Biomimetic Self-assembling Peptides Research Articles

A peptide selectively recognizes Gram-negative bacteria and forms a bacterial extracellular trap (BET) through interfacial self-assembly.

An innate immune system intricately leverages unique mechanisms to inhibit colonization of external invasive Bacteria, for example human defensin-6, through responsive encapsulation of bacteria. Infection and accompanying antibiotic resistance stemming from Gram-negative bacteria aggregation represent an emerging public health crisis, which calls for research into novel anti-bacterial therapeutics. Herein, inspired by naturally found host-defense peptides, we design a defensin-like peptide ligand, bacteria extracellular trap (BET) peptide, with modular design composed of targeting, assembly, and hydrophobic motifs with an aggregation-induced emission feature. The ligand specifically recognizes Gram-negative bacteria via targeting cell wall conserved lipopolysaccharides (LPS) and transforms from nanoparticles to nanofibrous networks in situ to trap bacteria and induce aggregation. Importantly, treatment of the BET peptide was found to have an antibacterial effect on the Pseudomonas aeruginosa strain, which is comparable to neomycin. Animal studies further demonstrate its ability to trigger aggregation of bacteria in vivo. This biomimetic self-assembling BET peptide provides a novel approach to fight against pathogenic Gram-negative bacteria.

Long-term cultures of human pancreatic islets in self-assembling peptides hydrogels.

Human pancreatic islets transplantation is an experimental therapeutic treatment for Type I Diabetes. Limited islets lifespan in culture remains the main drawback, due to the absence of native extracellular matrix as mechanical support after their enzymatic and mechanical isolation procedure. Extending the limited islets lifespan by creating a long-term in vitro culture remains a challenge. In this study, three biomimetic self-assembling peptides were proposed as potential candidates to recreate in vitro a pancreatic extracellular matrix, with the aim to mechanically and biologically support human pancreatic islets, by creating a three-dimensional culture system. The embedded human islets were analyzed for morphology and functionality in long-term cultures (14-and 28-days), by evaluating β-cells content, endocrine component, and extracellular matrix constituents. The three-dimensional support provided by HYDROSAP scaffold, and cultured into MIAMI medium, displayed a preserved islets functionality, a maintained rounded islets morphology and an invariable islets diameter up to 4 weeks, with results analogues to freshly-isolated islets. In vivo efficacy studies of the in vitro 3D cell culture system are ongoing; however, preliminary data suggest that human pancreatic islets pre-cultured for 2weeks in HYDROSAP hydrogels and transplanted under subrenal capsule may restore normoglycemia in diabetic mice. Therefore, engineered self-assembling peptide scaffolds may provide a useful platform for long-term maintenance and preservation of functional human pancreatic islets in vitro.

Evaluation of the remineralizing effect of biomimetic self-assembling peptides in post-orthodontic white spot lesions compared to fluoride-based delivery systems: randomized controlled trial

ObjectivesTo evaluate the clinical performance of self-assembling peptides versus fluoride-based delivery systems in post-orthodontic white spot lesions.Materials and methodsThe participants were randomly assigned into two groups (n = 58) according to the remineralizing agent used, where (A) group represented participants receiving a varnish containing 22.600 fluoride ppm and tricalcium phosphate, while the second group (B) represented participants receiving self-assembling peptide. The remineralizing process of the white spot lesion was assessed using the DIAGNOdent pen and ICDAS scoring system according to the time when the remineralizing agent was used (T), where T0 represented the score taken at baseline. T1 represented the score taken after 3 months of follow-ups and T2 score represented the score taken after 6 months of follow-up. Data were collected and statistically analyzed. The parametric data: two-way ANOVA was used to test the effect of interaction among different variables. The non-parametric data: Mann–Whitney test was used. The significance level was set at p ≤ 0.05.ResultsThere was a quantitative statistically significant difference via DIAGNOpen readings between Group A (fluoride material) and Group B (self-assembling peptides). The highest mean value of 10.51 was found in Group A, while the least mean value of 6.45 was found in Group B. Besides, there was a significant difference in each group concerning the time factors T0, T1, and T2 groups where (p < 0.001. As for the qualitative results concerning the ICDAS score, there was no significant difference between the two groups along with the follow-up periods T0, T1, and T2 where the p value is equal to 0.064, 0.087, and 0.277 respectively.ConclusionsThe visual assessment using ICDAS reveals that the biomimetic remineralization using self-assembling peptides and the fluoride-based varnish material showed a similar effect in masking post-orthodontic white spot lesions. However, the laser fluorescence using DIAGNOpen showed that the self-assembling peptides reveal higher performance in subsurface remineralization than the fluoride-based varnish material. Therefore, self-assembling peptides are considered a promising material for lesion regression in post-orthodontics white spot lesions.Clinical relevanceSelf-assembling peptide SAP-14 is a new approach to reverse and mask off post-orthodontics white spot lesions.

Short Peptides Derived from a Block Copolymer-like Barnacle Cement Protein Self-Assembled into Diverse Supramolecular Structures

Peptides capable of self-assembling into different supramolecular structures have potential applications in a variety of areas. The biomimetic molecular design offers an important avenue to discover novel self-assembling peptides. Despite this, a lot of biomimetic self-assembling peptides have been reported so far; to continually expand the scope of peptide self-assembly, it is necessary to find out more novel self-assembling peptides. Barnacle cp19k, a key underwater adhesive protein, shows special block copolymer-like characteristics and diversified self-assembly properties, providing an ideal template for biomimetic peptide design. In this study, inspired by Balanus albicostatus cp19k (Balcp19k), we rationally designed nine biomimetic peptides (P1-P9) and systematically studied their self-assembly behaviors for the first time. Combining microscale morphology observations and secondary structure analyses, we found that multiple biomimetic peptides derived from the central region and the C-terminus of Balcp19k form distinct supramolecular structures via different self-assembly mechanisms under acidic conditions. Specifically, P9 self-assembles into typical amyloid fibers. P7, which resembles ionic self-complementary peptides by containing nonstrictly alternating hydrophobic and charged amino acids, self-assembles into uniform, discrete nanofibers. P6 with amphipathic features forms twisted nanoribbons. Most interestingly, P4 self-assembles to form helical nanofibers and novel ring-shaped microstructures, showing unique self-assembly behaviors. Apart from their self-assembly properties, these peptides showed good cytocompatibility and demonstrated promising applications in biomedical areas. Our results expanded the repertoire of self-assembling peptides and provided new insights into the structure-function relationship of barnacle cp19k.

Peptide Hydrogel Scaffold for Mesenchymal Precursor Cells Implanted to Injured Adult Rat Spinal Cord.

A unique, biomimetic self-assembling peptide (SAP) hydrogel, Fmoc-DIKVAV, has been shown to be a suitable cell and drug delivery system in the injured brain. In this study, we assessed its utility in adult Fischer 344 (F344) rats as a stabilizing scaffold and vehicle for grafted cells after mild thoracic (thoracic level 10 [T10]) contusion spinal cord injury (SCI). Treatments were as follows: Fmoc-DIKVAV alone, Fmoc-DIKVAV containing viable or nonviable rat mesenchymal precursor cells (rMPCs), and rMPCs alone. The majority of post-SCI treatments were administered at 11-15 days (mean 13.5 days) and the results then compared to SCI-only control (no treatment) rats. Postinjury behavior was quantified using open field locomotion (BBB) and LadderWalk analysis. After perfusion at 8 weeks, longitudinal spinal cord sections were immunostained with a panel of antibodies. Qualitatively, in the SAP-only treatment group, implanted gels contained regenerate axons as well as astrocytic, immune cell, and extracellular matrix (ECM) component profiles. Grafts of Fmoc-DIKVAV plus viable or nonviable rMPCs also contained numerous macrophages/microglia and ECM components, but astrocytes were generally confined to implant margins, and axons were rare. Quantitative analysis showed that, while average cyst size was reduced in all experimental groups, the decrease compared to SCI-only controls was only significant in the SAP and rMPC treatment groups. There was gradual improvement in functionality after SCI, but a consistent trend was only seen between the rMPC treatment group and SCI-only controls. In summary, after contusion SCI, implantation of Fmoc-DIKVAV hydrogel provided a favorable microenvironment for cellular infiltration and axonal regrowth, a supportive role that unexpectedly appeared to be compromised by prior inclusion of rMPCs into the gel matrix. Impact statement The self-assembling peptide hydrogel, Fmoc-DIKVAV, is a biomimetic scaffold that is an effective cell and drug delivery system in the injured brain. We examined whether this hydrogel, alone or combined with mesenchymal precursor cells, was also able to stabilise spinal cord tissue after thoracic contusion injury and improve morphological and behavioral outcomes. While improved functionality was not consistently seen, there was reduced cyst size and increased tissue sparing in some groups. There was regenerative axonal growth into hydrogels, but only in initially cell-free implants. This type of polymer is a suitable candidate for further testing in spinal cord injury models.

Self-assembling Peptides in Current Nanomedicine: Versatile Nanomaterials for Drug Delivery.

The development of modern nanomedicine greatly depends on the involvement of novel materials as drug delivery system. In order to maximize the therapeutic effects of drugs and minimize their side effects, a number of natural or synthetic materials have been widely investigated for drug delivery. Among these materials, biomimetic self-assembling peptides (SAPs) have received more attention in recent years. Considering the rapidly growing number of SAPs designed for drug delivery, a summary of how SAPs-based drug delivery systems were designed, would be beneficial. We outlined research works on different SAPs that have been investigated as carriers for different drugs, focusing on the design of SAPs nanomaterials and how they were used for drug delivery in different strategies. Based on the principle rules of chemical complementarity and structural compatibility, SAPs such as ionic self-complementary peptide, peptide amphiphile and surfactant-like peptide could be designed. Determined by the features of peptide materials and the drugs to be delivered, different strategies such as hydrogel embedding, hydrophobic interaction, electrostatic interaction, covalent conjugation or the combination of them could be employed to fabricate SAPs-drug complex, which could achieve slow release, targeted or environment-responsive delivery of drugs. Furthermore, some SAPs could also be combined with other types of materials for drug delivery, or even act as drug by themselves. Various types of SAPs have been designed and used for drug delivery following various strategies, suggesting that SAPs as a category of versatile nanomaterials have promising potential in the field of nanomedicine.

Superior mechanical and optical properties of a heterogeneous library of cross-linked biomimetic self-assembling peptides

Self-assembling peptides (SAP) are ideal components for biomedical devices. However, their practical applications have been limited due to their intrinsic unstable, low-performance, and low-stress response given by non-covalent interactions involved in self-assembling. Herein, a library of SAPs featuring different self-assembled nanostructures was successfully cross-linked with genipin, allowing to produce nanofibrous hydrogels with enhanced mechanical properties (G′ ≥ 0.2 MPa, stress-failure ≥ 3.5 kPa) and enhanced thermostability (≥100 °C) while maintaining their native nanoarchitecture. Cross-linking dramatically changed the optical properties of SAPs: it triggered new absorption/fluorescence bands in the visible spectral range, which are attributed to charge transfer between peptide chains. Genipin cross-linking, fitted for different classes of SAPs, could be a powerful tool to obtain biomimetic SAP scaffolds with tunable stiffness and thermostability. Lastly, because of the changed absorption/emission properties and relaxation kinetics of cross-linked SAPs, genipin cross-linking may bestow novel optical properties to several well-known lysine-containing SAPs, with intriguing potential for biomedical imaging, photonics and optoelectronics.

Complementary remineralizing effect of self-assembling peptide (P11-4) with CPP-ACPF or fluoride: An in vitro study.

BackgroundSelf-assembling peptide has been recently introduced to promote hard tissue regeneration for treating early non-cavitated carious lesions. This study investigates the efficacy of biomimetic self-assembling peptide (P11-4) on enamel remineralization combined with CPP-ACPF or fluoride. Material and MethodsArtificial enamel lesions were created on buccal surface of 60 specimens and were randomly assigned to six groups according to the remineralizing agent: G1-(Control, artificial saliva), G2-(Fluoride varnish), G3-(CPP-ACPF varnish), G4-(Self-assembling peptide), G5-(Self-assembling peptide+fluoride varnish), G6-(Self-assembling peptide+CPP-ACPF varnish). All products were applied according to manufacturer’s instructions and specimens were stored in a daily renewed artificial saliva. Surface microhardness (SMH) and scanning electron microscope (SEM) were assessed at baseline, after demineralization, 1 week and 4 weeks storage. SMH values were analyzed using ANOVA and Tukey’s post-hoc test. ResultsThe highest statistically significant SMH values were found in G6 followed by G5, G4, G2 and G3 while the lowest values were found in G1. No statistically significant difference was found between G5 and G6. Also, no statistically significant difference was found between G2 and G3. SEM showed that G4, G5, G6 resulted in more pronounced remineralization, reversing the demineralized enamel fish scale pattern compared to G2 and G3 after 1 week and 4 week remineralization. ConclusionsComplementary effect was obtained after combining self-assembling peptide with CPP-ACPF or fluoride showing the highest remineralizing potential early after 1 week and even after 4 weeks compared to when each agent used alone. Added benefits can be obtained through combining self-assembling peptide with other remineralzing agents allowing faster and enhanced regeneration of non-cavitated caries lesions. Key words:Enamel regeneration, biomimetic remineralization, self-assembling peptide, CPP-ACPF, fluoride.

A biomimetic self-assembling peptide promotes bone regeneration in vivo: A rat cranial defect study.

Rationally designed, pH sensitive self-assembling β-peptides (SAPs) which are capable of reversibly switching between fluid and gel phases in response to environmental triggers are potentially useful injectable scaffolds for skeletal tissue engineering applications. SAP P11-4 (CH3COQQRFEWEFEQQNH2) has been shown to nucleate hydroxyapatite mineral de novo and has been used in dental enamel regeneration. We hypothesised that addition of mesenchymal stromal cells (MSCs) would enhance the in vivo effects of P11-4 in promoting skeletal tissue repair. Cranial defects were created in athymic rats and filled with either Bio-Oss® (anorganic bone chips) or P11-4 ± human dental pulp stromal cells (HDPSCs). Unfilled defects served as controls. After 4 weeks, only those defects filled with P11-4 alone showed significantly increased bone regeneration (almost complete healing), compared to unfilled control defects, as judged using quantitative micro-CT, histology and immunohistochemistry. In silico modelling indicated that fibril formation may be essential for any mineral nucleation activity. Taken together, these data suggest that self-assembling peptides are a suitable scaffold for regeneration of bone tissue in a one step, cell-free therapeutic approach.

Biomimetic Self-Assembling Peptide Hydrogels for Tissue Engineering Applications.

Tissue engineering is an appealing research field that involves the replacement and repair of damaged cells and tissues. Scientists and researchers are facing a great challenge to design and develop suitable scaffold materials with biological activities for the applications in tissue regeneration. Among a variety of natural and synthetic materials, biomimetic self-assembling peptides hold great promises as building blocks for fabricating hydrogel scaffolds with three-dimensional (3D) network structures, which could mimic the natural extracellular matrix (ECM). Furthermore, functionalized self-assembling peptides are easily obtained by introducing multiple bioactive peptide motifs derived from naturally occurring proteins. Over the past two decades, many kinds of biomimetic self-assembling peptides have been designed and developed, and these formed peptide hydrogel scaffolds show great potential applications in tissue engineering, such as angiogenesis, bone, cartilage, and nerve regeneration. In this chapter, we have endeavored to do a comprehensive review of biomimetic self-assembling peptides that form nanofiber hydrogel scaffolds. In particular, recent advances of biomimetic self-assembling peptide hydrogel for tissue engineering applications are also highlighted.

Comparative evaluation of remineralizing efficacy of biomimetic self-assembling peptide on artificially induced enamel lesions: An in vitro study.

Background:The biomimetic self-assembling peptide technology is a paradigm for dental hard tissue regeneration.Aim:To investigate the efficacy of biomimetic self-assembling peptide (P11-4) on enamel remineralization compared to casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) and fluoride-based delivery systems.Materials and Methods:Artificial enamel lesions were created on buccal surfaces of 40 extracted human molars. Specimens were randomly assigned to four groups (n = 10) according to the remineralizing agent used: G1 – control: artificial saliva, G2 – fluoride varnish, G3 – CPP-ACPF varnish, G4 – self-assembling peptide agent. All products were applied according to the manufacturer's instructions and the specimens were stored in daily renewed artificial saliva. Surface microhardness (SMH) was assessed at baseline, after demineralization, after 1 week and after 4 weeks storage. SMH values were analyzed using ANOVA and Tukey's post hoc test.Results:Self-assembling peptide showed the highest statistically significant mean SMH followed by fluoride and CPP-ACPF while the lowest mean SMH was found in artificial saliva. However, no statistically significant difference was found between fluoride and CPP-ACPF. Higher statistically significant mean SMH was found after 4 weeks compared to 1 week remineralization in all groups.Conclusions:Self-assembling peptide confers the highest remineralizing efficacy compared to fluoride and CPP-ACPF, showing a promising, noninvasive regeneration potential. Furthermore, extended period of time helped attain more benefits from the remineralizing regimens applied.

Piezoelectric properties of diphenylalanine microtubes prepared from the solution

Biomimetic self-assembling peptides form a variety of structures that can be used for the fabrication of functional devices. We are witnessing the emergence of a new era of bionanotechnology that opens up new possibilities for novel electronic, photonic and energy functionalities based on supramolecular green and lightweight structures. In this work, we study the emergent piezoelectric properties of linear dipeptide diphenylalanine (FF) that can self-assemble in the shape of microtubes. The matrix of piezoelectric coefficients is derived for the first time based on the hexagonal symmetry of FF structures and different configurations of the tubes are tested by the advanced Piezoresponse Force Microscopy (PFM). Strong piezoelectric anisotropy of piezoelectric coefficients is explained by the self-assembled structure of FF peptides. Possible applications of piezoelectric microtubes in functional devices are discussed.

Effect of self-assembling peptide P11 -4 on enamel erosion: AFM and SEM studies.

The aim of the present in vitro study was to evaluate the protective effect of self-assembling peptide P11 -4 (Curodont™ Protect/Credentis) on enamel erosion produced by a soft-drink, by using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Thirty human incisors were equally and randomly assigned to 6 groups. Group 1: intact enamel, group 2: soft drink, group 3: Curodont(™) Protect applied, group 4: Curodont(™) Protect applied + soft drink, group 5: soft drink + Curodont(™) Protect applied, group 6: soft drink + Curodont(™) Protect applied + soft drink. Specimens were observed through atomic force microscopy (AFM). The root mean-square roughness (Rrms) was obtained from the AFM images and the differences in the averaged values among the groups were analyzed by Shapiro-Wilk test in order to assess the normality of the distribution. Parametric ANOVA and post hoc Tuckey test were performed to assess the differences between the different groups. After demineralization process, enamel demonstrated a high degree of surface porosity. This morphological aspect was reflected in the increase of Rrms values. No significant differences (p > 0.05) were reported between intact enamel and enamel only treated with P11 -4 and between eroded enamel and enamel treated with P11 -4 and then demineralized. However significant differences (p < 0.05) were recorded when comparing softened enamel with softened enamel further remineralized with biomimetic self-assembling peptides and enamel treated with the protective paste between two acid attacks. The use of P11 -4 remineralizing may offer a degree of protection from enamel erosion. SCANNING 38:344-351, 2016. © 2015 Wiley Periodicals, Inc.

Summary of: Treatment of early caries lesions using biomimetic self-assembling peptides – a clinical safety trial

Objective We previously reported that a rationally designed biomimetic self-assembling peptide, P11-4, nucleated hydroxyapatite de novo and was apparently capable of in situ enamel regeneration following infiltration into caries-like lesions. Our present aim was to determine the safety and potential clinical efficacy of a single application of P11-4 on early enamel lesions. Materials and methods Fifteen healthy adults with Class V 'white spot' lesions received a single application of P11-4. Adverse events and lesion appearances were recorded over 180 days. Results Patients treated with P11-4 experienced a total of 11 adverse events during the study, of which two were possibly related to the protocol. Efficacy evaluation suggested that treatment with P11-4 significantly decreased lesion size (p = 0.02) after 30 days and shifted the apparent progression of the lesions from 'arrested/progressing' to 'remineralising' (p <0.001). A highly significant improvement in the global impression of change was recorded at day 30 compared with baseline (p <0.001). Conclusions The results suggest that treatment of early caries lesions with P11-4 is safe, and that a single application is associated with significant enamel regeneration, presumably by promoting mineral deposition within the subsurface tissue.

Biomimetic Self-Assembling Peptides as Scaffolds for Soft Tissue Engineering

Tissue engineered therapies are emerging as solutions to several of the medical challenges facing aging societies. To this end, a fundamental research goal is the development of novel biocompatible materials and scaffolds. Self-assembling peptides are materials that have undergone rapid development in the last two decades and they hold promise in meeting some of these challenges. Using amino acids as building blocks enables a great versatility to be incorporated into the structures that peptides form, their physical properties and their interactions with biological systems. This review discusses several classes of short self-assembling sequences, explaining the principles that drive their self-assembly into structures with nanoscale ordering, and highlighting in vitro and in vivo studies that demonstrate the potential of these materials as novel soft tissue engineering scaffolds.

Biomimetic Self-Assembling Peptides as Injectable Scaffolds for Hard Tissue Engineering

The production of bone-, dentine- and enamel-like biomaterials for the engineering of mineralized (hard) tissues is a high-priority in regenerative medicine and dentistry. An emerging treatment approach involves the use of short biomimetic peptides that self-assemble to form micrometer-long nanofibrils with well defined surface chemistry and periodicity that display specific arrays of functional groups capable of mineral nucleation. The fibrils also give rise to dynamically stable 3D scaffold gels for the potential control of crystal disposition and growth. Peptides can also be injected in their monomeric fluid state, with subsequent self-assembly and gelation in situ triggered by physiological conditions. In this way, they can infiltrate and self-assemble within irregular or microscopic cavities, for restorative treatment of bone defects, dentinal hypersensitivity or dental decay. Cell adhesion and proliferation is also supported by these scaffolds, offering further advantages for applications in hard tissue engineering. These self-assembling matrices also provide well defined model systems that can contribute greatly to the elucidation of the biological mechanisms of protein-mediated biomineralization.