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1.
Nanotechnology ; 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32235078

RESUMO

3D print technology provided an opportunity to achieve fast and accurate fabrication of wearable sensor arrays. In this paper, high-sensitivity flexible and stretchable silver coated carbon nanotubes (Ag@CNT) wearable strain sensor arrays are fabricated using 3D printing technology and composite nanomaterial synthesis. Ag@CNTs with uniform and compact particles were synthesized with different sizes of carbon nanotubes (CNTs) via reduction method. Strain sensor arrays were fabricated accurately and efficiently with the aid of 3D printed molds. Sensors with different Ag@CNTs were then compared comprehensively and it was found that Ag@CNT (Short) sensor, which had a GF of 62.8 in 0 to 14.44% stretch range and a GF of 831.3 in 14.44% to 21.11% stretch range, can significantly enhanced the detection of small movements. These wearable strain sensor arrays were utilized in the application of TCM pulse diagnosis and gesture recognition.

2.
Colloids Surf B Biointerfaces ; 188: 110768, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31945629

RESUMO

Thrombosis is a main complication of cancer. It can increase the mortality of cancer patients. Therefore, the anticoagulant heparin (Hep) as an adjuvant therapy was introduced to the drug delivery system based on doxorubicin hydrochloride (DOX)-carbon dots (CDs)-Hyaluronic acid (HA), which obviously enhanced the blood compatibility of the system. Drug release process of the CDs-HA-Hep/DOX system was dual-responsive by HA and pH value. Results of in vitro MTT and scratch tests demonstrated that the drug delivery system could targetedly inhibit growth and migration of cancerous cells. In addition, the system allows visual tracking of the drug based on fluorescence of CDs.

3.
J Nanosci Nanotechnol ; 20(2): 1013-1019, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31383099

RESUMO

Nanomaterial-based flexible strain sensors have developed rapidly in recent years. Here, we propose a flexible strain sensor based on polydimethylsiloxane with carbon nanotubes (CNTs) and graphene quantum dots (GQDs). Different weight ratios of CNTs and GQDs were used as the sensitive units of the strain sensors. After analyzing the results of current-voltage curves and the strain effects of the sensors, we concluded that the introduction of GQDs played an important role in improving the sensitivity of the sensors. The gauge factor of the as-prepared strain sensors ranges from 0 to 841.42.

4.
Nanoscale Res Lett ; 14(1): 356, 2019 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-31784841

RESUMO

Soft-strain-based sensors are being increasingly used across various fields, including wearable sensing, behavior monitoring, and electrophysiological diagnostics. However, throughout all applications, the function of these sensors is limited because of high sensitivity, high-dynamic range, and low-power consumption. In this paper, we focus on improving the sensitivity and strain range of the soft-strain-based sensor through structure, surface, and sensitive unit treatment. Nanosilver (Ag)-coated hydroxyl-functionalized multi-walled carbon nanotubes (OH-f MWCNTs) were explored for highly acute sensing. With stretching and depositing methods, Ag@OH-f MWCNTs and polydimethylsiloxane (PDMS) are fabricated into a wrinkled and sandwich structure for a soft-strain-based sensor. The electronic properties were characterized in that the gauge factor (GF) = ΔR/R0 was 412.32, and the strain range was 42.2%. Moreover, our soft-strain-based sensor exhibits features including flexibility, ultra-lightweight and a highly comfortable experience in terms of wearability. Finally, some physiological and behavioral features can be sampled by testing the exceptional resistance change, including the detection of breath, as well as facial and hand movement recognition. The experiment exhibits its superiority in terms of being highly sensitive and having an extensive range of sensing.

5.
IET Nanobiotechnol ; 13(9): 905-910, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31811758

RESUMO

The surface stress-based biosensor has been applied in fast and sensitive identification of Escherichia coli (E. coli)with significance for public health, food, and water safety. However, the stable sensitive element of flexible biosensor based on surface stress is still crucial and challengeable. Here, the authors reported surface stress-induced biosensors based on double-layer stable gold nanostructures (D-AuNS-SSMB) for E. coli O157:H7 detection. Bacterial detection demonstrates the high stability of the biosensor. The resistance change of biosensor is linear to the logarithmic value of the E. coli O157:H7 concentrations ranging from 103 to 107 CFU/mL with a limit of detection (LOD) of 43 CFU/mL. The captured signals of D-AuNS-SSMB comes from surface stress generated by antigen-antibody binding. In addition, the biosensor exhibits good stability, reproducibility and specificity in detection of E. coli O157:H7 as well. This study provides a new preparation method of stable sensitive element for the E. coli detection.

6.
Micromachines (Basel) ; 10(12)2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31835674

RESUMO

This work reports a microfluidic reactor that utilizes gold nanoparticles (AuNPs) for the highly efficient photocatalytic degradation of organic pollutants under visible light. The bottom of microchamber has a TiO2 film covering a layer of AuNPs (namely, TiO2/AuNP film) deposited on the F-doped SnO2 (FTO) substrate. The rough surface of FTO helps to increase the surface area and the AuNPs enables the strong absorption of visible light to excite electron/hole pairs, which are then transferred to the TiO2 film for photodegradation. The TiO2 film also isolates the AuNPs from the solution to avoid detachment and photocorrosion. Experiments show that the TiO2/AuNP film has a strong absorption over 400-800 nm and enhances the reaction rate constant by 13 times with respect to the bare TiO2 film for the photodegradation of methylene blue. In addition, the TiO2/AuNP microreactor exhibits a negligible reduction of photoactivity after five cycles of repeated tests, which verifies the protective function of the TiO2 layer. This plasmonic photocatalytic microreactor draws the strengths of microfluidics and plasmonics, and may find potential applications in continuous photocatalytic water treatment and photosynthesis. The fabrication of the microreactor uses manual operation and requires no photolithography, making it simple, easy, and of low cost for real laboratory and field tests.

7.
Mikrochim Acta ; 186(11): 736, 2019 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-31673784

RESUMO

Pyrophosphate-modified carbon quantum dots (PP-CDs) are demonstrated to be a viable fluorescent nanoprobe for mercury(II) (Hg2+) detection. Hg2+ reacts with the pyrophosphate groups on the surface of PP-CDs to form a non-fluorescent complex. This results in quenching of the green fluorescence which has excitation/emission peaks at 400/513 nm. Static quenching is shown to be the dominant mechanism. The probe works in 0.1 µM to 1.4 µM Hg2+ concentration range, and the limit of detection is 2 nM. The PP-CDs were also used to visualize Hg2+ inside human hepatocyte LO2 cells. Graphical abstract Schematic representation of pyrophosphate-modified carbon quantum dots (CDs) for selective and sensitive fluorometric determination of mercury(II). Hg(II) quenches the blue fluorescence of the CDs, and glutathione restores it. The method was used to detect Hg(II) in spiked tap water and inside cells.

8.
Molecules ; 24(22)2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31739407

RESUMO

Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS)-based organic electrochemical transistors (OECTs) are widely utilized to construct highly sensitive biosensors. However, the PSS phase exhibits insulation, weak acidity, and aqueous instability. In this work, we fabricated PEDOT OECT by alternating current electrodeposition in protic ionic liquids. The steady-state characteristics were demonstrated to be stable in long-term tests. In detail, the maximum transconductance, the on/off current ratio, and the hysteresis were stable at 2.79 mS, 504, and 0.12 V, respectively. Though the transient behavior was also stable, the time constant could reach 218.6 ms. Thus, the trade-off between switching speed and stability needs to be considered in applications that require a rapid response.

9.
Nanotechnology ; 31(1): 015501, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31530749

RESUMO

Here we develop a magnetoelastic (ME) nano-biosensor based on the competitive strategy for the detection of a carcinoembryonic antigen (CEA). Specifically, the gold-coated ME material provided a platform and the thiolated single-stranded DNA (HS-DNA) containing a half-complementary sequence towards the CEA aptamer was modified on the surface via Au-S bonding. DNA-templated silver nanoclusters (DNA-AgNCs) containing another half-complementary sequence towards the aptamer were used to amplify the signals by about 2.1 times, compared to those obtained using just the aptamer. CEA aptamers as a bio-recognition element were employed to link HS-DNA and DNA-AgNCs through DNA hybridization. The CEA aptamer preferentially combined with CEA rather than hybridized with DNA. Due to the magnetostrictive nature of the ME materials, the resonant frequency of the nano-biosensor would increase along with the release of DNA-AgNCs and CEA aptamers. The modification process was demonstrated by UV-vis spectra, x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, transmission electron microscope (TEM) and an atomic force microscope (AFM). The nano-biosensor has a linear response to the logarithmic CEA concentrations ranging from 2 pg ml-1 to 6.25 ng ml-1, with a limit of detection (LOD) of 1 pg ml-1 and a sensitivity of 105.05 Hz/ng · ml-1. This study provides a low-cost, highly sensitive and wireless method for selective detection of CEA.

10.
Nanomaterials (Basel) ; 9(9)2019 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-31547316

RESUMO

Flexible electronics devices with tactile perception can sense the mechanical property data of the environment and the human body, and they present a huge potential in the human health system. In particular, the introduction of ultra-flexible and self-powered characteristics to tactile sensors can effectively reduce the problems caused by rigid batteries. Herein, we report a triboelectric nanogenerator (TENG), mainly consisting of an ultra-flexible polydimethylsiloxane (PDMS) film with micro-pyramid-structure and sputtered aluminum electrodes, which achieves highly conformal contact with skin and the self-powered detection of human body motions. The flexible polyethylene terephthalate (PET) film was selected as spacer layer, which made the sensor work in the contact-separation mode and endowed the perfect coupling of triboelectrification and electrostatic induction. Moreover, the controllable and uniform micro-structure PDMS film was fabricated by using the micro-electro-mechanical system (MEMS) manufacturing process, bringing a good sensitivity and high output performance to the device. The developed TENG can directly convert mechanical energy into electric energy and light up 110 green Light-Emitting Diodes (LEDs). Furthermore, the TENG-based sensor displays good sensitivity (2.54 V/kPa), excellent linearity (R2 = 0.99522) and good stability (over 30,000 cycles). By virtue of the compact size, great electrical properties, and great mechanical properties, the developed sensor can be conformally attached to human skin to monitor joint movements, presenting a promising application in wearable tactile devices. We believe that the ultra-flexible and self-powered tactile TENG-based sensor could have tremendous application in wearable electrons.

11.
Nat Commun ; 10(1): 4049, 2019 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-31492867

RESUMO

Food production in green crops is severely limited by low activity and poor specificity of D-ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) in natural photosynthesis (NPS). This work presents a scientific solution to overcome this problem by immobilizing RuBisCO into a microfluidic reactor, which demonstrates a continuous production of glucose precursor at 13.8 µmol g-1 RuBisCO min-1 from CO2 and ribulose-1,5-bisphosphate. Experiments show that the RuBisCO immobilization significantly enhances enzyme stabilities (7.2 folds in storage stability, 6.7 folds in thermal stability), and also improves the reusability (90.4% activity retained after 5 cycles of reuse and 78.5% after 10 cycles). This work mimics the NPS pathway with scalable microreactors for continuous synthesis of glucose precursor using very small amount of RuBisCO. Although still far from industrial production, this work demonstrates artificial synthesis of basic food materials by replicating the light-independent reactions of NPS, which may hold the key to food crisis relief and future space colonization.


Assuntos
Enzimas Imobilizadas/metabolismo , Glucose/biossíntese , Microfluídica/métodos , Fotossíntese , Ribulose-Bifosfato Carboxilase/metabolismo , Dióxido de Carbono/metabolismo , Produtos Agrícolas/metabolismo , Estabilidade Enzimática , Glucose/química , Folhas de Planta/metabolismo , Reprodutibilidade dos Testes , Ribulosefosfatos/metabolismo , Temperatura Ambiente
12.
J Photochem Photobiol B ; 197: 111532, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31212245

RESUMO

Glutathione (GSH) plays critical roles in many physiological processes usually present in live cells, and altered levels have been linked to some clinical pathological conditions. However, current techniques of GSH detection with fluorescence assay strategies remain poorly researched. In this work, branched polyethylenimine-functionalized carbon dots (PEI-CDs) are synthesized by simple hydrothermal treatment of glucose and PEI. The fluorescence of the PEI-CDs could be efficiently quenched by Cu2+ and then recovered by some biothiols. Basing on this, a "turn-on" fluorescent probe for detecting GSH has been developed using PEI-CDs-Cu2+ system. Compared with traditional probes for GSH detection, a significant advantage of the PEI-CDs-Cu2+ system is that it can be used for GSH detection at both low and high concentrations with different concentration combinations of PEI-CDs and Cu2+. More specifically, two good linear relationships are achieved in the ranges of 0-80 µM and 0-1400 µM for GSH, respectively. Correspondingly, the detection limits of GSH are 0.33 µM and 9.49 µM, respectively. The quantum yields (QYs) of PEI-CDs and PEI-CDs-Cu2++GSH was 9.6% and 4.2%, respectively. Moreover, the PEI-CDs-Cu2+ has excellent optical stability and good biocompatibility. Additionally, it is worth noting that the developed probe has successfully realized the visualization of GSH detection in MGC-803 cells.


Assuntos
Cobre/química , Corantes Fluorescentes/química , Glutationa/análise , Polietilenoimina/química , Pontos Quânticos/química , Espectrometria de Fluorescência/métodos , Carbono/química , Linhagem Celular Tumoral , Humanos , Limite de Detecção , Microscopia Confocal , Neoplasias Gástricas/patologia
13.
Biosens Bioelectron ; 141: 111399, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31195199

RESUMO

Abnormal protein concentration levels in human body fluids, such as urine, serum etc., are considered to associate with disease states, providing essential information for the pre-clinical diagnosis. This paper presents a wireless immunoglobulin-coated magnetoelastic (ME) biosensor for fast, cost-effective detections of human serum albumin (HSA) with small sample volumes at a microliter scale. This is the first portable resonant sensor based on magnetostrictive effect that can monitor different molecular states of HSA. Anti-HSA Immunoglobulin G (IgG) was immobilized on the surface of the ME sensor to selectively capture HSA. The rapid conjugation between the antibody and antigen changed the sensor surface states and thus induced resonance frequency shifts (RFS), which were monitored in real time for the qualitative and quantitative analysis of HSA. This paper brings forward a System on Chip (SoC)-based system architecture to realize the function of RFS sampling. The performance of the portable device was validated to be comparable to that of the Vector Network Analyzer (VNA) AV3620 using different concentrations of HSA solution. The RFS were linearly proportional to the HSA concentrations in the range from 0.1 to 100 µg/mL with a linearity up to 0.998, a sensitivity of 8.70 Hz/µg.mL-1 and a detection limit of 0.039 µg/mL, indicating good feasibility of this method. Meanwhile, the response of this portable ME biosensor was quick and specific to HSA targets. This ME biosensor shows high potential to be used in diagnosing abnormal HSA.


Assuntos
Técnicas Biossensoriais/instrumentação , Albumina Sérica Humana/análise , Anticorpos Imobilizados/química , Desenho de Equipamento , Humanos , Imunoglobulina G/química , Limite de Detecção , Magnetismo/instrumentação
14.
Lab Invest ; 99(8): 1193-1202, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30837678

RESUMO

Hypoxia resulting in hypoxia-inducible factor-1 alpha (HIF-1α) induction is known to drive scar formation during cutaneous wound healing, and may be responsible for excessive fibrosis inherent to hypertrophic scars and keloids. Because epigenetic pathways play an important role in regulation of fibrosing processes, we evaluated patient scars for DNA hydroxymethylation (5-hydroxymethylcytosine; 5-hmC) status and documented a significant decrease in scar fibroblasts. To test this finding in vitro, human fibroblasts were cultured with cobalt chloride (CoCl2), a known stimulant of HIF-1α. HIF-1α induced so resulted in loss of 5-hmC similar to that seen in naturally occurring scars and was associated with significant downregulation of one of the 5-hmC converting enzymes-ten-eleven translocation 3 (TET3)-as well as increased expression of phosphorylated focal adhesion kinase (p-FAK), which is important in wound contracture. These changes were partially reversed by exposure to ascorbic acid, a recognized epigenetic regulator potentially capable of minimizing excessive scar formation and promoting a more regenerative healing response. Our results provide a novel and translationally relevant mechanism whereby epigenetic regulation of scar formation may be manipulated at the level of fibroblast DNA hydroxymethylation.

15.
Nanoscale Res Lett ; 14(1): 27, 2019 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-30656536

RESUMO

This paper presents a new flexible magnetic field sensor based on Ag nanowires and magnetic nanoparticles doped in polydimethylsiloxane (AgNWs & MNs-PDMS) with sandwich structure. The MNs act as the sensitive unit for magnetic field sensing in this work. Besides, the conductive networks are made by AgNWs during deformation. Magnetostriction leads to the resistance change of the AgNWs & MNs-PDMS sensors. Furthermore, the MNs increase the conductive paths for electrons, leading to lower initial resistance and higher sensitivity of the resulting sensor during deformation. A point worth emphasizing is that the interaction of the AgNWs and MNs plays irreplaceable role in magnetic field sensing, so the resistance change during stretching and shrinking was investigated. The flexible magnetic field sensor based on the mass ratio of MNs and AgNWs is 1:5 showed the highest sensitivity of 24.14 Ω/T in magnetic field sensing experiment. Finally, the magnetostrictive and piezoresistive sensing model were established to explore the mechanism of the sensor.

16.
Anal Bioanal Chem ; 411(5): 967-972, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30604036

RESUMO

Carbon dots (Cdots) with bright green fluorescence were applied to the rapid and selective cell imaging for a variety of cell lines. Different labeling distributions of hepatoma cells (HepG2) and normal human liver cells (LO2) were achieved using Cdots as imaging agents. For HepG2 cells, the Cdots could rapidly permeate the cell membrane and diffuse into the cytoplasm and nucleus within 3 min, and retained their location in the targets for 24 h. However, the Cdots exhibited bright fluorescence only in the cytoplasm of LO2 cell lines. Moreover, the Cdots were almost non-cytotoxic and exhibited superior photostability over a wide range of pH. Therefore, these Cdots have great potential for rapid, luminous and selective bioimaging applications, and are expected to be used as a nucleus-staining agent in cancer diagnosis. Graphical abstract ᅟ.


Assuntos
Carbono/química , Carcinoma Hepatocelular/diagnóstico por imagem , Corantes Fluorescentes/química , Neoplasias Hepáticas/diagnóstico por imagem , Nanopartículas/química , Imagem Óptica/métodos , Pontos Quânticos/química , Linhagem Celular , Células Hep G2 , Humanos , Modelos Moleculares , Imagem Óptica/economia , Pontos Quânticos/ultraestrutura , Fatores de Tempo
17.
Acta Ophthalmol ; 97(3): e435-e441, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-29696801

RESUMO

PURPOSE: In this article, we develop a dynamic Bayesian network (DBN) model to measure 3D visual fatigue. As far as our information goes, this is the first adaptation of a DBN structure-based probabilistic framework for inferring the 3D viewer's state of visual fatigue. METHODS: Our measurement focuses on the interdependencies between each factor and the phenomena of visual fatigue in stereoscopy. Specifically, the implementation of DBN with using multiple features (e.g. contextual, contactless and contact physiological features) and dynamic factor provides a systematic scheme to evaluate 3D visual fatigue. RESULTS: In contrast to measurement results between the mean opinion score (MOS) and Bayesian network model (with static Bayesian network and DBN), the visual fatigue in stereoscopy at time slice t is influenced by a dynamic factor (time slice t-1). In the presence of dynamic factors (time slice t-1), our proposed measuring scheme based on DBN is more comprehensive. CONCLUSION: (i) We cover more features for inferring the visual fatigue, more reliably and accurately; (ii) at different time slices, the dynamic factor features are significant for inferring the visual fatigue state of stereoscopy.


Assuntos
Algoritmos , Astenopia/diagnóstico , Teorema de Bayes , Percepção de Profundidade/fisiologia , Modelos Estatísticos , Astenopia/fisiopatologia , Humanos
18.
Nanotechnology ; 30(8): 085201, 2019 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-30523826

RESUMO

A comprehensive first-principles study of the correlation between zero-energy states and the tunability of the spin-selective semiconducting properties of zigzag-edged bowtie-shaped graphene nanoflakes under an electric field is presented for the first time. We demonstrate that the spin degenerate semiconducting ground state can be lifted by the electric field. In particular, we find that the number of zero-energy states ('the nullity') defined by the structural configuration determines the complexity and efficiency of the tunability of spin polarization. The fine-tuning of spin-dependent properties by the electric field originates from the manipulation of spin-polarized molecular orbital energies. We expect this study to aid the design of more effective and controllable low-dimensional molecular spintronics.

19.
Nanoscale Res Lett ; 13(1): 414, 2018 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-30584651

RESUMO

Here, we firstly report a wireless magnetoelastic (ME) nanobiosensor, based on ME materials and gold nanoparticles (AuNPs), for highly sensitive detection of atrazine employing the competitive immunoassay. In response to a time-varying magnetic field, the ME material longitudinally vibrates at its resonance frequency which can be affected by its mass loading. The layer of AuNPs coating on the ME material contributes to its biocompatibility, stability, and sensitivity. The atrazine antibody was oriented immobilized on the AuNPs-coated ME material surface through protein A, improving the nanobiosensor's performance. Atomic force microscope (AFM) analysis proved that the immobilization of atrazine antibody was successful. Furthermore, to enhance the sensitivity, atrazine-albumin conjugate (Atr-BSA) was induced to compete with atrazine for binding with atrazine antibody, amplifying the signal response. The resonance frequency shift is inversely and linearly proportional to the logarithm of atrazine concentrations ranging from 1 ng/mL to 100 µg/mL, with the sensitivity of 3.43 Hz/µg mL-1 and the detection limit of 1 ng/mL, which is significantly lower than the standard established by US Environmental Protection Agency (EPA). The experimental results indicated that the ME nanobiosensor displayed strong specificity and stability toward atrazine. This study provides a new convenient method for rapid, selective, and highly sensitive detection of atrazine, which has implications for its applications in water quality monitoring and other environmental detection fields.

20.
Micromachines (Basel) ; 9(11)2018 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-30428598

RESUMO

Although the lab-on-a-chip system has been successfully applied in a wide variety of fields, the goal of achieving a cell counter with simple operation, low cost, and high accuracy still attracts continuous research efforts. In this paper, the authors explore a cell counter based on light beam focusing to measure the density of adherent cells. In this sensor, the light emitted from the optical fibers is collimated by the collimating lens formed in polydimethylsiloxane (PDMS). The uniformly attached adherent cells act as a convex lens, focusing the collimated light propagated through them. The intensity of the focused light indicates the density of the adherent cells. For Hela cells, a detection limit of 8.3 × 104 cells/mL with a detection range from 0.1 × 106 cells/mL to 1.0 × 106 cells/mL is achieved. This sensor is particularly useful for drug screening, cell pathology analysis, and cancer pre-diagnosis.

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