Welded Gold Nanoparticle Assemblies Defined Plasmonic Coupling.

Nanoparticle assemblies with interparticle ohmic contacts are crucial for nanodevice fabrication. Despite tremendous progress in DNA-programmable nanoparticle assemblies, seamlessly welding discrete components into welded continuous three-dimensional (3D) configurations remains challenging. Here, we introduce a single-stranded DNA-encoded strategy to customize welded metal nanostructures with tunable morphologies and plasmonic properties. We demonstrate the precise welding of gold nanoparticle assemblies into continuous metal nanostructures with interparticle ohmic contacts through chemical welding in solution. We find that the welded gold nanoparticle assemblies show a consistent morphology with welded efficiency over 90%, such as the rod-like, triangular, and tetrahedral metal nanostructures. Next, we show the versatility of this strategy by welding gold nanoparticle assemblies of varied sizes and shapes. Furthermore, the experiment and simulation show that the welded gold nanoparticle assemblies exhibit defined plasmonic coupling. This single-stranded DNA encoded welding system may provide a new route for accurately building functional plasmonic nanomaterials and devices.

Memristor-Based Bionic Tactile Devices: Opening the Door for Next-Generation Artificial Intelligence.

Bioinspired tactile devices can effectively mimic and reproduce the functions of the human tactile system, presenting significant potential in the field of next-generation wearable electronics. In particular, memristor-based bionic tactile devices have attracted considerable attention due to their exceptional characteristics of high flexibility, low power consumption, and adaptability. These devices provide advanced wearability and high-precision tactile sensing capabilities, thus emerging as an important research area within bioinspired electronics. This paper delves into the integration of memristors with other sensing and controlling systems and offers a comprehensive analysis of the recent research advancements in memristor-based bionic tactile devices. These advancements incorporate artificial nociceptors and flexible electronic skin (e-skin) into the category of bio-inspired sensors equipped with capabilities for sensing, processing, and responding to stimuli, which are expected to catalyze revolutionary changes in human-computer interaction. Finally, this review discusses the challenges faced by memristor-based bionic tactile devices in terms of material selection, structural design, and sensor signal processing for the development of artificial intelligence. Additionally, it also outlines future research directions and application prospects of these devices, while proposing feasible solutions to address the identified challenges.

Aptamer-Modified Nb2C Multifunctional Nanomedicine for Targeted Photothermal/Chemotherapy Combined Therapy of Tumor.

The poor delivery efficiency of nanotherapeutic drugs and their potential off-target toxicity significantly limit their effectiveness and extensive application. An active targeting system with high efficiency and few side effects is a promising strategy for tumor therapy. Herein, a multifunctional nanomedicine Nb2C-PAA-DOX@Apt-M (NDA-M) was constructed for targeted photothermal/chemotherapy (PTT/CHT) combined tumor therapy. The specific targeting ability of aptamer could effectively enhance the absorption of nanomedicine by the MCF-7 cell. By employing Apt-M, the NDA-M nanosheets demonstrated targeted delivery to MCF-7 cells, resulting in enhanced intracellular drug concentration. Under 1060 nm laser irradiation, a rapid temperature increase of the NDA-M was observed within the tumor region to achieve PTT. Meanwhile, CHT was triggered when DOX release was induced by photothermal/acid stimulation. The experimental results demonstrated that aptamer-mediated targeting achieved enhanced PTT/CHT efficacy both in vitro and in vivo. Notably, NDA-M induced complete ablation of solid tumors without any adverse side effects in mice. This study demonstrated new and promising tactics for the development of nanomaterials for targeted tumor therapy.

Ultrasound-guided techniques for managing length- unstable femoral shaft fractures in children.

OBJECTIVE: The management of length-unstable femoral shaft fractures(LUFSFs) in pediatric patients is still controversial. This study aims to explore the clinical efficacy of ultrasound-guided closed reduction combined with external fixation for treating LUFSFs in children. METHODS: We conducted a retrospective analysis of clinical data from 19 pediatric patients with LUFSFs who underwent ultrasound-guided closed reduction and external fixation between January 2018 and January 2023. Ultrasound was employed not only to facilitate closed reduction of the fracture but also to guide real-time insertion of Schanz pins and monitor pin length as it traversed the opposite cortex. Surgical time, intraoperative fluoroscopy count, hospital stay length, fracture fixation duration, complication incidence, fracture reduction quality at the final follow-up were recorded. RESULTS: The patients' average age was 7.5 years( range: 5 to 11 years). The mean surgical duration was 70.4 min (range: 48-105 min), and the average intraoperative fluoroscopy count was 6.5 (range: 2-16). Fracture fixation lasted an average of 10.9 weeks (range: 7-20 weeks). All patients were followed up for more than one year. 6 cases of superficial pin tract infection occurred, which resolved with oral antibiotics and enhanced needle tract care. No deep infections were observed. Temporary stiffness of the knee joint was observed in 2 patients. According to Flynn's efficacy evaluation system, fracture reduction quality at the final follow-up was rated as excellent in 11 cases and satisfactory in 8 cases, yielding a combined success rate of 100% (19/19). CONCLUSIONS: The technique of ultrasound-guided closed reduction combined with external fixation offers favorable outcomes for children aged 5 to 11 years with LUFSFs, reducing reliance on fluoroscopic guidance.

DNA-mediated regioselective encoding of colloids for programmable self-assembly.

How far we can push chemical self-assembly is one of the most important scientific questions of the century. Colloidal self-assembly is a bottom-up technique for the rational design of functional materials with desirable collective properties. Due to the programmability of DNA base pairing, surface modification of colloidal particles with DNA has become fundamental for programmable material self-assembly. However, there remains an ever-lasting demand for surface regioselective encoding to realize assemblies that require specific, directional, and orthogonal interactions. Recent advances in surface chemistry have enabled regioselective control over the formation of DNA bonds on the particle surface. In particular, the structural DNA nanotechnology provides a simple yet powerful design strategy with unique regioselective addressability, bringing the complexity of colloidal self-assembly to an unprecedented level. In this review, we summarize the state-of-art advances in DNA-mediated regioselective surface encoding of colloids, with a focus on how the regioselective encoding is introduced and how the regioselective DNA recognition plays a crucial role in the self-assembly of colloidal structures. This review highlights the advantages of DNA-based regioselective modification in improving the complexity of colloidal assembly, and outlines the challenges and opportunities for the construction of more complex architectures with tailored functionalities.

Kynurenic acid blunts A1 astrocyte activation against neurodegeneration in HIV-associated neurocognitive disorders.

Despite extensive astrocyte activation in patients suffering from HIV-associated neurocognitive disorders (HAND), little is known about the contribution of astrocytes to HAND neuropathology. Here, we report that the robust activation of neurotoxic astrocytes (A1 astrocytes) in the CNS promotes neuron damage and cognitive deficits in HIV-1 gp120 transgenic mice. Notably, knockout of α7 nicotinic acetylcholine receptors (α7nAChR) blunted A1 astrocyte responses, ultimately facilitating neuronal and cognitive improvement in the gp120tg mice. Furthermore, we provide evidence that Kynurenic acid (KYNA), a tryptophan metabolite with α7nAChR inhibitory properties, attenuates gp120-induced A1 astrocyte formation through the blockade of α7nAChR/JAK2/STAT3 signaling activation. Meanwhile, compared with gp120tg mice, mice fed with tryptophan showed dramatic improvement in cognitive performance, which was related to the inhibition of A1 astrocyte responses. These initial and determinant findings mark a turning point in our understanding of the role of α7nAChR in gp120-mediated A1 astrocyte activation, opening up new opportunities to control neurotoxic astrocyte generation through KYNA and tryptophan administration.

Microcrack Arrays in Dense Graphene Films for Fast-Ion-Diffusion Supercapacitors.

Laminated graphene film has great potential in compact high-power capacitive energy storage owing to the high bulk density and opened architecture. However, the high-power capability is usually limited by tortuous cross-layer ion diffusion. Herein, microcrack arrays are fabricated in graphene films as fast ion diffusion channels, converting tortuous diffusion into straightforward diffusion while maintaining a high bulk density of 0.92 g cm-3 . Films with optimized microcrack arrays exhibit sixfold improved ion diffusion coefficient and high volumetric capacitance of 221 F cm-3 (240 F g-1 ), representing a critical breakthrough in optimizing ion diffusion toward compact energy storage. This microcrack design is also efficient for signal filtering. Microcracked graphene-based supercapacitor with 30 µg cm-2  mass loading exhibits characteristic frequency up to 200 Hz with voltage window up to 4 V, showing high promise for compact, high-capacitance alternating current (AC) filtering. Moreover, a renewable energy system is conducted using microcrack-arrayed graphene supercapacitors as filter-capacitor and energy buffer, filtering and storing the 50 Hz AC electricity from a wind generator into the constant direct current, stably powering 74 LEDs, demonstrating enormous potential in practical applications. More importantly, this microcracking approach is roll-to-roll producible, which is cost-effective and highly promising for large-scale manufacture.

Micropatterned Fluororubber-Based Dry Adhesive for Pan-Semiconductor Production Line with Complicated Operating Conditions.

The efficient and safe manipulation of precision materials (such as thin and fragile wafers and glass substrates for flat panel displays) under complicated operating conditions with vacuum, high temperature, and low preload stress is an essential task for pan-semiconductor production lines. However, current manipulation approaches such as suction-based gripping (invalid under vacuum conditions) and mechanical clamping (stress concentration at the contact interfaces) are challenged to satisfy such complex requirements. Herein, fluororubber (FKM) is employed as an adhesive material to overcome such challenges due to its outstanding thermostability, availability under vacuum environments, and high adhesion at low contacting preloads. However, the adhesion of the FKM film decreases significantly with increasing temperature (decrease by 84.83% at 245 °C). Consequently, a micropatterned FKM-based dry adhesive (MFA) fabricated by laser etching is developed. The experimental results reveal that MFAs are efficient in restraining adhesion attenuation at high temperatures (minimum 15% decrease at 245 °C). The numerical analysis and in situ observations reveal the mechanism of the MFAs in restraining adhesion attenuation. The contamination-free and high adhesion at low contacting preload of MFAs can be of great interest in pan-semiconductor production lines that require complicated operating conditions on temperature, vacuum, and interface stress.

Towards atom manufacturing with framework nucleic acids.

Atom manufacturing has become a blooming frontier direction in the field of material and chemical science in recent years, focusing on the fabrication of functional materials and devices with individual atoms or with atomic precision. Framework nucleic acids (FNAs) refer to nanoscale nucleic acid framework structures with novel properties distinct from those of conventional nucleic acids. Due to their ability to be precisely positioned and assembled at the nanometer or even atomic scale, FNAs are ideal materials for atom manufacturing. They hold great promise for the bottom-up construction of electronic devices by precisely arranging and integrating building blocks with atomic or near-atomic precision. In this review, we summarize the progress of atom manufacturing based on FNAs. We begin by introducing the atomic-precision construction of FNAs and the intrinsic electrical properties of DNA molecules. Then, we describe various approaches for the fabrication of FNAs templated materials and devices, which are classified as conducting, insulating, or semiconducting based on their electrical properties. We highlight the role of FNAs in the fabrication of functional electronic devices with atomic precision, as well as the challenges and opportunities for atom manufacturing with FNAs.

Actin cytoskeleton aggregation involves the water channel protein aquaporin 1-mediated human chondrocyte degeneration.

Water metabolism and actin cytoskeleton remoulding act as essential characters in the process of osteoarthritis (OA). However, the relation between water channel protein aquaporin 1 (AQP1) and actin filament during chondrocytes (CHs) degeneration is not evident. Therefore, the present study aimed to evaluate the role of actin remoulding in the AQP1 mediated CHs degeneration. Primary CHs were collected from human hip cartilage and were degenerated from long-time monolayer culture or IL-1ß stimulation. Besides, the CHs were transfected with AQP1­specific siRNA or vectors to mediate the AQP1 gene expression. The potent inhibitor of actin polymerization Cytochalasin D was also supplemented during culture. RT-PCR was performed to determine the relative gene expression. AQP1 and F-actin fluorescence staining were performed to determine the AQP1 and F-actin organization. Moreover, the cell area and viability were also analyzed. AQP1 and F-actin organization were both increased during seven days' CHs culture or three days' IL-1ß stimulation. Silencing of AQP1 prevented the cell area spreading and degenerated phenotype of CHs with suppression of F-actin aggregation in both natural or IL-1ß-caused inflammatory-related degeneration. Besides, upregulating the AQP1 in the CHs via gene editing promoted the cell area spreading, and F-actin accumulation, and accelerated the CHs degeneration, which can be alleviated by Cytochalasin D treatment. These findings suggested that AQP1-mediated human CHs degeneration is related to F-actin aggregation.

Prognostic role of pretreatment 18F-FDG PET/CT and hematological parameters in relapsed/refractory Hodgkin lymphoma patients treated with immune checkpoint inhibitors and chemotherapy: a dual-center cohort study.

BACKGROUND: The combination of anti-programmed death-1 antibodies and chemotherapy is effective; however, there are no reliable outcome prediction factors. We investigated the prognostic factors based on 18Fluorine-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) quantitative and hematological parameters to predict progression-free survival (PFS) in relapsed/refractory classical Hodgkin lymphoma (R/R cHL) patients treated with immune checkpoint inhibitors (ICIs) and chemotherapy. METHODS: This retrospective study included 31 patients who underwent 18F-FDG PET/CT before and during treatment. Pretreatment metabolic and hematological parameters were evaluated using Cox regression analysis to identify predictors of PFS. Based on the cut-off values calculated using the receiver operating characteristic (ROC) curve, patients were classified into low-, intermediate-, and high-risk groups. Kaplan-Meier curves and the log-rank test were used to compare survival differences between the groups. RESULTS: Cox multivariable analysis indicted that the treatment response based on Lactate dehydrogenase (LDH), Lugano classification and SUVmax were independent predictors of PFS (P = 0.004, 0.007 and 0.039, respectively). The optimal cut-off values for SUVmax and LDH were 11.62 and 258.5 U/L, respectively (P < 0.01). Survival curves showed that LDH ≥ 258.5U/L and SUVmax ≥ 11.62 were correlated to shorter PFS (P < 0.001, P = 0.003, respectively). The differences in PFS between the low-, intermediate-, and high-risk groups were statistically significant (P = 0.0043). CONCLUSION: In R/R cHL patients treated with ICIs and chemotherapy, Lugano classification, SUVmax, and LDH were significantly correlated with PFS. The combination of metabolic and hematological parameters predicts PFS and may help to improve patient selection.

Deep reinforcement learning-based approach for rumor influence minimization in social networks.

Spreading malicious rumors on social networks such as Facebook, Twitter, and WeChat can trigger political conflicts, sway public opinion, and cause social disruption. A rumor can spread rapidly across a network and can be difficult to control once it has gained traction.Rumor influence minimization (RIM) is a central problem in information diffusion and network theory that involves finding ways to minimize rumor spread within a social network. Existing research on the RIM problem has focused on blocking the actions of influential users who can drive rumor propagation. These traditional static solutions do not adequately capture the dynamics and characteristics of rumor evolution from a global perspective. A deep reinforcement learning strategy that takes into account a wide range of factors may be an effective way of addressing the RIM challenge. This study introduces the dynamic rumor influence minimization (DRIM) problem, a step-by-step discrete time optimization method for controlling rumors. In addition, we provide a dynamic rumor-blocking approach, namely RLDB, based on deep reinforcement learning. First, a static rumor propagation model (SRPM) and a dynamic rumor propagation model (DRPM) based on of independent cascade patterns are presented. The primary benefit of the DPRM is that it can dynamically adjust the probability matrix according to the number of individuals affected by rumors in a social network, thereby improving the accuracy of rumor propagation simulation. Second, the RLDB strategy identifies the users to block in order to minimize rumor influence by observing the dynamics of user states and social network architectures. Finally, we assess the blocking model using four real-world datasets with different sizes. The experimental results demonstrate the superiority of the proposed approach on heuristics such as out-degree(OD), betweenness centrality(BC), and PageRank(PR).

Single-Stranded DNA-Encoded Gold Nanoparticle Clusters as Programmable Enzyme Equivalents.

Nanozymes have emerged as a class of novel catalytic nanomaterials that show great potential to substitute natural enzymes in various applications. Nevertheless, spatial organization of multiple subunits in a nanozyme to rationally engineer its catalytic properties remains to be a grand challenge. Here, we report a DNA-based approach to encode the organization of gold nanoparticle clusters (GNCs) for the construction of programmable enzyme equivalents (PEEs). We find that single-stranded (ss-) DNA scaffolds can self-fold into nanostructures with prescribed poly-adenine (polyA) loops and double-stranded stems and that the polyA loops serve as specific sites for seed-free nucleation and growth of GNCs with well-defined particle numbers and interparticle spaces. A spectrum of GNCs, ranging from oligomers with discrete particle numbers (2-4) to polymer-like chains, are in situ synthesized in this manner. The polymeric GNCs with multiple spatially organized nanoparticles as subunits show programmable peroxidase-like catalytic activity that can be tuned by the scaffold size and the inter-polyA spacer length. This study thus opens new routes to the rational design of nanozymes for various biological and biomedical applications.

Risk factors for rib metastases of lung cancer patients with high-uptake rib foci on 99Tcm-MDP SPECT/CT.

BACKGROUND: 99Tcm-MDP SPECT/CT is widely used to diagnose early bone metastasis. Ribs are high-risk bone metastasis sites, while few study is related to ribs. The study is to investigate the risk factors of rib metastases in lung cancer patients. METHODS: We retrospectively analyzed the patients' clinical characteristics and SPECT/CT imaging features. The patients were divided into a rib metastasis group (108 cases) and a non-rib metastasis group (103 cases). RESULTS: In 211 patients, rib metastases were closely related to tumor markers, T stage, N stage, clinical staging, lymph node involvement, number of rib foci, localization on rib and foci type (P < 0.05). In 93 patients with pure rib foci, rib metastases were affected by clinical staging, lymph node involvement, localization on the rib and primary lung cancer localization (P < 0.001, 0.038, < 0.001, 0.034, respectively). In 100 patients with a solitary rib focus, rib metastases were associated with clinical staging, localization on the rib, and lymph node involvement (P < 0.001, 0.001, and 0.014, respectively). In all 633 rib foci, localization on the rib was an effective risk factor for rib metastases (P < 0.001). CONCLUSIONS: Patients with increased tumor markers, stage IV lung adenocarcinoma and multiple rib foci located ipsilaterally with the primary lung tumor, or rib foci accompanied other bone foci are more likely to develop rib metastasis. Patients with pure rib foci or a solitary rib focus, especially in the anterior rib with negative lymph node involvement, have a low probability of rib metastasis.

Nanoscopic Imaging of Nucleolar Stress Enabled by Protein-Mimicking Carbon Dots.

The nucleolus is a central hub for coordinating cellular stress responses during cancer development and treatment. Accurate identification of nucleolar stress response is crucially desired for nucleolus-based diagnostics and therapeutics but technically challenging due to the need to address the ultrastructural analysis. Here, we report a protein-like CD with the integration of fluorescent blinking domains and RNA-binding motifs, which offers the ability to perform enhanced super-resolution imaging of the nucleolar ultrastructure. This image allows extraction of multidimensional information from the nucleolus for accurate distinguishment of different cells from the same cell types. Furthermore, we demonstrate for the first time this CD-depicted nucleolar ultrastructure as a sensitive hallmark to identify and discriminate subtle responses to various stressors as well as to afford RNA-related information that has been inaccessible by conventional immunofluorescence methods. This protein-mimicking CD could become a broadly useful probe for nucleolar stress studies in cell diagnostics and therapeutics.

A propensity score-matched analysis of laparoscopic versus open surgical radical resection for gastric gastrointestinal stromal tumor.

Background: Surgery is the mainstay of treatment for gastric gastrointestinal stromal tumours (GIST). However, the choice of surgical approach for gastric GIST remains controversial. Aims and Objectives: To evaluate the short- and long-term efficacies of laparoscopic surgery versus conventional open surgery for gastric GIST. Materials and Methods: We retrospectively reviewed 148 patients with gastric GIST at our hospital between January 2013 and January 2020. The patients were categorised into the following two groups based on the surgery performed: The laparoscopic surgery group (LG) and the open surgery group (OG). Differences in the tumour size, surgical procedures and modified National Institutes of Health classification were statistically significant. To balance the intergroup confounders, we performed 1:1 propensity score matching (PSM). Results: A total of 104 patients were selected after PSM (52 in each group). We focused on the short- and long- term outcomes of patients. The baseline information was balanced between the two groups after PSM. The LG benefited from the advantages of a minimally invasive surgery (faster gastrointestinal function recovery, shorter time to drainage tube removal, less blood loss and shorter hospitalisation period), however, it also had high treatment costs. Moreover, both laparoscopic and open surgeries resulted in similar intra-operative and post-operative complications rates, overall survival time and disease-free survival time. Conclusion: Laparoscopic resection is feasible and oncologically safe for GIST. However, more prospective studies are required to confirm the findings.

DNA Origami-Encoded Integration of Heterostructures.

Integrating dissimilar materials at the nanoscale is crucial for modern electronics and optoelectronics. The structural DNA nanotechnology provides a universal platform for precision assembly of materials; nevertheless, heterogeneous integration of dissimilar materials with DNA nanostructures has yet to be explored. We report a DNA origami-encoded strategy for integrating silica-metal heterostructures. Theoretical and experimental studies reveal distinctive mechanisms for the binding and aggregation of silica and metal clusters on protruding double-stranded DNA (dsDNA) strands that are prescribed on the DNA origami template. In particular, the binding energy differences of silica/metal clusters and DNA molecules underlies the accessibilities of dissimilar material areas on DNA origami. By programming the densities and lengths of protruding dsDNA strands on DNA origami, silica and metal materials can be independently deposited at their predefined areas with a high vertical precision of 2 nm. We demonstrate the integration of silica-gold and silica-silver heterostructures with high site addressability. This DNA nanotechnology-based strategy is thus applicable for integrating various types of dissimilar materials, which opens up new routes to bottom-up electronics.

microRNA-377 acts as a suppressor in esophageal squamous cell carcinoma through CBX3-dependent P53/P21 pathway.

Stem cells play pivotal roles in esophageal squamous cell carcinoma (ESCC) recurrence and metastasis. The self-renewal ability of stem cells was associated with specific microRNAs (miRs). Herein, we identified the effects of miR-377 on ESCC stem cell activities. First, the expression of miR-377 in ESCC and adjacent normal tissues was determined. The relationship between miR-377 and chromobox protein homolog 3 (CBX3) was assessed by a dual-luciferase reporter gene assay. miR-377 was overexpressed or inhibited in ESCC stem cells to explore its role in ESCC. To further investigate the mechanism of miR-377 in ESCC, cells were introduced with short hairpin RNA against CBX3 or pifithrin-α (inhibitor of P53 pathway). Besides, the expression of P21, P53, CD133, CD13, Nanog, sex determining region Y-Box 2 (Sox2), and octamer-binding transcription factor 4 (Oct4), cell sphere formation, colony formation, and proliferation were evaluated respectively. Finally, limiting dilution assay in vivo and tumor xenograft in nude mice were conducted to confirm the roles of miR-377 in vivo. miR-377 was poorly expressed in ESCC. Overexpression of miR-377 could suppress the stem-like trait of ESCC as well as the tumor growth in vivo. miR-377 targeted CBX3 to activate the P53/P21 pathway. Besides, the expression of stem-like markers including CD133, CD13, Oct4, Sox2, and Nanog was decreased, and the abilities of cell sphere formation, colony formation, proliferation, and tumorigenicity were significantly reduced by overexpressing miR-377 or silencing CBX3. The results were reversed after inactivating the P53/P21 pathway. In summary, upregulation of miR-377 inhibits the self-renewal of ESCC stem cells by inhibiting CBX3 expression and promoting activation of the P53/P21 pathway.

Carbon Dot Blinking Enables Accurate Molecular Counting at Nanoscale Resolution.

Accurate counting of single molecules at nanoscale resolution is essential for the study of molecular interactions and distribution in subcellular fractions. By using small-sized carbon dots (CDs), we have now developed a quantitative single-molecule localization microscopy technique (qSMLM) based on spontaneous blinking to count single molecules with a localization precision of 10 nm, which can be accomplished on conventional microscopes without sophisticated laser control. We explore and adapt the blinking of CDs with diverse structures and demonstrate a counting accuracy of >97% at a molecular density of 500 per µm2. When applied to G-protein coupled receptors on a cell membrane, we discriminated receptor oligomerization and clustering and revealed ligand-regulated receptor distribution patterns. This is the first example of adapting nanoparticle self-blinking for molecular counting, and this demonstrates the power of CDs as SMLM probes to reliably decipher sub-diffraction structures that mediate crucial biological functions.

Deep-Learning-Assisted Single-Molecule Tracking on a Live Cell Membrane.

Single-molecule fluorescence imaging is a powerful tool to study protein function by tracking molecular position and distribution, but the precise and rapid identification of dynamic molecules remains challenging due to the heterogeneous distribution and interaction of proteins on the live cell membrane. We now develop a deep-learning (DL)-assisted single-molecule imaging method that can precisely distinguish the monomer and complex for rapid and real-time tracking of protein interaction. This DL-based model, which comprises convolutional layers, max pooling layers, and fully connected layers, is trained to reach an accuracy of >98% for identifying monomer and complex. We use this method to investigate the dynamic process of chemokine receptor CXCR4 on the live cell membrane during the early signaling stage. The results show that, upon ligand activation, the CXCR4 undergoes a dynamic process of forming a receptor complex. We further demonstrate that the CXCR4 complex tends to be internalized at 2.5-fold higher rate into the cell interior than the monomer via the clathrin-dependent pathway. This study is the first example to scrutinize the early signaling process of CXCR4 at the single-molecule level on the live cell membrane. We envision that this DL-assisted imaging method would be a broadly useful technique to study more protein families for elucidating their physiological and pathological functions.