A Fluorinated Supramolecular Self-Assembled Peptide as Nanovaccine Adjuvant for Enhanced Cancer Vaccine Therapy.

Adjuvants play an important role in enhancing vaccine-induced immune protection. Adequate cellular uptake, robust lysosomal escape, and subsequent antigen cross-presentation are critical steps for vaccine adjuvants to effectively elicit cellular immunity. Here, a fluorinated supramolecular strategy to generate a series of peptide adjuvants by using arginine (R) and fluorinated diphenylalanine peptide (DP) is adopted. It is found that the self-assembly ability and antigen-binding affinity of these adjuvants increase with the number of fluorine (F) and can be regulated by R. By comparison, 4RDP(F5) shows the strongest binding affinity with model antigen ovalbumin (OVA) and the best performance in dendritic cells maturation and antigen's lysosomal escape, which contributes to the subsequent antigen cross-presentation. As a consequence, 4RDP(F5)-OVA nanovaccine generates a strong cellular immunity in a prophylactic OVA-expressing EG7-OVA lymphoma model, leading to long-term immune memory for resisting tumor challenge. What's more, 4RDP(F5)-OVA nanovaccine in combination with anti-programmed cell death ligand-1 (anti-PD-L1) checkpoint blockade could effectively elicit anti-tumor immune responses and inhibit tumor growth in a therapeutic EG7-OVA lymphoma model. Overall, this study demonstrates the simplicity and effectiveness of fluorinated supramolecular strategies for constructing adjuvants and might provide an attractive vaccine adjuvant candidate for cancer immunotherapy.

An AIEgen-based "turn-on" probe for sensing cancer cells and tiny tumors with high furin expression.

Peptide-aggregation-induced emission (AIE) luminogen (AIEgen) conjugates are widely used in the bioimaging field for their good resistance to photobleaching, red and near-infrared light emission, good biocompatibility, etc. However, their peptides are mainly negatively charged and the positively charged peptide-AIEgen conjugates are rarely used in in vivo imaging due to their high non-specific interaction with protein to cause "false-positive" results and their potential risk of triggering hemolysis. Herein, we introduce a black hole quencher 3 (BHQ3) to RVRRGFF-AIE (FA) to build a "turn-on" probe, named BHQ3-RVRRGFF-AIE (BFA). Compared with FA, BFA has advantages in the anti-interference ability for different proteins and many solution environments. But, both BFA and FA have high risks of inducing hemolysis, which restricts their further application. Through co-assembly with poly-γ-glutamic acid (γ-PGA), molecular probes BFA and FA are formed into PGA-BFA and PGA-FA nanoparticles with high biocompatibility and suppressed phototoxicity. Cell studies show that PGA-BFA can discriminate cancer cells with high furin expression from low furin-expressed cancer cells and normal cells. In vivo studies show that PGA-BFA can light up tiny tumors in the abdominal cavity with a better tumor-to-intestine ratio (3.14) than that of PGA-FA (1.47), which is helpful for the accurate excision of tiny tumors. This study will advance the development of constructing good biosafety probes with a high signal-to-noise ratio for fluorescence image-guided cancer surgery.

Direct Modification of Extracellular Vesicles and Its Applications for Cancer Therapy: A Mini-Review.

Extracellular vesicles (EVs) are a class of lipid membrane-bound vesicles released by various cells and mediate cell-to-cell communication. By reason of their high physiochemical stability and biocompatibility, EVs are considered as novel drug delivery system. An increasing number of studies have indicated that EVs can be modified to enhance their loading efficiency, targeting ability and therapeutic capabilities for cancer therapy. Compared with the tedious process of gene engineering approaches, direct modification of EVs is easier, faster and versatile. This mini review will summarize the prevailing approaches for direct modification of EVs. Additionally, the potential applications of modified EVs in cancer therapy are also discussed, which will help readers gain a better understanding of the technologies and applications in this field.

Evoking Highly Immunogenic Ferroptosis Aided by Intramolecular Motion-Induced Photo-Hyperthermia for Cancer Therapy.

Immunogenic cell death (ICD) through apoptosis or necroptosis is widely adopted to improve the therapeutic effect in cancer treatment by triggering a specific antitumor immunity. However, the tumor resistance to apoptosis/necroptosis seriously impedes the therapeutic effect. Recently, ferroptosis featured with excessive lipid peroxidation is demonstrated capable of bypassing the apoptosis/necroptosis resistance to kill cancer cells. To date, numerous efficient ferroptosis inducers are developed and successfully utilized for sensitizing cancer cells to ferroptosis. Unfortunately, these inducers can hardly generate adequate immunogenicity during induction of ferroptotic cancer cell death, which distinctly attenuates the efficacy of triggering antitumor immune response, therefore leads to unsatisfactory therapeutic effect. Herein, a novel high-performance photothermal nanoparticle (TPA-NDTA NP) is designed by exploiting energy via excited-state intramolecular motion and employed for immensely assisting ferroptosis inducer to evoke highly efficient ICD through ferroptosis pathway. Tumor models with poor immunogenicity are used to demonstrate the tremendously enhanced therapeutic effect endowed by highly enhanced immunogenic ferroptosis in vitro and in vivo by virtue of the NPs. This study sheds new light on a previously unrecognized facet of boosting the immunogenicity of ferroptosis for achieving satisfactory therapeutic effect in cancer therapy.

Activatable Persistent Luminescence from Porphyrin Derivatives and Supramolecular Probes with Imaging-Modality Transformable Characteristics for Improved Biological Applications.

Persistent luminescence without excitation light and tissue autofluorescence interference holds great promise for biological applications, but is limited by available materials with long-wavelength emission and excellent clinical potential. Here, we report that porphyrin derivatives can emit near-infrared persistent luminescence over 60 min after cessation of excitation light or on interaction with peroxynitrite. A plausible mechanism of the successive oxidation of vinylene bonds was demonstrated. A supramolecular probe with a ß-sheet structure was constructed to enhance the tumor targeting ability and the photoacoustic and persistent luminescence signals. Such probes featuring light-triggered function transformation from photoacoustic imaging to persistent luminescence imaging permit advanced image-guided cancer surgery. Furthermore, peroxynitrite-activated persistent luminescence of the supramolecular probe also enables rapid and precise screening of immunogenic cell death drugs.

Targeted Enrichment of Enzyme-Instructed Assemblies in Cancer Cell Lysosomes Turns Immunologically Cold Tumors Hot.

Lysosome-relevant cell death induced by lysosomal membrane permeabilization (LMP) has recently attracted increasing attention. However, nearly no studies show that currently available LMP inducers can evoke immunogenic cell death (ICD) or convert immunologically cold tumors to hot. Herein, we report a LMP inducer named TPE-Py-pYK(TPP)pY, which can respond to alkaline phosphatase (ALP), leading to formation of nanoassembies along with fluorescence and singlet oxygen turn-on. TPE-Py-pYK(TPP)pY tends to accumulate in ALP-overexpressed cancer cell lysosomes as well as induce LMP and rupture of lysosomal membranes to massively evoke ICD. Such LMP-induced ICD effectively converts immunologically cold tumors to hot as evidenced by abundant CD8+ and CD4+ T cells infiltration into the cold tumors. Exposure of ALP-catalyzed nanoassemblies in cancer cell lysosomes to light further intensifies the processes of LMP, ICD and cold-to-hot tumor conversion. This work thus builds a new bridge between lysosome-relevant cell death and cancer immunotherapy.

A peptide-based aggregation-induced emission bioprobe for selective detection and photodynamic killing of Gram-negative bacteria.

Herein, we report a new bioprobe with aggregation-induced emission (AIE) characteristics by conjugation of a far-red/near-infrared emissive AIE luminogen and two polymyxinB peptides. Due to the strong binding effect between polymyxin B and the lipopolysaccharide in the cell wall of Gram-negative bacteria, the bioprobe can selectively visualize Gram-negative bacteria and effectively kill them via photodynamic treatment.

Bafilomycin A1 Accelerates Chronic Refractory Wound Healing in db/db Mice.

Numerous studies have reported that autophagy plays an important role in chronic wound healing, and enhancement of autophagic activity impairs cutaneous wound healing. The autophagy inhibitor Bafilomycin A1 (Baf A1) inhibits autophagy by preventing the formation of autophagosomes. This study aimed at elucidating the effect of Bafilomycin A1 on chronic refractory wound healing in diabetic mice. A total of 40 diabetic (db/db) mice and 20 nondiabetic (db/m) mice were used in this study. Full-thickness skin defects were generated in the db/db mice models, which were then divided into the following two groups: the nontreated (db/db group) and Baf A1-treated groups (Baf A1 group). The same skin defects were generated in db/m mice (db/m group) to serve as a control. We demonstrated that Baf A1 treatment significantly accelerated wound healing in db/db mice and exerted good healing effects. Moreover, Baf A1 inhibited autophagy in the newly generated epidermis and had minor effects on metabolism in db/db mice. PCNA expression, as detected by immunohistochemistry, and collagen thickness, as detected by Masson's trichrome staining on the 14th day, were higher in the db/m and Baf A1 groups than in the db/db group. In addition, the expression of the proinflammatory cytokine TNF-α in the db/m and Baf A1 groups increased significantly on day 6, and the expression of the anti-inflammatory cytokine IL-10 also increased significantly on day 9. However, there were no significant changes in the expression levels of TNF-α and IL-10 in the db/db group. Therefore, Baf A1 may accelerate diabetic chronic refractory wound healing by promoting cell proliferation, collagen production, and regulating the inflammatory balance.

Construction of small-sized superparamagnetic Janus nanoparticles and their application in cancer combined chemotherapy and magnetic hyperthermia.

Novel Janus nanoparticles (J-NPs) are developed by using single iron oxide (Fe3O4) nanoparticles as the core and hydrophobic/hydrophilic polymeric brushes as the cloak. Because of the superparamagnetism and asymmetric functionality of J-NPs, they are used as drug carriers and therapeutic agents for cancer chemotherapy and magnetic hyperthermia with a magnetic resonance imaging (MRI) guide. The asymmetric functionality is constituted of hydrophobic polymethyl methacrylate (PMMA) brushes and hydrophilic polyacrylic acid (PAA) brushes, which are 'grafting to' or 'grafting from' Fe3O4 nanoparticles via activators regenerated by electron transfer atom transfer radical polymerization. The terminal chains of PMMA and PAA brushes are coordinated with Fe3O4 nanoparticles, so PMMA/Fe3O4/PAA J-NPs possess structural stability in solvents. Because of the brush-structure, PMMA/Fe3O4/PAA J-NPs show high encapsulation efficiency (89.75 ± 2.35%) and loading capacity (8.95 ± 0.26%). Under the alternating magnetic field (AMF), drug-loaded J-NPs achieve the highest cell proliferation-inhibition ratio in the cell proliferation test in vitro and the tumor growth inhibition test in vivo compared to single chemotherapy or magnetic hyperthermia. Meanwhile, J-NPs show good T2 imaging.

Far-Red/Near-Infrared Emissive (1,3-Dimethyl)barbituric Acid-Based AIEgens for High-Contrast Detection of Metastatic Tumors in the Lung.

Despite of the enthusiastic research in aggregation-induced emission luminogens (AIEgens) in recent years, the ones that can be smoothly used for sophisticated biomedical applications such as in vivo bioimaging of pulmonary metastatic tumors during surgery are still limited. Herein, we report the design and synthesis of a new series of far-red/near-infrared (FR/NIR) fluorescent AIEgens that consist of methoxy-substituted tetraphenylethene (TPE) as the electron-donating moiety, (1,3-dimethyl)barbituric acid as the electron-withdrawing moiety, and different π-bridge units. As compared to benzene or 3,4-ethylenedioxythiophene, using thiophene as the π-conjugation unit between the donor and acceptor results in a relatively higher absolute fluorescence quantum yield (14.5 %) in water when formulating the corresponding AIEgens into nanoparticles (AIE dots) with an amphiphilic co-polymer as the doping matrix. The highly FR/NIR-emissive thiophene-based AIE dots are demonstrated to be potent for intraoperative detection of pulmonary metastatic tumors, particularly the micro-sized ones, with excellent signal-to-background ratio.

Light-driven transformable optical agent with adaptive functions for boosting cancer surgery outcomes.

Fluorescence and photoacoustic imaging have different advantages in cancer diagnosis; however, combining effects in one agent normally requires a trade-off as the mechanisms interfere. Here, based on rational molecular design, we introduce a smart organic nanoparticle whose absorbed excitation energy can be photo-switched to the pathway of thermal deactivation for photoacoustic imaging, or to allow opposed routes for fluorescence imaging and photodynamic therapy. The molecule is made of a dithienylethene (DTE) core with two surrounding 2-(1-(4-(1,2,2-triphenylvinyl)phenyl)ethylidene)malononitrile (TPECM) units (DTE-TPECM). The photosensitive molecule changes from a ring-closed, for photoacoustic imaging, to a ring-opened state for fluorescence and photodynamic effects upon an external light trigger. The nanoparticles' photoacoustic and fluorescence imaging properties demonstrate the advantage of the switch. The use of the nanoparticles improves the outcomes of in vivo cancer surgery using preoperative photoacoustic imaging and intraoperative fluorescent visualization/photodynamic therapy of residual tumours to ensure total tumour removal.

Metal-Organic-Framework-Assisted In Vivo Bacterial Metabolic Labeling and Precise Antibacterial Therapy.

Bacterial infection is one of the most serious physiological conditions threatening human health. There is an increasing demand for more effective bacterial diagnosis and treatment through noninvasive theranostic approaches. Herein, a new strategy is reported to achieve in vivo metabolic labeling of bacteria through the use of MIL-100 (Fe) nanoparticles (NPs) as the nanocarrier for precise delivery of 3-azido-d-alanine (d-AzAla). After intravenous injection, MIL-100 (Fe) NPs can accumulate preferentially and degrade rapidly within the high H2 O2 inflammatory environment, releasing d-AzAla in the process. d-AzAla is selectively integrated into the cell walls of bacteria, which is confirmed by fluorescence signals from clickable DBCO-Cy5. Ultrasmall photosensitizer NPs with aggregation-induced emission characteristics are subsequently designed to react with the modified bacteria through in vivo click chemistry. Through photodynamic therapy, the amount of bacteria on the infected tissue can be significantly reduced. Overall, this study demonstrates the advantages of metal-organic-framework-assisted bacteria metabolic labeling strategy for precise bacterial detection and therapy guided by fluorescence imaging.

NO prodrug-conjugated, self-assembled, pH-responsive and galactose receptor targeted nanoparticles for co-delivery of nitric oxide and doxorubicin.

Targeted delivery and controlled release of nitric oxide (NO) locoregionally are in high demand and challenging in cancer treatment. Herein, we report an example of galactose receptor targeted, pH-responsive and self-assembled nanoparticle-based delivery of the NO prodrug O2-(2,4-dinitrophenyl) 1-[4-(propargyloxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate (alkynyl-JSK), which was chemically conjugated to an amphiphilic block copolymer through a click reaction for the first time. The assembled NO prodrug nanoparticles show high NO capacity (the content of the NO prodrug in the copolymer, ∼23.4% (w/w)), good stability and a sustained NO release pattern with unique glutathione/glutathione S-transferase (GSH/GST) activated NO-releasing kinetics. Such NO-loaded nanoparticles exhibit superior cytotoxicity to HepG2 cells. More importantly, in combination with doxorubicin (DOX) chemotherapy a significant synergistic therapeutic effect was achieved, due to its excellent galactose receptor-targeting capability, rapid acid-triggered DOX release and sustained NO release. Our findings indicate that these multifunctional nanoparticles can serve as an efficient NO and chemotherapeutic agent delivery platform, holding great promise in cancer combinatorial treatment.

Composite Hydrogel Modified by IGF-1C Domain Improves Stem Cell Therapy for Limb Ischemia.

Stem cell treatment for critical limb ischemia yields a limited therapeutic effect due to cell loss and dysfunction caused by local ischemic environment. Biomimetic scaffolds emerge as ideal cell delivery vehicles for regulating cell fate via mimicking the components of stem cell niche. Herein, we prepared a bioactive hydrogel by mixing chitosan and hyaluronic acid that is immobilized with C domain peptide of insulin-like growth factor 1 (IGF-1C) and examined whether this hydrogel could augment stem cell survival and therapeutic potential. Our results showed that IGF-1C-modified hydrogel increased in vitro viability and proangiogenic activity of adipose-derived stromal cells (ADSCs). Moreover, cotransplantation of hydrogel and ADSCs into ischemic hind limbs of mice effectively ameliorated blood perfusion and muscle regeneration, leading to superior limb salvage. These therapeutic effects can be ascribed to improved ADSC retention, angiopoientin-1 secretion, and neovascularization, as well as reduced inflammatory cell infiltration. Additionally, hydrogel enhanced antifibrotic activity of ADSCs, as evidenced by decreased collagen accumulation at late stage. Together, our findings indicate that composite hydrogel modified by IGF-1C could promote survival and proangiogenic capacity of ADSCs and thereby represents a feasible option for cell-based treatment for critical limb ischemia.

Enzyme-instructed self-assembly leads to the activation of optical properties for selective fluorescence detection and photodynamic ablation of cancer cells.

Both fluorescence and photoactivity activatable probes are particularly valuable for cancer theranostics as they allow for sensitive fluorescence diagnosis and on-demand photodynamic therapy (PDT) against targeted cancer cells at the same time, which undoubtedly promote the diagnostic accuracy and reduce the side effects on normal tissues/cells. Here, we show that enzyme-instructed self-assembly (EISA) is an ideal strategy to develop a both fluorescence and reactive oxygen species (ROS) generation capability activatable probe with aggregation-induced emission (AIE) signature. As a proof-of-concept, we design and synthesize a precursor TPE-Py-FpYGpYGpY that consists of an AIE luminogen (TPE-Py) and a short peptide with three tyrosine phosphates (pY), which permits selective fluorescence visualization and PDT of alkaline phosphatase (ALP)-overexpressed cancer cells. TPE-Py-FpYGpYGpY has good aqueous solubility thanks to the hydrophilic phosphotyrosine residues and hence leads to weak fluorescence and negligible ROS generation ability. After ALP enzymatic dephosphorylation of the precursors, however, self-assembly of ALP-catalysed products occurs and the resultant nanostructures are activated to be highly emissive and efficiently produce ROS. Cellular studies reveal that TPE-Py-FpYGpYGpY is capable of differentiating cancer cells and normal cells, specifically pinpointing and suppressing ALP-overexpressed cancer cells. This study may inspire new insights into the design of advanced activatable molecular probes.

Amplification of near-infrared fluorescence in semiconducting polymer nanoprobe for grasping the behaviors of systemically administered endothelial cells in ischemia treatment.

To date, there have been few studies on using fluorescent cell trackers for non-invasively monitoring the in vivo fate of systemically administered cells. This is because only a relatively small number of cells can reach the disease site post systemic infusion, and thus achieving ideal in vivo cell tracking requires that the fluorescent cell trackers should hold combined merits of ultrahigh near-infrared (NIR) fluorescence, negligible interference on cell behavior and function, excellent retention within cells, as well as accurate long-term cell tracking ability. To address this challenge, we herein developed a highly NIR fluorescent nanoprobe (SPN) based on semiconducting π-conjugated polymers (SPs), by synthesis of a NIR SP-emitter, employment of fluorescence resonance energy transfer (FRET) strategy, and optimization of different FRET donor SPs. Due to the 53.7-fold intra-particle amplification of NIR fluorescence, the SPN could track as few as 2000 endothelial cells (ECs) upon intra-arterial injection into critical limb ischemia (CLI)-bearing mice, showing much higher sensitivity in ECs tracking compared with the most popular commercial cell trackers. What's more, the SPN could provide precise information on the behaviors of systemically injected ECs in CLI treatment including the in vivo fate and regenerative contribution of ECs for at least 21 days.

Polystyrene-divinylbenzene based nano-CaCO3 composites for the efficient removal of human tumor necrosis factor-α.

PS-DVB/nano-CaCO3, a novel abundant mesoporous structured polymer nano-composite, was successfully synthesized via suspension polymerization. Characterization of this type of bead nano-composite demonstrated that it exhibits significantly enhanced TNF-α adsorption from blood plasma and possesses good mechanical strength.

Preparation of a dual cored hepatoma-specific star glycopolymer nanogel via arm-first ATRP approach.

A reductase-cleavable and thermo-responsive star-shaped polymer nanogel was prepared via an "arm-first" atom transfer radical polymerization approach. The nanogel consists of a thermo- and redox-sensitive core and a zwitterionic copolymer block. The dual sensitive core is composed of poly(N-isopropylacrylamide) that is formed by disulfide crosslinking of N-isopropylacrylamide. The zwitterionic copolymer block contains a poly(sulfobetaine methacrylate) component, a known anti-adsorptive moiety that extends blood circulation time, and a lactose motif of poly(2-lactobionamidoethyl methacrylamide) that specifically targets the asialoglycoprotein receptors (ASGP-Rs) of hepatoma. Doxorubicin (DOX) was encapsulated into the cross-linked nanogels via solvent extraction/evaporation method and dialysis; average diameter of both blank and DOX-loaded nanogels was ~120 nm. The multi-responsiveness of nanogel drug release in different temperatures and redox conditions was assessed. After 24 h, DOX release was only ~20% at 30°C with 0 mM glutathione (GSH), whereas over 90% DOX release was observed at 40°C and 10 mM GSH, evidence of dual responsiveness to temperature and reductase GSH. The IC50 value of DOX-loaded nanogels was much lower in human hepatoma (HepG2) cells compared to non-hepatic HeLa cells. Remarkably, DOX uptake of HepG2 cells differed substantially in the presence and absence of galactose (0.31 vs 1.42 µg/mL after 48 h of incubation). The difference was non-detectable in HeLa cells (1.21 vs 1.57 µg/mL after 48 h of incubation), indicating that the overexpression of ASGP-Rs leads to the DOX-loaded lactosylated nanogels actively targeting hepatoma. Our data indicate that the lactose-decorated star-shaped nanogels are dual responsive and hepatoma targeted, and could be employed as hepatoma-specific anti-cancer drug delivery vehicle for cancer chemotherapy.

Long wavelength excitable near-infrared fluorescent nanoparticles with aggregation-induced emission characteristics for image-guided tumor resection.

Near infrared (NIR) fluorescence imaging (700-900 nm) is a promising technology in preclinical and clinical tumor diagnosis and therapy. The availability of excellent NIR fluorescent contrast agents is still the main barrier to implementing this technology. Herein, we report the design and synthesis of two series of NIR fluorescent molecules with long wavelength excitation and aggregation-induced emission (AIE) characteristics by fine-tuning their molecular structures and substituents. Further self-assembly between an amphiphilic block co-polymer and the obtained AIE molecules leads to AIE nanoparticles (AIE NPs), which have absorption maxima at 635 nm and emission maxima between 800 and 815 nm with quantum yields of up to 4.8% in aggregated states. In vitro and in vivo toxicity results demonstrate that the synthesized AIE NPs are biocompatible. Finally, the synthesized AIE NPs have been successfully used for image-guided tumor resection with a high tumor-to-normal tissue signal ratio of 7.2.

Spatiotemporal Control of Supramolecular Self-Assembly and Function.

The enzyme-triggered self-assembly of peptides has flourished in controlling the self-assembly kinetics and producing nanostructures that are typically inaccessible by conventional self-assembly pathways. However, the diffusion and nanoscale chemical gradient of self-assembling peptides generated by the enzyme also significantly affect the outcome of self-assembly, which has not been reported yet. In this work, we demonstrated for the first time a spatiotemporal control of enzyme-triggered peptide self-assembly. By simply adjusting the temperature, we could change both the catalytic activity of the enzyme of phosphatase and their aggregation states. The strategy kinetically controls the production rate of self-assembling peptides and spatially controls their distribution in the system, leading to the formation of nanoparticles at 37 °C and nanofibers at 4 °C. The nanofibers showed ∼10 times higher cellular uptake by 3T3 cells than the nanoparticles, thanks to their higher stability and more ordered structures. Using such spatiotemporal control, we could prepare optimized nanoprobes with low background fluorescence, rapid and high cellular uptake, and high sensitivity. We postulate that this strategy would be very useful in general for preparing self-assembled nanomaterials with controllable morphology and function.