Peptide Receptor-Targeted Fluorescent Probe: Visualization and Discrimination between Chronic and Acute Ulcerative Colitis

Orally-deliverable liposome-microgel complexes dynamically remodel intestinal environment to enhance probiotic ulcerative colitis therapy via TLR4 inhibition and tryptophan metabolic crosstalk

Probiotics emerges as a promising option for ulcerative colitis (UC) treatment, but its application remains challenging due to insufficient colon-targeted delivery efficiency and survival against the inflammation-associated intestinal oxidative stress. To address these issues, here we report a supramolecular liposome-microgel complex (SLMC) incorporated with Bacillus subtilis spores (BSSs) and dexamethasone (DEX) for orally-deliverable probiotic UC therapy. Specifically, BSSs and cholesterols were conjugated with gelatin via diselenide ligation to prepare microgels, followed by supramolecular complexation with UC-targeted DEX-loaded liposome via microfluidic engineering. The orally-administered SLMC efficiently accumulated in UC-affected colonic sites to release BSSs and DEX. DEX elicited rapid anti-inflammatory effect to reduce ROS generation, which cooperated with the ROS consumption by spore germination and diselenide cleavage to orchestrate an anaerobic intestinal microenvironment, thus promoting Bacillus subtilis colonization to restore gut homeostasis and initiate anti-inflammatory microbiota-macrophage metabolic crosstalk. Indeed, in vivo analysis showed that the SLMC treatment markedly inhibited pro-inflammatory TLR4-NF-κB signaling activities in mucosal macrophages through localized DEX delivery and boosting tryptophan metabolite production, leading to robust and durable UC abolishment. This study offers a practical approach for improving UC treatment in the clinic.

Fluorescent probes in autoimmune disease research: current status and future prospects

Autoimmune diseases (AD) present substantial challenges for early diagnosis and precise treatment due to their intricate pathogenesis and varied clinical manifestations. While existing diagnostic methods and treatment strategies have advanced, their sensitivity, specificity, and real-time applicability in clinical settings continue to exhibit significant limitations. In recent years, fluorescent probes have emerged as highly sensitive and specific biological imaging tools, demonstrating substantial potential in AD research.This review examines the response mechanisms and historical evolution of various types of fluorescent probes, systematically summarizing the latest research advancements in their application to autoimmune diseases. It highlights key applications in biomarker detection, dynamic monitoring of immune cell functions, and assessment of drug treatment efficacy. Furthermore, this article analyzes the technical challenges currently encountered in probe development and proposes potential directions for future research. With ongoing advancements in materials science, nanotechnology, and bioengineering, fluorescent probes are anticipated to achieve higher sensitivity and enhanced functional integration, thereby facilitating early detection, dynamic monitoring, and innovative treatment strategies for autoimmune diseases. Overall, fluorescent probes possess substantial scientific significance and application value in both research and clinical settings related to autoimmune diseases, signaling a new era of personalized and precision medicine.

Application of chitosan as nano carrier in the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn's disease (CD), is characterized by persistent and recurrent gastrointestinal inflammation. Conventional IBD therapies often involve the use of antibiotics, NSAIDs, biological agents, and immunomodulators. While these medications can mitigate acute inflammatory symptoms, their long-term efficacy is frequently compromised due to cumulative toxic effects. In recent years, significant attention has shifted toward nanoparticle (NP)-based therapies as potential alternatives for IBD management. Various drug delivery strategies, including those targeting microbiota interactions, ligand-receptor binding, pH sensitivity, biodegradability, pressure response, and specific charge and size parameters, have been explored and optimized in animal studies. This review provides a comprehensive overview of the current landscape of chitosan NP-mediated drug delivery systems for IBD treatment. Additionally, it will discuss the prevailing challenges and propose future research directions to advance chitosan NP-based therapeutic strategies for IBD.

Isolation, structure, biological activity and application progress of ginseng polysaccharides from the Araliaceae family

Phytopolysaccharides are a class of natural macromolecules with a range of biological activities. Ginseng, red ginseng, American ginseng, and Panax notoginseng are all members of the Araliaceae family. They are known to contain a variety of medicinal properties and are typically rich in a wide range of medicinal values. Polysaccharides represent is one of the principal active ingredients in the aforementioned plants. However, there is a paucity of detailed reports on the separation methods, structural characteristics and comparison of various pharmacological effects of these polysaccharides. This paper presents a review of the latest research reports on ginseng, red ginseng, American ginseng and ginseng polysaccharides. The differences in extraction, separation, purification, structural characterization, and pharmacological activities of the four polysaccharides are compared and clarified. Upon examination of the current research literature, it becomes evident that the extraction and separation processes of the four polysaccharides are highly similar. Modern pharmacological studies have corroborated the multiple biological activities of these polysaccharides. These activities encompass a range of beneficial effects, including antioxidant stress injury, fatigue reduction, tumor inhibition, depression alleviation, regulation of intestinal flora, immunomodulation, diabetes management, central nervous system protection, anti-aging, and improvement of skin health. This paper presents a review of studies on the extraction, purification, characterization, and bioactivities of four natural plant ginseng polysaccharides. Furthermore, the review presents the most recent research findings on their pharmacological activities. The information provides a theoretical basis for the future application of natural plant polysaccharides and offers a new perspective for the in-depth development of the medicinal value of ginseng in the clinical practice of traditional Chinese medicine.

Molecular Engineering of Activatable NIR-II Hemicyanine Reporters for Early Diagnosis and Prognostic Assessment of Inflammatory Bowel Disease

Molecular imaging in the second near-infrared window (NIR-II) provides high-fidelity visualization of biopathological events in deep tissue. However, most NIR-II probes produce "always-on" output and demonstrate poor signal specificity toward biomarkers. Herein, we report a series of hemicyanine reporters (HBCs) with tunable emission to NIR-II window (715-1188 nm) and structurally amenable to constructing activatable probes. Such manipulation of emission wavelengths relies on rational molecular engineering by integrating benz[c,d]indolium, benzo[b]xanthonium, and thiophene moieties to a conventional hemicyanine skeleton. In particular, HBC4 and HBC5 possess bright and record long emission over 1050 nm, enabling improved tissue penetration depth and superior signal to background ratio for intestinal tract mapping than NIR-I fluorophore HC1. An activatable inflammatory reporter (AIR-PE) is further constructed for pH-triggered site-specific release in colon. Due to minimized background interference, oral gavage of AIR-PE allows clear delineation of irritated intestines and assessment of therapeutic responses in a mouse model of inflammatory bowel disease (IBD) through real-time NIRF-II imaging. Benefiting from its high fecal clearance efficiency (>90%), AIR-PE can also detect IBD and evaluate the effectiveness of colitis treatments via in vitro optical fecalysis, which outperforms typical clinical assays including fecal occult blood testing and histological examination. This study thus presents NIR-II molecular scaffolds that are not only applicable to developing versatile activatable probes for early diagnosis and prognostic monitoring of deeply seated diseases but also hold promise for future clinical translations.

Luminol-conjugated cyclodextrin biological nanoparticles for the treatment of severe burn-induced intestinal barrier disruption

Background

The breakdown of intestinal barrier integrity occurs after severe burn injury and is responsible for the subsequent reactions of inflammation and oxidative stress. A new protective strategy for the intestinal barrier is urgently needed due to the limitations of the traditional methods. Recently, the application of nanoparticles has become one of the promising therapies for many inflammation-related diseases or oxidative damage. Herein, we developed a new anti-inflammatory and antioxidant nanoparticle named luminol-conjugated cyclodextrin (LCD) and aimed to evaluate its protective effects in severe burn-induced intestinal injury.

Methods

First, LCD nanoparticles, engineered with covalent conjugation between luminol and β-cyclodextrin (β-CD), were synthesized and examined. Then a mouse burn model was successfully established before the mouse body weight, intestinal histopathological manifestation, permeability, tight junction (TJ) expression and pro-inflammatory cytokines were determined in different groups. The proliferation, apoptosis, migration and reactive oxygen species (ROS) of intestinal epithelial cells (IECs) were assessed. Intraepithelial lymphocytes (IELs) were isolated and cultured for analysis by flow cytometry.

Results

LCD nanoparticle treatment significantly relieved the symptoms of burn-induced intestinal injury in the mouse model, including body weight loss and intestinal permeability abnormalities. Moreover, LCD nanoparticles remarkably recovered the mechanical barrier of the intestine after severe burn, renewed TJ structures, promoted IEC proliferation and migration, and inhibited IEC apoptosis. Mechanistically, LCD nanoparticles dramatically alleviated pro-inflammation factors (tumor necrosis factor-α, IL-17A) and ROS accumulation, which could be highly involved in intestinal barrier disruption. Furthermore, an increase in IL-17A and the proportion of IL-17A+Vγ4+ γδ T subtype cells was also observed in vitro in LPS-treated Vγ4+ γδ T cells, but the use of LCD nanoparticles suppressed this increase.

Conclusions

Taken together, these findings demonstrate that LCD nanoparticles have the protective ability to ameliorate intestinal barrier disruption and provide a therapeutic intervention for burn-induced intestinal injury.

Bridging the Mind and Gut: Uncovering the Intricacies of Neurotransmitters, Neuropeptides, and their Influence on Neuropsychiatric Disorders

BACKGROUND

The gut-brain axis (GBA) is a bidirectional signaling channel that facilitates communication between the gastrointestinal tract and the brain. Recent research on the gut-brain axis demonstrates that this connection enables the brain to influence gut function, which in turn influences the brain and its cognitive functioning. It is well established that malfunctioning of this axis adversely affects both systems' ability to operate effectively.

OBJECTIVE

Dysfunctions in the GBA have been associated with disorders of gut motility and permeability, intestinal inflammation, indigestion, constipation, diarrhea, IBS, and IBD, as well as neuropsychiatric and neurodegenerative disorders like depression, anxiety, schizophrenia, autism, Alzheimer's, and Parkinson's disease. Multiple research initiatives have shown that the gut microbiota, in particular, plays a crucial role in the GBA by participating in the regulation of a number of key neurochemicals that are known to have significant effects on the mental and physical well-being of an individual.

METHODS

Several studies have investigated the relationship between neuropsychiatric disorders and imbalances or disturbances in the metabolism of neurochemicals, often leading to concomitant gastrointestinal issues and modifications in gut flora composition. The interaction between neurological diseases and gut microbiota has been a focal point within this research. The novel therapeutic interventions in neuropsychiatric conditions involving interventions such as probiotics, prebiotics, and dietary modifications are outlined in this review.

RESULTS

The findings of multiple studies carried out on mice show that modulating and monitoring gut microbiota can help treat symptoms of such diseases, which raises the possibility of the use of probiotics, prebiotics, and even dietary changes as part of a new treatment strategy for neuropsychiatric disorders and their symptoms.

CONCLUSION

The bidirectional communication between the gut and the brain through the gut-brain axis has revealed profound implications for both gastrointestinal and neurological health. Malfunctions in this axis have been connected to a range of disorders affecting gut function as well as cognitive and neuropsychiatric well-being. The emerging understanding of the role of gut microbiota in regulating key neurochemicals opens up possibilities for novel treatment approaches for conditions like depression, anxiety, and neurodegenerative diseases.

From the updated landscape of the emerging biologics for IBDs treatment to the new delivery systems

Inflammatory bowel diseases (IBDs) treatments have shifted from small-molecular therapeutics to the oncoming biologics. The first-line biologics against the moderate-to-severe IBDs are mainly involved in antibodies against integrins, cytokines and cell adhesion molecules. Besides, other biologics including growth factors, antioxidative enzyme, anti-inflammatory peptides, nucleic acids, stem cells and probiotics have also been explored at preclinical or clinical studies. Biologics with variety of origins have their unique potentials in attenuating immune inflammation or gut mucosa healing. Great advances in use of biologics for IBDs treatments have been archived in recent years. But delivering issues for biologic have also been confronted due to their liable nature. In this review, we will focus on biologics for IBDs treatments in the recent publications; summarize the current landscapes of biologics and their promise to control disease progress. Alternatively, the confronted challenges for delivering biologics will also be analyzed. To combat these drawbacks, some new delivering strategies are provided: firstly, designing the functional materials with high affinity toward biologics; secondly, the delivering vehicle systems to encapsulate the liable biologics; thirdly, the topical adhering delivery systems as enema. To our knowledge, this review is the first study to summarize the updated usage of the oncoming biologics for IBDs, their confronted challenges in term of delivery and the potential combating strategies.

Orally Administrable Aggregation-Induced Emission-Based Bionic Probe for Imaging and Ameliorating Dextran Sulfate Sodium-Induced Inflammatory Bowel Diseases

As macrophage infiltration is significantly related to the progression of inflammatory bowel disease (IBD), monitoring the macrophages is a valuable strategy for IBD diagnosis. However, owing to the harsh physiological environment of the gastrointestinal tract and enzymatic degradation, the development of orally administrable imaging probes for tracking macrophages remains a considerable challenge. Accordingly, herein, an orally administrable aggregation-induced emission biomimetic probe (HBTTPIP/β-glucan particles [GPs]) is developed for tracing macrophages; HBTTPIP/GPs can diagnose and alleviate dextran sulfate sodium (DSS)-induced colonic inflammation and self-report the treatment efficiency. The fluorophore HBTTPIP can effectively aggregate in GPs, restricting intramolecular rotation and activating the fluorescence of HBTTPIP. After being orally administrated, HBTTPIP/GPs are phagocytosed by intestinal macrophages, which then migrate to colonic lesions, enabling non-invasive monitoring of the severity of IBD via in vivo fluorescence imaging. Notably, oral HBTTPIP/GPs ameliorate DSS-induced IBD by inhibiting the expressions of pro-inflammatory factors and improving colonic mucosal barrier function. Furthermore, these HBTTPIP/GPs realize self-feedback of the therapeutic effects of GPs on DSS-induced colitis. The oral biomimetic probe HBTTPIP/GPs reported herein provide a novel theranostic platform for IBD, integrating non-invasive diagnosis of IBD in situ and the corresponding treatment.

Computer-Aided Screening and Revealing Action Mechanism of Food-Derived Tripeptides Intervention in Acute Colitis

Food-derived tripeptides can relieve colitis symptoms; however, their alleviation mode has not been systematically evaluated as an alternative nutritional compound. This study aimed to reveal the potential mechanism of 8000 food-derived tripeptides against acute colitis using a computer-aided screening strategy. Forty-one potential hub targets related to colitis with a Fit score > 4.0 were screened to construct the protein-protein and protein-tripeptide network based on the PharmMapper database and STRING software (Ver. 11.5). In addition, 30 significant KEGG signaling pathways with p-values < 0.001 that the 41 hub targets mainly participated in were identified using DAVID software (Ver. 6.8), including inflammatory, immunomodulatory, and cell proliferation and differentiation-related signaling pathways, particularly in the Ras- and PI3K-Akt signaling pathways. Furthermore, molecular docking was performed using the Autodock against majorly targeted proteins (AKT1, EGFR, and MMP9) with the selected 52 tripeptides. The interaction model between tripeptides and targets was mainly hydrogen-bonding and hydrophobic interactions, and most of the binding energy of the tripeptide target was less than −7.13 kcal/mol. This work can provide valuable insight for exploring food-derived tripeptide mechanisms and therapeutic indications.

In situ mucoadhesive hydrogel capturing tripeptide KPV: the anti-inflammatory, antibacterial and repairing effect on chemotherapy-induced oral mucositis

The self-healing of chemotherapy-induced oral mucositis is difficult in practice because of both local bacterial infection and severe inflammation. Herein, in situ mucoadhesive hydrogels (PPP_E) were successfully prepared by using temperature-sensitive PLGA-PEG-PLGA (PPP) as a matrix and epigallocatechin-3-gallate (EGCG) with inherent antibacterial activity as an adhesion enhancer. A series of PPP_E precursor solutions with various EGCG concentrations (1%, 2% and 5%) were prepared by fixing the PPP concentration at 25%. EGCG slightly decreased the sol-gel transition temperature and shortened the sol-gel transition time of the PPP hydrogel. Moreover, the incorporation of EGCG could significantly increase the tissue adhesion properties of the PPP hydrogel at 37 °C. PPP_2%E displayed a suitable gelation temperature (36.2 °C), gelation time (100 s) and storage modulus (48 Pa). Tripeptide KPV as a model drug was easily dissolved in cold PPP_2%E precursor solution to prepare KPV@PPP_2%E hydrogel. The anti-inflammatory activity and promotion of cell migration potential by KPV in PPP-2% E hydrogel were well maintained. Moreover, KPV@PPP_2%E exhibited strong antibacterial efficacy against S. aureus. PPP_2%E precursor solution rapidly transformed to a hydrogel and adhered to the wound surface for 7 hours when administrated to the gingival mucosa of rats. Treatment with KPV@PPP_2%E hydrogel greatly improved the food intake and body weight recovery of rats with chemotherapy-induced oral mucositis. Moreover, the tissue morphology of the ulcerated gingiva after application of KPV@PPP_E hydrogel was also well repaired by promoting CK10 and PCNA expression. In addition, the inflammatory cytokines including IL-1β and TNF-α were significantly inhibited by KPV@PPP_2%E hydrogel while IL-10 was up-regulated. KPV@PPP_2%E hydrogel also had an anti-bacterial effect on MRSA-infected gingival ulcer wounds, which resulted in the obvious inhibition of infiltration by inflammatory cells into submucosal tissues. Conclusively, KPV@PPP_E may be a promising practical application for cancer patients with chemotherapy-induced oral mucositis.

Modulation of Naturally Occurring Linear Dipeptide Chirality to Reduce the Affinity for Oligopeptide Transporter 1 and Increase Intestinal Stability for an Enhanced Colon-Targeting Effect in the Treatment of Inflammatory Bowel Disease: An Application of trans-4-l-Hydroxyprolyl-l-serine

The naturally occurring linear dipeptide JBP923 (trans-4-l-Hyp-l-Ser, HS-tLL) with anti-inflammatory effects showed potential for the treatment of inflammatory bowel disease (IBD). However, colon-specific delivery after oral administration is still a challenge because its absorption is mediated by oligopeptide transporter 1 (PEPT1) in the upper small intestine and because of its instability in the gastrointestinal tract. Therefore, we aimed to enhance the colon-targeting efficiency by modulating HS-tLL chirality to synthesize eight enantiomers. Among these enantiomers, trans-4-d-Hyp-d-Ser, cis-4-l-Hyp-d-Ser, cis-4-d-Hyp-l-Ser, and cis-4-d-Hyp-d-Ser did not work as substrates of PEPT1 and were stable in the gastrointestinal tract, resulting in enhanced colonic accumulation through the paracellular pathway due to the loose tight junctions in IBD. Interestingly, cis-4-d-Hyp-d-Ser exerted the most potent therapeutic effect on IBD. Our findings revealed the impact of chirality on the colonic accumulation of the linear dipeptide, providing strategies for the colon-targeted delivery of the linear dipeptide for the treatment of IBD.

The endoscopic diagnosis of mucosal healing and deep remission in inflammatory bowel disease

The therapeutic goal in inflammatory bowel disease (IBD) patients has shifted from controlling the clinical activity alone to managing other associated problems. The concept of mucosal healing (MH) and deep remission (DR) are advocated and regarded as new therapeutic goals in IBD. However, the definition of MH still remains controversial. It is unclear whether or not the histological structures or functional factors should be included in the definition of DR in addition to clinical remission and MH. The classifications of white-light imaging (e.g. Mayo endoscopic subscore, UCEIS, CD Endoscopic Index of Severity, simple Endoscopic Score-CD) have been proposed and are now widely used to assess the severity as well as the MH of inflammation in IBD. In ulcerative colitis, magnifying chromoendoscopy has been shown to be useful to assess the MH of inflammation while other types of image-enhanced endoscopy, such as narrow-band imaging, have not. Endocytoscopy and confocal laser endomicroscopy (CLE) are also applied to assess the activity in IBD. These endoscopic procedures can estimate MH with more precision through observing the details of superficial structures, such as crypt openings. In addition, CLE can partially assess the mucosal function by detecting fluorescence leakage. Molecular imaging can possibly detect the molecules associated with inflammation, intestinal regeneration and differentiation, and various functions including the intestinal barrier and mucus secretion. These novel procedures may improve the diagnosis strategy of DR through the assessment of DR-associated factors such as the histological structures and functional factors in the near future.

Oral delivery of natural active small molecules by polymeric nanoparticles for the treatment of inflammatory bowel diseases

The incidence of inflammatory bowel disease (IBD) is rapidly rising throughout the world. Although tremendous efforts have been made, limited therapeutics are available for IBD management. Natural active small molecules (NASMs), which are a gift of nature to humanity, have been widely used in the prevention and alleviation of IBD; they have numerous advantageous features, including excellent biocompatibility, pharmacological activity, and mass production potential. Oral route is the most common and acceptable approach for drug administration, but the clinical application of NASMs in IBD treatment via oral route has been seriously restricted by their inherent limitations such as high hydrophobicity, instability, and poor bioavailability. With the development of nanotechnology, polymeric nanoparticles (NPs) have provided a promising platform that can efficiently encapsulate versatile NASMs, overcome multiple drug delivery barriers, and orally deliver the loaded NASMs to targeted tissues or cells while enhancing their stability and bioavailability. Thus, NPs can enhance the preventive and therapeutic effects of NASMs against IBD. Herein, we summarize the recent knowledge about polymeric matrix-based carriers, targeting ligands for drug delivery, and NASMs. We also discuss the current challenges and future developmental directions.

Receptor-mediated targeted drug delivery systems for treatment of inflammatory bowel disease: Opportunities and emerging strategies

Inflammatory bowel disease (IBD) is a chronic intestinal disease with painful clinical manifestations and high risks of cancerization. With no curative therapy for IBD at present, the development of effective therapeutics is highly advocated. Drug delivery systems have been extensively studied to transmit therapeutics to inflamed colon sites through the enhanced permeability and retention (EPR) effect caused by the inflammation. However, the drug still could not achieve effective concentration value that merely utilized on EPR effect and display better therapeutic efficacy in the inflamed region because of nontargeted drug release. Substantial researches have shown that some specific receptors and cell adhesion molecules highly expresses on the surface of colonic endothelial and/or immune cells when IBD occurs, ligand-modified drug delivery systems targeting such receptors and cell adhesion molecules can specifically deliver drug into inflamed sites and obtain great curative effects. This review introduces the overexpressed receptors and cell adhesion molecules in inflamed colon sites and retrospects the drug delivery systems functionalized by related ligands. Finally, challenges and future directions in this field are presented to advance the development of the receptor-mediated targeted drug delivery systems for the therapy of IBD.

Urokinase Plasminogen Activator Receptor-Mediated Targeting of a Stable Nanocomplex Coupled with Specific Peptides for Imaging of Cancer

Targeting peptides are a promising tool for early diagnosis and therapy of cancer. Overexpression of urokinase plasminogen activator receptor (uPAR) leads to the progression of tumors including prostate, colorectal, ovarian, and breast cancers. To improve the diagnosis and imaging efficiency, herein we report a stable nanocomplex comprising methoxy-PEG-hydrazide (mPEG-H-M)-modified gold nanoparticles (AuNPs) conjugated to uPAR (urokinase plasminogen activator receptor)-targeting peptides GFD (growth factor domain-G) and SMB (somatomedian B-S) for efficient imaging of uPAR-overexpressing cancer cells. Fluorescently labeled targeting peptides were covalently linked to mPEG-H coated AuNPs, characterized, and analyzed by UV-vis spectroscopy, diffraction light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and fluorescence spectroscopy. In vitro evaluation was assessed with a fluorescence-activated cell sorter (FACS), cell adhesion, and fluorescence microscopy. The peptide-functionalized nanocomplex showed a higher uptake of AuNPs@MGS in comparison with AuNPs@G or AuNPs@S alone in uPAR-overexpressing cells and exhibits no toxicity when analyzed with MTT assay. Our results demonstrated that the developed nanocomplex can be used as a platform for imaging and diagnosis of metastatic tumors.

Small-molecule fluorescence-based probes for interrogating major organ diseases

Chemical tools that allow the real-time monitoring of organ function and the visualisation of organ-related processes at the cellular level are of great importance in biological research. The upregulation/downregulation of specific biomarkers is often associated with the development of organ related diseases. Small-molecule fluorescent probes have the potential to create advances in our understanding of these disorders. Viable probes should be endowed with a number of key features that include high biomarker sensitivity, low limit of detection, fast response times and appropriate in vitro and in vivo biocompatibility. In this tutorial review, we discuss the development of probes that allow the targeting of organ related processes in vitro and in vivo. We highlight the design strategy that underlies the preparation of various promising probes, their optical response to key biomarkers, and proof-of-concept biological studies. The inherent drawbacks and limitations are discussed as are the current challenges and opportunities in the field. The hope is that this tutorial review will inspire the further development of small-molecule fluorescent probes that could aid the study of pathogenic conditions that contribute to organ-related diseases.

A Targeted Erythrocyte Membrane-Encapsulated Drug-Delivery System with Anti-osteosarcoma and Anti-osteolytic Effects

Chemotherapy is one of the main treatment methods for osteosarcoma. However, conventional chemotherapy lacks targeting properties, and its long-term and extensive use will have serious side effects on patients. For this reason, a multifunctional nanodrug system (V-RZCD) targeting osteosarcoma was developed in this study. V-RZCD consists of two parts: (1) the core (ZCD), wherein calcium ions (Ca2+) and zoledronic acid (ZA) form a metal-organic framework for loading doxorubicin (DOX), and (2) the shell (V-R), a vascular endothelial growth factor (VEGF) ligand-modified red blood cell membrane nanovesicle. By targeting the VEGF, V-RZCD can specifically bind to the VEGF receptors that are highly expressed on the surface of osteosarcoma cells. Importantly, compared with free ZA and DOX, V-RZCD not only clearly inhibits the proliferation of osteosarcoma but also significantly inhibits osteolysis induced by osteosarcoma. In summary, V-RZCD represents a new way to treat osteosarcoma.

Antifibrotic and Anti-Inflammatory Actions of α-Melanocytic Hormone: New Roles for an Old Player

The melanocortin system encompasses melanocortin peptides, five receptors, and two endogenous antagonists. Besides pigmentary effects generated by α-Melanocytic Hormone (α-MSH), new physiologic roles in sexual activity, exocrine secretion, energy homeostasis, as well as immunomodulatory actions, exerted by melanocortins, have been described recently. Among the most common and burdensome consequences of chronic inflammation is the development of fibrosis. Depending on the regenerative capacity of the affected tissue and the quality of the inflammatory response, the outcome is not always perfect, with the development of some fibrosis. Despite the heterogeneous etiology and clinical presentations, fibrosis in many pathological states follows the same path of activation or migration of fibroblasts, and the differentiation of fibroblasts to myofibroblasts, which produce collagen and α-SMA in fibrosing tissue. The melanocortin agonists might have favorable effects on the trajectories leading from tissue injury to inflammation, from inflammation to fibrosis, and from fibrosis to organ dysfunction. In this review we briefly summarized the data on structure, receptor signaling, and anti-inflammatory and anti-fibrotic properties of α-MSH and proposed that α-MSH analogues might be promising future therapeutic candidates for inflammatory and fibrotic diseases, regarding their favorable safety profile.

In Vivo Imaging of Hypoxia Associated with Inflammatory Bowel Disease by a Cytoplasmic Protein-Powered Fluorescence Cascade Amplifier

Accurate and sensitive imaging of hypoxia associated with inflammatory bowel disease (IBD) is significant for the precise diagnosis and treatment of this disease, but it remains a challenge for traditional hypoxia-activatable fluorescence probes because of a more moderate hypoxic state during IBD than under other pathological conditions. To address this issue, herein, we designed a hypoxia-activatable and cytoplasmic protein-powered fluorescence cascade amplifier, named HCFA, to image hypoxia associated with IBD in vivo. In our design, a 4-aminobenzoic acid (azo)-modified mesoporous silica nanoparticle (MSN) was used as a container to load black hole quencher 2 (BHQ2) and cytoplasmic protein-binding squarylium dye (SQ); then, the β-cyclodextrin polymer (β-CDP) combined with azo through a host-guest interaction to form HCFA. Upon passive stagnation in the inflamed tissue of IBD, the azo band would be cleaved under a hypoxic microenvironment, and SQ was released to activate the fluorescence of HCFA. Moreover, the unconstrained SQ can bind with cytoplasmic protein to exhibit drastic fluorescence intensity enhancement, realizing the fluorescence signal amplification for imaging of hypoxia. When one takes advantage of the large load capacity of MSN and the unique property of SQ, HCFA can sense oxygen levels in the range of 0% to 10%. Meanwhile, the fluorescence imaging results demonstrate that HCFA can sensitively distinguish different levels of cellular hypoxia and monitor the variations of hypoxia in vivo, highlighting HCFA as a promising tool for the detection of hypoxia associated with IBD.

Synthesis of Small Fluorescent Molecules and Evaluation of Photophysical Properties

A series of aniline-based fluorophores were newly synthesized. To increase their fluorescence quantum yields, it was particularly important to substitute 3,3,3-trifluoroprop-1-enyl (TFPE) groups next to the amino group to benefit from an extended π-electron delocalization. Among these, 5-CN-2-TFPE-aniline was found to behave as an excellent fluorophore with a reasonable fluorescence quantum yield of 0.89 even in aqueous solution. l-Alanine peptide, a nonfluorescent analogue of 5-CN-2-TFPE-aniline, was synthesized and successfully employed as an enzyme probe to detect aminopeptidase N activity.

In situ imaging of aminopeptidase N activity in hepatocellular carcinoma: a migration model for tumour using an activatable two-photon NIR fluorescent probe

CD13/aminopeptidase N (APN), which is a zinc-dependent metalloproteinase, plays a vital role in the growth, migration, angiogenesis, and metastasis of tumours. Thus, in situ molecular imaging of endogenous APN levels is considerably significant for investigating APN and its different functions. In this study, a novel two-photon near-infrared (NIR) fluorescence probe DCM-APN was prepared to perform in vitro and in vivo tracking of APN. The N-terminal alanyl site of probe DCM-APN was accurately hydrolysed to the amino group, thereby liberating strong fluorescence owing to the recovery of the Intramolecular Charge Transfer (ICT) effect. By considering its outstanding selectivity, ultra-sensitivity (DL 0.25 ng mL-1) and favourable biocompatibility, the probe DCM-APN was used to distinguish between normal cells (LO2 cells) and cancer cells (HepG-2 and B16/BL6 cells). Furthermore, migration of hepatocellular carcinoma cells was apparently inhibited by ensuring that the APN catalytic cavity was occupied by bestatin. The identification of three-dimensional (3D) fluorescence in cancer tissues was completed under two-photon excitation coupled with lighting up hepatocellular carcinoma tumours in situ; this revealed that probe DCM-APN is an effective tool for detecting APN, thereby assisting in the early diagnosis of tumour in clinical medicine.