efficient construction of amides through NHC-mediated oxidation of imines is described. This work has the advantages of wide scope, fast assembly and high yield, and can avoid the use of coupling agents, such as HATU, DCC, etc.

Brightening up Biology: Advances in Luciferase Systems for in Vivo Imaging

Bioluminescence imaging (BLI) using luciferase reporters is an indispensable method for the noninvasive visualization of cell populations and biochemical events in living animals. BLI is widely performed with preclinical rodent models to understand disease processes and evaluate potential cell- or gene-based therapies. However, in vivo BLI remains constrained by low photon production and tissue attenuation, limiting the sensitivity of reporting from small numbers of cells in deep locations and hindering its application to larger animal models. This Review highlights recent advances in the development of luciferase systems that improve the sensitivity of in vivo BLI and discusses the expanding array of biological applications.

Molecular Design of d-Luciferin-Based Bioluminescence and 1,2-Dioxetane-Based Chemiluminescence Substrates for Altered Output Wavelength and Detecting Various Molecules

Optical imaging including fluorescence and luminescence is the most popular method for the in vivo imaging in mice. Luminescence imaging is considered to be superior to fluorescence imaging due to the lack of both autofluorescence and the scattering of excitation light. To date, various luciferin analogs and bioluminescence probes have been developed for deep tissue and molecular imaging. Recently, chemiluminescence probes have been developed based on a 1,2-dioxetane scaffold. In this review, the accumulated findings of numerous studies and the design strategies of bioluminescence and chemiluminescence imaging reagents are summarized.

Recent achievements of bioluminescence imaging based on firefly luciferin-luciferase system

Bioluminescence imaging (BLI) is a newly developed noninvasive visual approach which facilitates the understanding of a plethora of biological processes in vitro and in vivo due to the high sensitivity, resolution and selectivity, low background signal, and the lack of external light excitation. BLI based on firefly luciferin-luciferase system has been widely used for the activity evaluation of tumor-specific enzymes, for the detection of diseases-related bioactive small molecules and metal ions, and for the diagnosis and therapy of diseases including the studies of drug transport, the research of immune response, and the evaluation of drug potency and tissue distribution. In this review, we highlight the recent achievements in luciferin derivatives with red-shifted emission spectra, mutant luciferase-luciferin pairs, and the diagnostic and therapeutic application of BLI based on firefly luciferin-luciferase system. The development and application of BLI will expand our knowledge of the occurrence and development of diseases and shed light on the diagnosis and treatment of various diseases.

Lessons Learned from Luminous Luciferins and Latent Luciferases

Compared to the broad palette of fluorescent molecules, there are relatively few structures that are competent to support bioluminescence. Here, we focus on recent advances in the development of luminogenic substrates for firefly luciferase. The scope of this light-emitting chemistry has been found to extend well beyond the natural substrate and to include enzymes incapable of luciferase activity with d-luciferin. The broadening range of luciferin analogues and evolving insight into the bioluminescent reaction offer new opportunities for the construction of powerful optical reporters of use in live cells and animals.

cybLuc: An Effective Aminoluciferin Derivative for Deep Bioluminescence Imaging

To enhance the efficiency of firefly luciferase/luciferin bioluminescence imaging, a series of N-cycloalkylaminoluciferins (cyaLucs) were developed by introducing lipophilic N-cycloalkylated substitutions. The experimental results demonstrate that these cyaLucs are effective substrates for native firefly luciferase (Fluc) and can produce elevated bioluminescent signals in vitro, in cellulo, and in vivo. It should be noted that, in animal studies, N-cyclobutylaminoluciferin (cybLuc) at 10 μM (0.1 mL), which is 0.01% of the standard dose of d-luciferin (dLuc) used in mouse imaging, can radiate 20-fold more bioluminescent light than d-luciferin (dLuc) or aminoluciferin (aLuc) at the same concentration. Longer in vivo emission imaging using cybLuc suggests that it can be used for long-time observation. Regarding the mechanism of cybLuc, our cocrystal structure data from firefly luciferase with oxidized cybLuc suggested that oxidized cybLuc fits into the same pocket as oxyluciferin. Most interestingly, our results demonstrate that the sensitivity of cybLuc in brain tumor imaging contributes to its extended application in deep tissues.

Brominated Luciferins Are Versatile Bioluminescent Probes

We report a set of brominated luciferins for bioluminescence imaging. These regioisomeric scaffolds were accessed by using a common synthetic route. All analogues produced light with firefly luciferase, although varying levels of emission were observed. Differences in photon output were analyzed by computation and photophysical measurements. The brightest brominated luciferin was further evaluated in cell and animal models. At low doses, the analogue outperformed the native substrate in cells. The remaining luciferins, although weak emitters with firefly luciferase, were inherently capable of light production and thus potential substrates for orthogonal mutant enzymes.

“AND” luminescent “reactive” molecular logic gates: a gateway to multi-analyte bioimaging and biosensing

This feature article focuses on the recent development of “AND” luminescent molecular logic gates, in which the optical output is produced in response to multiple (bio)chemical inputs and through cascades of covalent bond-modifying reactions triggered by target (bio)analytes, for biosensing and bioimaging applications in complex media.