Biofunctionality with a twist: the importance of molecular organisation, handedness and configuration in synthetic biomaterial design

The building blocks of life – nucleotides, amino acids and saccharides – give rise to a large variety of components and make up the hierarchical structures found in Nature. Driven by chirality and non-covalent interactions, helical and highly organised structures are formed and the way in which they fold correlates with specific recognition and hence function. A great amount of effort is being put into mimicking these highly specialised biosystems as biomaterials for biomedical applications, ranging from drug discovery to regenerative medicine. However, as well as lacking the complexity found in Nature, their bio-activity is sometimes low and hierarchical ordering is missing or underdeveloped. Moreover, small differences in folding in natural biomolecules (e.g., caused by mutations) can have a catastrophic effect on the function they perform. In order to develop biomaterials that are more efficient in interacting with biomolecules, such as proteins, DNA and cells, we speculate that incorporating order and handedness into biomaterial design is necessary. In this review, we first focus on order and handedness found in Nature in peptides, nucleotides and saccharides, followed by selected examples of synthetic biomimetic systems based on these components that aim to capture some aspects of these ordered features. Computational simulations are very helpful in predicting atomic orientation and molecular organisation, and can provide invaluable information on how to further improve on biomaterial designs. In the last part of the review, a critical perspective is provided along with considerations that can be implemented in next-generation biomaterial designs

Optimization of Amino Acid Sequence of Fmoc-Dipeptides for Interaction with Lipid Membranes

Fmoc-dipeptides appear as highly relevant building blocks in smart hydrogels and nanovehicles for biological applications. The interactions of the Fmocdipeptides with the cell membrane determine the efficiency of the nanomaterials based on the Fmoc-dipeptides’ internalization of nanovehicles for drug delivery. Here, we aim to understand the interplay of the interactions between the Fmoc-dipeptides and a phospholipid surface as a function of the amino acid sequence. The DMPA (1,2-dimyristoyl-snglycero- 3-phosphate) phospholipid in Langmuir monolayers was used as a model cell surface. A set of seven derivatives of Fmoc-dipeptides with a broad range of hydrophobicity were included. Mixed monolayers composed of DMPA/Fmoc-dipeptides in an equimolar ratio were built and characterized in situ at the air/water interface. Surface pressure−molecular area isotherms (π−A), Brewster angle microscopy (BAM), and UV−vis reflection spectroscopy (ΔR) were combined to provide a holistic picture of the interactions of the Fmoc-dipeptide with the phospholipid molecules. An increase in the hydrophobicity led to enhanced interaction of the Fmoc-dipeptide and DMPA molecules. The compression of the mixed monolayer could displace a significant fraction of the Fmoc-dipeptide from the monolayer. High hydrophobicity promoted self-assembly of the Fmoc-dipeptides over interaction with the phospholipid surface. The interplay of these two phenomena was analyzed as a function of the amino acid sequence of the Fmoc-dipeptides. The toxicity effect of Fmoc-FF could be observed and detailed at the molecular level. This study suggests that the adjustment of the hydrophobicity of the Fmoc-dipeptides within a defined range might optimize their efficiency for interaction with the lipid membranes. A semiquantitative guide for the chemical design of Fmoc-dipeptides for biological applications is proposed herein

A New L-Proline Amide Hydrolase with Potential Application within the Amidase Process

This research was supported by the Spanish Ministry of Science and Innovation/FEDER funds grant PID2020-116261GB-I00/AEI/10.13039/501100011033 (JAG), from the FEDER/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades grants P18-FR-3533 (LAC) and P12-FQM-790 (RCM), and from the University of Granada grant PPJI2017-1 (SMR).L-proline amide hydrolase (PAH, EC 3.5.1.101) is a barely described enzyme belonging to the peptidase S33 family, and is highly similar to prolyl aminopeptidases (PAP, EC. 3.4.11.5). Besides being an S-stereoselective character towards piperidine-based carboxamides, this enzyme also hydrolyses different L-amino acid amides, turning it into a potential biocatalyst within the Amidase Process. In this work, we report the characterization of L-proline amide hydrolase from Pseudomonas syringae (PsyPAH) together with the first X-ray structure for this class of L-amino acid amidases. Recombinant PsyPAH showed optimal conditions at pH 7.0 and 35 degrees C, with an apparent thermal melting temperature of 46 degrees C. The enzyme behaved as a monomer at the optimal pH. The L-enantioselective hydrolytic activity towards different canonical and non-canonical amino-acid amides was confirmed. Structural analysis suggests key residues in the enzymatic activity.Spanish GovernmentEuropean Commission PID2020-116261GB-I00/AEI/10.13039/501100011033FEDER/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades P18-FR-3533 P12-FQM-790University of Granada PPJI2017-1 CTS-20

Bioorthogonal uncaging of cytotoxic paclitaxel through Pd nanosheet-hydrogel frameworks

The promising potential of bioorthogonal catalysis in biomedicine is inspiring incremental efforts to design strategies that regulate drug activity in living systems. To achieve this, it is not only essential to develop customized inactive prodrugs and biocompatible metal catalysts but also the right physical environment for them to interact and enable drug production under spatial and/or temporal control. Toward this goal, here, we report the first inactive precursor of the potent broad-spectrum anticancer drug paclitaxel (a.k.a. Taxol) that is stable in cell culture and labile to Pd catalysts. This new prodrug is effectively uncaged in cancer cell culture by Pd nanosheets captured within agarose and alginate hydrogels, providing a biodegradable catalytic framework to achieve controlled release of one of the most important chemotherapy drugs in medical practice. The compatibility of bioorthogonal catalysis and physical hydrogels opens up new opportunities to administer and modulate the mobility of transition metal catalysts in living environs

Mitochondrial pH Nanosensors for Metabolic Profiling of Breast Cancer Cell Lines

We thank the company Nanogetic S.L. (Granada, Spain) for support with the synthesis of the SS peptides and the Centro de Instrumentacion Cientifica (CIC) of the Universidad de Granada for use of the TEM facilities.The main role of mitochondria, as pivotal organelles for cellular metabolism, is the production of energy (ATP) through an oxidative phosphorylation system. During this process, the electron transport chain creates a proton gradient that drives the synthesis of ATP. One of the main features of tumoral cells is their altered metabolism, providing alternative routes to enhance proliferation and survival. Hence, it is of utmost importance to understand the relationship between mitochondrial pH, tumoral metabolism, and cancer. In this manuscript, we develop a highly specific nanosensor to accurately measure the intramitochondrial pH using fluorescence lifetime imaging microscopy (FLIM). Importantly, we have applied this nanosensor to establish differences that may be hallmarks of different metabolic pathways in breast cancer cell models, leading to the characterization of different metabophenotypes.Spanish Ministerio de Ciencia, Innovacion y Universidades CTQ2014-56370-R CTQ2017-86568-REuropean Union (EU)Spanish Agencia Estatal de InvestigacionFundacion Ramon Arece

Extending the pool of compatible peptide hydrogels for protein crystallization

Short-peptide supramolecular (SPS) hydrogels are a class of materials that have been found to be useful for (bio)technological applications thanks to their biocompatible nature. Among the advantages reported for these peptides, their economic a ordability and easy functionalization or modulation have turned them into excellent candidates for the development of functional biomaterials. We have recently demonstrated that SPS hydrogels can be used to produce high-quality protein crystals, improve their properties, or incorporate relevant materials within the crystals. In this work, we prove that hydrogels based on methionine and tyrosine are also good candidates for growing high-quality crystals of the three model proteins: lysozyme, glucose isomerase, and thaumatin.This study was supported by projects BIO2016-74875-P and FIS2017-85954-R (Ministerio de Economía, Industria y Competitividad, MINECO, and Agencia Estatal de Investigación, AEI, Spain, cofunded by Fondo Europeo de Desarrollo Regional, FEDER, European Union)

Unravelling the 2D self-assembly of Fmoc-dipeptides at fluid interfaces

Dipeptides self-assemble into supramolecular structures showing plenty of applications in the nanotechnology and biomedical fields. A set of Fmoc-dipeptides with different aminoacid sequences has been synthesized and their self-assembly at fluid interfaces has been assessed. The relevant molecular parameters for achieving an efficient 2D self-assembly process have been established. The selfassembled nanostructures of Fmoc-dipeptides displayed significant chirality and retained the chemical functionality of the aminoacids. The impact of the sequence on the final supramolecular structure has been evaluated in detail using in situ characterization techniques at air/water interfaces. This study provides a general route for the 2D self-assembly of Fmoc-dipeptides

Anisotropic magnetic hydrogels: design, structure and mechanical properties

Anisotropy is an intrinsic feature of most of the human tissues (e.g. muscle, skin or cartilage). Because of this, there has been an intense effort in the search of methods for the induction of permanent anisotropy in hydrogels intended for biomedical applications. The dispersion of magnetic particles or beads in the hydrogel precursor solution prior to cross-linking, in combination with applied magnetic fields, which gives rise to columnar structures, is one of the most recently proposed approaches for this goal. We have gone even further and, in this paper, we show that it is possible to use magnetic particles as actuators for the alignment of the polymer chains in order to obtain anisotropic hydrogels. Furthermore, we characterize the microstructural arrangement and mechanical properties of the resulting hydrogels. This article is part of a theme issue ‘Heterogeneous materials: metastable and non-ergodic internal structures’

A Conformation Selective Mode of Inhibiting SRC Improves Drug Efficacy and Tolerability

43 p.-5 fig.Despite the approval of several multikinase inhibitors that target SRC and the overwhelming evidence of the role of SRC in the progression and resistance mechanisms of many solid malignancies, inhibition of its kinase activity has thus far failed to improve patient outcomes. Here we report the small molecule eCF506 locks SRC in its native inactive conformation, thereby inhibiting both enzymatic and scaffolding functions that prevent phosphorylation and complex formation with its partner FAK. This unprecedented mechanism of action resulted in highly potent and selective pathway inhibition, in culture and in vivo. Treatment with eCF506 resulted in increased antitumor efficacy and tolerability in syngeneic murine cancer models, demonstrating significant therapeutic advantages over existing SRC/ABL inhibitors. Therefore, this novel mode of inhibiting SRC could lead to improved treatment of SRC-associated disorders.C.T. thanks the CMVM of the University of Edinburgh (Principal's scholarship). D.L. acknowledges support from the Spanish Ministry of Science, Innovation and Universities for the Spanish State Research Agency Retos Grant RTI2018-099318-B-I00, cofunded by the European Regional Development Fund (FEDER). E.R.W., J.C.D. and K.G.M. are funded by CRUK. J.R.L.O. acknowledges support from the Molecular Interactions Facility funds at the CIB-CSIC. T.V. is funded by H2020-MSCA-IF-2016-749299. RCM thanks the support from the Vice Rectorate for Research of the University of Granada. X.-F.L. and B.-Z.Q. are funded by a CRUK Career Development Fellowship (C49791/A17367). B.-Z.Q. also acknowledges support from an ERC Starting Grant (716379). C.S, M.C.F. and V.G.B are funded by CRUK Programme Grant C157/A15703. N.O.C. and A.U.B are grateful to the CMVM of the University of Edinburgh and Wellcome Trust for financial support (ISSF3).Peer reviewe

Protein crystallization in short-peptide supramolecular hydrogels: A versatile strategy towards biotechnological composite materials

Protein crystallization in hydrogels has been explored with the main purpose of facilitating the growth of high quality crystals while increasing their size to enhance their manipulation. New avenues are currently being built for the use of protein crystals as source materials to create sensors and drug delivery vehicles, to name just a few. In this sense, short-peptide supramolecular hydrogels may play a crucial role in integrating protein crystals within a wider range of applications. In this article, we show that protein crystallization in short-peptide supramolecular hydrogels is feasible and independent of the type of peptide that forms the hydrogel and/or the protein, although the output is not always the same. As a general trend, it is confirmed that hydrogel fibers are always incorporated within crystals so that novel composite materials for biotechnological applications with enhanced properties are produced.This research was funded by the MICINN (Spain) projects BIO2010-6800 (JAG), CTQ2012-34778 (JJDM), and “Factoría Española de Cristalización” Consolider-Ingenio 2010 (JAG & MCM), and by Junta de Andalucía (Spain) project P12-FQM- 2721 (LAC). EDRF funds JAG, LAC & JMC. JJDM thanks MICINN for a Ramon y Cajal Fellowship and MCM thanks CSIC for her JAE Fellowshi