As baby boomers age, diabetes mellitus, cancer, osteoarthritis, cardiovascular diseases, and orthopedic disorders are more widespread and the demand for better biomedical devices and functional ...biomaterials is increasing rapidly. Owing to the good biocompatibility, chemical stability, catalytic efficiency, plasticity, mechanical properties, as well as strength‐to‐weight ratio, titanium dioxide (TiO2) based nanostructured materials are playing important roles in tissue reconstruction and diagnosis of these diseases. Here, recent advance in the research of nanostructured TiO2 based biomaterials pertaining to bone tissue engineering, intravascular stents, drug delivery systems, and biosensors is described.
TiO2 based nanomaterials with various structures have been widely used for a variety of biomedical applications ranging from tissue engineering to diseases diagnosis systems. Here, recent advances pertaining to nanostructured TiO2 in four important areas are reviewed, namely bone scaffolds, intravascular stents, drug delivery systems, and biosensors.
3D printing alias additive manufacturing can transform 3D virtual models created by computer-aided design (CAD) into physical 3D objects in a layer-by-layer manner dispensing with conventional ...molding or machining. Since the incipiency, significant advancements have been achieved in understanding the process of 3D printing and the relationship of component, structure, property and application of the created objects. Because hydrogels are one of the most feasible classes of ink materials for 3D printing and this field has been rapidly advancing, this Review focuses on hydrogel designs and development of advanced hydrogel-based biomaterial inks and bioinks for 3D printing. It covers 3D printing techniques including laser printing (stereolithography, two-photon polymerization), extrusion printing (3D plotting, direct ink writing), inkjet printing, 3D bioprinting, 4D printing and 4D bioprinting. It provides a comprehensive overview and discussion of the tailorability of material, mechanical, physical, chemical and biological properties of hydrogels to enable advanced hydrogel designs for 3D printing. The range of hydrogel-forming polymers covered encompasses biopolymers, synthetic polymers, polymer blends, nanocomposites, functional polymers, and cell-laden systems. The representative biomedical applications selected demonstrate how hydrogel-based 3D printing is being exploited in tissue engineering, regenerative medicine, cancer research, in vitro disease modeling, high-throughput drug screening, surgical preparation, soft robotics and flexible wearable electronics. Incomparable by thermoplastics, thermosets, ceramics and metals, hydrogel-based 3D printing is playing a pivotal role in the design and creation of advanced functional (bio)systems in a customizable way. An outlook on future directions of hydrogel-based 3D printing is presented.
BackgroundThe goal of this study was to characterize viral loads and factors affecting viral clearance in persons with severe influenza MethodsThis was a 1-year prospective, observational study ...involving consecutive adults hospitalized with influenza. Nasal and throat swabs were collected at presentation, then daily until 1 week after symptom onset. Real-time reverse-transcriptase polymerase chain reaction to determine viral RNA concentration and virus isolation were performed. Viral RNA concentration was analyzed using multiple linear or logistic regressions or mixed-effect models ResultsOne hundred forty-seven inpatients with influenza A (H3N2) infection were studied (mean age ± standard deviation, 72±16 years). Viral RNA concentration at presentation positively correlated with symptom scores and was significantly higher than that among time-matched outpatients (control subjects). Patients with major comorbidities had high viral RNA concentration even when presenting >2 days after symptom onset (mean ± standard deviation, 5.06±1.85 vs 3.62±2.13 log10 copies/mL; P=.005; β, +0.86 95% confidence interval, +0.03 to +1.68). Viral RNA concentration demonstrated a nonlinear decrease with time; 26% of oseltamivir-treated and 57% of untreated patients had RNA detected at 1 week after symptom onset. Oseltamivir started on or before symptom day 4 was independently associated with an accelerated decrease in viral RNA concentration (mean β standard error, −1.19 0.43 and −0.68 0.33 log10 copies/mL for patients treated on day 1 and days 2–3, respectively; P<.05) and viral RNA clearance at 1 week (odds ratio, 0.10 95% confidence interval, 0.03–0.35 and 0.30 0.10–0.90 for patients treated on day 1–2 and day 3–4, respectively). Conversely, major comorbidities and systemic corticosteroid use for asthma or chronic obstructive pulmonary disease exacerbations were associated with slower viral clearance. Viral RNA clearance was associated with a shorter hospital stay (7.0 vs 13.5 days; P=.001) ConclusionPatients hospitalized with severe influenza have more active and prolonged viral replication. Weakened host defenses slow viral clearance, whereas antivirals started within the first 4 days of illness enhance viral clearance
The prevalence of bacterial infections and resistance to existing antibiotics make new effective antibacterial strategies urgently needed. Photocatalytic antibacterial, an effective strategy relying ...on exogenous excitation, has drawn increasing attention over the past decades, owing to its controllable, safe, and non-invasive characteristics. Many photoresponsive agents have been developed. With exceptional features of abundance, facile synthesis, suitable band structure, high stability, and low toxicity, metal-free polymeric two-dimensional nanomaterial graphitic carbon nitride (g-C3N4) is an attractive photosensitizer for antibiotic-free antibacterial application. In this review, the basic structural characteristics and preparation methods of g-C3N4 are summarized. The photocatalytic antibacterial mechanism of g-C3N4 through reactive oxygen species (ROS) generation is also discussed. In order to achieve more precise and efficient antibacterial effects, we pay special attention to two aspects: (1) how to increase the utilization of visible light and reduce the recombination of electron-hole pairs, thereby enhancing the production of ROS; and (2) how to obtain effective bacteria-killing activity while maintaining good biocompatibility and environmental friendliness, which determines the practical applications of materials. Several significant modification strategies are thus introduced, including structure design, surface modification, element doping, and construction of g-C3N4-based heterojunctions. Furthermore, various typical examples of combining the photocatalytic antibacterial effect of g-C3N4 with other strategies to exert good synergistic effects are summarized. Lastly, the potential challenges and perspectives are offered. This review is expected to inspire more follow-up work to design high-performance g-C3N4-based materials for photocatalytic antibacterial application.
Titanium (Ti) and its alloys are the most widely used materials for biomedical applications, owing to their good corrosion resistance, mechanical properties, and biocompatibility. However, their ...long-term performance is compromised by the post-surgery complications such as implant-associated infection and mechanical loosening. Surface modification can be adopted to alleviate these concerns while preserving the desirable bulk attributes. Among various techniques, electrochemical methods offer merits such as mild processing conditions, non-line-of-sight operation, low cost, as well as large-scale production. This paper gives a brief overview of surface engineering of the Ti-based alloys from the perspective of electrochemistry. It mainly focuses on three major electrochemical techniques: low voltage anodization, micro-arc oxidation, and electrodeposition. Overall, effects have been made to bring out a comprehensive understanding of electrochemical modification of Ti-based alloys for biomedical applications.
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Although polymerase chain reaction (PCR) is the most widely used method for DNA amplification, the requirement of thermocycling limits its non-laboratory applications. Isothermal DNA amplification ...techniques are hence valuable for on-site diagnostic applications in place of traditional PCR. Here we describe a true isothermal approach for amplifying and detecting double-stranded DNA based on a CRISPR-Cas9-triggered nicking endonuclease-mediated Strand Displacement Amplification method (namely CRISDA). CRISDA takes advantage of the high sensitivity/specificity and unique conformational rearrangements of CRISPR effectors in recognizing the target DNA. In combination with a peptide nucleic acid (PNA) invasion-mediated endpoint measurement, the method exhibits attomolar sensitivity and single-nucleotide specificity in detection of various DNA targets under a complex sample background. Additionally, by integrating the technique with a Cas9-mediated target enrichment approach, CRISDA exhibits sub-attomolar sensitivity. In summary, CRISDA is a powerful isothermal tool for ultrasensitive and specific detection of nucleic acids in point-of-care diagnostics and field analyses.
Although silicon is a promising anode material for lithium-ion batteries, scalable synthesis of silicon anodes with good cyclability and low electrode swelling remains a significant challenge. ...Herein, we report a scalable top-down technique to produce ant-nest-like porous silicon from magnesium-silicon alloy. The ant-nest-like porous silicon comprising three-dimensional interconnected silicon nanoligaments and bicontinuous nanopores can prevent pulverization and accommodate volume expansion during cycling resulting in negligible particle-level outward expansion. The carbon-coated porous silicon anode delivers a high capacity of 1,271 mAh g
at 2,100 mA g
with 90% capacity retention after 1,000 cycles and has a low electrode swelling of 17.8% at a high areal capacity of 5.1 mAh cm
. The full cell with the prelithiated silicon anode and Li(Ni
Co
Mn
)O
cathode boasts a high energy density of 502 Wh Kg
and 84% capacity retention after 400 cycles. This work provides insights into the rational design of alloy anodes for high-energy batteries.
Bacterial infection and lack of bone tissue integration are two major concerns of orthopedic implants. In addition, osteoinductivity often decreases and toxicity may arise when antibacterial agents ...are introduced to increase the antibacterial ability. Here hybrid ZnO/polydopamine (PDA)/arginine-glycine-aspartic acid-cysteine (RGDC) nanorod (NR) arrays are designed and prepared on titanium (Ti) implants to not only enhance the osteoinductivity but also effectively kill bacteria simultaneously, which are ascribed to the selective physical puncture and the biofunctionalization of ZnO/PDA/RGDC nanorods during the competition between bacteria and osteoblasts. That is, owing to the much larger size of osteoblasts than bacteria, the hybrid NRs can puncture bacteria but not damage osteoblasts. Meanwhile, the cytocompatibility can be enhanced through the suppression of both reactive oxygen species and higher Zn2+ concentration by the covering of PDA and RGDC. The in vitro results confirm the selective puncture of the bacterial membrane and the better osteoinductivity. In vivo tests also show much higher antibacterial efficacy of the hybrid NRs with far less amounts of lobulated neutrophils and adherent bacteria in the surrounding tissues. In addition, the hybrid NRs also accelerate formation of new bone tissues (20.1% higher than pure Ti) and osteointegration between implants and newly formed tissues (32.0% higher than pure Ti) even in the presence of injected bacteria. This work provides a surface strategy for designing implants with desirable ability of osseointegration and infection prevention simultaneously, which will exhibit tremendous clinical potential in orthopedic and dental applications.
A surface plasmon resonance (SPR) sensor with two open-ring channels based on a photonic crystal fiber (PCF) is described. The sensor is designed to detect low refractive indexes between 1.23 and ...1.29 with the operation wavelength in mid-infrared region between 2550 nm and 2900 nm. The coupling characteristics and sensing properties are numerically analyzed by the finite element method. The average spectral sensitivity is 5500 nm/RIU and a maximum resolution of 7.69 × 10
RIU can be obtained. Our analysis shows that the PCF-SPR sensor is suitable for mid-infrared detection.
The fabrication of multiple heterojunctions with tunable photocatalytic reactivity in full-range BiOBr–BiOI composites based on microstructure modulation and band structures is demonstrated. The ...multiple heterojunctions are constructed by precipitation at room temperature and characterized systematically. Photocatalytic experiments indicate that there are two types of heterostructures with distinct photocatalytic mechanisms, both of which can greatly enhance the visible-light photocatalytic performance for the decomposition of organic pollutants and generation of photocurrent. The large separation and inhibited recombination of electron–hole pairs rendered by the heterostructures are confirmed by electrochemical impedance spectra (EIS) and photoluminescence (PL). Reactive species trapping, nitroblue tetrazolium (NBT, detection agent of •O2 –) transformation, and terephthalic acid photoluminescence (TA-PL) experiments verify the charge-transfer mechanism derived from the two types of heterostructures, as well as different enhancements of the photocatalytic activity. This article provides insights into heterostructure photocatalysis and describes a novel way to design and fabricate high-performance semiconductor composites.
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