Universal Affinity Research Articles

A Generic Antibody-Blocking Protein That Enables pH-Switchable Activation of Antibody Activity.

Molecular strategies that allow for reversible control of antibody activity have drawn considerable interest for both therapeutic and diagnostic applications. Protein M is a generic antibody-binding protein that binds to the Fv domain of IgGs and, in doing so, blocks antigen binding. However, the dissociation of protein M is essentially irreversible, which has precluded its use as an antibody affinity reagent and molecular mask to control antibody activity. Here, we show that introduction of 8 histidine residues on the Fv binding interface of protein M results in a variant that shows pH-switchable IgG binding. This protein M-8his variant provides an attractive and universal affinity resin for the purification of IgGs, antibody fragments (Fab and single-chain variable fragments (scFv)), and antibody conjugates. Moreover, protein M-8his enables the pH-dependent blocking of therapeutic antibodies, allowing the selective targeting of cells at pH 6.0.

Three on Three: Universal and High-Affinity Molecular Recognition of the Symmetric Homotrimeric Spike Protein of SARS-CoV-2 with a Symmetric Homotrimeric Aptamer.

Our previously discovered monomeric aptamer for SARS-CoV-2 (MSA52) possesses a universal affinity for COVID-19 spike protein variants but is ultimately limited by its ability to bind only one subunit of the spike protein. The symmetrical shape of the homotrimeric SARS-CoV-2 spike protein presents the opportunity to create a matching homotrimeric molecular recognition element that is perfectly complementary to its structural scaffold, causing enhanced binding affinity. Here, we describe a branched homotrimeric aptamer with three-fold rotational symmetry, named TMSA52, that not only possesses excellent binding affinity but is also capable of binding several SARS-CoV-2 spike protein variants with picomolar affinity, as well as pseudotyped lentiviruses expressing SARS-CoV-2 spike protein variants with femtomolar affinity. Using Pd-Ir nanocubes as nanozymes in an enzyme-linked aptamer binding assay (ELABA), TMSA52 was capable of sensitively detecting diverse pseudotyped lentiviruses in pooled human saliva with a limit of detection as low as 6.3 × 103 copies/mL. The ELABA was also used to test 50 SARS-CoV-2-positive and 60 SARS-CoV-2-negative patient saliva samples, providing sensitivity and specificity values of 84.0 and 98.3%, respectively, thus highlighting the potential of TMSA52 for the development of future rapid tests.

Protein metalation in a nutshell.

Metalation, the acquisition of metals by proteins, must avoid mis-metalation with tighter binding metals. This is illustrated by four selected proteins that require different metals: all show similar ranked orders of affinity for bioavailable metals, as described in a universal affinity series (the Irving-Williams series). Crucially, cellular protein metalation occurs in competition with other metal binding sites. The strength of this competition defines the intracellular availability of each metal: its magnitude has been estimated by calibrating a cells' set of DNA-binding, metal-sensing, transcriptional regulators. This has established that metal availabilities (as free energies for forming metal complexes) are maintained to the inverse of the universal series. The tightest binding metals are least available. With these availabilities, correct metalation is achieved.

Entrustable Professional Activities: Reflecting on Where We Are to Define a Path for the Next Decade.

Entrustable Professional Activities: Reflecting on Where We Are to Define a Path for the Next Decade.

Learning from the ligand: using ligand-based features to improve binding affinity prediction.

Machine learning scoring functions for protein-ligand binding affinity prediction have been found to consistently outperform classical scoring functions. Structure-based scoring functions for universal affinity prediction typically use features describing interactions derived from the protein-ligand complex, with limited information about the chemical or topological properties of the ligand itself. We demonstrate that the performance of machine learning scoring functions are consistently improved by the inclusion of diverse ligand-based features. For example, a Random Forest (RF) combining the features of RF-Score v3 with RDKit molecular descriptors achieved Pearson correlation coefficients of up to 0.836, 0.780 and 0.821 on the PDBbind 2007, 2013 and 2016 core sets, respectively, compared to 0.790, 0.746 and 0.814 when using the features of RF-Score v3 alone. Excluding proteins and/or ligands that are similar to those in the test sets from the training set has a significant effect on scoring function performance, but does not remove the predictive power of ligand-based features. Furthermore a RF using only ligand-based features is predictive at a level similar to classical scoring functions and it appears to be predicting the mean binding affinity of a ligand for its protein targets. Data and code to reproduce all the results are freely available at http://opig.stats.ox.ac.uk/resources. Supplementary data are available at Bioinformatics online.

The typology of the distribution of Edge: the propensity for bipositionality

We discuss the grammatical conditions that can be imposed between segmental content (features) and syllable structure (positions) and how a representational preference can influence diachronic development. The discussion centers on the co-distribution of two properties: occlusivity and bipositionality. The first is the phonological feature that induces occlusivity and reduces amplitude (that is: |ʔ|, which we will refer to as Edge(*) ), the second is the autosegmental structural property of belonging to multiple positions (which we refer to as ‘C.C’). Edge(*) and bipositionality have a universal affinity but they are not reducible to each other. Instead, the inherent diachronic tendency to preserve Edge(*) in bipositional structures can become grammaticalised through licensing conditions that dictate the alignment of the two properties. This can be expressed bidirectionally, forming two major language types. Type A has the condition stated from the featural perspective ( Edge(*) must be found in C.C). While, Type B comes from the other direction (C.C must contain Edge(*) ). Crucially, the same structure is diachronically stable: ( Edge(*) -C.C). What varies is the distribution of those properties elsewhere (given the direction of licensing condition). Type A excludes Edge(*) from {#__,V_V}, while Type B excludes C.Cs without Edge(*) . Although there is variation on this point, there is a UG component, because there are no anti-Type A/B languages where Edge(*) repels bipositionality.

Graphene-Templated Synthesis of Magnetic Metal Organic Framework Nanocomposites for Selective Enrichment of Biomolecules.

Successful control of homogeneous and complete coating of graphene or graphene-based composites with well-defined metal organic framework (MOF) layers is a great challenge. Herein, novel magnetic graphene MOF composites were constructed via a simple strategy for self-assembly of well-distributed, dense, and highly porous MOFs on both sides of graphene nanosheets. Graphene functionalized with magnetic nanoparticles and carboxylic groups on both sides was explored as the backbone and template to direct the controllable self-assembly of MOFs. The prepared composite materials have a relatively high specific surface area (345.4 m(2) g(-1)), and their average pore size is measured to be 3.2 nm. Their relatively high saturation magnetization (23.8 emu g(-1)) indicates their strong magnetism at room temperature. Moreover, the multifunctional composite was demonstrated to be a highly effective affinity material in selective extraction and separation of low-concentration biomolecules from biological samples, in virtue of the size-selection property of the unique porous structure and the excellent affinity of the composite materials. Besides providing a solution for the construction of well-defined functional graphene-based MOFs, this work could also contribute to selective extraction of biomolecules, in virtue of the universal affinity between immobilized metal ions and biomolecules.

Identification of an adeno-associated virus binding epitope for AVB sepharose affinity resin

Recent successes of adeno-associated virus (AAV)–based gene therapy have created a demand for large-scale AAV vector manufacturing and purification techniques for use in clinical trials and beyond. During the development of purification protocols for rh.10, hu.37, AAV8, rh.64R1, AAV3B, and AAV9 vectors, based on a widely used affinity resin, AVB sepharose (GE), we found that, under the same conditions, different serotypes have different affinities to the resin, with AAV3B binding the best and AAV9 the poorest. Further analysis revealed a surface-exposed residue (amino acid number 665 in AAV8 VP1 numbering) differs between the high-affinity AAV serotypes (serine in AAV3B, rh.10, and hu.37) and the low-affinity ones (asparagine in AAV8, rh.64R1, and AAV9). The residue locates within a surface-exposed, variable epitope flanked by highly conserved residues. The substitution of the epitope in AAV8, rh.64R1, and AAV9 with the corresponding epitope of AAV3B (SPAKFA) resulted in greatly increased affinity to AVB sepharose with no reduction in the vectors’ in vitro potency. The presence of the newly identified AVB-binding epitope will be useful for affinity resin selection for the purification of novel AAV serotypes. It also suggests the possibility of vector engineering to yield a universal affinity chromatography purification method for multiple AAV serotypes.

Fluorogen-activating-proteins as universal affinity biosensors for immunodetection.

Fluorogen-activating-proteins (FAPs) are a novel platform of fluorescence biosensors utilized for protein discovery. The technology currently demands molecular manipulation methods that limit its application and adaptability. Here, we highlight an alternative approach based on universal affinity reagents for protein detection. The affinity reagents were engineered as bi-partite fusion proteins, where the specificity moiety is derived from IgG-binding proteins-Protein A or Protein G-and the signaling element is a FAP. In this manner, primary antibodies provide the antigenic selectivity against a desired protein in biological samples, while FAP affinity reagents target the constant region (Fc) of antibodies and provide the biosensor component of detection. Fluorescence results using various techniques indicate minimal background and high target specificity for exogenous and endogenous proteins in mammalian cells. Additionally, FAP-based affinity reagents provide enhanced properties of detection previously absent using conventional affinity systems. Distinct features explored in this report include: (1) unfixed signal wavelengths (excitation and emission) determined by the particular fluorogen chosen, (2) real-time user controlled fluorescence on-set and off-set, (3) signal wavelength substitution while performing live analysis, and (4) enhanced resistance to photobleaching.

A General Molecular Affinity Strategy for Global Detection and Proteomic Analysis of Lysine Methylation

Lysine methylation of histone proteins regulates chromatin dynamics and plays important roles in diverse physiological and pathological processes. However, beyond histone proteins, the proteome-wide extent of lysine methylation remains largely unknown. We have engineered the naturally occurring MBT domain repeats of L3MBTL1 to serve as a universal affinity reagent for detecting, enriching, and identifying proteins carrying a mono- or dimethylated lysine. The domain is broadly specific for methylated lysine ("pan-specific") and can be applied to any biological system. We have used our approach to demonstrate that SIRT1 is a substrate of the methyltransferase G9a both in vitro and in cells, to perform proteome-wide detection and enrichment of methylated proteins, and to identify candidate in-cell substrates of G9a and the related methyltransferase GLP. Together, our results demonstrate a powerful new approach for global and quantitative analysis of methylated lysine, and they represent the first systems biology understanding of lysine methylation.

Detection of typical and atypical bovine spongiform encephalopathy and scrapie prion strains by prion protein motif-grafted antibodies

To evaluate further the reactivity of prion-specific monoclonal antibodies containing the 89-112 or 136-158 prion protein (PrP) polypeptides, immunoprecipitations were performed on brain extracts from Italian bovines, sheep and goats with transmissible spongiform encephalopathies. No binding of IgG 89-112 or IgG 136-158 to PrP in normal brain extracts was detected. Conversely, both reagents immunoprecipitated PrP from bovine and bovine amyloidotic spongiform encephalopathies, and from typical and atypical scrapie brain extracts. The immunoprecipitated PrP bands mirrored the Western blot (WB) profile of the different prion strains, indicating universal affinity of two independent PrP regions for disease-associated PrP conformers regardless of species source and strain properties. Immunoprecipitation with motif-grafted antibodies increased the sensitivity of conventional detection methods based on centrifugation followed by WB, which was confirmed by assay of diluted samples using both methods. These reagents or derivative molecules may thus find broad applications in prion detection and research.

Adsorption Kinetics of Amphiphilic Diblock Copolymers: From Kinetically Frozen Colloids to Macrosurfactants

We investigated the spontaneous adsorption properties of charged amphiphilic diblock copolymers on hydrophobic surfaces and explained the transition of behavior from depleting frozen colloids (that do not adsorb at all) to fast adsorbing macrosurfactants when the hydrophobicity of the nonsoluble block is reduced. Three copolymer families have been used with the same hydrophilic block poly(acrylic acid), a weak acid whose ionization alpha can be varied by changing the pH. The hydrophobic blocks polystyrene, PS, poly(n-butyl acrylate), PBA, and poly(diethylene glycol ethyl ether acrylate), PDEGA, have interfacial tensions with water gammacore/solvent, respectively, of 32, 20, and 3 mN/m. We were mainly interested in the regime of high ionization alpha > 0.3, where PAA chains have no affinity for hydrophobic surfaces, and we verified experimentally that micelles do not adsorb directly. With the three copolymer families we show that the adsorption kinetics at an early stage is driven by the self-assembly properties in bulk solution: adsorption is hampered for PS-b-PAA (physically/kinetically frozen micelles in solution), controlled by unimer extraction for PBA-b-PAA (nonequilibrium micelles in solution with very low CMC < 10-4 wt %), and controlled by unimer diffusion and electrostatic repulsion for PDEGA-b-PAA (micelles at equilibrium in solution with high CMC is approximately 1-5 wt %). This explains the power law dependences of adsorption with concentration as C-1 for PBA-b-PAA and C-2 for PDEGA-b-PAA. It is finally the interfacial tension with water of the nonsoluble block and not its glass transition that is the main control of bulk solution self-assembly and consequently of the adsorption kinetics properties of amphiphilic diblocks. We also proved by preparative GPC that the fraction of non-self-assembling diblock chains, which exists in all highly hydrophobic amphiphilic diblock systems, plays a negligible role in the adsorption properties. Finally, we investigated the intrinsic thermodynamic affinity between amphiphilic diblocks and hydrophobic surfaces. We show quantitatively that this affinity depends dominantly on the interfacial energies between the hydrophobic block, the surface, and water: diblocks with strongly hydrophobic nonsoluble blocks (PS, PBA) have a low affinity for weakly hydrophobic surfaces, and oppositely, diblocks with weakly hydrophobic nonsoluble block (PDEGA) have a universal affinity for hydrophobic surfaces (like small-molecule surfactants but for different physical reasons). Finally, we showed via surface rheology that when adsorption occurs anchoring is strong and irreversible for very hydrophobic diblocks (PBA-b-PAA) and weaker and (partially) reversible for less hydrophobic diblocks (PDEGA-b-PAA).

Development of an universal affinity fusion tag (Poly‐DOPA) for immobilizing recombinant proteins on biomaterials

AbstractThe covalent and non‐covalent immobilization of growth factors such as recombinant human bone morphogenetic protein 2 (rhBMP‐2) on metals and bone replacement materials in bioactive form is a recent development. Up to now the immobilization technology usually involved the chemical modification and activation of the biomaterial surface followed by attachment of the bioactive protein. Here we suggest an alternative method in which an affinity tag fused to an active protein will allow immobilization without additional chemistry. For biomaterials such as minerals, metals (titanium, steel, CoCrMo), glass ceramics, teflon and possibly bone and teeth ideal adhesion molecules would be the foot proteins (Mefps) of the mussel M. edulis which contain the rare amino acid dihydroxy phenylalanine (DOPA). Recently it could be shown by Messersmith's group that a single DOPA‐molecule can be non‐covalently bound to titanium dioxide surface with a dissociation energy of 22.2 kcal/mol (Lee, H.; Scherer, N. F.; Messersmith, P. B. Proc. Natl. Acad. Sci. U. S. A 2006, 103, 12999–13003).We therefore propose the DOPA‐tag as a general and versatile affinity tag for the immobilization of proteins on biomaterials.

Application of the avidin–biotin interaction to immobilize DNA in the development of electrochemical impedance genosensors

Impedance spectroscopy is a rapidly developing technique for the transduction of biosensing events at the surface of an electrode. The immobilization of biomaterial as DNA strands on the electrode surface alters the capacitance and the interfacial electron transfer resistance of the conductive electrodes. The impedimetric technique is an effective method of probing modifications to these interfacial properties, thus allowing the differentiation of hybridization events. In this work, an avidin bulk-modified graphite-epoxy biocomposite (Av-GEB) was employed to immobilize biotinylated oligonucleotides as well as double-stranded DNA onto the electrode surface. Impedance spectra were recorded to detect the change in the interfacial electron transfer resistance (R (et)) of the redox marker ferrocyanide/ferricyanide at a polarization potential of +0.17 V. The sensitivity of the technique and the good reproducibility of the results obtained with it confirm the validity of this method based on a universal affinity biocomposite platform coupled with the impedimetric technique.

Bioaffinity platforms based on carbon-polymer biocomposites for electrochemical biosensing

Rigid conducting biocomposites are interesting transducing materials for the construction of electrochemical immunosensors, genosensors and enzymosensors, particularly if the material is modified with universal affinity biomolecules. Examples of these ‘universal affinity biocomposites' for electrochemical biosensing are reviewed, in which the common base material is a graphite–epoxy composite. The first approach relies on strept(avidin)–graphite–epoxy biocomposite transducer, as a universal immobilization platform whereon biotinylated biomolecules, such as DNAs, enzymes or antibodies can be captured by means of strept(avidin)–biotin reaction. The second approach is based on Protein A–graphite–epoxy biocomposite. Protein A is able to bind the Fc region of antibodies serving as generic affinity matrix for immuno-immobilization on the transducer. Biocomposite electrodes offer many potential advantages compared to more traditional electrodes based on a surface-modified conducting phase. The capability of integrating various materials into a single one is their main advantage, besides the improved electrochemical properties. These materials can just be prepared through ‘dry chemistry’ using procedures that can be easily transferred to mass fabrication of thick film devices. The different properties of these materials are discussed. Analytical response as well as other parameters such as the easiness in preparation, robustness, sensitivity, surface regeneration, costs, and transfer to mass production of these different approaches is also considered.

Electrochemical biosensing of pesticide residues based on affinity biocomposite platforms

A novel and very sensitive electrochemical immunosensing strategy for the detection of atrazine based on affinity biocomposite transducers is presented. Firstly, the graphite-epoxy composite transducer was bulk-modified with different universal affinity biomolecules, such as avidin and Protein A. Two strategies for the immobilization of the anti-atrazine antibodies on both biocomposite transducers were evaluated: 'wet-affinity' and 'dry-assisted affinity' immobilization. Finally, the performance of a novel anti-atrazine immunocomposite bulk-modified with anti-atrazine antibodies was also evaluated. The better immobilization performance of the anti-atrazine antibodies was achieved by 'dry-assisted affinity' immobilization on Protein A (2%) graphite-epoxy biocomposite (ProtA(2%)-GEB) as a transducer. The immunological reaction for the detection of atrazine performed on the ProtA(2%)-GEB biosensors is based on a direct competitive assay using atrazine-HRP tracer as the enzymatic label. The electrochemical detection is thus achieved through a suitable substrate and a mediator for the enzyme HRP. This novel strategy was successfully evaluated using spiked orange juice samples. The detection limit for atrazine in orange juices using the competitive electrochemical immunosensing assay was found to be 6 x 10(-3) microgL-1 (0.03 nmolL-1) thus this biosensing method accomplishes by far the LODs required for the European Community directives for potable water and food samples (0.1 microgL-1). This strategy offers great promise for rapid, simple, cost effective, and on-site biosensing of biological, food, and environmental samples.

Multiple Effects of Somatostatin Analogs Verified in Three Cases of Metastasized Neuroendocrine Tumors of the Gastroenteropancreatic System

In neuroendocrine tumors of the gastroenteropancreatic (GEP) system, radiolabeled analogs of somatostatin (SST) are useful to the surgeon in different phases of treatment: preoperatively, to identify the lesion with somato-statin receptor scintigraphy (SRS), intraoperatively for localization using a hand-held gamma probe, and postoperatively acting directly to eliminate any residual tumor cells. Additional features of these analogs that are of value in treating such GEP tumors include their antiproliferative potential, which is in the process of being verified, and, above all, their anti-secretory action, so effective in symptom control. In this study the authors, based on their own experience, evaluate the effectiveness of SST analogs in treating GEP endocrine tumors. Three patients with malignant GEP apudomas were studied. In case 1, an insulinoma, the patient underwent four surgical procedures for ablation of the pancreatic tumor and of hepatic and lymph node metastases in addition to local radiofrequency treatment and radiometabolic therapy. Case 2 was a carcinoid tumor of the small intestine with hepatic metastases, managed by ileal resection, local radiofrequency treatment and receptor-mediated radionuclide therapy. In case 3, a non-functioning pancreatic carcinoma with liver and lymph node metastases, the patient underwent four surgical procedures, hepatic chemoembolization, antiproliferative treatment using octreotide (OCT) and metabolic radionuclide therapy. In all three cases SRS proved highly sensitive in the early detection of even the smallest recurrences. There was uncertainty, however, regarding the effectiveness of therapy with radiolabeled SST analogs. Hepatic metastases from the carcinoid were completely unresponsive, but in the case of the insulinoma, the hepatic metastases showed necrosis following treatment, while lymph node metastases were unaffected. In the case of the non-functioning carcinoma, there was a correlation between treatment and a marked improvement in the patient's clinical condition, although the appearance of the lesions themselves remained unchanged. The antiproliferative effect of OCT in this case was nil. SRS proved highly accurate in detecting recurrences during follow-up. The merits of radiometabolic therapy, on the other hand, were unclear, a finding reported elsewhere in the literature, and in the only case treated by prolonged OCT treatment, no antiproliferative action was observed. The diagnostic usefulness of SRS was thus confirmed and it appears likely that radiolabeled analogs used intraoperatively for tumor localization will prove equally of value. The effectiveness of receptor-mediated radionuclide therapy is still in the process of being verified. Based on the expectation of analogs with an universal affinity for SST receptors (sst), it is reasonable to look forward to a significant increase in the efficacy of this type of therapy.

Electrochemical Genosensing Based on Rigid Carbon Composites. A Review

The development of novel and sensitive assays for DNA hybridization and detection has become an increasingly important research field. The design and fabrication of DNA‐modified surfaces and materials that are reproducible, stable, and selective to complementary DNA sequences are the main goal in the development of emerging analytical tools such as DNA chips or user‐friendly diagnostic devices for detecting a few DNA sequences such as electrochemical genosensors. Carbon‐based materials are widely used for this task due to their electrochemical, physical, and mechanical properties; their commercial availability; and their compatibility with modern microchip fabrication technology. Various approaches for electrochemical DNA determination are reviewed, in which the common element is the use of rigid carbon composite material as the electrochemical transducer. A stable DNA layer can be easily obtained by physical adsorption of DNA on graphite‐epoxy composite (GEC). Moreover, a universal affinity platform for electrochemical genosensing can be easily achieved by modifying the graphite‐epoxy composite with avidin to obtain an avidin biocomposite (Av‐GEB) whereon biotinylated DNA can be rapidly single‐point attached. Additionally, DNA‐modified magnetic beads are easily attached to magneto graphite‐epoxy composite (m‐GEC). The main strategies for electrochemical genosensing when using rigid carbon composites such as electrochemical transducer are discussed. Parameters such as ease of preparation, robustness, sensitivity, surface regeneration, costs, and transfer to mass production of these different DNA detection strategies are also considered.

Electrochemical biosensing based on universal affinity biocomposite platforms

Rigid conducting biocomposites are versatile and effective transducing materials for the construction of a wide range of amperometric biosensors such as immunosensors, genosensors and enzymosensors, particularly if the transducer is bulk-modified with universal affinity biomolecules. The strept(avidin)-graphite-epoxy biocomposite could be considered as an universal immobilization platform whereon biotinylated DNAs, oligonucleotides, enzymes or antibodies can be captured by means of the highly affinity (strept)avidin-biotin reaction. Universal affinity biocomposite-based biosensors offer many potential advantages compared to more traditional electrochemical biosensors commonly based on a biologically surface-modified transducer. The integration of many materials into one matrix is their main advantage. As biological bulk-modified materials, the conducting biocomposites act not only as transducers, but also as reservoir for the biomaterial. After its use, the electrode surface can be renewed by a simple polishing procedure, establishing a clear advantage of these approaches relative to classical biosensors and other common biological assays. Moreover, the same material is useful for the analysis of many molecules whose determinations are based on genetic, enzymatic or immunological reactions. The different strategies for electrochemical genosensing, immunosensing and enzymosensing, all of them being dependent on the presence of a redox enzyme marker for the generation of the electrochemical signal, based on this universal affinity biocomposite platform are all presented and discussed.

Self-assembling biomaterials: Liquid crystal phases of cholesteryl oligo(l-lactic acid) and their interactions with cells

We report here on the synthesis and characterization of a series of self-assembling biomaterials with molecular features designed to interact with cells and scaffolds for tissue regeneration. The molecules of these materials contain cholesteryl moieties, which have universal affinity for cell membranes, and short chains of lactic acid, a common component of biodegradable tissue engineering matrices. The materials were synthesized in good yields with low polydispersities in the range of 1.05-1.15, and their characterization was carried out by small-angle x-ray diffraction, transmission electron microscopy, electron diffraction, differential scanning calorimetry, and atomic force microscopy. These molecular materials form layered structures that can be described as smectic phases and can also order into single-crystal stacks with an orthorhombic unit cell. Their layer spacings range from 58 to 99 A, corresponding to bilayers of oligomers with an average of 10 and 37 lactic acid residues, respectively. The self-organized layered structures were found to promote improved fibroblast adhesion and spreading, although the specific mechanism for this observed response remains unknown. The ability of self-assembling materials to present ordered and periodic bulk structures to cells could be a useful strategy in tissue engineering.