Efficient cell reprogramming using bioengineered surfaces

Designing Polyelectrolyte Microneedles Based on Borylated Poly(β-aminoester) Polymers To Enhance Transdermal pH-Controlled Delivery of Nucleic Acids

The use of transdermal delivery for nucleic acid administration is an interesting approach to overcoming limitations of systemic administration routes, such as first-pass effects, the painful needle injection, or their poor biodistribution. Thus, the use of a microneedle-based patch could represent a turning point for nucleic acid delivery, thanks to the possibility of self-administration of the actives in a painless and easy procedure. However, the design of transdermal systems with a higher degree of precision release is a clear need that has not been fully resolved. Committed to tackling this challenge, we present here a microneedle patch that involves a smart delivery system supported by the well-established ability of boronic acid to interact with carbohydrates in a pH-dependent manner. This system builds up a multilayer structure over a solid microneedle platform whose surface has been modified to immobilize glucosamine units that are able to interact with an oligopeptide-end terminated poly(β-aminoester) that presents a 4-carboxy-3-fluorophenylboronic acid (Bor-pBAE). Thus, sequential layers of the Bor-pBAE and plasmid DNA have been assembled, thanks to the ability of the polymer to interact with the nucleic acid at a basic pH and then gradually release the plasmid under two different conditions of pH (the physiological pH = 7.4 and the acidic pH = 5.1). We set up the design and implementation of this first proof of concept while demonstrating microneedles' safety and functionality. Additionally, we have shown the efficacy of the construct to express the encoded genes in model cell lines. In conclusion, we have established the basis to confirm that this generation of borylated poly(β-aminoesters) holds great promise as a transdermal local nucleic acid delivery system.

Plasma-induced nanostructured metallic silver surfaces: study of bacteriophobic effect to avoid bacterial adhesion on medical devices

Biofilm formation in medical devices represents one of the major problems for the healthcare system, especially those that occur on implantable silicone-based devices. To provide a general solution to avoid biofilm formation in the first stages of development, this work studied how nanostructured metallic silver coatings hinder bacteria-surface interaction by preventing bacteria adhesion. The three studied silver nanostructures (“Sharp blades”, “Thick blades” and “Leaves”) combined superhydrophobic behavior with a physical impediment of the coating nanostructure that produced a bacteriophobic effect avoiding the adhesion mechanism of different bacterial strains. These silver nanostructures are immobilized on stretchable substrates through a polymeric thin film of plasma–polymerized penta-fluorophenyl methacrylate. The control over the nanostructures and therefore its bacteriophobic—bactericidal effect depends on the plasma polymerization conditions of the polymer. The characterization of this bacteriophobic effect through FE-SEM microscopy, live/dead cell staining, and direct bacterial adhesion counts, provided a complete mapping of how bacteria interact with the surface in each scenario. Results revealed that the bacterial adhesion was reduced by up to six orders of magnitude in comparison with uncoated surfaces thereby constituting an effective strategy to avoid the formation of biofilm on medical materials.

Improving linking interface between collagen-based hydrogels and bone-like substrates

Regenerative medicine requires the use of heterogeneous scaffolds when the tissue that needs to be repaired presents a gradient in its properties and cannot be replaced by a homogeneous graft. Then, an intimate contact between the different layers is critical to guarantee the optimal performance of the construct. This work presents a procedure that allows the immobilization of collagen-based hydrogels by self-assembly onto any desired substrate, by means of a pentafluorophenyl methacrylate (PFM) coating obtained by plasma enhanced chemical vapor deposition and a collagen monolayer. The latter is attached onto the PFM-coated substrate thanks to its high reactivity towards amines and it will act as anchoring point for the subsequent collagen fibrillation and hydrogel formation. The interaction between collagen and PFM-coated substrates has been evaluated using the quartz crystal microbalance with dissipation (QCM-D) technique. In addition, QCM-D has been used to design and monitor the collagen fibril formation process. A correlation between QCM-D data and optical microscopy has been established, and fibril formation has been confirmed by atomic force microscopy (AFM).

Novel grafted electrochemical interface for covalent glucose oxidase immobilization using reactive pentafluorophenyl methacrylate

One of the most important factors for the proper functioning of enzymatic electrochemical biosensors is the enzyme immobilization strategy. In this work, glucose oxidase was covalently immobilized using pentafluorophenyl methacrylate (PFM) by applying two different surface modification techniques (plasma polymerization and plasma-grafting). The grafted surface was specifically designed to covalently anchor enzyme molecules. It was observed using QCM-D measurements the PFM plasma-grafted surfaces were able to retain a higher number of active enzyme molecules than the PFM polymerized surfaces. An amperometric glucose biosensor using titanium dioxide nanotubes array (TiO₂NTAs) modified by PFM plasma-grafted surface was prepared. The resulting biosensor exhibited a fast response and short analysis time (approximately eight minutes per sample). Moreover, this biosensor achieved high sensitivity (9.76 μA mM^-1) with a linear range from 0.25 to 1.49 mM and a limit of detection (LOD) equal to 0.10 mM of glucose. In addition, the glucose content of 16 different food samples was successfully measured using the developed biosensor. The obtained results were compared with the respective HPLC value and a deviation smaller than 10% was obtained in all the cases. Therefore, the biosensor was able to overcome all possible interferences in the selected samples/matrices.

The epigenetic mechanisms of nanotopography-guided osteogenic differentiation of mesenchymal stem cells via high-throughput transcriptome sequencing

BACKGROUND

Nanotopography directs stem cell fate; however, the underlying mechanisms, especially those at the epigenetic level, remain vague. The TiO₂-nanotube array, a classical example of nanotopography, is a good model to investigate topography-cell interactions because of its good controllability and easy manufacturing process. Previously, we found that a TiO₂-nanotube array with an optimal diameter promoted osteogenic differentiation of human adipose-tissue-derived stem cells (hASCs).

METHODS

We used RNA sequencing and bioinformatics to reveal the overall gene expression profile of hASCs on TiO₂-nanotube arrays.

RESULTS

Bioinformatics analyses revealed that the epigenetic regulatory network plays an important role in TiO₂-nanotube-guided osteogenic differentiation. Changes in cell adhesion and cytoskeletal reorganization are linked to epigenetic alterations, including upregulation of KDM4E and downregulation of histone deacetylases. Meanwhile, microRNAs, including miR-24-1-5p, miR-24-3 p, miR-154-3 p, miR-154-5 p, miR-433-5 p, miR-589-3 p, and miR-589-5 p were downregulated, whereas miR-186-5 p and miR-770-5 p were upregulated. Long non-coding RNAs, including LINC00941, LINC01279, and ZFAS1, were downregulated in this process.

CONCLUSION

Using next-generation sequencing, we illustrated the overall picture of the regulatory mechanisms of TiO₂ nanotubes, thus providing a basis for future clinical applications of nanotopography in the field of bone tissue engineering. Our results offer insights into material-based nanomedicine and epigenetic therapy.

Biomaterial Cues Regulate Epigenetic State and Cell Functions-A Systematic Review

Biomaterial cues can act as potent regulators of cell niche and microenvironment. Epigenetic regulation plays an important role in cell functions, including proliferation, differentiation, and reprogramming. It is now well appreciated that biomaterials can alter epigenetic states of cells. In this study, we systematically reviewed the underlying epigenetic mechanisms of how different biomaterial cues, including material chemistry, topography, elasticity, and mechanical stimulus, influence cell functions, such as nuclear deformation, cell proliferation, differentiation, and reprogramming, to summarize the differences and similarities among each biomaterial cues and their mechanisms, and to find common and unique properties of different biomaterial cues. Moreover, this work aims to establish a mechanogenomic map facilitating highly functionalized biomaterial design, and renders new thoughts of epigenetic regulation in controlling cell fates in disease treatment and regenerative medicine.

Design of a Nanostructured Active Surface against Gram-Positive and Gram-Negative Bacteria through Plasma Activation and in Situ Silver Reduction

Nowadays there is an increasing focus for avoiding bacterial colonization in a medical device after implantation. Bacterial infection associated with prosthesis implantation, or even along the lifetime of the implanted prosthesis, entails a serious problem, emphasized with immunocompromised patients. This work shows a new methodology to create highly hydrophobic micro-/nanostructured silver antibacterial surfaces against Gram-positive and Gram-negative bacteria, using low-pressure plasma. PDMS (polydimethylsiloxane) samples, typically used in tracheal prosthesis, are coated with PFM (pentafluorophenyl methacrylate) through PECVD (plasma enhance chemical vapor deposition) technique. PFM thin films offer highly reactive ester groups that allow them to react preferably with amine bearing molecules, such as amine sugar, to create controlled reductive surfaces capable of reducing silver salts to a nanostructured metallic silver. This micro-/nanostructured silver coating shows interesting antibacterial properties combined with an antifouling behavior causing a reduction of Gram-positive and Gram-negative bacteria viability. In addition, these types of silver-coated samples show no apparent cytotoxicity against COS-7 cells.

Comparison of two different plasma surface-modification techniques for the covalent immobilization of protein monolayers

The immobilization of biologically active species is crucial for the fabrication of smart bioactive surfaces. For this purpose, plasma polymerization is frequently used to modify the surface nature without affecting the bulk properties of the material. Thus, it is possible to create materials with surface functional groups that can promote the anchoring of all kinds of biomolecules. Different methodologies in protein immobilization have been developed in recent years, although some drawbacks are still not solved, such as the difficulties that some procedures involve and/or the denaturalization of the protein due to the immobilization process. In this work, two different strategies to covalently attach bovine serum albumin (BSA) protein are developed. Both techniques are compared in order to understand how the nature of the surface modification affects the conformation of the protein upon immobilization.