Self-assembling peptide-based nanodrug delivery systems

Advances of biological macromolecules hemostatic materials: A review

Achieving hemostasis is a necessary intervention to rapidly and effectively control bleeding. Conventional hemostatic materials currently used in clinical practice may aggravate the damage at the bleeding site due to factors such as poor adhesion and poor adaptation. Compared to most traditional hemostatic materials, polymer-based hemostatic materials have better biocompatibility and offer several advantages. They provide a more effective method of stopping bleeding and avoiding additional damage to the body in case of excessive blood loss. Various hemostatic materials with greater functionality have been developed in recent years for different organs using diverse design strategies. This article reviews the latest advances in the development of polymeric hemostatic materials. We introduce the coagulation cascade reaction after bleeding and then discuss the hemostatic mechanisms and advantages and disadvantages of various polymer materials, including natural, synthetic, and composite polymer hemostatic materials. We further focus on the design strategies, properties, and characterization of hemostatic materials, along with their applications in different organs. Finally, challenges and prospects for the application of hemostatic polymeric materials are summarized and discussed. We believe that this review can provide a reference for related research on hemostatic materials, contributing to the further development of polymer hemostatic materials.

Review of recent preclinical and clinical research on ligand-targeted liposomes as delivery systems in triple negative breast cancer therapy

Triple-negative breast Cancer (TNBC) is one of the deadliest types, making up about 20% of all breast cancers. Chemotherapy is the traditional manner of progressed TNBC treatment; however, it has a short-term result with a high reversibility pace. The lack of targeted treatment limited and person-dependent treatment options for those suffering from TNBC cautions to be the worst type of cancer among breast cancer patients. Consequently, appropriate treatment for this disease is considered a major clinical challenge. Therefore, various treatment methods have been developed to treat TNBC, among which chemotherapy is the most common and well-known approach recently studied. Although effective methods are chemotherapies, they are often accompanied by critical limitations, especially the lack of specific functionality. These methods lead to systematic toxicity and, ultimately, the expansion of multidrug-resistant (MDR) cancer cells. Therefore, finding novel and efficient techniques to enhance the targeting of TNBC treatment is an essential requirement. Liposomes have demonstrated that they are an effective method for drug delivery; however, among a large number of liposome-based drug delivery systems annually developed, a small number have just received authorization for clinical application. The new approaches to using liposomes target their structure with various ligands to increase therapeutic efficiency and diminish undesired side effects on various body tissues. The current study describes the most recent strategies and research associated with functionalizing the liposomes' structure with different ligands as targeted drug carriers in treating TNBCs in preclinical and clinical stages.

Current status of development and biomedical applications of peptide-based antimicrobial hydrogels

Microbial contamination poses a serious threat to human life and health. Through the intersection of material science and modern medicine, advanced bionic hydrogels have shown great potential for biomedical applications due to their unique bioactivity and ability to mimic the extracellular matrix environment. In particular, as a promising antimicrobial material, the synthesis and practical biomedical applications of peptide-based antimicrobial hydrogels have drawn increasing research interest. The synergistic effect of peptides and hydrogels facilitate the controlled release of antimicrobial agents and mitigation of their biotoxicity while achieving antimicrobial effects and protecting the active agents from degradation. This review reports on the progress and trends of researches in the last five years and provides a brief outlook, aiming to provide theoretical background on peptide-based antimicrobial hydrogels and make suggestions for future related work.

Nano-Drug Delivery Systems Based on Natural Products

Natural products have proven to have significant curative effects and are increasingly considered as potential candidates for clinical prevention, diagnosis, and treatment. Compared with synthetic drugs, natural products not only have diverse structures but also exhibit a range of biological activities against different disease states and molecular targets, making them attractive for development in the field of medicine. Despite advancements in the use of natural products for clinical purposes, there remain obstacles that hinder their full potential. These challenges include issues such as limited solubility and stability when administered orally, as well as short durations of effectiveness. To address these concerns, nano-drug delivery systems have emerged as a promising solution to overcome the barriers faced in the clinical application of natural products. These systems offer notable advantages, such as a large specific surface area, enhanced targeting capabilities, and the ability to achieve sustained and controlled release. Extensive in vitro and in vivo studies have provided further evidence supporting the efficacy and safety of nanoparticle-based systems in delivering natural products in preclinical disease models. This review describes the limitations of natural product applications and the current status of natural products combined with nanotechnology. The latest advances in nano-drug delivery systems for delivery of natural products are considered from three aspects: connecting targeting warheads, self-assembly, and co-delivery. Finally, the challenges faced in the clinical translation of nano-drugs are discussed.

Nanocarrier-Mediated Delivery of MicroRNAs for Fibrotic Diseases

MicroRNAs (miRNAs) are endogenous noncoding RNAs that mediate the fibrotic process by regulating multiple targets. MicroRNA-based therapy can restore or inhibit miRNA expression and is expected to become an effective approach to prevent and alleviate fibrotic diseases. However, the safe, targeted, and effective delivery of miRNAs is a major challenge in translating miRNA therapy from bench to bedside. In this review, we briefly describe the pathophysiological process of fibrosis and the mechanism by which miRNAs regulate the progression of fibrosis. Additionally, we summarize the miRNA nanodelivery tools for fibrotic diseases, including chemical modifications and polymer-based, lipid-based, and exosome-based delivery systems. Further clarification of the role of miRNAs in fibrosis and the development of a novel nanodelivery system may facilitate the prevention and alleviation of fibrotic diseases in the future.

Platinum-based drugs and hydrogel: a promising anti-tumor combination

Platinum-based drugs are widely used as first-line anti-tumor chemotherapy agents. However, they also have nonnegligible side effects due to the free drugs in circulation. Therefore, it is necessary to develop efficient and safe delivery systems for better tumor cell targeting. Hydrogel is a promising anti-tumor drug carrier that can form a platinum/hydrogel combination system for drug release, which has shown better anti-tumor effects in some studies. However, there is a lack of systematic summary in this field. This review aims to provide a comprehensive overview of the platinum/hydrogel combination system with the following sections: firstly, an introduction of platinum-based drugs; secondly, an analysis of the platinum/hydrogel combination system; and thirdly, a discussion of the advantages of the hydrogel-based delivery system. We hope this review can offer some insights for the development of the platinum/hydrogel combination system for better cancer therapy.

Is a non-cytotoxic and non-genotoxic novel bioinspired dipeptide structure synthesis possible for theragnostic applications?

The diagnosis and treatment of the diseases in a certain coordination is a subject that has been emphasized in recent years. Theragnostics approaches allow simultaneous diagnosis and treatment of chronic diseases such as cancer. An ideal theragnostic should be biocompatible and can be used safely in humans. Although several types of theragnostics have been developed, none of yet satisfied these criteria. Bioinspired materials with noble metal centers encapsulating therapeutic and imaging agents were shown to possess theragnostic activities. In this study, it was aimed to synthesize, characterize, and evaluate the cytotoxic and genotoxic effects of self-assembly of diphenylalanine (Phe-Phe) dipeptides presence of mercury (Hg2+) ions to be used for theragnostic. Cytotoxicity and genotoxicity studies were done in mouse fibroblast (NIH/3T3) cells by 3-(4,5-Dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) and single cell gel electrophoresis (Comet) assays, respectively. It was found that cell viability decreased in a dose-dependent manner in 24-, 48-, and 72-h treatment. Also, Phe-Phe dipeptides did not cause any significant changes in DNA damage at the concentrations of 1, 2, and 5 mg/mL in 4- and 24-h exposures. In the 48-h exposure, Phe-Phe peptide exposure at concentrations of 2 and 5 mg/mL caused a significant increase in DNA damage and in the 72-h of exposure, a significant increase in DNA damage was observed at all studied concentrations. According to the results of the study, it can be said that Phe-Phe dipeptides presence of Hg2+ ions are biocompatible and can be used safely for theragnostic purposes.

Peptide Amphiphilic Supramolecular Nanogels: Competent Host for Notably Efficient Lipase-Catalyzed Hydrolysis of Water-Insoluble Substrates

The present work depicts the development of stable nanogels in an aqueous medium that were exploited for efficient surface-active lipase-catalyzed hydrolysis of water-insoluble substrates. Surfactant-coated gel nanoparticles (neutral NG1, anionic NG2, and cationic NG3) were prepared from peptide amphiphilic hydrogelator (G1, G2, and G3, respectively) at different hydrophilic and lipophilic balance (HLB). Chromobacterium viscosum (CV) lipase activity towards hydrolysis of water-insoluble substrates (p-nitrophyenyl-n-alkanoates (C4-C10)) in the presence of nanogels got remarkably improved by ~1.7-8.0 fold in comparison to that in aqueous buffer and other self-aggregates. An increase in hydrophobicity of the substrate led to a notable improvement in lipase activity in the hydrophilic domain (HLB>8.0) of nanogels. The micro-heterogeneous interface of small-sized (10-65 nm) nanogel was found to be an appropriate scaffold for immobilizing surface-active lipase to exhibit superior catalytic efficiency. Concurrently, the flexible conformation of lipase immobilized in nanogels was reflected in its secondary structure having the highest α-helix content from the circular dichroism spectra.

Cancer Stem-Like Cells-Oriented Surface Self-Assembly to Conquer Radioresistance

Cancer stem-like cells (CSCs), capable of indefinite self-renewal and differentiation, are considered to be the root cause of tumor radiotherapy (RT) resistance. However, the CSCs-targeted therapy still remains to be a great challenge because they are commonly located in the deep tumor making drugs hard to approach, and their hypoxic and acidic niche can further aggravate radioresistance. Herein, based on the finding that hypoxic CSCs highly express carbonic anhydrase IX (CAIX) on the cell membrane, a CAIX-targeted induced in situ self-assembly system on the surface of CSC is reported to overcome hypoxic CSC-mediated radioresistance. Via the sequential processes of "monomer release-target accumulation-surface self-assembly", the constructed peptide-based drug delivery system (CA-Pt) exhibits the advantages of deep penetration, amplified CAIX inhibition, and enhanced cellular uptake, which greatly relieves the hypoxic and acidic microenvironment to promote the hypoxic CSC differentiation and combines with platinum to boost the RT-inducing DNA damage. In both lung cancer tumor mouse and zebrafish embryo models, CA-Pt treatment can effectively assist RT in suppressing tumor growth and preventing tumor invasion and metastasis. This study uses a surface-induced self-assembly strategy to differentiate hypoxic CSCs, which may provide a universal treatment strategy for overcoming tumor radioresistance.

A Serum-Stable supramolecular drug carrier for chemotherapeutics fabricated by a Peptide-Photosensitizer conjugate

Supramolecular assemblies fabricated by peptide-photosensitizer conjugates have attracted increasing attentions in recent years as drug carriers for chemotherapeutics (CTs). However, these assemblies have been known to suffer from disintegration by serum components leading to off-target drug release, and thereby impairing antitumor effects and causing systemic toxicities. To address this problem, this study reports a nano-architectural self-assembly peptide-photosensitizer carrier (NSPC) fabricated by conjugating a phthalocyanine derivative (MCPZnPc) and ε-poly-l-lysine (EPL). By engineering the core and peripheral interactions, MCPZnPC-EPL (M-E) NSPC firmly encapsulated multiple CTs, creating CT@M-E NSPCs that were highly stable against disintegration in serum. More importantly, CT@M-E NSPCs exhibited controlled release of CTs in tumor tissues. The antitumor effects of CTs were further promoted by the synergism with the reactivated photodynamic effect. Furthermore, M-E NSPC-encapsulation optimized CTs' biodistribution reducing adverse effects in vivo. This study provides a serum-stable supramolecular drug delivery system with photodynamic effect, which is applicable for a broad-range of CTs to promote antitumor effects and ameliorate adverse effects.

Nanomaterials and nanomaterials-based drug delivery to promote cutaneous wound healing

Various factors could damage the structure and integrity of skin to cause wounds. Nonhealing or chronic wounds seriously affect the well-being of patients and bring heavy burdens to the society. The past few decades have witnessed application of numerous nanomaterials to promote wound healing. Owing to the unique physicochemical characteristics at nanoscale, nanomaterials-based therapy has been regarded as a potential approach to promote wound healing. In this review, we first overview the wound categories, wound healing process and critical influencing factors. Then applications of nanomaterials with intrinsic therapeutic effect and nanomaterials-based drug delivery systems to promote wound healing are addressed in detail. Finally, current limitations and future perspectives of nanomaterials in wound healing are discussed.

Supramolecular Phenylalanine-Derived Hydrogels for the Sustained Release of Functional Proteins

Protein-based therapeutics have emerged as next-generation pharmaceutical agents for oncology, bone regeneration, autoimmune disorders, viral infections, and other diseases. The clinical application of protein therapeutics has been impeded by pharmacokinetic and pharmacodynamic challenges including off-target toxicity, rapid clearance, and drug stability. Strategies for the localized and sustained delivery of protein therapeutics have shown promise in addressing these challenges. Hydrogels are critical materials that enable these delivery strategies. Supramolecular hydrogels composed of self-assembled materials have demonstrated biocompatibility advantages over polymer hydrogels, with peptide and protein-based gels showing strong potential. However, cost is a significant drawback of peptide-based supramolecular hydrogels. Supramolecular hydrogels composed of inexpensive low-molecular-weight (LMW) gelators, including modified amino acid derivatives, have been reported as viable alternatives to peptide-based materials. Herein, we report the encapsulation and release of proteins from supramolecular hydrogels composed of perfluorinated fluorenylmethyloxcarbonyl-modified phenylalanine (Fmoc-F₅-Phe-DAP). Specifically, we demonstrate release of four model proteins (ribonuclease A (RNase A), trypsin inhibitor (TI), bovine serum albumin (BSA), and human immunoglobulin G (IgG)) from these hydrogels. The emergent viscoelastic properties of these materials are characterized, and the functional and time-dependent release of proteins from the hydrogels is demonstrated. In addition, it is shown that the properties of the aqueous solution used for hydrogel formulation have a significant influence on the in vitro release profiles, as a function of the isoelectric point and molecular weight of the protein payloads. These studies collectively validate that this class of supramolecular LMW hydrogel possesses the requisite properties for the sustained and localized release of protein therapeutics.

Bio-Inspired Drug Delivery Systems: From Synthetic Polypeptide Vesicles to Outer Membrane Vesicles

Nanomedicine is a broad field that focuses on the development of nanocarriers to deliver specific drugs to targeted sites. A synthetic polypeptide is a kind of biomaterial composed of repeating amino acid units that are linked by peptide bonds. The multiplied amphiphilicity segment of the polypeptide could assemble to form polypeptide vesicles (PVs) under suitable conditions. Different from polypeptide vesicles, outer membrane vesicles (OMVs) are spherical buds of the outer membrane filled with periplasmic content, which commonly originate from Gram-negative bacteria. Owing to their biodegradability and excellent biocompatibility, both PVs and OMVs have been utilized as carriers in delivering drugs. In this review, we discuss the recent drug delivery research based on PVs and OMVs. These related topics are presented: (1) a brief introduction to the production methods for PVs and OMVs; (2) a thorough explanation of PV- and OMV-related applications in drug delivery including the vesicle design and biological assessment; (3) finally, we conclude with a discussion on perspectives and future challenges related to the drug delivery systems of PVs and OMVs.

Enhancing Photothermal Therapy Efficacy by In Situ Self-Assembly in Glioma

The residence time of some small molecular imaging and therapeutic agents in tumor tissue is short and the molecules can be easily dispersed, which decreases treatment efficacy. Therefore, methods that enhance oncotherapy performance are of significant importance. Here, we report an in situ self-assembly strategy aimed at enhancing the photothermal therapy of glioblastomas. The probe, ICG-PEP-c(RGD)fk, consisted of a glutathione-reactive self-assembling polypeptide as the skeleton, indocyanine green (ICG) as a theranostic agent, and cyclic Arg-Gly-Asp [c(RGD)fk] peptides as the targeting group. ICG-PEP-c(RGD)fk was synthesized and found to be assembled in the glutathione environment at 9.446 μM in vitro. Human glioblastoma cell line U87MG-luc with high integrin αvβ3 expression was applied to invivo experiments. ICG-PEP-c(RGD)fk provided clearer tumor imaging and had a tumor retention time of 6.12 times longer than that of ICG-c(RGD)fk. In therapeutic experiments, ICG-PEP-c(RGD)fk significantly suppressed glioblastoma growth and the tumor volume was 2.61 times smaller than in the ICG-c(RGD)fk group at the end of the observation period. Moreover, the median survival time of ICG-PEP-c(RGD)fk group was significantly improved by 2.78 times compared with that of the control group. In conclusion, glutathione-reactive self-assembling peptides are capable of increasing the tumor retention time and improving the photothermal therapeutic effect. The in situ self-assembly strategy is a potential and feasible method to enhance oncotherapy.

Self-Assembled Peptide-Based Nanodrugs: Molecular Design, Synthesis, Functionalization, and Targeted Tumor Bioimaging and Biotherapy

Functional nanomaterials as nanodrugs based on the self-assembly of inorganics, polymers, and biomolecules have showed wide applications in biomedicine and tissue engineering. Ascribing to the unique biological, chemical, and physical properties of peptide molecules, peptide is used as an excellent precursor material for the synthesis of functional nanodrugs for highly effective cancer therapy. Herein, recent progress on the design, synthesis, functional regulation, and cancer bioimaging and biotherapy of peptide-based nanodrugs is summarized. For this aim, first molecular design and controllable synthesis of peptide nanodrugs with 0D to 3D structures are presented, and then the functional customization strategies for peptide nanodrugs are presented. Then, the applications of peptide-based nanodrugs in bioimaging, chemotherapy, photothermal therapy (PTT), and photodynamic therapy (PDT) are demonstrated and discussed in detail. Furthermore, peptide-based drugs in preclinical, clinical trials, and approved are briefly described. Finally, the challenges and potential solutions are pointed out on addressing the questions of this promising research topic. This comprehensive review can guide the motif design and functional regulation of peptide nanomaterials for facile synthesis of nanodrugs, and further promote their practical applications for diagnostics and therapy of diseases.

Peptide-Based Materials That Exploit Metal Coordination

Metal-ion coordination has been widely exploited to control the supramolecular behavior of a variety of building blocks into functional materials. In particular, peptides offer great chemical diversity for metal-binding modes, combined with inherent biocompatibility and biodegradability that make them attractive especially for medicine, sensing, and environmental remediation. The focus of this review is the last 5 years' progress in this exciting field to conclude with an overview of the future directions that this research area is currently undertaking.

Anion Effects on the Supramolecular Self-Assembly of Cationic Phenylalanine Derivatives

Supramolecular hydrogels have emerged as a class of promising biomaterials for applications such as drug delivery and tissue engineering. Self-assembling peptides have been well studied for such applications, but low molecular weight (LMW) amino acid-derived gelators have attracted interest as low-cost alternatives with similar emergent properties. Fluorenylmethyloxycarbonyl-phenylalanine (Fmoc-Phe) is one such privileged motif often chosen due to its inherent self-assembly potential. Previously, we developed cationic Fmoc-Phe-DAP gelators that assemble into hydrogel networks in aqueous NaCl solutions of sufficient ionic strength. The chloride anions in these solutions screen the cationic charge of the gelators to enable self-assembly to occur. Herein, we report the effects of varying the anions of sodium salts on the gelation potential, nanoscale morphology, and hydrogel viscoelastic properties of Fmoc-Phe-DAP and two of its fluorinated derivatives, Fmoc-3F-Phe-DAP and Fmoc-F₅-Phe-DAP. It was observed that both the anion identity and gelator structure had a significant impact on the self-assembly and gelation properties of these derivatives. Changing the anion identity resulted in significant polymorphism of the nanoscale morphology of the assembled states that was dependent on the chemical structure of the gelator. The emergent viscoelastic character of the hydrogel networks was also found to be reliant on the anion identity and gelator structure. These results demonstrate the complex interplay between the gelator and environment that have a profound and often unpredictable impact on both self-assembly properties and emergent viscoelasticity in supramolecular hydrogels formed by LMW compounds. This work also illustrates the current lack of understanding that limits the rational design of potential biomaterials that will be in contact with complex biological fluids and provides motivation for additional research to correlate the chemical structure of LMW gelators with the structure and emergent properties of the resulting supramolecular assemblies as a function of environment.

Polarization of tumor-associated macrophages by TLR7/8 conjugated radiosensitive peptide hydrogel for overcoming tumor radioresistance

Radioresistance reduces the antitumor efficiency of radiotherapy and further restricts its clinical application, which is mainly caused by the aggravation of immunosuppressive tumor microenvironment (ITM). Especially tumor-associated macrophages (TAMs) usually display the tumor-promoting M2 phenotype during high-dose fractional radiotherapy mediating radiotherapy resistance. Herein, the toll like receptor agonist TLR7/8a was conjugated with radiosensitive peptide hydrogel (Smac-TLR7/8 hydrogel) to regulate TAMs repolarization from M2 type into M1 type, thus modulating the ITM and overcoming the radioresistance. The Smac-TLR7/8 hydrogel was fabricated through self-assembly with nanofibrous morphology, porous structure and excellent biocompatibility. Upon γ-ray radiation, Smac-TLR7/8 hydrogel effectively polarized the macrophages into M1 type. Notably, combined with radiotherapy, TAMs repolarization regulated by Smac-TLR7/8 hydrogel could increase tumor necrosis factor secretion, activate antitumor immune response and effectively inhibit tumor growth. Moreover, TAMs repolarization rebuilt the ITM and elicited the immunogenic phenotypes in solid tumors, thus enhanced the PD1-blockade efficacy through increasing tumor infiltrating lymphocytes (TILs) and decreasing Treg cells in two different immune activity tumor mice models. Overall, this study substantiated that recruiting and repolarization of TAMs were critical in eliciting antitumor immune response and overcoming radioresistance, thus improving the efficacy of radiotherapy and immunotherapy.

“Motile-targeting” drug delivery platforms based on micro/nanorobots for tumor therapy

Traditional drug delivery systems opened the gate for tumor-targeted therapy, but they generally took advantage of enhanced permeability and retention or ligand-receptor mediated interaction, and thus suffered from limited recognition range (<0.5 nm) and low targeting efficiency (0.7%, median). Alternatively, micro/nanorobots (MNRs) may act as emerging “motile-targeting” drug delivery platforms to deliver therapeutic payloads, thereby making a giant step toward effective and safe cancer treatment due to their autonomous movement and navigation in biological media. This review focuses on the most recent developments of MNRs in “motile-targeting” drug delivery. After a brief introduction to traditional tumor-targeted drug delivery strategies and various MNRs, the representative applications of MNRs in “motile-targeting” drug delivery are systematically streamlined in terms of the propelling mechanisms. Following a discussion of the current challenges of each type of MNR in biomedical applications, as well as future prospects, several promising designs for MNRs that could benefit in “motile-targeting” drug delivery are proposed. This work is expected to attract and motivate researchers from different communities to advance the creation and practical application of the “motile-targeting” drug delivery platforms.

Side-chain halogen effects on self-assembly and hydrogelation of cationic phenylalanine derivatives

Low molecular weight (LMW) supramolecular hydrogels have great potential as next-generation biomaterials for drug delivery, tissue engineering, and regenerative medicine. The design of LMW gelators is complicated by the lack of understanding regarding how the chemical structure of the gelator correlates to self-assembly potential and emergent hydrogel material properties. The fluorenylmethyloxycarbonyl-phenylalanine (Fmoc-Phe) motif is a privileged scaffold that is prone to undergo self-assembly into self-supporting hydrogel networks. Cationic Fmoc-Phe-DAP derivatives modified with diaminopropane (DAP) at the C-terminus have been developed that self-assemble into hydrogel networks in aqueous solutions of sufficient ionic strength. We report herein the impact of side-chain halogenation on the self-assembly and hydrogelation properties of Fmoc-Phe-DAP derivatives. A systematic study of the self-assembly and hydrogelation of monohalogenated Fmoc-Phe-DAP derivatives with F, Cl, or Br atoms in the ortho, meta, or para positions of the phenyl side chain reveal significant differences in self-assembly and gelation potential, nanoscale assembly morphology, and hydrogel viscoelastic properties as a function of halogen identity and substitution position. These results demonstrate the profound impact that subtle changes to the chemical scaffold can have on the behavior of LMW supramolecular gelators and illustrate the ongoing difficulty of predicting the emergent self-assembly and hydrogelation behavior of LMW gelators that differ even modestly in chemical structure.

Recent Advances in Peptides-Based Stimuli-Responsive Materials for Biomedical and Therapeutic Applications: A Review

Smart materials are engineered materials that have one or more properties that are introduced in a controlled fashion by surrounding stimuli. Engineering of biomacromolecules like proteins into a smart material call for meticulous artistry. Peptides have grabbed notable attention as a preferred source for smart materials in the medicinal field, promoted by their versatile chemical and biophysical attributes of biocompatibility, and biodegradability. Recent advances in the synthesis of multifunctional peptides have proliferated their application in diverse domains: agriculture, nanotechnology, medicines, biosensors, therapeutics, and soft robotics. Stimuli such as pH, temperature, light, metal ions, and enzymes have vitalized physicochemical properties of peptides by augmented sensitivity, stability, and selectivity. This review elucidates recent (2018-2021) advances in the design and synthesis of smart materials, from stimuli-responsive peptides followed by their biomedical and therapeutic applications.

Water soluble organometallic small molecules as promising antibacterial agents: synthesis, physical-chemical properties and biological evaluation to tackle bacterial infections

The Na[3,3'-Fe(8-I-1,2-C₂B₉H₁₀)₂] and Na[2,2'-M(1,7-C₂B₉H₁₁)] (M = Co³⁺, Fe³⁺) small molecules are synthesized and the X-ray structures of [(H₃O)(H₂O)₅][2,2'-Co(1,7-C₂B₉H₁₁)₂] and [Cs(MeCN)][8,8'-I₂-Fe(1,2 C₂B₉H₁₀)₂], both displaying a transoid conformation of the [M(C₂B₉)₂]^- framework, are reported. Importantly, the supramolecular structure of [(H₃O)(H₂O)₅][2,2'-Co(1,7-C₂B₉H₁₁)₂] presents 2D layers leading to a lamellar arrangement of the anions while the cation layers form polymeric water rings made of six- and four-membered rings of water molecules connected via OH⋯H hydrogen bonds; B-H⋯O contacts connect the cationic and anionic layers. Herein, we highlight the influence of the ligand isomers (ortho-/meta-), the metal effect (Co³⁺/Fe³⁺) on the same isomer, as well as the influence of the presence of the iodine atoms on the physical-chemical and biological properties of these molecules as antimicrobial agents to tackle antibiotic-resistant bacteria, which were tested with four Gram-positive bacteria, five Gram-negative bacteria, and three Candida albicans strains that have been responsible for human infections. We have demonstrated an antimicrobial effect against Candida species (MIC of 2 and 3 nM for Na[3,3'-Co(8-I-1,2-C₂B₉H₁₀)₂] and Na[2,2'-Co(1,7-C₂B₉H₁₁)₂], respectively), and against Gram-positive and Gram-negative bacteria, including multiresistant MRSA strains (MIC of 6 nM for Na[3,3'-Co(8-I-1,2-C₂B₉H₁₀)₂]). The selectivity index for antimicrobial activity of Na[3,3'-Co(1,2-C₂B₉H₁₁)₂] and Na[3,3'-Co(8-I-1,2-C₂B₉H₁₀)₂] compounds is very high (165 and 1180, respectively), which reveals that these small anionic metallacarborane molecules may be useful to tackle antibiotic-resistant bacteria. Moreover, we have demonstrated that the outer membrane of Gram-negative bacteria constitutes an impermeable barrier for the majority of these compounds. Nonetheless, the addition of two iodine groups in the structure of the parent Na[3,3'-Co(1,2-C₂B₉H₁₁)₂] had an improved effect (3-7 times) against Gram-negative bacteria. Possibly the changes in their physical-chemical properties make the meta-isomers and the ortho-di-iodinated small molecules more permeable for crossing this barrier. It should be emphasized that the most active metallabis(dicarbollide) small molecules are both transoid conformers in contrast to the ortho- [3,3'-Co(1,2-C₂B₉H₁₁)₂]^- that is cisoid. The fact that these small molecules cross the mammalian membrane and have antimicrobial properties but low toxicity for mammalian cells (high selectivity index, SI) represents a promising tool to treat infectious intracellular bacteria. Since there is an urgent need for antibiotic discovery and development, this study represents a relevant advance in the field.

Influence of Parameters on Photodynamic Therapy of Au@TiO2-HMME Core-Shell Nanostructures

Photodynamic therapy (PDT) is a promising tumor therapy and has been proven to be an effective, safe and minimally invasive technique. Hematoporphyrin monomethyl ether (HMME) mediated PDT has been used in clinical treatment of port wine stain (PWS) due to its single component, high yield of singlet oxygen and short light-sensitive period. However, as an amphiphilic photosensitizer, HMME is easy to aggregate due to the presence of a hydrophobic group, which undesirably reduced its generation of singlet oxygen and bioavailability. In this study, we synthesized the stable conjugate of Au@TiO₂ core-shell nanostructure with HMME, and the influence of different factors on PTD efficiency were studied. The results showed that the nanostructure had higher PTD efficiency for KB cells than that of HMME. The irradiation wavelength, gold nanoparticle shape and the shell thickness are all important factors for KB cell PDT.

Self-assembled dipeptide based fluorescent nanoparticles as a platform for developing cellular imaging probes and targeted drug delivery chaperones

Self-assembled peptide-based nanostructures, comprised of naturally occurring amino acids, display excellent biocompatibility, biodegradability, flexible responsiveness, and synthetic feasibility and can be customized for various biomedical applications. However, the lack of inherent optical properties of peptide-based nanoparticles is a limitation on their use as imaging probes or drug delivery vehicles. To overcome this impediment, we generated Boc protected tyrosine-tryptophan dipeptide-based nanoparticles (DPNPs) with structure rigidification by Zn(ii), which shifted the peptide's intrinsic fluorescent properties from the ultraviolet to the visible range. These DPNPs are photostable, biocompatible and have visible fluorescence signals that allow for real-time monitoring of their entry into cells. We further show that two DPNPs (PS1-Zn and PS2-Zn) can encapsulate the chemotherapeutic drug doxorubicin (Dox) and facilitate intracellular drug delivery resulting in cancer cell killing actions comparable to the unencapsulated drug. Finally, we chemically modified our DPNPs with an aptamer directed toward the epithelial cell surface marker EPCAM, which improved Dox delivery to the lung cancer epithelial cell line A549. In contrast, the aptamer conjugated DPNPs failed to deliver Dox into the cardiomyocyte cell line AC16. Theoretically, this strategy could be employed in vivo to specifically deliver Dox to cancer cells while sparing the myocardium, a major source of dose-limiting adverse events in the clinic. Our work represents an important proof-of-concept exercise demonstrating that ultra-short peptide-based fluorescent nanostructures have great promise for the development of new imaging probes and targeted drug delivery vehicles.

Construction and antitumor properties of a targeted nano-drug carrier system responsive to the tumor microenvironment

Doxorubicin (DOX) is one of the most commonly used and effective chemotherapy drugs among anthracyclines. An inherent limitation of DOX is its nonspecificity, which can cause serious side effects, thereby preventing the therapeutic use of high drug doses. In this study, we designed and created a simple nano-drug delivery system (PEG-MAF = P) with low biological toxicity that was responsive to the tumor environment. PEG-MAF = P was designed to self-assemble into nanospheres via control of a phenylalanine dipeptide (FF). The N-terminus of the peptide was linked to aldehyde groups at both ends of oxidized Pluronic F127 (F127-CHO) via Schiff bonds. The acidic environment surrounding the tumors was suitable for triggering the Schiff bonds, causing the nanospheres to disintegrate. The C-terminus of FF was connected to a ligand peptide, ATN-161, which was able to recognize cells expressing high levels of integrin α5β1 antigens both in vivo and in vitro. To prevent the impediment in drug release, PEG was linked via a matrix metalloproteinase-9 response peptide. Therefore, in an acidic tumor microenvironment containing MMP-9, PEG-MAF = P disintegrated and rapidly released the drug. PEG-MAF = P exhibited low cytotoxicity, high drug-loading rate, and excellent antitumor properties both in vivo and in vitro. Compared with free DOX, PEG-MAF = P-DOX reduced injury to normal tissues.

Facile preparation of nanomicelles using polymyxin E for enhanced antitumor effects

Chemotherapy is a major cancer treatment that uses antitumor drugs to kill fast-growing cancer cells. Many kinds of drug carriers have been developed to deliver and achieve controlled release of small-molecule therapeutic agents. However, many therapeutic agent carriers need complex preparation process. The natural polypeptides may serve as proper drug carriers. More specifically, polymyxin E (PE) is a kind of natural antibiotic lipopeptides. It is commonly used to treat infections caused by multidrug-resistant Gram-negative bacteria. Herein, we present a facile method to prepare DOX-loaded polymyxin E micelles (PE-DOX micelles) to enhance the therapeutic effect of anticancer drug doxorubicin (DOX). The hydrodynamic sizes and zeta potential of the prepared nanomedicine (PE-DOX micelles) were 142.0 nm and 6.47 mV, respectively. The release of DOX from PE-DOX micelles was faster at pH 5.5 than that at pH 7.4. Furthermore, PE exhibited negligible cytotoxicity to A549 cells and HeLa cells within 50 μg/mL, while PE-DOX micelles caused higher cytotoxicity than that of free DOX. Moreover, the intravenously injected PE-DOX micelles showed good biocompatibility and obvious antitumor effect after 14 days' treatment in vivo. The PE-DOX micelles have great potential to be used as anticancer agent in the future.

Polyamine-Responsive Morphological Transformation of a Supramolecular Peptide for Specific Drug Accumulation and Retention in Cancer Cells

The precise accumulation and extended retention of nanomedicines in the tumor tissue has been highly desired for cancer therapy. Here a novel supramolecular-peptide derived nanodrug (SPN) that can be transformed to microfibers in response to intracellular polyamine in cancer cells for significantly enhanced tumor specific accumulation and retention is developed. The supramolecular-peptide is constructed via the non-covalent interactions between cucurbit[7]uril (CB[7]) and Phe on Phe-Phe-Val-Leu-Lys-camptothecin conjugates (FFVLK-CPT, PC). The resultant amphiphilic supramolecular complex subsequently self-assembles into nanoparticles with a hydrodynamic diameter of 164.2 ± 3.7 nm. Upon internalization into spermine-overexpressed cancer cells, the CB[7]-Phe host-guest pairs can be competitively dissociated by spermine and can release free PC, which immediately form β-sheet structures and subsequently reorganize into microfibers, leading to dramatically improved accumulation, retention, and sustained release of CPT in tumor cells for highly effective cancer therapy. Accordingly, this SPN exhibit rather low toxicity against non-cancerous cells due to the morphological stability and fast exocytosis of the nanodrugs in those cells without abundant spermine. This study reports the first supramolecular peptide capable of polyamine-responsive "nanoparticle-to-microfiber" transformation for specific tumor therapy with minimal side effects. This work also offers novel insights to the design and development of stimuli-responsive nanomaterials as precision medicine.

High-Loading Self-Assembling Peptide Nanoparticles as a Lipid-Free Carrier for Hydrophobic General Anesthetics

Purpose

Typical hydrophobic amino acids (HAAs) are important motifs for self-assembling peptides (SAPs), but they lead to low water-solubility or compact packing of peptides, limiting their capacity for encapsulating hydrophobic drugs. As an alternative, we designed a peptide GQY based on atypical HAAs, which could encapsulate hydrophobic drugs more efficiently. Although hydrophobic general anesthetics (GAs) have been formulated as lipid emulsions, their lipid-free formulations have been pursued because of some side effects inherent to lipids. Using GAs as targets, potential application of GQY as a carrier for hydrophobic drugs was evaluated.

Methods

Thioflavin-T (ThT) binding test, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to examine the self-assembling ability of GQY. Pyrene and 8-Anilino-1-naphthalenesulfonic acid (ANS) were used to confirm formation of hydrophobic domain in GQY nanoparticles. Using pyrene as a model, GQY’s capacity to encapsulate hydrophobic drugs was evaluated. GAs including propofol, etomidate and ET26 were encapsulated by GQY. Loss of righting reflex (LORR) test was conducted to assess the anesthetic efficacy of these lipid-free formulations. Paw-licking test was used to evaluate pain-on-injection of propofol-GQY (PROP-GQY) formulation. Hemolytic and cytotoxicity assay were used to evaluate biocompatibility of GQY.

Results

Stable nanoparticles containing plenty of hydrophobic cavities could be formed by GQY, which could encapsulate hydrophobic drugs at very high concentration and form stable suspensions. Propofol, etomidate and ET26 formulated by GQY showed anesthetic efficacy comparable to their currently available formulations. Unlike clinic lipid emulsion, PROP-GQY formulation did not cause pain-on-injection in rats. Neither obvious cytotoxicity nor hemolytic activity of GQY was observed.

Conclusion

GQY could encapsulate GAs to obtain stable and effective formulations. As a lipid-free carrier, GQY exhibited considerable biocompatibility and other side benefits such as reducing pain-on-injection. More SAPs based on atypical HAAs could be designed as promising carriers for hydrophobic drugs.

Protein-Based Nanohydrogels for Bioactive Delivery

Hydrogels possess a unique three-dimensional, cross-linked network of polymers capable of absorbing large amounts of water and biological fluids without dissolving. Nanohydrogels (NGs) or nanogels are composed of diverse types of polymers of synthetic or natural origin. Their combination is bound by a chemical covalent bond or is physically cross-linked with non-covalent bonds like electrostatic interactions, hydrophobic interactions, and hydrogen bonding. Its remarkable ability to absorb water or other fluids is mainly attributed to hydrophilic groups like hydroxyl, amide, and sulphate, etc. Natural biomolecules such as protein- or peptide-based nanohydrogels are an important category of hydrogels which possess high biocompatibility and metabolic degradability. The preparation of protein nanohydrogels and the subsequent encapsulation process generally involve use of environment friendly solvents and can be fabricated using different proteins, such as fibroins, albumin, collagen, elastin, gelatin, and lipoprotein, etc. involving emulsion, electrospray, and desolvation methods to name a few. Nanohydrogels are excellent biomaterials with broad applications in the areas of regenerative medicine, tissue engineering, and drug delivery due to certain advantages like biodegradability, biocompatibility, tunable mechanical strength, molecular binding abilities, and customizable responses to certain stimuli like ionic concentration, pH, and temperature. The present review aims to provide an insightful analysis of protein/peptide nanohydrogels including their preparation, biophysiochemical aspects, and applications in diverse disciplines like in drug delivery, immunotherapy, intracellular delivery, nutraceutical delivery, cell adhesion, and wound dressing. Naturally occurring structural proteins that are being explored in protein nanohydrogels, along with their unique properties, are also discussed briefly. Further, the review also covers the advantages, limitations, overview of clinical potential, toxicity aspects, stability issues, and future perspectives of protein nanohydrogels.

A coassembled peptide hydrogel boosts the radiosensitization of cisplatin

We constructed a novel supramolecular hydrogel by carrying out a coassembly of cisplatin and short naproxen-capped peptides. This procedure boosted the radiosensitization effect of cisplatin by increasing the number of Pt-DNA adducts, arresting the cell cycle, and inhibiting cyclooxygenase-2.

Dynamic Continuum of Nanoscale Peptide Assemblies Facilitates Endocytosis and Endosomal Escape

Alkaline phosphatase (ALP) enables intracellular targeting by peptide assemblies, but how the ALP substrates enter cells remains elusive. Here we show that nanoscale phosphopeptide assemblies cluster ALP to enable caveolae-mediated endocytosis (CME) and endosomal escape. Specifically, fluorescent phosphopeptides undergo enzyme-catalyzed self-assembly to form nanofibers. Live cell imaging unveils that phosphopeptides nanoparticles, coincubated with HEK293 cells overexpressing red fluorescent protein-tagged tissue-nonspecific ALP (TNAP-RFP), cluster TNAP-RFP in lipid rafts to enable CME. Further dephosphorylation of the phosphopeptides produces peptidic nanofibers for endosomal escape. Inhibiting TNAP, cleaving the membrane anchored TNAP, or disrupting lipid rafts abolishes the endocytosis. Decreasing the transformation to nanofibers prevents the endosomal escape. As the first study establishing a dynamic continuum of nanoscale assemblies for cellular uptake, this work illustrates an effective design for enzyme-responsive supramolecular therapeutics and provides mechanism insights for understanding the dynamics of cellular uptake of proteins or exogenous peptide aggregates.

Peptide-Protein Interactions: From Drug Design to Supramolecular Biomaterials

The self-recognition and self-assembly of biomolecules are spontaneous processes that occur in Nature and allow the formation of ordered structures, at the nanoscale or even at the macroscale, under thermodynamic and kinetic equilibrium as a consequence of specific and local interactions. In particular, peptides and peptidomimetics play an elected role, as they may allow a rational approach to elucidate biological mechanisms to develop new drugs, biomaterials, catalysts, or semiconductors. The forces that rule self-recognition and self-assembly processes are weak interactions, such as hydrogen bonding, electrostatic attractions, and van der Waals forces, and they underlie the formation of the secondary structure (e.g., α-helix, β-sheet, polyproline II helix), which plays a key role in all biological processes. Here, we present recent and significant examples whereby design was successfully applied to attain the desired structural motifs toward function. These studies are important to understand the main interactions ruling the biological processes and the onset of many pathologies. The types of secondary structure adopted by peptides during self-assembly have a fundamental importance not only on the type of nano- or macro-structure formed but also on the properties of biomaterials, such as the types of interaction, encapsulation, non-covalent interaction, or covalent interaction, which are ultimately useful for applications in drug delivery.

Synthesis and Self-Assembly Properties of Bola-Amphiphilic Glycosylated Lipopeptide-Type Supramolecular Hydrogels Showing Colour Changes Along with Gel-Sol Transition

Supramolecular hydrogels formed by self-assembly of low-molecular-weight amphiphiles (hydrogelators) have attracted significant attention, as smart and soft materials. However, most of the observed stimuli-responsive behaviour of these supramolecular hydrogels are limited to gel-sol transitions. In this study, we present bola-amphiphilic glycosylated lipopeptide-type supramolecular hydrogelators that exhibit reversible thermochromism along with a gel-sol transition. The bola-amphiphiles have mono-, di-, tri- or tetra-phenylalanine (F) as a short peptide moiety. We investigate and discuss the effects of the number of F residues on the gelation ability and the morphology of the self-assembled nanostructures.

Supramolecular Biopolymers for Tissue Engineering

Supramolecular biopolymers (SBPs) are those polymeric units derived from macromolecules that can assemble with each other by noncovalent interactions. Macromolecular structures are commonly found in living systems such as proteins, DNA/RNA, and polysaccharides. Bioorganic chemistry allows the generation of sequence-specific supramolecular units like SBPs that can be tailored for novel applications in tissue engineering (TE). SBPs hold advantages over other conventional polymers previously used for TE; these materials can be easily functionalized; they are self-healing, biodegradable, stimuli-responsive, and nonimmunogenic. These characteristics are vital for the further development of current trends in TE, such as the use of pluripotent cells for organoid generation, cell-free scaffolds for tissue regeneration, patient-derived organ models, and controlled delivery systems of small molecules. In this review, we will analyse the 3 subtypes of SBPs: peptide-, nucleic acid-, and oligosaccharide-derived. Then, we will discuss the role that SBPs will be playing in TE as dynamic scaffolds, therapeutic scaffolds, and bioinks. Finally, we will describe possible outlooks of SBPs for TE.

Peptide-based supramolecular hydrogels for bioimaging applications

Peptide-based supramolecular hydrogels have unique merits in bioimaging applications.

Self-assembling peptide-etoposide nanofibers for overcoming multidrug resistance

We developed a new strategy to overcome the MDR of etoposide using self-assembling nanofibers. Compared with the original etoposide, the inhibitory activity of Nap-GFFpYK-etoposide1/2 against murine Lewis lung cancer or breast cancer cells was increased 10 times, and 20 times on these cells with artificially overexpressed MDR1. Our method to synthesize and separate etoposide isomers provides a new strategy for the modification of this drug.

Fine structural tuning of the assembly of ECM peptide conjugates via slight sequence modifications

The self-assembly of nanostructures from conjugates of elastin-like peptides and collagen-like peptides (ELP-CLP) has been studied as means to produce thermoresponsive, collagen-binding drug delivery vehicles. Motivated by our previous work in which ELP-CLP conjugates successfully self-assembled into vesicles and platelet-like nanostructures, here, we extend our library of ELP-CLP bioconjugates to a series of tryptophan/phenylalanine-containing ELPs and GPO-based CLPs [W2F x -b-(GPO) y ] with various domain lengths to determine the impact of these modifications on the thermoresponsiveness and morphology. The lower transition temperature of the conjugates with longer ELP or CLP domains enables the formation of well-defined nanoparticles near physiological temperature. Moreover, the morphological transition from vesicles to platelet-like nanostructures occurred when the ratio of the lengths of ELP/CLP decreased. Given the previously demonstrated ability of many ELP-CLP bioconjugates to bind to both hydrophobic drugs and collagen-containing materials, our results suggest new opportunities for designing specific thermoresponsive nanostructures for targeted biological applications.

Electrostatic interactions regulate the release of small molecules from supramolecular hydrogels

Supramolecular hydrogels have great potential as biomaterials for sustained delivery of therapeutics. While peptide-based supramolecular hydrogels have been developed that show promise for drug delivery applications, the high cost of production has limited their widespread adoption. Low molecular weight (LMW) supramolecular hydrogels are emerging as attractive and inexpensive alternatives to peptide-based hydrogels. We recently reported novel cationic fluorenylmethyloxycarbonyl-modified phenylalanine (Fmoc-Phe) hydrogels for localized and sustained in vivo release of an anti-inflammatory agent for functional pain remediation. In an effort to further elucidate design principles to optimize these materials for delivery of a variety of molecular agents, we herein report a systematic examination of electrostatic effects on the release of cargo molecules from Fmoc-Phe derived hydrogels. Specifically, we interrogate the release of cationic, anionic, and neutral cargo molecules from a series of cationic and anionic Fmoc-Phe derived hydrogels. We observed that cargo was readily released from the hydrogels except when the cargo and hydrogel network had complementary charges, in which case the cargo was highly retained in the network. These results demonstrate that the electrostatic characteristics of both the hydrogel network and the specific cargo are critical design parameters in the formulation of LMW supramolecular hydrogel systems in the development of next-generation materials for drug delivery applications.

Supramolecular β-Sheet Forming Peptide Conjugated with Near-Infrared Chromophore for Selective Targeting, Imaging, and Dysfunction of Mitochondria

Herein, conjugation of the amyloid-β (Aβ) peptide fragment, Lys-Leu-Val-Phe-Phe (KLVFF, fragment of Aβ_16-20), with an unsymmetrical near-infrared (NIR) cyanine-5 (Cy-5) chromophore is achieved using microwave-assisted solid phase synthesis on 2-chlorotrityl chloride resin. Selective mitochondria tracking and staining in human carcinoma cells are accomplished by the KLVFF/Cy-5 conjugate containing triphenylphosphonium functionality, and this is compared to a control molecule KLVFF/Cy-5c. Mitochondrial target specificity of KLVFF/Cy-5 is established by the colocalization assay using mitochondria selective probe MitoTracker Red, which is monitored by confocal laser scanning microscope and shows a high Pearson's correlation coefficient. The KLVFF/Cy-5 conjugate has high photostability, NIR absorption/emission, high molar extinction coefficient, narrow absorption/emission band, high fluorescence lifetime, and high fluorescence quantum yield. Moreover, mitochondria targeting KLVFF/Cy-5 conjugate reaches the critical aggregation concentration inside the mitochondria of cancer cells due to the strong negative inner mitochondrial membrane potential [(ΔΨ_m)_cancer -220 mV] and self-assembles to form amyloid fibrils at the target site, which is responsible for the mitochondrial dysfunction and cytotoxicity. Annexin V-FITC/PI apoptosis detection assay is used to determine the signal pathway of mitochondria targeted cellular dysfunction.

MT1-MMP activatable fluorogenic probes with enhanced specificity via high-affinity peptide conjugation for tumor imaging

Overlapping substrate specificities within the family of matrix metalloproteinases (MMPs), usually caused by their highly conserved structural topology, increase the potential for a substrate to be cleaved by multiple enzymes within this family, which leads to the decrease in the selectivity of MMP substrate-based probes. To resolve this issue, MT1-MMP activatable fluorogenic probes for tumor detection with enhanced specificity were developed by combining a fluorescence resonance energy transfer (FRET) peptide substrate and its specific binding peptide with different lengths of linkers. The specificity of the probes increased profiting from the high affinity of the MT1-MMP specific binding peptide while keeping the ability to amplify the output imaging signals in response to MMP activity with the FRET substrate. Enzyme kinetics analysis clearly demonstrated that the conjugation of P-1 and MT1-AF7p enhanced both the specificity and selectivity of the fluorogenic probes for MT1-MMP, and introducing a linker composed of 12 PEG subunits into these two fragments led to optimized specificity and selectivity of the fluorogenic probe for MT1-MMP. Both in vitro and in vivo results revealed that the imaging probe with the linker composed of 12 PEG subunits based on our designed strategy could be effectively applied for MT1-MMP positive tumor imaging. Since this strategy for enhancing the specificity of protease sensing probes can be applied to other proteases and is not just limited to MT1-MMP, it is an appealing platform to achieve selective tumor imaging.

Tumor-associated O-glycans of MUC1: Carriers of the glyco-code and targets for cancer vaccine design

The transformation from normal to malignant phenotype in human cancers is associated with aberrant cell-surface glycosylation. It has frequently been reported that MUC1, the heavily glycosylated cell-surface mucin, is altered in both, expression and glycosylation pattern, in human carcinomas of the epithelium. The presence of incomplete or truncated glycan structures, often capped by sialic acid, commonly known as tumor-associated carbohydrate antigens (TACAs), play a key role in tumor initiation, progression, and metastasis. Accumulating evidence suggests that expression of TACAs is associated with tumor escape from immune defenses. In this report, we will give an overview of the oncogenic functions of MUC1 that are exerted through TACA interactions with endogenous carbohydrate-binding proteins (lectins). These interactions often lead to creation of a pro-tumor microenvironment, favoring tumor progression and metastasis, and tumor evasion. In addition, we will describe current efforts in the design of cancer vaccines with special emphasis on synthetic MUC1 glycopeptide vaccines. Analysis of the key factors that govern structure-based design of immunogenic MUC1 glycopeptide epitopes are described. The role of TACA type, position, and density on observed humoral and cellular immune responses is evaluated.

Recent advances: peptides and self-assembled peptide-nanosystems for antimicrobial therapy and diagnosis

Bacterial infections, especially the refractory treatment of drug-resistant bacteria, are one of the greatest threats to human health. Self-assembling peptide-based strategies can specifically detect the bacteria at the site of infection in the body and kill it.

Emerging antibacterial nanomedicine for enhanced antibiotic therapy

This review highlights the different mechanisms of current nano-antibiotic systems for combatting serious antibiotic resistance of bacteria.