Spatiotemporal Tracing of the Cellular Internalization Process of Rod-Shaped Nanostructures

Intermetallics triggering pyroptosis and disulfidptosis in cancer cells promote anti-tumor immunity

Pyroptosis, an immunogenic programmed cell death, could efficiently activate tumor immunogenicity and reprogram immunosuppressive microenvironment for boosting cancer immunotherapy. However, the overexpression of SLC7A11 promotes glutathione biosynthesis for maintaining redox balance and countering pyroptosis. Herein, we develop intermetallics modified with glucose oxidase (GOx) and soybean phospholipid (SP) as pyroptosis promoters (Pd2Sn@GOx-SP), that not only induce pyroptosis by cascade biocatalysis for remodeling tumor microenvironment and facilitating tumor cell immunogenicity, but also trigger disulfidptosis mediated by cystine accumulation to further promote tumor pyroptosis in female mice. Experiments and density functional theory calculations show that Pd2Sn nanorods with an intermediate size exhibit stronger photothermal and enzyme catalytic activity compared with the other three morphologies investigated. The peroxidase-mimic and oxidase-mimic activities of Pd2Sn cause potent reactive oxygen species (ROS) storms for triggering pyroptosis, which could be self-reinforced by photothermal effect, hydrogen peroxide supply accompanied by glycometabolism, and oxygen production from catalase-mimic activity of Pd2Sn. Moreover, the increase of NADP+/NADPH ratio induced by glucose starvation could pose excessive cystine accumulation and inhibit glutathione synthesis, which could cause disulfidptosis and further augment ROS-mediated pyroptosis, respectively. This two-pronged treatment strategy could represent an alternative therapeutic approach to expand anti-tumor immunotherapy.

Probing Twist-Induced Endocytotic Membrane Fission using Anisotropic Gold Homodimers

Membrane fission involves a crucial step of lipid remodeling, in which the dynamin collar constricts and severs the tubulated lipid membrane at the neck of budding vesicles. Nevertheless, the difficulty in accurately determining the rotational dynamics of live endocytotic vesicles poses a limit on the elucidation of dynamin-induced membrane remodeling for endocytotic vesicle scission. Herein, we designed a DNA-modified gold homodimer (AuHD)-based anisotropic plasmonic probe with uniform surface chemistry, minimizing orientational fluctuation within vesicle encapsulation. Using AuHDs as cargos to image the dynamics of cargo-containing vesicles during endocytosis, we showed that, prior to detachment from plasma membrane, the cargo-containing vesicles underwent multiple intermittent twists of ~4° angular orientation relative to plasma membrane with a ~0.2 s dwell time. These findings suggest that the membrane torques resulting from dynamin actions in vivo constitute the pathway to membrane fission, potentially shedding light on how dynamin-mediated lipid remodeling orchestrates membrane fission.

Bridging Smart Nanosystems with Clinically Relevant Models and Advanced Imaging for Precision Drug Delivery

Intracellular delivery of nano-drug-carriers (NDC) to specific cells, diseased regions, or solid tumors has entered the era of precision medicine that requires systematic knowledge of nano-biological interactions from multidisciplinary perspectives. To this end, this review first provides an overview of membrane-disruption methods such as electroporation, sonoporation, photoporation, microfluidic delivery, and microinjection with the merits of high-throughput and enhanced efficiency for in vitro NDC delivery. The impact of NDC characteristics including particle size, shape, charge, hydrophobicity, and elasticity on cellular uptake are elaborated and several types of NDC systems aiming for hierarchical targeting and delivery in vivo are reviewed. Emerging in vitro or ex vivo human/animal-derived pathophysiological models are further explored and highly recommended for use in NDC studies since they might mimic in vivo delivery features and fill the translational gaps from animals to humans. The exploration of modern microscopy techniques for precise nanoparticle (NP) tracking at the cellular, organ, and organismal levels informs the tailored development of NDCs for in vivo application and clinical translation. Overall, the review integrates the latest insights into smart nanosystem engineering, physiological models, imaging-based validation tools, all directed towards enhancing the precise and efficient intracellular delivery of NDCs.

Atomic Force Microscopy: An Introduction

Imaging of nano-sized particles and sample features is crucial in a variety of research fields, for instance, in biological sciences, where it is paramount to investigate structures at the single particle level. Often, two-dimensional images are not sufficient, and further information such as topography and mechanical properties are required. Furthermore, to increase the biological relevance, it is desired to perform the imaging in close to physiological environments. Atomic force microscopy (AFM) meets these demands in an all-in-one instrument. It provides high-resolution images including surface height information leading to three-dimensional information on sample morphology. AFM can be operated both in air and in buffer solutions. Moreover, it has the capacity to determine protein and membrane material properties via the force spectroscopy mode. Here we discuss the principles of AFM operation and provide examples of how biomolecules can be studied. New developments in AFM are discussed, and by including approaches such as bimodal AFM and high-speed AFM (HS-AFM), we show how AFM can be used to study a variety of static and dynamic single biomolecules and biomolecular assemblies.

Diatom-derived mesoporous silica nanoparticles loaded with fucoidan for enhanced chemo-photodynamic therapy

Combination therapy merges chemical photodynamic therapy (CPDT) to improve cancer treatment. It synergizes chemotherapy with photodynamic therapy (PDT), using photosensitizers to produce reactive oxygen species (ROS) when exposed to light, effectively killing drug-resistant cancer cells. It is not affected by drug resistance, making it an attractive option for combination with chemotherapy. In this study, the focus was on the design of a combination therapy of chemotherapy and PDT. They synthesized diatomaceous earth mesoporous silica nanoparticles (dMSN) containing lanthanide metal ions in a PDT composition. These nanoparticles can generate ROS under near-infrared light irradiation and have MRI and fluorescence imaging capabilities, confirming their phototherapeutic effect on HCT116 cancer cells at a 200 μg/mL concentration. Fucoidan, derived from brown algae, was used as the chemotherapy component. The fucoidan extracted from Sargassum oligocystum in Pingtung Haikou showed the highest anticancer activity, with cell viability of 57.4 % at 200 μg/mL on HCT116 cancer cells. For combination therapy, fucoidan was loaded into nanoparticles (dMSN-EuGd@fucoidan). Cell viability experiments revealed that at 200 μg/mL, the cell survival rate of dMSN-EuGd@Fucoidan on HCT116 cancer cells was 47.7 %. Combination therapy demonstrated superior anticancer efficacy compared to PDT or chemotherapy alone, successfully synthesizing nanoparticles for combined chemotherapy and photodynamic therapy.

Programming an Enhanced Uptake and the Intracellular Fate of Magnetic Microbeads

This study compares two kinds of magnetic microbeads with different surface features and cell entry pathways, aiming to provide insights into how to program their cell uptake and intracellular fate. It is found that a rougher surface enhances the cell uptake of the microbeads, regardless of whether they are pulled by a magnetic field gradient or adsorbed by the cell membrane. However, the entry route affects the intracellular localization of the microbeads: The magnetically dragged microbeads reach the cytoplasm, while the adsorbed microbeads stay in the late endosomes and lysosomes. This suggests that different strategies can be used to target different cellular compartments with magnetic microbeads. Moreover, it is demonstrated that the cells containing the microbeads can be moved and regrown at specific locations by applying a magnetic field gradient, showing the potential of these magnetic microbeads for cell delivery and manipulation.

Thermal-controlled cellular uptake of "hot" nanoparticles

Nanoparticles (NPs) have shown immense potential in the field of biomedical applications, particularly in NP-based photothermal therapy, which offers a remote-controlled approach to achieve precise temperature control for site-specific heating and sub-cellular tumor treatment. However, the molecular mechanisms underlying related cellular activities, such as the cellular uptake behavior of irradiated NPs in photothermal effects, remain elusive. In this study, we conducted a thorough investigation of the interaction between an irradiated NP with elevated temperature (ranging from 270 to 360 K) and a model bilayer membrane composed of DPPC or DOPC using nonequilibrium coarse-grained molecular dynamics simulations with the implicit-solvent Dry Martini force field. We observe that the interaction between a "hot" NP and a membrane is thermally regulated. In addition, the wrapping of membranes around NPs exhibits a strong dependence on the temperature of the irradiated NP, demonstrating a step-like change in behavior. This membrane wrapping effect is attributed to the heat conduction between NPs and membrane lipids, which occurs almost simultaneously with the membrane deformation and wrapping of NPs during the NP-membrane interaction process. Especially, during the process of heat conduction, a gel-to-fluid phase transition of the membrane may occur, which plays a crucial role in determining the deformation behavior of the membrane. Moreover, it is found that the membrane lipids in the two leaflets exhibit obvious and asymmetric molecular-level responses to heat flux, characterized by significant changes in packing states (e.g., the order parameter of lipid tails and area per lipid) and possible interdigitation between lipids. Furthermore, the thermal-controlled wrapping effect is tightly linked to the properties of NPs (e.g., size, NP-lipid affinity) and lipid species. Our findings are valuable for comprehending the thermal-regulated cellular internalization of NPs and offer insights into devising strategies to precisely modulate NP endocytosis by exploiting the interplay between heating and NP properties.

Investigation on protein dimerization and evaluation of medicine effects by single molecule force spectroscopy

Monitoring the dimerization state of the mesenchymal-epithelial transition factor (Met) was essential for in-depth understanding of the tumor signal transduction network. At present, the dimerization activation pathway of Met protein was mainly studied at the macro level, while the research at the single molecule level was far from comprehensive. Herein, the dimerization activation of Met protein's extracellular domain induced by ligand hepatocyte growth factor (HGF) was dynamically studied by single-molecule force spectroscopy. Met protein was immobilized on a biomimetic lipid membrane for ensuring its physiological environment, and then the Met dimers were recognized by bivalent probe which was formed by two Met-binding aptamers. Then the dimeric state of Met protein could be distinguished from monomeric state of Met protein through some parameters, (such as unimodal ratio, bimodal ratio and separation work). The unimodal indicates the occurrence of single molecule binding event, and the bimodal represents the occurrence of double binding event (also represents the presence of Met dimer). Before HGF treatment, most of the Met protein on the lipid membrane was still in the form of monomer, so the unimodal ratio in the force curve was larger (78.8 ± 5.2%), and the bimodal ratio was smaller (17.0 ± 4.1%). After HGF treatment, the unimodal ratio decreased to 54.0 ± 7.4%, and the bimodal ratio increased to 43.2 ± 7.3%. It was due to the formation of dimers after the binding of Met protein on the fluidity lipid membrane with HGF. In addition, the average separation work increased to about 2 times after HGF treatment. Given that studies of Met protein dimerization inhibitors have contributed to the development of more potent and safe inhibitors to significantly inhibit tumor metastasis, the effects of different medicines (including anticoagulant medicines, different antibiotics and anti-cancer medicines) on the dimerization activation of Met protein were then explored by the platform described above. The results showed that anticoagulant medicines heparin and its analogs can significantly inhibit HGF-mediated Met protein activation, while different antibiotics and anticancer medicines had no significant effect on the dimerization of Met protein. This work provided a platform for studying protein dimerization as well as for screening Met protein dimerization inhibitors at the single-molecule level.

Spatiotemporal tracking of the transport of RNA nano-drugs: from transmembrane to intracellular delivery

The popularity of RNA nanoparticles (RNPs) has risen rapidly during the past decade due to the development of RNA nanotechnology. Understanding the fast dynamic process of cell entry and intracellular delivery of RNPs is essential for the design of intelligent therapeutic RNA nano-drugs and mRNA vaccines.How the interaction between the membrane and target ligand of RNPs influences the cell entry, and how the dynamic mechanism of RNPs takes place in different organelles remain ill-defined. Herein, the cell entry of Antimir21-RNP-Apt is monitored using a force tracing technique with a high spatiotemporal resolution at the single particle level, the specific interaction of Apt and EGFR promotes the cell entry efficiency and achieves long-lasting curative effects. Furthermore, the intracellular delivery pathway through different organelles is discovered using fluorescence tracking, and the low motility in early endosomes and the high motility in late endosomes are analyzed. This report provides key strategies for engineering RNA nanomedicines and facilitating clinical translation.