Benchtop Fabricated Nano-Roughened Microstructured Electrodes for Electrochemical and Surface-Enhanced Raman Scattering Sensing.

Tailoring a material's surface with hierarchical structures from the micro- to the nanoscale is key for fabricating highly sensitive detection platforms. To achieve this, the fabrication method should be simple, inexpensive, and yield materials with a high density of surface features. Here, using benchtop fabrication techniques, gold surfaces with hierarchically structured roughness are generated for sensing applications. Hierarchical gold electrodes are prepared on pre-stressed polystyrene substrates via electroless deposition and amperometric pulsing. Electrodes fabricated using 1 mm H[AuCl4] and roughened with 80 pulses revealed the highest electroactive surface area. These electrodes are used for enzyme-free detection of glucose in the presence of bovine serum albumin and achieved a limit of detection of 0.36 mm, below glucose concentrations in human blood. The surfaces nanoroughened with 100 pulses also showed excellent surface-enhanced Raman scattering (SERS) response for the detection of rhodamine 6G, with an enhancement factor of ≈2 × 106 compared to detection in solution, and for the detection of a self-assembled monolayer of thiophenol, with an enhancement factor of ≈30 compared to the response from microstructured gold surfaces. It is envisioned that the simplicity and low fabrication cost of these gold-roughened structures will expedite the development of electrochemical and SERS sensing devices.

Shrinking Devices: Shape-Memory Polymer Fabrication of Micro-and Nanostructured Electrodes.

The front cover artwork is provided by Prof. Jose Moran-Mirabal's group at McMaster University in Hamilton, Ontario, Canada. The image shows a 3D rendering and electron microscopy images of micro/nanostructured electrodes, fabricated through thermal shrinking of a shape memory polymer. Read the full text of the Review at 10.1002/cphc.202300535.

Shrinking Devices: Shape-Memory Polymer Fabrication of Micro-and Nanostructured Electrodes.

Since their discovery in the 1940s, shape memory polymers (SMPs) have been used in a broad spectrum of applications for research and industry.[1] SMPs can adopt a temporary shape and promptly return to their original form when submitted to an external stimulus. They have proven useful in fields such as wearable and stretchable electronics,[2] biomedicine,[3] and aerospace..[4] These materials are attractive and unique due to their ability to "remember" a shape after being submitted to elastic deformation. By combining the properties of SMPs with the advantages of electrochemistry, opportunities have emerged to develop structured sensing devices through simple and inexpensive fabrication approaches. The use of electrochemistry for signal transduction provides several advantages, including the translation into inexpensive sensing devices that are relatively easy to miniaturize, extremely low concentration requirements for detection, rapid sensing, and multiplexed detection. Thus, electrochemistry has been used in biosensing,[5] pollutant detection,[6] and pharmacological[7] applications, among others. To date, there is no review that summarizes the literature addressing the use of SMPs in the fabrication of structured electrodes for electrochemical sensing. This review aims to fill this gap by compiling the research that has been done on this topic over the last decade.

Simple and Inexpensive Fabrication of High Surface-Area Paper-Based Gold Electrodes for Electrochemical and Surface-Enhanced Raman Scattering Sensing.

Paper has emerged as an excellent alternative to create environmentally benign disposable electrochemical sensing devices. The critical step to fabricating electrochemical sensors is making paper conductive. In this work, paper-based electrodes with a high electroactive surface area (ESA) were fabricated using a simple electroless deposition technique. The polymerization time of a polydopamine adhesion layer and the gold salt concentration during the electroless deposition step were optimized to obtain uniformly conductive paper-based electrodes. The optimization of these fabrication parameters was key to obtaining the highest ESA possible. Roughening factors (Rf) of 7.2 and 2.3 were obtained when cyclic voltammetry was done in sulfuric acid and potassium ferricyanide, respectively, demonstrating a surface prone to fast electron transfer. As a proof of concept, mercury detection was done through anodic stripping, achieving a limit of quantification (LOQ) of 0.9 ppb. By changing the metal deposition conditions, the roughness of the metalized papers could also be tuned for their use as surface-enhanced Raman scattering (SERS) sensors. Metallized papers with the highest SERS signal for thiophenol detection yielded a LOQ of 10 ppb. We anticipate that this method of fabricating nanostructured paper-based electrodes can accelerate the development of simple, cost-effective, and highly sensitive electrochemical and SERS sensing platforms.

High-Fidelity Extrusion Bioprinting of Low-Printability Polymers Using Carbopol as a Rheology Modifier.

Extrusion three-dimensional (3D) bioprinting is a promising technology with many applications in the biomedical and tissue engineering fields. One of the key limitations for the widespread use of this technology is the narrow window of printability that results from the need to have bioinks with rheological properties that allow the extrusion of continuous filaments while maintaining high cell viability within the materials during and after printing. In this work, we use Carbopol (CBP) as rheology modifier for extrusion printing of biomaterials that are typically nonextrudable or present low printability. We show that low concentrations of CBP can introduce the desired rheological properties for a wide range of formulations, allowing the use of polymers with different cross-linking mechanisms and the introduction of additives and cells. To explore the opportunities and limitations of CBP as a rheology modifier, we used ink formulations based on poly(ethylene glycol)diacrylate with extrusion 3D printing to produce soft, yet stable, hydrogels with tunable mechanical properties. Cell-laden constructs made with such inks presented high viability for cells seeded on top of cross-linked materials and cells incorporated within the bioink during printing, showing that the materials are noncytotoxic and the printed structures do not degrade for up to 14 days. To our knowledge, this is the first report of the use of CBP-containing bioinks to 3D-print complex cell-laden structures that are stable for days and present high cell viability. The use of CBP to obtain highly printable inks can accelerate the evolution of extrusion 3D bioprinting by guaranteeing the required rheological properties and expanding the number of materials that can be successfully printed. This will allow researchers to develop and optimize new bioinks focusing on the biochemical, cellular, and mechanical requirements of the targeted applications rather than the rheology needed to achieve good printability.

Efficient capture of recombinant SARS-CoV-2 receptor-binding domain (RBD) with citrate-coated magnetic iron oxide nanoparticles.

Several vaccines against COVID-19 use a recombinant SARS-CoV-2 receptor-binding domain (RBD) as antigen, making the purification of this protein a key step in their production. In this work, citrate-coated magnetic iron oxide nanoparticles were evaluated as nano adsorbents in the first step (capture) of the purification of recombinant RBD. The nanoparticles were isolated through coprecipitation and subsequently coated with sodium citrate. The citrate-coated nanoparticles exhibited a diameter of 10 ± 2 nm, a hydrodynamic diameter of 160 ± 3 nm, and contained 1.9 wt% of citrate. The presence of citrate on the nanoparticles' surface was confirmed through FT-IR spectra and thermogravimetric analysis. The crystallite size (10.1 nm) and the lattice parameter (8.3646 Å) were determined by X-ray diffraction. In parallel, RBD-containing supernatant extracted from cell culture was exchanged through ultrafiltration and diafiltration into the adsorption buffer. The magnetic capture was then optimized using different concentrations of nanoparticles in the purified supernatant, and we found 40 mg mL-1 to be optimal. The ideal amount of nanoparticles was assessed by varying the RBD concentration in the supernatant (between 0.113 mg mL-1 and 0.98 mg mL-1), which resulted in good capture yields (between 83 ± 5% and 94 ± 4%). The improvement of RBD purity after desorption was demonstrated by SDS-PAGE and RP-HPLC. Furthermore, the magnetic capture was scaled up 100 times, and the desorption was subjected to chromatographic purifications. The obtained products recognized anti-RBD antibodies and bound the ACE2 receptor, proving their functionality after the developed procedure.

Functionalization of 3D Printed Scaffolds Using Polydopamine and Silver Nanoparticles for Bone-Interfacing Applications.

The prevention of bacterial colonization and the stimulation of osseointegration are two major requirements for bone-interfacing materials to reduce the incidence of complications and promote the restoration of the patient's health. The present investigation developed an effective, two-step functionalization of 3D printed scaffolds intended for bone-interfacing applications using a simple polydopamine (PDA) dip-coating method followed by the formation of silver nanoparticles (AgNPs) after a second coating step in silver nitrate. 3D printed polymeric substrates coated with a ∼20 nm PDA layer and 70 nm diameter AgNPs proved effective in hindering Staphylococcus aureus biofilm formation, with a 3000-8000-fold reduction in the number of bacterial colonies formed. The implementation of porous geometries significantly accelerated osteoblast-like cell growth. Microscopy characterization further elucidated homogeneity, features, and penetration of the coating inside the scaffold. A proof-of-concept coating on titanium substrates attests to the transferability of the method to other materials, broadening the range of applications both in and outside the medical sector. The antibacterial efficiency of the coating is likely to lead to a decrease in the number of bacterial infections developed after surgery in the presence of these coatings on prosthetics, thus translating to a reduction in revision surgeries and improved health outcomes.

Electrochemical Nano-Roughening of Gold Microstructured Electrodes for Enhanced Sensing in Biofluids.

A key challenge for sensor miniaturization is to create electrodes with smaller footprints, while maintaining or increasing sensitivity. In this work, the electroactive surface of gold electrodes was enhanced 30-fold by wrinkling followed by chronoamperometric (CA) pulsing. Electron microscopy showed increased surface roughness in response to an increased number of CA pulses. The nanoroughened electrodes also showed excellent fouling resistance when submerged in solutions containing bovine serum albumin. The nanoroughened electrodes were used for electrochemical detection of Cu2+ in tap water and of glucose in human blood plasma. In the latter case, the nanoroughened electrodes allowed highly sensitive enzyme-free sensing of glucose, with responses comparable to those of two commercial enzyme-based sensors. We anticipate that this methodology to fabricate nanostructured electrodes can accelerate the development of simple, cost-effective, and high sensitivity electrochemical platforms.

Multi-scale structuring of cell-instructive cellulose nanocrystal composite hydrogel sheets via sequential electrospinning and thermal wrinkling.

Structured hydrogel sheets offer the potential to mimic the mechanics and morphology of native cell environments in vitro; however, controlling the morphology of such sheets across multiple length scales to give cells consistent multi-dimensional cues remains challenging. Here, we demonstrate a simple two-step process based on sequential electrospinning and thermal wrinkling to create nanocomposite poly(oligoethylene glycol methacrylate)/cellulose nanocrystal hydrogel sheets with a highly tunable multi-scale wrinkled (micro) and fibrous (nano) morphology. By varying the time of electrospinning, rotation speed of the collector, and geometry of the thermal wrinkling process, the hydrogel nanofiber density, fiber alignment, and wrinkle geometry (biaxial or uniaxial) can be independently controlled. Adhered C2C12 mouse myoblast muscle cells display a random orientation on biaxially wrinkled sheets but an extended morphology (directed preferentially along the wrinkles) on uniaxially wrinkled sheets. While the nanofiber orientation had a smaller effect on cell alignment, parallel nanofibers promoted improved cell alignment along the wrinkle direction while perpendicular nanofibers disrupted alignment. The highly tunable structures demonstrated are some of the most complex morphologies engineered into hydrogels to-date without requiring intensive micro/nanofabrication approaches and offer the potential to precisely regulate cell-substrate interactions in a "2.5D" environment (i.e. a surface with both micro- and nano-structured topographies) for in vitro cell screening or in vivo tissue regeneration. STATEMENT OF SIGNIFICANCE: While structured hydrogels can mimic the morphology of natural tissues, controlling this morphology over multiple length scales remains challenging. Furthermore, the incorporation of secondary morphologies within individual hydrogels via simple manufacturing techniques would represent a significant advancement in the field of structured biomaterials and an opportunity to study complex cell-biomaterial interactions. Herein, we leverage a two-step process based on electrospinning and thermal wrinkling to prepare structured hydrogels with microscale wrinkles and nanoscale fibers. Fiber orientation/density and wrinkle geometry can be independently controlled during the electrospinning and thermal wrinkling processes respectively, demonstrating the flexibility of this technique for creating well-defined multiscale hydrogel structures. Finally, we show that while wrinkle geometry is the major determinant of cell alignment, nanofiber orientation also plays a role in this process.

Superación profesional en la Universidad de Ciencias Médicas de Villa Clara. Su progresión entre 2012-2014 / Professional upgrading in Villa Clara University of Medical Sciences. Its progression from 2012 to 2014

Fundamento: la superación profesional tiene como objetivo la formación permanente y la actualización sistemática de los graduados universitarios, el perfeccionamiento del desempeño de sus actividades profesionales y académicas, así como el enriquecimiento de su acervo cultural. Objetivo: caracterizar el comportamiento progresivo de la superación profesional en la Universidad de Ciencias Médicas de Villa Clara en el curso académico 2013-2014, con respecto al 2012-2013. Métodos: se realizó un estudio descriptivo transversal en el que se utilizaron métodos teóricos y empíricos, estos últimos se basaron principalmente en la revisión de las bases de datos de superación profesional de la Dirección de Posgrado; con la información obtenida se realizó el análisis estadístico, para lo cual se utilizaron las frecuencias absolutas y porcentaje. Resultados: en el período analizado predominaron los cursos y talleres como las modalidades más utilizadas; los temas generales fueron estrategias para el análisis de situación de salud, la superación vinculada a los nuevos servicios y tecnologías y otros de formación general integral. El mayor número de incremento en actividades y participantes corresponde al Programa de Enfermedades Transmisibles; el segundo lugar, al de Atención Materno Infantil, le siguen las Enfermedades Crónicas No Transmisibles, el Programa de Atención al Adulto Mayor y el de Suicidio. Todos ellos responden a necesidades expresadas en el cuadro de salud de la provincia. Conclusiones: en la mayoría de los programas de salud se produjeron incrementos considerables en actividades y participantes, lo cual permite aseverar el estado progresivo de la superación profesional en Villa Clara, ocurrido entre 2012-2014.

Background: the professional upgrading has as objective the steady formation and the systematic updating of the graduate university students, the improvement of performance in their professional and academic activities, as well as the enrichment of their cultural background. Objective: to characterize the progressive behavior of the professional upgrading in Villa Clara University of Medical Sciences in the academic year 2013-2014, in respect to 2012-2013. Methods: it was carried out a cross-sectional descriptive study in which theoretical and empiric methods were used, these last ones were mainly based on the review of the databases of professional upgrading of the Post graduate Direction; the statistical analysis with the obtained information was carried out, the absolute frequencies and percentage were used for that purpose. Results: courses and workshops were the predominant modalities in the analyzed period; the general topics were strategies for the analysis of health picture, the upgrading linked to the new services and technologies and others of comprehensive general formation. The biggest increment in activities and participants corresponds to the Program of Transmissible diseases; in the second place, the Infant- Maternity Attention Program, then, non Transmissible Chronic diseases, the Elderly People Attention Program and that of Suicide. All of them respond to necessities expressed in the health picture of the province. Conclusions: considerable increments in activities and participants took place in most of the health programs; it represents a progressive state of the professional upgrading in Villa Clara, from 2012 to 2014.

Superación profesional en la Universidad de Ciencias Médicas de Villa Clara. Su progresión entre 2012-2014 / Professional upgrading in Villa Clara University of Medical Sciences. Its progression from 2012 to 2014

Fundamento: la superación profesional tiene como objetivo la formación permanente y la actualización sistemática de los graduados universitarios, el perfeccionamiento del desempeño de sus actividades profesionales y académicas, así como el enriquecimiento de su acervo cultural.Objetivo: caracterizar el comportamiento progresivo de la superación profesional en la Universidad de Ciencias Médicas de Villa Clara en el curso académico 2013-2014, con respecto al 2012-2013.Métodos: se realizó un estudio descriptivo transversal en el que se utilizaron métodos teóricos y empíricos, estos últimos se basaron principalmente en la revisión de las bases de datos de superación profesional de la Dirección de Posgrado; con la información obtenida se realizó el análisis estadístico, para lo cual se utilizaron las frecuencias absolutas y porcentaje. Resultados: en el período analizado predominaron los cursos y talleres como las modalidades más utilizadas; los temas generales fueron estrategias para el análisis desituación de salud, la superación vinculada a los nuevos servicios y tecnologías y otros de formación general integral. El mayor número de incremento en actividades y participantes corresponde al Programa de Enfermedades Transmisibles; el segundo lugar, al de Atención Materno Infantil, le siguen las Enfermedades Crónicas No Transmisibles, el Programa de Atención al Adulto Mayor y el de Suicidio. Todos ellos responden a necesidades expresadas en el cuadro de salud de la provincia. Conclusiones: en la mayoría de los programas de salud se produjeron incrementos considerables en actividades y participantes, lo cual permite aseverar el estado progresivo de la superación profesional en Villa Clara, ocurrido entre 2012-2014(AU)