Search for: All records

The ability to prepare molecular ions in selected quantum states enables studies in areas such as chemistry, metrology, spectroscopy, quantum information, and precision measurements. Here, we demonstrate (2 + 1) resonance-enhanced multiphoton ionization (REMPI) of oxygen, both in a molecular beam and in an ion trap. The two-photon transition in the REMPI spectrum is rotationally resolved, allowing ionization from a selected rovibrational state of O2. Fits to this spectrum determine spectroscopic parameters of the O2d1Πg state and resolve a discrepancy in the literature regarding its band origin. The trapped molecular ions are cooled by co-trapped atomic ions. Fluorescence mass spectrometry nondestructively demonstrates the presence of the photoionized O2+. We discuss strategies for maximizing the fraction of ions produced in the ground rovibrational state. For (2 + 1) REMPI through the d1Πg state, we show that the Q(1) transition is preferred for neutral O2 at rotational temperatures below 50 K, while the O(3) transition is more suitable at higher temperatures. The combination of state-selective loading and nondestructive detection of trapped molecular ions has applications in optical clocks, tests of fundamental physics, and control of chemical reactions. 

Abstract Lipid nanoparticles (LNPs) have emerged as the preeminent nonviral drug delivery vehicles for nucleic acid therapeutics, as exemplified by their usage in the mRNA COVID‐19 vaccines. As a safe and highly modular delivery platform, LNPs are attractive for a wide range of applications. In addition to vaccines, LNPs are being utilized as platforms for other immunoengineering efforts, especially as cancer immunotherapies by modulating immune cells and their functionality via nucleic acid delivery. In this review, we focus on the methods and applications of LNP‐based immunotherapy in five cell types: T cells, NK cells, macrophages, stem cells, and dendritic cells. Each of these cell types has wide‐reaching applications in immunotherapy but comes with unique challenges and delivery barriers. By combining knowledge of immunology and nanotechnology, LNPs can be developed for improved immune cell targeting and transfection, ultimately working toward novel clinical therapeutics. 

Abstract Nucleic acid delivery with mRNA lipid nanoparticles are being developed for targeting a wide array of tissues and cell types. However, targeted delivery to the bone microenvironment remains a significant challenge in the field, due in part to low local blood flow and poor interactions between drug carriers and bone material. Here we report bone‐targeting ionizable lipids incorporating a piperazine backbone and bisphosphate moieties, which bind tightly with hydroxyapatite ([Ca₅(PO₄)₃OH]), a key component of mineralized tissues. These lipids demonstrate biocompatibility and low toxicity in both vitro and in vivo studies. LNP formulated with these lipids facilitated efficient cellular transfection and improved binding to hydroxyapatite in vitro, and targeted delivery to the bone microenvironment in vivo following systemic administration. Overall, our findings demonstrate the critical role of the piperazine backbone in a novel ionizable lipid, which incorporates a bisphosphonate group to enable efficient bone‐targeted delivery, highlighting the potential of rational design of ionizable lipids for next‐generation bone‐targeting delivery systems.