Microneedle (MN), a miniaturized needle with a length‐scale of hundreds of micrometers, has received a great deal of attention because of its minimally invasive, pain‐free, and easy‐to‐use nature. However, a major challenge for controlled long‐term drug delivery or biosensing using MN is its low tissue adhesion. Although microscopic structures with high tissue adhesion are found from living creatures in nature (e.g., microhooks of parasites, barbed stingers of honeybees, quills of porcupines), creating MNs with such complex microscopic features is still challenging with traditional fabrication methods. Here, a MN with bioinspired backward‐facing curved barbs for enhanced tissue adhesion, manufactured by a digital light processing 3D printing technique, is presented. Backward‐facing barbs on a MN are created by desolvation‐induced deformation utilizing cross‐linking density gradient in a photocurable polymer. Barb thickness and bending curvature are controlled by printing parameters and material composition. It is demonstrated that tissue adhesion of a backward‐facing barbed MN is 18 times stronger than that of barbless MN. Also demonstrated is sustained drug release with barbed MNs in tissue. Improved tissue adhesion of the bioinspired MN allows for more stable and robust performance for drug delivery, biofluid collection, and biosensing.
This paper reports the results of a research project that allowed children to define their capabilities as the basis of a bottom-up strategy for understanding the relevant dimensions of children's well-being. The subjects of this research were children participating in the 'Children's World Congress on Child Labour' held in Florence in May 2004, organized by the Global March against Child Labour and other associations. Children were invited to interact and express their opinions on the most relevant issues related to their childhood and adolescence. The paper has three main aims. The first is to propose and legitimate a view that considers children not simply as recipients of freedoms, but also as participants in the process of delineating a set of core capabilities. The second is to propose a methodological approach to the conceptualization of a list of relevant capabilities. The third is to identify a tentative list of relevant capabilities for children through a participatory bottom-up approach. One of the key findings of the research is that, among the capabilities conceptualized, education, love and care are primary in terms of relevance.
In the last 20 years, surface plasmon resonance (SPR) and its advancement with imaging (SPRi) emerged as a suitable and reliable platform in clinical analysis for label-free, sensitive, and real-time monitoring of biomolecular interactions. Thus, we report in this review the state of the art of clinical target detection with SPR-based biosensors in complex matrices (e.g., serum, saliva, blood, and urine) as well as in standard solution when innovative approaches or advanced instrumentations were employed for improved detection. The principles of SPR-based biosensors are summarized first, focusing on the physical properties of the transducer, on the assays design, on the immobilization chemistry, and on new trends for implementing system analytical performances (e.g., coupling with nanoparticles (NPs). Then we critically review the detection of analytes of interest in molecular diagnostics, such as hormones (relevant also for anti-doping control) and biomarkers of interest in inflammatory, cancer, and heart failure diseases. Antibody detection is reported in relation to immune disorder diagnostics. Subsequently, nucleic acid targets are considered for revealing genetic diseases (e.g., point mutation and single nucleotides polymorphism, SNPs) as well as new emerging clinical markers (microRNA) and for pathogen detection. Finally, examples of pathogen detection by immunosensing were also analyzed. A parallel comparison with the reference methods was duly made, indicating the progress brought about by SPR technologies in clinical routine analysis.
Low-cost piezoresistive strain/pressure sensors with large working range, at the same time able to reliably detect ultralow strain (≤0.1%) and pressure (≤1 Pa), are one of the challenges that have still to be overcome for flexible piezoresistive materials toward personalized health-monitoring applications. In this work, we report on unprecedented, simultaneous detection of ultrasmall strain (0.1%, i.e., 10 μm displacement over 10 mm) and subtle pressure (20 Pa, i.e., a force of only 2 mN over an area of 1 cm) in compression mode, coupled with a large working range (i.e., up to 60% for strain-6 mm in displacement-and 50 kPa for pressure) using piezoresistive, flexible three-dimensional (3D) macroporous polydimethylsiloxane (pPDMS) foams decorated with pristine multiwalled carbon nanotubes (CNTs). pPDMS/CNT foams with pore size up to 500 μm (i.e., twice the size of those of commonly used foams, at least) and porosity of 77%, decorated with a nanostructured surface network of CNTs at densities ranging from 7.5 to 37 mg/cm are prepared using a low-cost and scalable process, through replica molding of sacrificial sugar templates and subsequent drop-casting of CNT ink. A thorough characterization shows that piezoresistive properties of the foams can be finely tuned by controlling the CNT density and reach an optimum at a CNT density of 25 mg/cm, for which a maximum change of the material resistivity (e.g., ρ/ρ = 4 at 50% strain) is achieved under compression. Further static and dynamic characterization of the pPDMS/CNT foams with 25 mg/cm of CNTs highlights that detection limits for strain and pressure are 0.03% (3 μm displacement over 10 mm) and 6 Pa (0.6 mN over an area of 1 cm), respectively; moreover, good stability and limited hysteresis are apparent by cycling the foams with 255 compression-release cycles over the strain range of 0-60%, at different strain rates up to 10 mm/min. Our results on piezoresistive, flexible pPDMS/CNT foams pave the way toward breakthrough applications for personalized health care, though not limited to these, which have not been fully addressed to date with flexible strain/stress sensors.
In-field analysis (e.g., clinical and diagnostics) using nanostructured porous silicon (PSi) for label-free optical biosensing has been hindered so far by insufficient sensitivity of PSi biosensors. Here we report on a label-free PSi interferometric aptasensor able to specifically detect tumor necrosis factor alpha (TNFα, a protein biomarker of inflammation and sepsis) at concentration down to 3.0 nM with signal-to-noise ratio (S/N) of 10.6 and detection limit (DL) of 200 pM. This represents a 10 000-fold improvement with respect to direct (i.e., nonamplified) label-free PSi biosensors and pushes PSi biosensors close to the most sensitive optical and label-free transduction techniques, e.g., surface plasmon resonance (SPR) for which a lowest DL of 100 pM in aptasensing has been reported. A factor 1000 in improvement is achieved by introducing a novel signal-processing technique for the optical readout of PSi interferometers, namely, interferogram average over wavelength (IAW) reflectance spectroscopy. The IAW reflectance spectroscopy is shown to significantly improve both sensitivity and reliability of PSi biosensors with respect to commonly used fast Fourier transform (FFT) reflectance spectroscopy. A further factor 10 is achieved by enabling preparation of PSi interferometers with enlarged pore sizes (up to a 3× increase in diameter) at constant current density (i.e., constant porosity and, in turn, constant refractive index). This method is in contrast to standard PSi preparation where pore size is increased by increasing etching current density (i.e., porosity), and allows tackling mass-limited diffusion of biomolecules into the nanopores without worsening PSi interferometer optical features.
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