Medical devices & sensors最新文献

The invisible realm of the human microbiota contains patterns that, when properly detected and interpreted, could indicate much about the health or disease of its host, the human body. Biosensing techniques for the detection of the human microbiota have the potential to transform clinical diagnostics, yet point-of-care (POC) biosensors for direct detection of disturbances in microbial communities are not presently available in clinical settings. The objective of this review paper is to explore the potential for biosensors to usher the study of the microbiome into the spaces of clinical diagnostics and big data collection. To achieve this goal, we first outline the types of biosensor methods that have been used to detect multiple targets from clinical and field samples, discuss the challenges inherent in multiplex detection from complex samples and examine the potential for biosensors to integrate microbiome analysis with the diagnostic process. We then consider the potential pitfalls of biosensor-based microbiome analysis and highlight the anticipation for machine-learning techniques to address the unique challenges associated with the large variability in microbiota composition between individuals. We finally conclude that biosensor technologies with integrated machine learning algorithms will shape the future of microbiome analysis by allowing for acquisition of vast amounts of microbiome data that can eventually be harnessed in clinical settings for more rapid and accurate diagnoses.

The advancement of reliable encapsulation techniques for long-term implantable biomedical microdevices is of vital importance for the safe and steady operation of implants for chronic applications. Conventional techniques based on titanium or ceramic enclosures, however, cannot meet the packaging requirements of emerging innovations in medical implants due to issues related to scalability, incompatibility with microfabrication processes and challenges with miniaturization. A variety of polymeric materials have been identified for encapsulation of implantable systems, including polyimide, parylene, liquid crystal polymer (LCP), and polydimethylsiloxane (PDMS). These materials are not as hermetic as conventional metal or ceramic packages nor as widely adopted in regulative licensed devices for long-term implantation. However, studies have shown promising results regarding their potential for long-term encapsulation, in particular for devices fabricated on polymeric substrates. This review offers a summary of the encapsulation performance of these emerging polymeric materials with a specific focus on their long-term performance and quantification of their expected lifetime.

The era of personalized medicine calls for rapid detection of key biomolecules, such as serum proteins, as general indicators of a healthy/sickness state. The fabrication, biofunctionalization and calibration of a fibrinogen biosensing platform based on plasmonic gallium nanoparticles are detailed in the present work. The first step consisted in the deposition of Ga nanoparticles on Si substrates by means of Joule-effect thermal evaporation technique. A distribution of nanodroplets could be evidenced by scanning electron microscopy. The biofunctionalization of the samples was carried out using aminosilane–titanate thin hybrid layers prepared by a sol–gel route. The integration of functional amino groups could be confirmed by spectroscopic methods. Then, in order to sensitize the platform surface to fibrinogen, specific immunoglobulins have been immobilized. We monitored the plasmon wavelength changes along the fabrication cascade and during detection assays with calibrated fibrinogen solutions in phosphate-buffered saline. From the ellipsometric analysis, three operational ranges as a function of fibrinogen concentration can be identified, with an out-of-range response for low concentration, a linear response behaviour in the 1–10 µM healthy range and a tendency to saturation at high concentration.

Among the several 3D printing technologies, fused deposition modelling (FDM) is gaining popularity because it can fabricate geometrically complex shapes of polymeric bio-implants at reasonable quality and cost mainly due to lower cost of FDM-based 3D printers as well as the filament form of feedstock material. Particularly, to cater the need of cost-effective biomedical applications, both poly(lactic) acid (PLA) and stainless-steel materials individually displayed the biocompatibility for various biomedical applications. The pure polymeric components are generally lower in mechanical strength, but these limitations can be resolved by developing a polymer–metallic composite; therefore, the recently developed PLA–stainless-steel composite was selected for the present work. This is new material and the current literature lacks in providing the necessary FDM processing parameters to obtain desired functional properties of PLA–stainless-steel components with unaltered biocompatibility. Therefore, the objective here is to obtain the optimized processing parameters through the design of experiments that shows the desired functional properties of PLA–stainless-steel specimens manufactured by FDM and later validate the structural strength through the tensile and impact tests. It was observed that the PLA–stainless-steel composite has a toughness of 18 kJ/m² and has an ultimate tensile strength of ~69 MPa at 45° and ~23 MPa at 90° raster orientation of the print. Biocompatibility of the PLA–stainless-steel polymeric composite was assessed using pre-osteoblast cells, and materials were found to have biocompatibility unchanged from pure PLA. Overall, it was proved from this work that the low-cost desktop FDM printer can be numerically optimized using statistical analyses to fabricate the next-generation biomaterials for biomedical implants with tailored dimensions and surface finish with required mechanical strength and biocompatibility.

A growing number of research papers report similarities in cell types, neuronal connections and information-processing principles between chick and rodent cortical tissues, which have very different architectures. This paper extends these comparisons beyond the cortical tissues. Using microelectrode array technology, we report three remarkable functional similarities between our original chick data and rodent data from the literature: (a) the pattern of spontaneous spiking activity from chick spinal cord neuron biosensors is very similar to that of rodent spinal cord neuron biosensors (i.e. rodent counterparts). (b) The spontaneous spiking activity pattern of the chick forebrain neuron biosensors is very similar to that of the rodent cortical neuron biosensors, but chick forebrain neuron biosensors contain not only cortical neurons, but also diencephalic neurons. In other words, chick forebrain neuron biosensors cannot be considered the counterparts of rodent cortical neuron biosensors. (c) Chick forebrain neuron biosensors respond to several classical neuroactive agents in a way similar to rodent cortical neuron biosensors as reflected in their agent-specific concentration–response curves and their values of EC₅₀ (the effective concentration that causes 50% of the maximal effect of an agent). These preliminary findings provide both direct and indirect support for a positive answer to the big research question in the title: ‘Do chick and rodent neuron biosensors function similarly’ if the sources of the neurons are homologous between chick and rodent? Our findings are of particular value to comparative biology/physiology, pharmacology, neurotoxicology and bioengineering and to research on the more cost-effective extended application of chick neuron biosensors.

Spherical carbon nanomaterial coatings on the purified carbon fibres were obtained and characterized. The use of exactly the same conditions of electrophoretic deposition process made it possible to compare the impact of the initial carbon nanomaterial properties on the behaviour of various prepared surfaces. Obtained samples were characterized by scanning electron microscopy, atomic force microscopy, flat surface ζ-potential and water contact angle measurements. Additionally, cytotoxic tests were carried out to compare biocompatibility of coated carbon fibres. Presented results show the impact of the initial materials properties on the characteristics of the deposited coatings.

Cathodic electrical stimulation has been investigated as a way to treat implant-associated infection of orthopaedic devices. One of the proposed mechanisms of these effects is the changes in chemical gradients adjacent to the implant generated by the cathodic reaction products. Of these reaction products, both alkaline pH and hydrogen peroxide have been implicated as antimicrobial agents. However, direct measurement of these chemical effects has yet to be fully characterized for orthopaedic biomaterials. Microelectrodes are powerful tools that can be used to measure localized chemical conditions. Most commercially available sensors are fabricated from pulled glass pipettes, which make them quite fragile. In order to more easily make measurements of the effects of electrical stimulation, more durable sensors are desired. Solid-state electrodes were fabricated from platinum and iridium micro-wires to make H₂O₂ and pH-sensitive electrodes, respectively. Additionally, a similar method was used to fabricate electrodes that were housed within a stainless steel needle, which could be used to penetrate and measure in solid samples without damaging the sensor. The H₂O₂ microelectrode was found to have a sensitivity of 34.1 pA/µM and a R² value of .996. The pH microelectrode was found to have a linear calibration from 2 to 12 with a sensitivity of 76.7 mV/pH and a R² of .996. The needle-based electrodes were found to be able to detect changes in both H₂O₂ and pH when tested in an agar gel model.

Intracellular pH plays critical roles in cell and tissue functions during processes such as metabolism, proliferation, apoptosis, ion transportation, endocytosis and muscle contraction. It is thus an important biomarker that can readily be used to monitor the physiological status of a cell. Thus, disrupted intracellular pH may serve as an early indicator of cell dysfunction and deterioration. Various methods have been developed to detect cellular pH, such as pH-sensitive labelling reagents with fluorescent or Raman signals. However, excessive cellular uptake of these reagents will not only disrupt cell viability but also compromise effective long-term monitoring. Here, we present a novel fibre-optic fluorescent nanoprobe with a high spatial resolution for label-free, subcellular pH sensing. The probe has a fast response time (~20 s) with minimum invasiveness and excellent pH resolution (0.02 pH units) within a biologically relevant pH environment ranging from 6.17 to 8.11. Its applicability was demonstrated on cultured A549 lung cancer cells, and its efficacy was further testified in two typical cytotoxic cases using carbonylcyanide 3-chlorophenyl hydrazine, titanium dioxide and nanoparticles. The probe can readily detect the pH variations among cells under toxin/nanoparticles administration, enabling direct monitoring of the early onset of physiological or pathological events with high spatiotemporal resolution. This platform has excellent promise as a minimum invasive diagnostic tool for pH-related cellular mechanism studies, such as inflammation, cytotoxicity, drug resistance, carcinogenesis and stem cell differentiation.

The present review compiles different biomedical relevant polymers that have been modified to enhance their properties, giving hydrophilicity to their surfaces, antifouling properties to avoid bacterial adhesion, biocompatibility, incorporation of drug delivery systems and the improving of their mechanical properties to use them in the manufacturing of medical devices as prosthesis or implants, or other medical applications as wound dressers or scaffolds to cell culture. Other content of this work is a general description of the different techniques to modify and graft molecules, biomolecules and other polymers onto polymeric matrices in order to obtain high-performance biomaterials and medical devices.

The development of optical biosensors based on silicon dioxide or silicon nitride transducers requires the chemical activation of their surface to achieve stable, repeatable and homogeneous binding of biomolecules. In the present study, the chemical activation of silicon dioxide and silicon nitride surfaces with 3-aminopropyl-triethoxysilane (APTES) was optimized so as to enable the immobilization of biomolecules by adsorption or covalent bonding. Chemical activation was performed with either aqueous or organic solution of APTES, and the surfaces were used to immobilize directly protein molecules by physical adsorption or further modified with glutaraldehyde to allow covalent binding of protein molecules. The protein immobilization capacity of the chemically activated silicon dioxide and silicon nitride surfaces was evaluated through incubation with mouse γ-globulins and reaction with a fluorescently labelled goat antimouse IgG antibody. By determining the surface fluorescence signal intensity, it was found that modification with 5% (v/v) APTES solution in ethanol followed by modification with glutaraldehyde provided 30% higher fluorescence signals than all the other protocols tested. In addition, this method provided the lower signal variation between different chips. To test the possible advantages of the chemical activation protocols for optical biosensing applications, they were also applied to a label-free white light interference spectroscopy sensor and evaluated through (a) real-time monitoring of the reaction between immobilized on the sensor surface mouse γ-globulins with an unlabelled goat antimouse IgG antibody and (b) a non-competitive immunoassay for the determination of C-reactive protein. The results showed that in case of antibody, physical absorption provided marginally higher binding capacity to covalent bonding.