Confocal Fluorescence Imaging Research Articles

IR-780 Dye-based Targeting of Cancer-associated Fibroblasts Improves Cancer Immunotherapy by Increasing Intra-tumoral T Lymphocytes Infiltration.

Immune-checkpoint inhibitors (ICIs) against programmed death (PD)-1/PD-L1 pathway immunotherapy have been demonstrated to be effective in only a subset of patients with cancer, while the rest may exhibit low response or may develop drug resistance after initially responding. Previous studies have indicated that extensive collagen-rich stroma secreted by cancer-associated fibroblasts (CAFs) within the tumor microenvironment is one of the key obstructions of the immunotherapy for some tumors by decreasing the infiltrating cytotoxic T cells. However, there is still a lack of effective therapeutic strategies to control the extracellular matrix by targeting CAFs. The enhanced uptake of IR-780 by CAFs was assessed by using in vivo or ex vivo nearinfrared fluorescence imaging, confocal NIR fluorescent imaging, and CAFs isolation testing. The fibrotic phenotype down-regulation effects and in vitro CAFs killing effect of IR-780 were tested by qPCR, western blot, and flow cytometry. The in vivo therapeutic enhancement of anti-PD-L1 by IR-780 was evaluated on EMT6 and MC38 subcutaneous xenograft mice models. IR-780 has been demonstrated to be preferentially taken up by CAFs and accumulate in the mitochondria. Further results identified low-dose IR-780 to downregulate the fibrotic phenotype, while high-dose IR-780 could directly kill both CAFs and EMT6 cells in vitro. Moreover, IR-780 significantly inhibited extracellular matrix (ECM) protein deposition in the peri-tumoral stroma on subcutaneous EMT6 and MC38 xenografts, which increased the proportion of tumor-infiltrating lymphocytes (TILs) in the deep tumor and further promoted anti-PD-L1 therapeutic efficacy. This work provides a unique strategy for the inhibition of ECM protein deposition in the tumor microenvironment by targeted regulating of CAFs, which destroys the T cell barrier and further promotes tumor response to PD-L1 monoclonal antibody. IR-780 has been proposed as a potential therapeutic small-molecule adjuvant to promote the effect of immunotherapy.

Supported Biomembrane Systems Incorporating Multiarm Polymers and Bioorthogonal Tethering.

To functionalize interfaces with supported biomembranes and membrane proteins, the challenge is to build stabilized and supported systems that mimic the native lipid microenvironment. Our objective is to control substrate-to-biomembrane spacing and the tethering chemistry so proteoliposomes can be fused and conjugated without perturbation of membrane protein function. Furthermore, the substrates need to exhibit low protein and antibody nonspecific binding to use these systems in assays. We have employed protein orthogonal coupling schemes in concert with multiarm poly(ethylene glycol) (PEG) technology to build supported biomembranes on microspheres. The lipid bilayer structures and tailored substrates of the microsphere-supported biomembranes were analyzed via flow cytometry, confocal fluorescence, and super-resolution imaging microscopy, and the lateral fluidity was quantified using fluorescence recovery after photobleaching (FRAP) techniques. Under these conditions, the 4-arm-PEG20,000-NH2 based configuration gave the most desirable tethering system based on lateral diffusivity and coverage.

Ingenious designed a HER2-Specific macrophage biomimetic multifunctional nanoplatform for enhanced bio-photothermal synergistic therapy in HER2 positive breast cancer

Photothermal therapy (PTT) has garnered extensive attention as an efficient strategy for cancer therapy. Unfortunately, there are currently no suitable photothermal agents (PTAs) capable of effectively treating HER2-positive breast cancer (HER2+ BC) due to the challenges in addressing blood circulation and tumor accumulation. Here, we propose a HER2-specific macrophage biomimetic nanoplatform IR820@ZIF-8@EM (AMBP) for enhanced bio-photothermal therapy of HER2+ BC. An anti-HER2 antibody was expressed in engineered macrophages using the transmembrane expression technique. As an efficient PTAs, IR820 dyes were assembled into ZIF-8 as to develop a “nano-thermal-bomb”. Homology modeling methods support that the expressed anti-HER2 antibody can specifically recognize the HER2 receptor. Moreover, antibody-dependent cell-mediated cytotoxicity can also be induced in HER2+ BC cells by AMBP. In vitro fluorescence confocal imaging showed that AMBP promoted the uptake of HER2+ cancer cells while in vivo anti-tumor experiments demonstrated that AMBP efficiently accumulates in the tumor regions. Finally, under spatiotemporally controlled near-infrared (NIR) irradiation, three of the six tumors were eradicated in AMBP-treated mice, demonstrating a safe and effective strategy. In conclusion, our research opens a new paradigm for antibody-specific macrophage, and it is expected that these characteristics will have substantial clinical translation potential for BC treatment.

A near-infrared fluorescent probe for the detection of Cu2+ in Chinese herbal medicine and imaging in living cells

Copper is one of the common among the heavy metal pollution in Chinese herbal medicine (CHM). So, it is essential to develop rapid and accurate testing method to quantify the Cu2+ content in CHM. Herein, we prepared a coordination-based near-infrared fluorescent probe (NRh6G-FA) by introducing a hemicyanine dye in rhodamine 6G scaffold. NRh6G-FA had a high sensitivity, anti-interference performance, fast response (within 60 s), visualization (from light yellow to green) for Cu2+ and excellent sensing performance for the detection of Cu2+ at low concentrations (LOD = 0.225 μM). The most likely mechanism was verified on the basis of Job’s plot, ESI-HRMS and DFT calculations. NRh6G-FA could be successfully applied for the detection and “naked eye” recognition of Cu2+ in CHM samples. Moreover, NRh6G-FA was used to visualize Cu2+ in living MCF-7 cells by confocal fluorescence imaging.

Reactive gliosis in adult zebrafish telencephalon following daily nanoplastic consumption

Background: Polystyrene nanoplastics are one of the most pervasive plastic contaminates and have been shown to infiltrate multiple mediums that are ingested by humans including air, food and water. Additionally, polystyrene nanoparticles have been shown to cross the blood brain barrier (BBB), the brain's first defense against pathogens and toxins. Following insult, the neuronal immune network enters a pro-inflammatory state referred to as reactive gliosis. Reactive gliosis is characterized by the recruitment of microglia and astroglia, the resident immune cells of the central nervous system (CNS), into a pro-inflammatory state that leads to the release of cytokines and the creation of a glial scar. This cascade of morphological and chemical changes in the CNS following prolonged insult can induce significant damage to the brain. Experiments in rodent models and cell culture indicate that exposure to plastic nanoparticles can induce inflammatory processes in the brain. This has been relatively underexplored in the zebrafish model system. In the current study we investigate the hypothesis that daily exposure to nanoplastics via the food chain can induce a chronic inflammatory state in the brain that may lead to permanent brain damage. The purpose of the current study is to investigate reactive gliosis in the telencephalon of adult zebrafish following the consumption of polystyrene-contaminated food. Methods: One thousand brine shrimp ( Artemia) per zebrafish were collected and incubated in artificial sea water (ASW) containing 44 nanometer (nm) fluorescent polystyrene (nPS) at a concentration of 0.15 milligrams (mg) nPS/50 milliliters (mL) ASW for 24 hours. Zebrafish were fed polystyrene-enriched brine shrimp once per day for fourteen consecutive days. On day fifteen, the telencephalon was removed and homogenized for western blot analysis. Reactive microglia were measured using the monoclonal 4C4 antibody which has been found to label reactive microglia. Reactive astrogliosis was quantified by measuring glial fibrillary acidic protein (GFAP), a marker for reactive astrocytes. Results: Confocal fluorescent imaging and spectrophotometry showed that Artemia were enriched with red-fluorescently tagged polystyrene nanoplastics. Additionally, the quantity of nanoplastic within one thousand shrimp was estimated to be 5 +/- 1.9 micrograms. There was an observed increase in 4C4 normalized to actin. Increases in GFAP were also detected. These data indicate that reactive gliosis by microglia and astroglia was enhanced in the zebrafish telencephalon after consuming polystyrene-contaminated food for fourteen consecutive days. Funding is supported by the Georgia Southern Department of Biology and Mercer University College of Medicine. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Long-Term Intrauterine Hypoxia Disrupts Calcium Sparks in Middle Cerebral Arterial Myocytes of Fetal Sheep

Local activation of ryanodine receptors (RyRs) on the sarcoplasmic reticulum in vascular smooth muscle cells (VSMCs) generates rapid subcellular changes in cellular Ca2+ that are commonly known as Ca2+ sparks. These Ca2+ sparks are well regarded for their role in the autoregulation of vascular contractility and cerebral blood flow through activation of potassium channels and feedback modulation of the membrane potential. Gestational hypoxia disrupts cerebrovascular development, increasing the risk of intracranial hemorrhage and stroke in the newborn. Due to the role of RyR’s in regulating neonatal cerebrovascular blood flow, understanding intracellular Ca2+ release patterns in VSMCs can offer insight into hypoxia-related perinatal cerebrovascular disease. The central aim of this study is to determine the extent to which gestational hypoxia disrupts RyR activity. This was achieved through examination of RyR activity in VSMCs of fetal ovine middle cerebral arteries (MCAs). MCAs were isolated from term fetal sheep (~140 days of gestation) delivered by cesarean section from ewes held at low- (700 m) and high-altitude conditions (3801 m) for 100+ days of gestation. Arteries were bathed in a physiological buffer with 5 mm K+ (control) or were treated with either 30 mM K+ (30K), to depolarize myocytes and increase Ca2+ spark events, in the presence or absence of 10 μM ryanodine, to block RyR mediated Ca2+ release. Ca2+ spark activity was measured in situ using line scan confocal microscopy fluorescence imaging techniques. Automated analysis of Ca2+ sparks in the records was conducted using SparkLab 5.8. Membrane depolarization with 30K increased Ca2+ spark activity. Long term hypoxia, however, reduced spark activity in the 30K group. Ryanodine attenuated Ca2+ spark activity in both low- and high-altitude groups. Hypoxia’s influence on the spatial and temporal aspects of Ca2+ sparks in fetal myocytes varied. These findings corroborate previous evidence demonstrating that long-term hypoxia attenuates Ca2+ spark activity. The disruption in Ca2+ spark activity could impact brain blood flow in the neonate, potentially impacting brain development and the likelihood of a traumatic event. R01HL155295, R01HL149608, Advanced Imaging and Microscopy Core Loma Linda University School of Medicine. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Chronic Hypoxia during Gestation Disrupts Spontaneous Ca2+ Oscillations in Middle Cerebral Arterial Myocytes of Fetal Sheep

Long Term Hypoxic (LTH) stress is associated with an elevated risk of intracranial hemorrhage and stroke in newborns. Existing evidence illustrates that fetal sheep subjected to LTH conditions exhibit compromised cerebrovascular reactivity and arterial development, leading to perturbations in cerebral blood flow. Given the critical role of whole-cell Ca2+ waveforms in the contraction of middle cerebral arterial (MCA) myocytes and the regulation of cerebral blood flow, a comprehensive understanding of Ca2+ signaling patterns can provide insight into hypoxia-related cerebrovascular disease in neonates. This study was designed to test the hypothesis that intrauterine LTH disrupts whole-cell Ca2+ oscillations in fetal MCA myocytes. The hypothesis was addressed using MCAs isolated from term fetal sheep (approximately 140 days of gestation) delivered by cesarean section. These fetuses were carried by ewes residing at low-altitude (700 m) or high-altitude conditions (3801 m) for over 100 days of gestation. Ca2+ oscillatory activity was recorded using confocal fluorescence imaging techniques in an en face myocyte preparation. Spontaneous Ca2+ oscillations were evaluated in the presence and absence of 30 mM K+ to depolarize the myocytes, with or without 10 μM ryanodine, which blocks ryanodine receptor mediated Ca2+ release. The results of the study reveal that LTH decreases oscillatory activity and restricts the augmentation of activity following membrane depolarization. Furthermore, LTH induces dysregulation in spatial and temporal Ca2+ signals, manifesting as reduced event amplitude, shortened event duration, and decreased area under the curve (AUC). These findings highlight the impact of gestational hypoxia on multiple aspects of Ca2+ signaling in fetal lamb MCA, which may contribute to cerebrovascular dysfunction in the newborn. R01HL155295, R01HL149608, Advanced Imaging and Microscopy Core Loma Linda University School of Medicine. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Amphiphilic Rhodamine Fluorescent Probes Combined with Basal Imaging for Fine Structures of the Cell Membrane.

Confocal fluorescence imaging of fine structures of the cell membrane is important for understanding their biofunctions but is often neglected due to the lack of an effective method. Herein, we develop new amphiphilic rhodamine fluorescent probe RMGs in combination with basal imaging for this purpose. The probes show high signal-to-noise ratio and brightness and low internalization rate, making them suitable for imaging the fine substructures of the cell membrane. Using the representative probe RMG3, we not only observed the cell pseudopodia and intercellular nanotubes but also monitored the formation of migrasomes in real time. More importantly, in-depth imaging studies on more cell lines revealed for the first time that hepatocellular carcinoma cells secreted much more adherent extracellular vesicles than other cell lines, which might serve as a potential indicator of liver cells. We believe that RMGs may be useful for investigating the fine structures of the cell membrane.

A novel colormetric and light-up fluorescent sensor from flavonol derivative grafted cellulose for rapid and sensitive detection of Hg2+ and its applications in biological and environmental system

Mercury ion (Hg2+) is one of harmful heavy metal ions that can accumulate inside the human organism and cause some health problems. In the article, a highly effective fluorescent probe named EC-T-PCBM was prepared by grafting flavonol derivatives onto ethyl cellulose for the specific recognition of Hg2+. EC-T-PCBM exhibited a remarkable fluorescence light-up response toward Hg2+ with excellent sensitivity. EC-T-PCBM possessed several prominent sensing properties for Hg2+, such as low detection limit (43.9 nM), short response time (5 min), and wide detection pH range (6–9). The response mechanism of EC-T-PCBM to Hg2+ has been verified through 1H NMR titration and DFT computation. Additionally, EC-T-PCBM not only can be used for accurately determining trace amount of Hg2+ in actual environmental water samples, but also can serve as a portable and rapid device by loading it on test strips for sensitive and selective visualization of Hg2+. More importantly, the confocal fluorescence imaging of onion cells suggested the favorable cell membrane permeability of EC-T-PCBM and its prominent ability to continuously monitor the enrichment from Hg2+ within fresh plant tissues.

Quantitative imaging and semiotic phenotyping of mitochondrial network morphology in live human cells.

The importance of mitochondria in tissue homeostasis, stress responses and human diseases, combined to their ability to transition between various structural and functional states, makes them excellent organelles for monitoring cell health. There is therefore a need for technologies to accurately analyze and quantify changes in mitochondrial organization in a variety of cells and cellular contexts. Here we present an innovative computerized method that enables accurate, multiscale, fast and cost-effective analysis of mitochondrial shape and network architecture from confocal fluorescence images by providing more than thirty features. In order to facilitate interpretation of the quantitative results, we introduced two innovations: the use of Kiviat-graphs (herein named MitoSpider plots) to present highly multidimensional data and visualization of the various mito-cellular configurations in the form of morphospace diagrams (called MitoSigils). We tested our fully automated image analysis tool on rich datasets gathered from live normal human skin cells cultured under basal conditions or exposed to specific stress including UVB irradiation and pesticide exposure. We demonstrated the ability of our proprietary software (named MitoTouch) to sensitively discriminate between control and stressed dermal fibroblasts, and between normal fibroblasts and other cell types (including cancer tissue-derived fibroblasts and primary keratinocytes), showing that our automated analysis captures subtle differences in morphology. Based on this novel algorithm, we report the identification of a protective natural ingredient that mitigates the deleterious impact of hydrogen peroxide (H2O2) on mitochondrial organization. Hence we conceived a novel wet-plus-dry pipeline combining cell cultures, quantitative imaging and semiotic analysis for exhaustive analysis of mitochondrial morphology in living adherent cells. Our tool has potential for broader applications in other research areas such as cell biology and medicine, high-throughput drug screening as well as predictive and environmental toxicology.

Construction of a mitochondrial targeted H2O2 fluorescence probe with a large Stokes shift and its application in bacterial infection

Macrophages are crucial innate immune system cells that have the ability to generate large amounts of H2O2 in the cytoplasm to combat germs. Macrophage mitochondria also produce H2O2 to participate in the antimicrobial response when infected by bacteria. However, visualization of H2O2 production in the mitochondria of bacterially infected macrophages is extremely challenging due to the lack of appropriate research methods. Here, by developing a new mitochondrial-targeting fluorescent H2O2 probe, combined with confocal fluorescence imaging, we report for the first time that H2O2 production in the mitochondria of bacterially infected macrophages (Raw264.7 cells) was visualized with a fluorescent probe. In addition, the developed probe has accurate mitochondrial targeting ability, large Stokes shift, fast response capability, high selectivity and sensitivity (detection limit of 4.346 × 10−7 M), and the probe can be used to detect H2O2 in living cells and zebrafish. Therefore, this work is expected to be used to further reveal the biological function of H2O2 in subcellular mitochondria.

Abstract 2611: Non-specific elimination of tumor-associated neutrophils by antibody-drug conjugates boosts anti-tumor immunity for PD-1 immunotherapy

Abstract Background: Antibody-drug conjugates (ADCs) play a key role in targeted therapy of solid tumors. However, few studies have examined the impact of ADCs on the tumor microenvironment (TME), particularly on innate immune cells. To elucidate this, this study focuses on investigating the comprehensive impacts of ICAM1-DXd on the tumor microenvironment, especially on tumor-associated neutrophils (TAN) and its synergistic effect with PD-1 immunotherapy. Methods: Firstly, the efficacy and prognosis of ICAM1-DXd, a potent ADC for cervical cancer, were determined in pre-clinical tumor models, providing crucial transcriptomic and biological function information by using RNA-seq. Then, pathological studies were performed to evaluate the abundance and location of TAN (Ly6G+/MPO+) in TME post-ADC treatment. The interaction between TAN and ICAM1-DXd and subsequent impacts on adaptive immune cells (e.g., CD8+ cells) was examined by flow cytometry (FACS), confocal fluorescent imaging, and western blot techniques (WB). Eventually, the synergistic effect of ICAM1-DXd and PD-1 monoclonal antibody were investigated in an immunocompetent animal model. Results: ICAM1-DXd potently inhibits cervical tumor growth in preclinical models, and RNA-seq analysis revealed that ICAM1-DXd treatment induces a strong down-regulation of neutrophil activation, especially for Ly6G+/MPO+ TANs, a subtype with pro-tumor function. IHC and FACS results confirmed that pro-tumor TANs were efficiently eliminated in TME by ICAM1-DXd treatment via non-specific phagocytosis in comparison with peripheral blood neutrophils. ICAM1-DXd-phagocytised TANs also elicit a strong bystander killing effect by cleaving the quadra peptide linker of ICAM1-DXD by cathepsin B. This ADC-mediated TAN elimination effectively ameliorates immunosuppressive TME and works in synergy with PD-1 immunotherapy in preclinical models. Conclusion: In preclinical models of cervical cancer, ICAM1-DXd not only directly ablates cancer cells via antigen recognition but also non-specifically kills tumor-promoting TANs, resulting in an improved tumor immune microenvironment, providing a shred of mechanistic evidence supporting ADC and PD-1 combination therapy. Citation Format: Shili Yao, Lu Sun, Xiu Zhu, Hanfei Xie, Tong Yang, Peng Guo, Huarong Tang, Tao Zhu. Non-specific elimination of tumor-associated neutrophils by antibody-drug conjugates boosts anti-tumor immunity for PD-1 immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2611.

Abstract 7255: Peptide-based siRNA delivery for tumor-specific targeting of lactate dehydrogenase C

Abstract Background: Breast cancer is the most common cancer worldwide and the leading cause of female cancer-related deaths, highlighting the pressing need for novel therapeutic interventions. Treatment of triple negative breast cancer in particular remains a challenge due to disease aggressiveness and the lack of durable treatment options. We speculate that targeting of Lactate Dehydrogenase C (LDHC) could be a novel approach given its highly tumor specific expression and immunogenic properties. We recently demonstrated that LDHC acts as a key regulator of the DNA damage response and tumor mitotic fidelity. Moreover, silencing of LDHC significantly improved treatment response to DNA damage response related anti-cancer drugs, highlighting its therapeutic potential for cancer precision medicine. Methods: We characterized and evaluated several cell penetrating peptide-siRNA complexes for efficient silencing of LDHC in tumor cells using a 10R polyarginine peptide or bifunctional 10R-RGD, cRGD-10R or iRGD-10R peptides with tumor homing and penetrating abilities. Results: Peptide-siRNA complex formation and tumor cellular uptake was confirmed using gel retardation assays and fluorescent confocal imaging. Biophysiochemical characterization and transmission electron microscopy revealed the complexes to be uniform in size with a low polydispersity index and positive zeta potentials. LDHC silencing in breast cancer cells using the peptide complexes demonstrated a 30-53% reduction in LDHC expression, with the 10R-siRNA and cRGD-10R-siRNA complexes showing the highest silencing efficiency. In 3D breast cancer spheroids, transfection with the 10R-siRNA complex resulted in a 20% downregulation of LDHC expression. Further analysis of the bifunctional-siRNA complexes in 3D cultures is ongoing as well as cytotoxicity analyses on non-cancerous cell lines. Conclusions: Our findings demonstrate that peptide-mediated delivery of LDHC siRNA can reduce LDHC expression in 2D and 3D breast cancer cultures, suggesting that they could be used as a valuable approach for therapeutic intervention. Citation Format: Adviti Naik, Hanan Qasem, Julie Decock. Peptide-based siRNA delivery for tumor-specific targeting of lactate dehydrogenase C [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7255.

A near-infrared fluorescence probe with large Stokes shift for selectively monitoring nitroreductase in living cells and mouse tumor models

Hypoxia is commonly regarded as a typical feature of solid tumors, which originates from the insufficient supply of oxygen. Herein, the development of an efficient method for assessing hypoxia levels in tumors is strongly desirable. Nitroreductase (NTR) is an overexpressed reductase in the solid tumors, has been served as a potential biomarker to evaluate the degrees of hypoxia. In this work, we elaborately synthesized a new near-infrared (NIR) fluorescence probe (MR) to monitor NTR activity for assessment of hypoxia levels in living cells and in tumors. Upon exposure of NTR, the nitro-unit of MR could be selectively reduced to amino-moiety with the help of nicotinamide adenine dinucleotide. Moreover, the obtained fluorophore emitted a prominent NIR fluorescence, because it possessed a classical “push-pull” structure. The MR displayed several distinguished characters toward NTR, including intense NIR fluorescent signals, large Stokes shift, high selectivity and low limit of detection (46 ng/mL). Furthermore, cellular confocal fluorescence imaging results validated that the MR had potential of detecting NTR levels in hypoxic cells. Significantly, using the MR, the elevated of NTR levels were successfully visualized in the tumor-bearing mouse models. Therefore, this detecting platform based on this probe may be tactfully constructed for monitoring the variations of NTR and estimating the degrees of hypoxia in tumors.

Flipping the GPCR Switch: Structure-Based Development of Selective Cannabinoid Receptor 2 Inverse Agonists.

We report a blueprint for the rational design of G protein coupled receptor (GPCR) ligands with a tailored functional response. The present study discloses the structure-based design of cannabinoid receptor type 2 (CB2R) selective inverse agonists (S)-1 and (R)-1, which were derived from privileged agonist HU-308 by introduction of a phenyl group at the gem-dimethylheptyl side chain. Epimer (R)-1 exhibits high affinity for CB2R with Kd = 39.1 nM and serves as a platform for the synthesis of a wide variety of probes. Notably, for the first time these fluorescent probes retain their inverse agonist functionality, high affinity, and selectivity for CB2R independent of linker and fluorophore substitution. Ligands (S)-1, (R)-1, and their derivatives act as inverse agonists in CB2R-mediated cAMP as well as G protein recruitment assays and do not trigger β-arrestin-receptor association. Furthermore, no receptor activation was detected in live cell ERK1/2 phosphorylation and Ca2+-release assays. Confocal fluorescence imaging experiments with (R)-7 (Alexa488) and (R)-9 (Alexa647) probes employing BV-2 microglial cells visualized CB2R expressed at endogenous levels. Finally, molecular dynamics simulations corroborate the initial docking data in which inverse agonists restrict movement of toggle switch Trp2586.48 and thereby stabilize CB2R in its inactive state.

Porous silicon nanotube bundles as nanocarriers for small interfering RNA delivery

AbstractWe describe in this work an evaluation of bundles of hollow mesoporous silicon nanotubes to facilitate transfection of HeLa cells using small interfering RNA designed to knock down expression of Enhanced Green Fluorescent Protein (eGFP). These experiments entail direct visualization of the nanotube bundles associated with the cells using both scanning electron microscopy (SEM) and confocal fluorescence imaging. These nanotube bundles are generated by surface modification of nanotube arrays with aminopropyl‐triethoxysilane (APTES), followed by their ultrasonication in water, to create the amine‐terminated structures capable of electrostatic conjugation of siRNA at an efficiency of 23%–50% (depending on initial siRNA concentration). Delivery and transfection to HeLa cells are verified by quantification of fluorescence imaging; an average percent knockdown of ∼50% eGFP is achieved. As nanoscale drug delivery vehicles are expected to be resorbed in clinical use, we also assess SiNT bundle degradation during the above in vitro timescale using scanning and transmission electron (TEM) microscopies. We conclude with a brief discussion of challenges and opportunities in future experiments involving this platform.

Improved synergistic anticancer action of quercetin and tamoxifen citrate supported by an electrospun complex nanostructure

A tri-fluid electrospinning process was successfully developed to prepare tri-chamber complex nanofibers. The core–shell and Janus structure were combined to form a delicate and complicated architecture for solving the problem of co-administration of quercetin and tamoxifen citrate, improving the oral bioavailability, and enhancing their synergistic anti-breast cancer actions. Scanning electron microscope, transmission electron microscope and confocal fluorescent microscopy images showed the complex structure of the designed nanofibers. Fourier transform infrared and X-ray diffraction analyses verified that the model drugs and the polymeric excipients had good compatibility and were presented in an amorphous state. The in vitro release study certified that the tri-chamber nanofibers facilitated the rapid release of quercetin compared with that of the crude drug (90% versus 38%) and the delayed and sustained release of tamoxifen citrate at the same time interval (decreased by 1.88 times). The in vivo pharmacokinetic and pharmacodynamic analysis verified that the tri-chamber nanofibers could result in increased oral bioavailability and enhanced synergistic anticancer action of quercetin and tamoxifen citrate. The findings proved that a new medicated drug delivery system with advanced dual-, time-, and target-specific drug release profiles was developed using the electrospun complex nanostructure.

Co-delivery of PD-L1- and EGFR-targeting siRNAs by synthetic PEG12-KL4 peptide to the lungs as potential strategy against non-small cell lung cancer

BackgroundSmall interfering RNA (siRNA) holds great promise for treating various lung diseases, but the lack of safe and efficient pulmonary siRNA delivery systems has hindered its advance into the clinics. The epidermal growth factor receptor (EGFR) which promotes cell proliferation, and the programmed cell death ligand 1 (PD-L1) which plays a crucial role in suppressing cytotoxic T cells activity, are two important targets for treating non-small cell lung cancer (NSCLC). Here, we explored the potential of PEG12-KL4, a synthetic peptide, to deliver siRNA to various NSCLC cells and to lung tissues in mice. MethodsPEG12-KL4 was used to transfect siRNAs targeted at both EGFR and PD-L1 into NSCLC cells. Immunoblotting was used to evaluate the siRNA silencing effects in HCC827 and NCI-H1975 NSCLC cells. CD8+ T cell-mediated NSCLC cell killing was employed to demonstrate the functional effects of PD-L1 siRNA knock-down. Fluorescent siRNAs were used to visualise siRNA uptake in cells as well as to enable biodistribution studies in BALB/c mice. ResultsOur results showed that PEG12-KL4 was efficient in mediating siRNA knock-down of EGFR and PD-L1 in various NSCLC cells. Importantly, the PEG12-KL4 peptide enabled significantly better siRNA delivery than the commercial Lipofectamine 2000 reagent. We hypothesised that PEG12-KL4 peptide enabled siRNA to either escape from or bypass endosomal degradation as indicated by confocal fluorescence imaging. Notably, combined knock-down of EGFR and PD-L1 in NCI-H1975 cells resulted in better effector T cell-mediated cancer cell killing than knock-down of PD-L1 alone. Moreover, biodistribution of PEG12-KL4/siRNA complexes following intravenous administration revealed poor lung delivery with the fluorescent siRNA accumulating in the liver. In contrast, intratracheal delivery of PEG12-KL4/siRNA complexes resulted in the fluorescent siRNA to be detected in the lung with retarded renal excretion. ConclusionIn conclusion, we demonstrated that the co-delivery of siRNAs targeting EGFR and PD-L1 using PEG12-KL4 is feasible and represents a promising future strategy to treat NSCLC, whereby pulmonary siRNA delivery is favourable to intravenous administration.

Dynamic fluorescence imaging and controllable capture/release of guests based on thermo-responsive perylene-cyclodextrin conjugates

In view of the fact that multivalent intermolecular noncovalent interactions are the main elements for the formation of phase separation, supramolecular entities are a type of multivalent system. However, the phase separation system based on single supramolecular molecules was limited. In this paper, two permethyl-β-cyclodextrin modified perylene monoamide derivatives (PMI-B-CD and PMI-N-CD) with modification of benzene and naphthalene groups at the bay position of perylene backbone were synthesized. Of interest, PMI-B-CD and PMI-N-CD showed a LCST effect due to a self-inclusion interaction between PMCD and the benzene or naphthalene groups in the bay position of perylene monoamide backbone. Dynamic confocal fluorescence imaging of PMI-B-CD and PMI-N-CD showed thermo-responsive phase separation process. It is surprised that PMI-B-CD and PMI-N-CD achieved thermo-responsive capture and release of aromatic guests. Dynamic phase separation and controllable capture and release of guests with thermo-responsive phase transition process are found, which opens a novel supramolecular principle of liquid-liquid transition.

Nitrodopamine modified MnO2 NS-MoS2QDs hybrid nanocomposite for the extracellular and intracellular detection of glutathione.

We have developed a highly sensitive and reliable fluorescence resonance energy transfer (FRET) probe using nitro-dopamine (ND) and dopamine (DA) coated MnO2 nanosheet (ND@MnO2 NS and DA@MnO2 NS) as an energy acceptor and MoS2 quantum dots (QDs) as an energy donor. By employing surface-modified MnO2 NS, we can effectively reduce the fluorescence intensity of MoS2 QDs through FRET. It can reduce MnO2 NS to Mn2+ and facilitate the fluorescence recovery of the MoS2 QDs. This ND@MnO2 NS@MoS2 QD-based nanoprobe demonstrates excellent sensitivity to GSH, achieving an LOD of 22.7 nM in an aqueous medium while exhibiting minimal cytotoxicity and good biocompatibility. Moreover, our sensing platform shows high selectivity to GSH towards various common biomolecules and electrolytes. Confocal fluorescence imaging revealed that the nanoprobe can image GSH in A549 cells. Interestingly, the ND@MnO2 NS nanoprobe demonstrates no cytotoxicity in living cancer cells, even at concentrations up to 100 μg mL-1. Moreover, the easy fabrication and eco-friendliness of ND@MnO2 NS make it a rapid and simple method for detecting GSH. We envision the developed nanoprobe as an incredible platform for real-time monitoring of GSH levels in both extracellular and intracellular mediums, proving valuable for biomedical research and clinical diagnostics.