Cyanine Dyes for Photo-Thermal Therapy: A Comparison of Synthetic Liposomes and Natural Erythrocyte-Based Carriers.

Cyanine fluorescent dyes are attractive diagnostic or therapeutic agents due to their excellent optical properties. However, in free form, their use in biological applications is limited due to the short circulation time, instability, and toxicity. Therefore, their encapsulation into nano-carriers might help overcome the above-mentioned issues. In addition to indocyanine green (ICG), which is clinically approved and therefore the most widely used fluorescent dye, we tested the structurally similar and cheaper alternative called IR-820. Both dyes were encapsulated into liposomes. However, due to the synthetic origin of liposomes, they can induce an immunogenic response. To address this challenge, we proposed to use erythrocyte membrane vesicles (EMVs) as "new era" nano-carriers for cyanine dyes. The optical properties of both dyes were investigated in different biological relevant media. Then, the temperature stability and photo-stability of dyes in free form and encapsulated into liposomes and EMVs were evaluated. Nano-carriers efficiently protected dyes from thermal degradation, as well as from photo-induced degradation. Finally, a hemotoxicity study revealed that EMVs seem less hemotoxic dye carriers than clinically approved liposomes. Herein, we showed that EMVs exhibit great potential as nano-carriers for dyes with improved stability and hemocompatibility without losing excellent optical properties.

Reactive Oxygen Species-Responsive Liposomes via Boronate-Caged Phosphatidylethanolamine.

Liposomes have proven to be effective nanocarriers due to their ability to encapsulate and deliver a wide variety of therapeutic cargo. A key goal of liposome research is to enhance control over content release at diseased sites. Though a number of stimuli have been explored for triggering liposomal release, reactive oxygen species (ROS), which have received significantly less attention, provide excellent targets due to their key roles in biology and overabundance in diseased cells. Here, we report a ROS-responsive liposome platform through the inclusion of lipid 1 bearing a boronate ester headgroup and a quinone-methide (QM) generating self-immolative linker attached onto a dioleoylphosphatidylethanolamine (DOPE) lipid scaffold. Fluorescence-based dye release assays validated that this system enables release of both hydrophobic and hydrophilic contents upon hydrogen peroxide (H2O2) addition. Details of the release process were carefully studied, and data showed that oxidative removal of the boronate headgroup is sufficient to result in hydrophobic content release, while production of DOPE is needed for hydrophilic cargo leakage. These results showcase that lipid 1 can serve as a promising ROS-responsive liposomal delivery platform for controlled release.

Assessment of Amphiphilic Poly-N-vinylpyrrolidone Nanoparticles' Biocompatibility with Endothelial Cells in Vitro and Delivery of an Anti-Inflammatory Drug.

Nanoparticles (NPs) produced from amphiphilic derivatives of poly-N-vinylpyrrolidone (Amph-PVP), composed of various molecular weight polymeric hydrophilic fragments linked into hydrophobic n-alkyl chains of varying lengths, were previously shown to exert excellent biocompatibility. Although routes of administration can be different, finally, most nanosystems enter the blood circulation or lymphatic vessels, and by this, they establish direct contact with endothelial cells. In this study, Amph-PVP NPs and fluorescently labeled Amph-PVP-based NPs, namely "PVP" NPs (Amph-PVP-NPs (6000 Da) unloaded) and "F"-NPs (Amph-PVP-NPs (6000 Da) loaded with fluorescent FITC), were synthesized to study Amph-PVP NPs interactions with HMEC-1 endothelial cells. PVP NPs were readily uptaken by HMEC-1 cells in a concentration-dependent manner, as demonstrated by immunofluorescence imaging. Upon uptake, the FITC dye was localized to the perinuclear region and cytoplasm of treated cells. The generation of lipopolysaccharide (LPS)-induced activated endothelium model revealed an increased uptake of PVPNPs, as shown by confocal microscopy. Both unloaded PVP NPs and F-NPs did not affect EC viability in the 0.01 to 0.066 mg/mL range. Furthermore, we focused on the potential immunological activation of HMEC-1 endothelial cells upon PVPNPs treatment by assessing the expression of their E-Selectin, ICAM-1, and VCAM-1 adhesion receptors. None of the adhesion molecules were affected by NP treatments of both activated by LPS and nonactivated HMEC-1 cells, at the utilized concentrations (p = NS). In this study, PVP (6000 Da) NPs were used to encapsulate indomethacin, a widely used anti-inflammatory drug. The synthesized drug carrier complex did not affect HMEC-1 cell growth and expression of E-selectin, ICAM-1, and VCAM-1 adhesion receptors. In summary, PVP-based NPs are safe for use on both basal and activated endothelium, which more accurately mimics pathological conditions. Amph-PVP NPs are a promising drug delivery system.

Development of l-Amino-Acid-Based Hydroxyl Functionalized Biodegradable Amphiphilic Polyesters and Their Drug Delivery Capabilities to Cancer Cells.

Hydroxyl-functionalized amphiphilic polyesters based on l-amino acid bioresources were designed and developed, and their nanoassemblies were explored as intracellular enzyme-biodegradable scaffolds for delivering anticancer drugs and fluorophores to cancer cells. To accomplish this task, acetal-masked multifunctional dicarboxylic ester monomer from l-aspartic acid was tailor-made, and it was subjected to solvent-free melt transesterification polycondensation with commercial diols to produce acetal-functionalized polyesters. Acid-catalyzed postpolymerization deprotection of these acetal-polyesters produced amphiphilic hydroxyl-functionalized polyesters. The amphiphilic polyesters were self-assembled in aqueous medium to produce nanoparticles of size <200 nm. Wide ranges of both water-soluble and water-insoluble anticancer drugs such as doxorubicin (DOX), camptothecin (CPT), and curcumin (CUR) and fluorophores such as Nile red (NR), Rose Bengal (RB), and Congo red (CR) were encapsulated in hydroxyl polyesters nanoparticles. In vitro drug release studies revealed that the aliphatic polyester backbone underwent lysosomal enzymatic-biodegradation to release the loaded cargoes at the intracellular compartments. Lysotracker-assisted live-cell confocal microscopy studies further confirmed the colocalization of the polymer nanoscaffolds in the lysosomes and supported their enzymatic-biodegradation for drug delivery. In vitro cytotoxicity studies showed that the nascent polymers were not toxic, whereas their anticancer drug-loaded nanoparticles exhibited excellent cell killing in cervical cancer (HeLa) cell lines. The drug-loaded (CPT, CUR, and DOX) and the fluorophore-loaded (NR, RB, and CR) polymer nanoparticles were highly luminescent; thus, the encapsulated polymer nanoparticles enabled the multiple color-tunable bioimaging in cancer cells in the entire visible region from blue to deep red. Time-dependent live-cell confocal microscopy studies established that the cellular uptake of drugs and fluorophores was 5 to 10-fold higher while they were delivered from the hydroxyl polyester platform. The hydroxyl polyester nanocarrier design strategy opens up new opportunities in drug delivery to cancer cells from a biodegradable polymer platform based on l-amino acids.

Oxidative instability of boronic acid-installed polycarbonate nanoparticles.

Oxidative stress, caused by the overproduction of reactive oxygen species (ROS), is often observed in degenerative and/or metabolic diseases, tumors, and inflamed tissues. Boronic acids are emerging as a unique class of responsive biomaterials targeting ROS because of their reactivity toward H2O2. Herein, we examine the oxidative reactivity of nanoparticles from a boronic acid-installed polycarbonate. The extent of oxidation under different concentrations of H2O2 was tracked by the change in fluorescence intensity of an encapsulated solvatochromic reporter dye, demonstrating their sensitivity to biologically-relevant concentrations of hydrogen peroxide. Oxidation-triggered particle destabilization, however, was shown to be highly dependent on the concentration of the final oxidized polymer product, and was only achieved if it fell below polymer critical micelle concentration. Our results indicate that these nanocarriers serve as an excellent dual pH/H2O2 responsive vehicle for drug delivery.

Microfluidic Sonication To Assemble Exosome Membrane-Coated Nanoparticles for Immune Evasion-Mediated Targeting.

Using natural membranes to coat nanoparticles (NPs) provides an efficient means to reduce the immune clearance of NPs and improve their tumor-specific targeting. However, fabrication of these drug-loaded biomimetic NPs, such as exosome membrane (EM)- or cancer cell membrane (CCM)-coated poly(lactic-co-glycolic acid) (PLGA) NPs, remains a challenging task owing to the heterogeneous nature of biomembranes and labor-intensive procedures. Herein, we report a microfluidic sonication approach to produce EM-, CCM-, and lipid-coated PLGA NPs encapsulated with imaging agents in a one-step and straightforward manner. Tumor cell-derived EM-coated PLGA NPs consisting of both endosomal and plasma membrane proteins show superior homotypic targeting as compared to CCM-PLGA NPs of similar sizes and core-shell structures in both in vitro and in vivo models. The underlying mechanism is associated with a significantly reduced uptake of EM-PLGA NPs by macrophages and peripheral blood monocytes, revealing an immune evasion-mediated targeting of EM-PLGA NPs to homologous tumors. Overall, this work illustrates the promise of using microfluidic sonication approach to fabricate biomimetic NPs for better biocompatibility and targeting efficacy.

An Activatable Polymeric Reporter for Near-Infrared Fluorescent and Photoacoustic Imaging of Invasive Cancer.

Discriminative detection of invasive and noninvasive breast cancers is crucial for their effective treatment and prognosis. However, activatable probes able to do so in vivo are rare. Herein, we report an activatable polymeric reporter (P-Dex) that specifically turns on near-infrared (NIR) fluorescent and photoacoustic (PA) signals in response to the urokinase-type plasminogen activator (uPA) overexpressed in invasive breast cancer. P-Dex has a renal-clearable dextran backbone that is linked with a NIR dye caged with an uPA-cleavable peptide substrate. Such a molecular design allows P-Dex to passively target tumors, activate NIR fluorescence and PA signals to effectively distinguish invasive MDA-MB-231 breast cancer from noninvasive MCF-7 breast cancer, and ultimately undergo renal clearance to minimize the toxicity potential. Thus, this polymeric reporter holds great promise for the early detection of malignant breast cancer.

Liposomes Enhance Dye Localization within the Mammary Ducts of Porcine Nipples.

Transductal and transepidermal diffusion are two distinct penetration routes of molecules administered via the nipple. To improve the therapeutic potential of this drug administration technique, drug penetration into the mammary ducts should be maximized, which may be accomplished through design optimization of drug delivery vehicles. In this study, we evaluated liposomes, ranging in size from 100 to 3000 nm, to improve ductal penetration of model fluorescent dyes using fluorescence microscopy and image analysis. Liposomes encapsulating a model fluorescent lipophilic dye, nile red, or hydrophilic dye, sulforhodamine B, were applied topically on porcine nipples for 6 h in vitro. Liposome encapsulation of sulforhodamine B significantly reduced the total amount of dye penetrating the nipple, while penetration of liposome-encapsulated nile red varied depending on vesicle size, as compared to their solution controls. However, the fluorescence intensity localized at the ductal epithelium was higher at extended nipple depths in tissues treated with liposomes versus dye solutions, suggesting a higher concentration of dye penetrating the nipple via the ducts. In contrast, the fluorescence intensity measured at the stratum corneum was reduced (sulforhodamine B) or unchanged (nile red) in nipples treated with liposomes versus dye solutions, suggesting a decrease or no change in dye penetration of the nipple via the stratum corneum. Furthermore, the limited penetration distance into the connective tissue beyond the ductal epithelium for both liposome-encapsulated nile red and sulforhodamine B suggests that liposomes remain intact over the 6 h duration of this study when penetrating through the ducts and enhance retention within the ductal lumen. However, the varied penetration profiles into the connective tissue beyond the stratum corneum between liposome-encapsulated nile red and sulforhodamine B suggests that the liposomes destabilize when penetrating the outer tissues layers of the nipple. Overall, liposomes, regardless of size, improved penetration into and retention within the mammary ducts, while limiting penetration into the stratum corneum, indicating their capacity to target the mammary ductal network.

Subchronic intravenous toxicity study of biofunctional ZnO and its application as a fluorescence probe for cell-specific targeting.

Successful development of safe and highly effective nanoprobes for targeted imaging of in vivo early cancer is a great challenge. Herein, we choose the visible-light emitting zinc oxide non-core/shell type nanoparticle (NP) fluorophores (ZHIE) as prototypical materials. We have reported on these materials previously. The results showed that the ZHIE NPs exhibited good water solubility and good biocompatibility. This study was conducted to investigate the toxicity of ZHIE NPs when intravenously administered to mice repeatedly at the dose required for successful tumor imaging in vivo. Anti-macrophage-1 antigen (Mac1), a macrophage differentiation antigen, antibody-conjugated ZHIE NPs successfully realized targeted imaging of murine macrophage cell line Raw264.7 cells. In conclusion, ZHIE NPs are not toxic in vivo and antibody-conjugated ZHIE NPs have great potential in applications, such as single cell labeling.

Reporter nanoparticle that monitors its anticancer efficacy in real time.

The ability to monitor the efficacy of an anticancer treatment in real time can have a critical effect on the outcome. Currently, clinical readouts of efficacy rely on indirect or anatomic measurements, which occur over prolonged time scales postchemotherapy or postimmunotherapy and may not be concordant with the actual effect. Here we describe the biology-inspired engineering of a simple 2-in-1 reporter nanoparticle that not only delivers a cytotoxic or an immunotherapy payload to the tumor but also reports back on the efficacy in real time. The reporter nanoparticles are engineered from a novel two-staged stimuli-responsive polymeric material with an optimal ratio of an enzyme-cleavable drug or immunotherapy (effector elements) and a drug function-activatable reporter element. The spatiotemporally constrained delivery of the effector and the reporter elements in a single nanoparticle produces maximum signal enhancement due to the availability of the reporter element in the same cell as the drug, thereby effectively capturing the temporal apoptosis process. Using chemotherapy-sensitive and chemotherapy-resistant tumors in vivo, we show that the reporter nanoparticles can provide a real-time noninvasive readout of tumor response to chemotherapy. The reporter nanoparticle can also monitor the efficacy of immune checkpoint inhibition in melanoma. The self-reporting capability, for the first time to our knowledge, captures an anticancer nanoparticle in action in vivo.

Physicochemical Analysis of DPPC and Photopolymerizable Liposomal Binary Mixture for Spatiotemporal Drug Release.

The development of a spatiotemporal drug delivery system with a long release profile, high loading efficiency, and robust therapeutic effects is still a challenge. Liposomal nanocarriers have secured a fortified position in the biomedical field over decades. Herein, liposomal binary mixtures of 1,2-dipalmitoyl- sn-glycero-3-phosphocholine (DPPC) and photopolymerizable 1,2-bis(10,12-tricosadiynoyl)- sn-glycero-3-phosphocholine (DC8,9PC) phospholipids were prepared for drug delivery applications. The diacetylenic groups of DC8,9PC produce intermolecular cross-linking following UV irradiation. Exposure of the liposomal mixture to 254 nm radiation induces a pore within the lipid bilayer, expediting the release of its entrapped 5,6-carboxyfluorescein dye. The dosage and rate of the released content are highly dependent on the number and size of the induced pore. Photochemical cross-linking studies at different exposure times were reported through the analysis of UV-visible spectrophotometry, nano differential scanning calorimetry, Fourier transform infrared spectroscopy, and Raman spectroscopy. The optimal irradiation time was established after 8 min of exposure, inducing lipid cross-linking with minimal oxidative degradation, which plays an essential role in the pathogenesis of numerous diseases due to the formation of primary and secondary oxidation products, accordingly reducing the encapsulated drug therapeutic level.

Multi-Functional Nanogels as Theranostic Platforms: Exploiting Reversible and Nonreversible Linkages for Targeting, Imaging, and Drug Delivery.

Nanogels that are amenable to facile multi-functionalization with imaging, therapeutic, and targeting agents are attractive theranostic platforms for addressing challenges in conventional diagnostics and therapy. In this work, reactive copolymers containing poly(ethylene glycol), maleimide, and pendant hydroxyl groups as side chains are used to construct nanogels by employing their thermoresponsive self-assembly in aqueous media. Subsequent cross-linking of these nanosized aggregates with dithiols using thiol-maleimide chemistry yields nanogels containing maleimide, thiol, and hydroxyl groups. The hydroxyl groups are readily activated to N-hydroxysuccinimide based carbonates that undergo conjugation with amine-containing molecules through carbamate linkage under mild conditions. As a demonstration of multi-functionalization, the maleimide, thiol, and activated carbonate groups were functionalized with a thiol-containing cancer cell targeting peptide, a maleimide-containing fluorescent indocyanine Cy5 dye, and an anticancer drug doxorubicin, respectively. It was observed that enhanced drug release from nanogels occurs under acidic conditions. While the parent nanogel vehicles did not possess any toxicity, drug conjugated constructs with and without targeting group were cytotoxic against MDA-MB-231 breast cancer cells. The cyclic peptide containing targeted nanogel exhibited slightly higher cytotoxicity than its counterpart devoid of any targeting group. Furthermore, higher level of drug internalization into MDA-MB-231 cells was observed for the targeting group containing construct. It can be envisioned that facile fabrication and multi-functionalization of these reactive nanogels simultaneously through nonreversible and reversible linkages offers a modular platform that can be configured as a theranostic agent for addressing challenges in conventional therapy of various diseases.

Harnessing Biology to Deliver Therapeutic and Imaging Entities via Cell-Based Methods.

The accumulation of therapeutic and imaging agents at sites of interest is critical to their efficacy. Similarly, off-target effects (especially toxicity) are a major liability for these entities. For this reason, the use of delivery vehicles to improve the distribution characteristics of bio-active agents has become ubiquitous in the field. However, the majority of traditionally employed, cargo-bearing platforms rely on passive accumulation. Even in cases where "targeting" functionalities are used, the agents must first reach the site in order for the ligand-receptor interaction to occur. The next stage of vehicle development is the use of "recruited" entities, which respond to biological signals produced in the tissues to be targeted, resulting in improved specificities. Recently, many advances have been made in the utilization of cells as delivery agents. They are biocompatible, exhibit excellent circulation lifetimes and tissue penetration capabilities, and respond to chemotactic signals. In this Minireview, we will explore various cell types, modifications, and applications where cell-based delivery agents are used.

Core Cross-linked Micelles Made of Glycopolymers Bearing Dopamine and Cholic Acid Pendants.

A series of block glycopolymers bearing galactose, dopamine, and cholic acid (CA) pendants have been synthesized by RAFT polymerization. These copolymers can self-assemble into micelles in water. The dopamine moieties, located near the interface of the core and shell of the micelles, can self-polymerize in a weakly basic solution, stabilizing the micelles in both water and organic solvent (DMSO). The cross-linked micelles are smaller in size than the uncross-linked precursors. Introducing more CA groups into the copolymers promotes the self-assembly to form larger aggregates, controls the cross-linking of the stabilized micelles, and facilitates the encapsulation of hydrophobic compounds such as Nile Red (NR). The amount of CA comonomers added also helps to control the cross-linking density, which affects the loading and release of NR. The core cross-linked micelles displayed a slow but sustained NR release and interact effectively with lectin (RCA120), demonstrating their potential use as a biocompatible multifunctional platform for targeted release of drugs.

Nanoparticle mucoadhesive system as a new tool for fish immune system modulation.

Recently, chitosan-based nanoparticles with mucoadhesive properties emerged as a strategy for mucosal drug release. This study aimed to characterize the interaction of mucoadhesive system chitosancoated PLGA nanoparticles (NPMA) with fish external mucus. NP suspensions with fluorescent probe were prepared and characterized by size, polydispersity, zeta potential and pH measures. In post-exposure fish were observed an increase in fluorescence imaging over time and it was significantly influenced by NPMA concentration. We also observed the main predominance the fluorescence in the spleen, followed by liver, gill and other tissues. The use of mucoadhesive nanocarriers becomes an alternative for administration of drugs and immunomodulators in immersion systems since the nanosystem can adhere to the mucosal surface of the fish with little residual effect in the water.

Optimization of liposomal indocyanine green for imaging of the urinary pathways and a proof of concept in a pig model.

BACKGROUND: Iatrogenic ureteral injury is an increasing concern in the laparoscopic era, affecting both patient morbidity and costs. Current techniques enabling intraoperative ureteral identification require invasive procedures or radiations. Our aim was to develop a real-time, non-invasive, radiation-free method to visualize ureters, based on near-infrared (NIR) imaging. For this purpose, we interfered with the biliary excretion pathway of the indocyanine green (ICG) fluorophore by loading it into liposomes, enabling renal excretion. In this work, we studied various parameters influencing ureteral imaging. METHODS: Fluorescence intensity (FI) of various liposomal ICG sizes and doses were characterized in vitro and subsequently tested in vivo in mice and pigs. Quantification was performed by measuring FI in multiple points and applying the ureteral/retroperitoneum ratio (U/R). RESULTS: The optimal liposomal ICG loading dose was 20%, for the different liposomes' sizes tested (30, 60, 100 nm). Higher concentration of ICG decreased FI. In vivo, the optimal liposome size for ureteral imaging was 60 nm, which yielded a U/R of 5.2 ± 1.7 (p < 0.001 vs. free ICG). The optimal ICG dose was 8 mg/kg (U/R = 2.1 ± 0.4, p < 0.05 vs. 4 mg/kg). Only urine after liposomal ICG injection had a measurable FI, and not after free ICG injection. Using a NIR-optimized laparoscopic camera, ureters could be effectively imaged in pigs, from 10 min after injection and persisting for at least 90 min. Ureteral peristaltic waves could be clearly identified only after liposomal ICG injection. CONCLUSIONS: Optimization of liposomal ICG allowed to visualize enhanced ureters in animal models and seems a promising fluorophore engineering, which calls for further developments.

Fluorescent Imaging Analysis for Distribution of Fluorescent Dye Labeled- or Encapsulated-Liposome in Monocrotaline-Induced Pulmonary Hypertension Model Rat.

Pulmonary hypertension (PH) is a life-threatening lung disease. Despite the availability of several approved drugs, the development of a new treatment method is needed because of poor prognosis. Tissue selective drug delivery systems can avoid the adverse effects of current therapy and enhance efficacy. We evaluated the possibility of delivering drugs to the lungs of a PH rat model using fluorescence dye-labeled nanosized liposomes. To evaluate the tissue distribution following systemic exposure, fluorescent dye-labeled, 40-180 nm liposomes with and without polyethylene glycol (PEG) were intravenously administered to a monocrotaline-induced PH (MCT) rat model and tissue fluorescence was measured. Fluorescent dye-containing liposomes were intratracheally administered to the MCT model to evaluate the distribution of the liposome-encapsulated compound following local administration to reduce systemic exposure. The lung vascular permeability, plasma concentration of surfactant protein (SP)-D, lung reactive oxygen species (ROS) production, and macrophage marker gene cluster of differentiation (CD68) expression were measured. PEG and 80-nm liposome accumulation in the lung was elevated in the MCT model compared to that in normal rats. The intratracheally administered liposomes were delivered selectively to the lungs of the MCT model. The lung vascular permeability, plasma SP-D concentration, and CD68 expression were significantly elevated in the lungs of the MCT model, and were all significantly and positively correlated to liposome lung accumulation. Liposomes can accumulate in the lungs of an MCT model by enhancing vascular permeability by the inflammatory response. Therefore, drug encapsulation in liposomes could be an effective method of drug delivery in patients with PH.

Multifunctional Liposome: A Bright AIEgen-Lipid Conjugate with Strong Photosensitization.

Liposomes have been used as popular drug delivery systems for cancer therapy. However, it is difficult to track traditional liposome delivery systems in an efficient and stable fashion to assess their delivery efficacy and biodistribution after administration. Meanwhile, conventional fluorescent liposomes containing optical tracers face the challenge of aggregation-caused quenching. Herein, we report a strategy for the integration of an aggregation-induced emission fluorogen with a liposome to yield an AIEgen-lipid conjugate, termed "AIEsome". The AIEsome exhibits bright red fluorescence along with great photostability and biocompatibility, and can be used for in vitro cancer cell labeling and in vivo tumor targeting. Meanwhile, benefiting from the excellent photosensitizing ability of the AIEgen and its good oxygen exposure in aqueous media, the AIEsome also performs well in efficient photodynamic therapy (PDT) for both in vitro cancer cell ablation and in vivo antitumor therapy after white light illumination.

Fluorescence-labeled liposome accumulation in injured colon of a mouse model of T-cell transfer-mediated inflammatory bowel disease.

Drug delivery systems maximize the efficacy of drugs by improving their pharmacokinetic profiles, pharmacodynamic effects, or both and reducing their adverse effects. One of the most advanced, clinically available formulations are liposome-encapsulated drugs. In this study, we aimed to determine if liposomes can selectively deliver compounds in gastrointestinal diseases. Initially, we evaluated the correlation between the diarrhea score and accumulation of fluorescence (FL)-labeled liposome using in vivo imaging systems in various disease states of an inflammatory bowel disease mouse model. The result showed that FL-labeled liposome accumulation and colon tissue weight, which reflect the disease state were highly and positively correlated. Then, to confirm the accumulation of liposomes at injured sites of the colon, we administered both FL-labeled liposomes and luminescence probes for detecting reactive oxygen species (ROS) to the mouse model. The imaging data showed that liposome accumulation tended to coincide with ROS detected sites and the correlation coefficient indicated a significantly positive correlation between liposome accumulation and ROS detection levels. Finally, we evaluated the involvement of macrophages in the uptake mechanism of the liposomes by analyzing the relationship between FL-labeled liposome accumulation and macrophage marker gene expression levels. The result showed that the expression of each macrophage marker gene and liposome accumulation showed a significant positive correlation. Therefore, the macrophages considerably contributed to the uptake mechanism of the liposomes. These data suggest that liposomes could be an attractive delivery tool for enhancing the accumulation of drug candidates through macrophages in injured colonic tissues. This approach is expected to provide new treatment options for patients with colitis.

Self-Assembly of a Tripodal Triszwitterion Forms a pH-Switchable Hydrogel that Can Reversibly Encapsulate Hydrophobic Guests in Water.

The development of supramolecular smart materials, which exhibit physicochemical structural changes in response to external stimuli is of current interest for various applications. Herein, we have developed the novel tripodal triszwitterion 1, derived from a C3 -symmetric benzene-1,3,5-tricarboxamide (BTA) core, which forms a thermo-reversible and pH-switchable transparent hydrogel through intermolecular self-complementary zwitterionic interactions at a neutral pH value. The hierarchical supramolecular self-aggregation was fully analyzed by microscopy (AFM, field emission scanning electron microscopy (FESEM)), viscosity, dynamic light scattering (DLS), and rheology studies. Moreover, compound 1 enables to encapsulate hydrophobic guests, such as the dye Nile red in aqueous medium at pH 6, which makes it an interesting candidate for drug delivery and controlled release.