Two-component polymer sorting to obtain high-purity s-SWCNTs for all-carbon photodetectors.

The advancement of carbon-based electronics is reliant on the development of semiconducting carbon nanotubes with high purity and yield. We developed a new extraction strategy to efficiently sort SWCNTs with superior yields and purity. The approach uses two polymers, poly[N-(1-octylnonyl)-9H-carbazol-2,7-diyl](PCz) and poly(9,9-n-dihexyl-2,7-fluorene-alt-9-phenyl-3,6-carbazole)(PDFP), and two sonication processes to eliminate surface polymer contamination. PCz selectively wraps large-diameter s-SWCNTs, with PDFP added as an enhancing molecule to increase sorting efficiency at 4-fold compared to the efficiency of only PCz alone sorting. The purity of the sorted s-SWCNTs was confirmed to be above 99 % using absorption and Raman spectra. Field-effect transistors and photodetectors made from the sorted s-SWCNTs exhibited excellent semiconductor properties and broad-spectrum detection, with good long-term stability. Furthermore, a photodetector using large-tube diameter s-SWCNTs achieved broad-spectrum detection, which the photoresponsivity is 0.35 mA/W and the detectivity is 4.7×106 Jones. The s-SWCNTs/graphene heterojunction photodetector achieved a photoresponsivity of 3 mA/W and a detectivity of 6.3×106 Jones. This new strategy provides a promising approach to obtain high-purity and high-yield s-SWCNTs for carbon-based photodetectors.

Recent Progress and Perspective of an Evolving Carbon Family From 0D to 3D: Synthesis, Biomedical Applications, and Potential Challenges.

A variety of imaging techniques are available for detecting biological processes with sufficient penetration depth and temporal resolution. However, inflammation, cardiovascular, and cancer-related disorders might be difficult to diagnose with typical bioimaging methods because of the lack of resolution in the imaging of deep tissues. Therefore, nanomaterials are the most promising candidate to overcome this hurdle. This review is on the utilization of carbon-based nanomaterials (CNMs), ranging from zero-dimension (0D) to three-dimension (3D), in the development of fluorescence (FL) imaging, photoacoustic imaging (PAI), and biosensing for the early detection of cancer. Nanoengineered CNMs, such as graphene, carbon nanotubes (CNTs), and functional carbon quantum dots (QDs), are being further studied for multimodal biometrics and targeted therapy. CNMs have many advantages over conventional dyes in FL sensing and imaging, including clear emission spectra, long photostability, low cost, and high FL intensity. Nanoprobe production, mechanical illustrations, and diagnostic therapeutic applications are the key areas of focus. The bioimaging technique has facilitated a greater understanding of the biochemical events underlying multiple disease etiologies, consequently facilitating disease diagnosis, evaluation of therapeutic efficacy, and drug development. This review may lead to the development of interdisciplinary research in bioimaging and sensing as well as possible future concerns for researchers and medical physicians.

Two-Stage Targeted Bismuthene-Based Composite Nanosystem for Multimodal Imaging Guided Enhanced Hyperthermia and Inhibition of Tumor Recurrence.

A key challenge for nanomedicines in clinical application is to reduce the dose while achieving excellent efficacy, which has attracted extensive attention in dose toxicity and potential risks. It is thus necessary to reasonably design nanomedicine with high-efficiency targeting and accumulation. Here, we designed and synthesized a tetragonal bismuthene-based "all-in-one" composite nanosystem (TPP-Bi@PDA@CP) with two-stage targeting, multimodal imaging, photothermal therapy, and immune enhancement functions. Through the elaborate design of its structure, the composite nanosystem possesses multiple properties including (i) two-stage targeting function of hepatoma cells and mitochondria [the aggregation at the tumor site is 2.63-fold higher than that of traditional enhanced permeability and retention (EPR) effect]; (ii) computed tomography (CT) contrast-enhancement efficiency as high as ∼51.8 HU mL mg-1 (3.16-fold that of the clinically available iopromide); (iii) ultrahigh photothermal conversion efficiency (52.3%, 808 nm), promising photothermal therapy (PTT), and high-contrast infrared thermal (IRT)/photoacoustic (PA) imaging of tumor; (iv) benefitting from the two-stage targeting function and excellent photothermal conversion ability, the dose used in this strategy is one of the lowest doses in hyperthermia (the inhibition rate of tumor cells was 50% at a dose of 15 µg mL-1 and 75% at a dose of 25 µg mL-1); (v) the compound polysaccharide (CP) shell with hepatoma cell targeting and immune enhancement functions effectively inhibited the recurrence of tumor. Therefore, our work reduces the dose toxicity and potential risk of nanomedicines and highlights the great potential as an all-in-one theranostic nanoplatform for two-stage targeting, integrated diagnostic imaging, photothermal therapy, and inhibition of tumor recurrence.

A PdMo bimetallene with precise wavelength adjustment and catalysis for synergistic photothermal ablation and hydrogen therapy of cancer at different depths.

By delivering the idea of green and safe hydrogen energy and novel photothermal therapy to the biomedical field, engineering of therapeutic nanomaterials for treatment of major diseases (such as cancer) holds great significance. In this work, a novel PdMo bimetallene was synthesized by a solvothermal reduction method, and it was explored and applied in the field of anti-tumor therapy for the first time. The absorption peak of the PdMo bimetallene can be precisely adjusted in the NIR biological window (700-1350 nm) only by changing the synthesis time. At the same time, it also shows strong light absorption and high photothermal conversion efficiency. Specifically, the photothermal conversion efficiencies at 808 nm, 980 nm and 1064 nm are 43.1%, 51.7% and 69.15%, respectively. Surprisingly, a PdMo bimetallene is an efficient catalyst, which can effectively promote hydrogen production from the hydrolysis of ammonia borane (AB) under acidic and photothermal conditions. Benefitting from these excellent properties, a multifunctional composite nano therapeutic agent (PdMo@AB@HA) was developed via layer-by-layer surface modification with AB and hyaluronic acid (HA). In this way, the synergistic PTT/hydrogen therapy of PdMo@AB@HA composite nanosheets in the NIR-I and NIR-II windows (808 nm, 980 nm, and 1064 nm) on mouse tumor xenografts of different depths was realized. Furthermore, the controlled release of hydrogen, targeted endocytosis, efficient eradication of tumors of different depths and high biosafety were systematically proved in vitro and in vivo. This work not only provides a novel and efficient theranostic nanoplatform for efficient cancer theranostics, but also provides a new strategy for the development of safe and efficient new anti-tumor therapies.

Surface modification engineering of two-dimensional titanium carbide for efficient synergistic multitherapy of breast cancer.

Cancer is a leading cause of human mortality. Given that it is difficult for conventional therapeutic approaches to effectively eradicate tumors and inhibit their recurrence and metastasis, new therapeutic strategies for solving this problem are urgently needed. In this work, we report the development of a two-dimensional titanium carbide nanocomposite drug delivery system. The system can be used for the synergistic treatment of tumors through photothermal/photodynamic/chemotherapy and can also inhibit tumor recurrence and metastasis by activating the immune system. A surface modification engineering strategy has been elaborately designed to realize the multifunctionalization of an MXene, Ti3C2. In this strategy, the nanocomposite drug delivery system (Ti3C2@Met@CP) was established via layer by layer adsorption of metformin (Met) and compound polysaccharide (CP) on the surface of Ti3C2 nanosheets. Among these materials, the synthesized (AlOH)4--functionalized Ti3C2 nanosheets possess strong near-infrared absorption (extinction coefficient of 36.2 L g-1 cm-1), high photothermal conversion efficiency (∼59.6%) and effective singlet oxygen generation (1O2). Compound polysaccharide (CP) is a new immunomodulator formed by mixing lentinan, pachymaran and tremella polysaccharides in optimal proportions. Especially, the decoration of CP onto the Ti3C2 nanosheets endows Ti3C2 with a well-defined shell, improves its tumor site aggregation and biocompatibility, and activates the host's immune functions. The synergistic eradication and inhibition of tumor recurrence and metastasis have been systematically evaluated by in vivo and in vitro experiments.

Automatic Detection of COVID-19 Using X-ray Images with Deep Convolutional Neural Networks and Machine Learning

The COVID-19 pandemic continues to have a devastating effect on the health and well-being of the global population. A vital step in the combat towards COVID-19 is a successful screening of contaminated patients, with one of the key screening approaches being radiological imaging using chest radiography. This study aimed to automatically detect COVID- 19 pneumonia patients using digital chest x- ray images while maximizing the accuracy in detection using deep convolutional neural networks (DCNN). The dataset consists of 864 COVID- 19, 1345 viral pneumonia and 1341 normal chest x- ray images. In this study, DCNN based model Inception V3 with transfer learning have been proposed for the detection of coronavirus pneumonia infected patients using chest X-ray radiographs and gives a classification accuracy of more than 98% (training accuracy of 97% and validation accuracy of 93%). The results demonstrate that transfer learning proved to be effective, showed robust performance and easily deployable approach for COVID-19 detection.

Efficient Toroidal Formation of Sorted Metallic and Semiconducting Single-Walled Carbon Nanotubes via General Pickering Emulsion.

Single-walled carbon nanotubes (SWNTs) with a toroidal/coiled geometry-shaped structure sustain innovative preference to future technology material. The toroidal shape can be used in designing nanoelectronic devices for various prospective applications such as tactile sensors, electromagnetic absorbers, and energy storage devices. In this study, we demonstrate the fabrication of toroidal geometry shapes of metallic (m-) and semiconducting (s-) SWNTs, which can be revealed by simply mixing a few solutions in the correct ratio, both oil-in-water (hydrophobic) and water-in-oil (hydrophilic) emulsion processes. Herein, the letter communicates the formation of pure m- and s-SWNTs (metallic and semiconducting) by annular, obtained from gel column chromatography, via the emulsion approach. We have also studied the surfactant sodium dodecyl sulfate removal of sorted species from a gel column by a simple method named as chloroform/methanol/water extraction.

A simple MWCNTs@paper biosensor for CA19-9 detection and its long-term preservation by vacuum freeze drying.

This paper introduces a cheap simple MWCNTs@paper biosensor for the detection of CA19-9, which is a biomarker of pancreatic cancer. By adding the CA19-9 antibody to the surface of MWCNTs which are deposited on the microporous filter paper, the correlation between the concentration of CA19-9 and resistance of biosensor element was linear due to the site-specific binding of antigen and antibody. The detection range is wide (0 U/mL-at least 1000 U/mL), and even in the low concentration of CA19-9, the linearity remains satisfying. Based on this property, it could be used for the detection of early-stage pancreatic cancer. Besides, this research originally introduces a vacuum freeze-drying method for the long-term preservation of biosensor, prolonging its storage time from 3 h to at least 7 days, which signifcantly promoted its value in practical application. One piece of the MWCNTs@paper biosensor only cost $2 (about 30 times cheaper than ELISA) approximately, and the detection speed is satisfying (2 h, 12 times faster than ELISA), which will possibly increase its opportunity of mass production and clinical practice.

Enrichment of large-diameter semiconducting single-walled carbon nanotubes by a mixed-extractor strategy.

In this work, we report a new mixed-extractor strategy to improve the sorting yield of large-diameter semiconducting single-walled carbon nanotubes (s-SWCNTs) with high purity. In the new mixed-extractor strategy, two kinds of conjugated polymers with different rigidity, poly(9,9-n-dihexyl-2,7-fluorene-alt-9-phenyl-3,6-carbazole) (PDFP) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (P8BT), are used to sort large-diameter s-SWCNTs through two simple sonication processes. To our surprise, although PDFP itself shows no selectivity toward s-SWCNTs, it can greatly enhance the sorting yield of P8BT. Using the PDFP/P8BT mixed-extractor method, the yield of sorted s-SWCNTs has been enhanced by 5 times with a purity above 99 % in comparison to that using P8BT single-extractor method. In addition, the photoluminescence (PL) excitation maps shows that the PDFP/P8BT mixed-extractor system not only enhances the sorting yield substantially, but also tends to be enrichment of (15,4) SWCNTs with the diameter of 1.36 nm.

Lentinan in-situ coated tungsten oxide nanorods as a nanotherapeutic agent for low power density photothermal cancer therapy.

Development of high photothermal performance and biocompatible nanotherapeutic agents is of great importance for photothermal cancer treatment. In this paper, we have developed lentinan decorated tungsten oxide nanorods (W18O49@LTN NRs) via a mild one-step solvothermal route. Owing to the numerous surface hydroxyl groups of polymer chains, the presence of lentinan layer in the surface of W18O49 NRs lead to good biocompatibility. The lentinan layer also affects the crystal structure of W18O49 and improves near-infrared absorption (~1.7 × 109 M-1 cm-1 at 980 nm), which is two orders of higher than previously reported PEGylated W18O49 nanowires. Even under near-infrared (NIR) laser irradiation at a very low power density of 0.4 W/cm2, the temperature of W18O49@LTN NRs aqueous dispersion (125 µg/mL) could increase by 15.1 °C. The photothermal conversion efficiency of W18O49@LTN NRs reaches 33.86%, which is higher than previously reported WO3-x hierarchical nanostructures (28.1%). Importantly, when cancer cells were treated with W18O49@LTN NRs (200 µg/mL) and 980 nm laser (0.4 W/cm2), a significant photo-induced cell killing behavior was observed. This work demonstrates that W18O49@LTN NRs have the potential for precise cancer treatment.

Obtaining high mechanical performance silk fibers by feeding purified carbon nanotube/lignosulfonate composite to silkworms.

Silkworm fibers have attracted widespread attention for their superb glossy texture and promising mechanical performance. The mechanical properties can be reinforced with carbon nanofillers, particularly carbon nanotubes (CNTs), depending on the CNT content in the silk fibers. In order to increase the CNT content, lignosulfonate (LGS) was used as a surfactant to ameliorate the CNT solubility, dispersibility, and biocompatibility. The resulting CNT/LGS nano-composite was further processed through an additional purification method to remove excess surfactant and enhance the CNT/LGS ratio. Then the purified biocompatible single and multiple-walled CNTs were fed to silkworms, leading to a large CNT content in the resulting silk fibers. Reinforced silk fibers were produced with a mechanical strength as high as 1.07 GPa and a strain of 16.8%. The toughness modulus is 1.69 times than that of the unpurified group. The CNT-embedded silk fibers were characterized via Raman spectrometry and thermogravimetric analysis (TGA), demonstrating that the CNT content in the silk fibers increased 1.5-fold in comparison to the unpurified group. The increased CNT content not only contributed to the self-assembly into buffering knots of silk fibers, but it also enhanced the conductivity of graphitized silk. Our coating and purification strategies provide a potential facile way to obtain natural silk fibers with high mechanical performance.

Enhanced response of tamoxifen toward the cancer cells using a combination of chemotherapy and photothermal ablation induced by lentinan-functionalized multi-walled carbon nanotubes.

A lentinan (LEN) functionalized multi-walled carbon nanotubes (MWCNTs) drug delivery system, using tamoxifen (TAM) as a model anticancer agent, was developed by a simple non-covalent approach. This developed system (MWCNTs-TAM-LEN) possessed good stability, water dispersibility and extraordinary photothermal properties. It was demonstrated by the in vitro experiments that MWCNTs-TAM-LEN had enhanced cellular uptake, antitumor activity and cell apoptosis on Mcf-7 cells in comparison with TAM and MWCNTs-TAM. The cell inhibition rate and apoptosis rate of Mcf-7 cells treated by MWCNTs-TAM-LEN with near-infrared (NIR) were 67.1% and 66.5% higher than that of equivalent concentration of TAM with NIR irradiation treatment, respectively. The enhanced antitumor efficacy of MWCNTs-TAM-LEN was realized via the synergistic function of chemotherapy and photothermal ablation under NIR laser irradiation.

A carbon nanotube-gemcitabine-lentinan three-component composite for chemo-photothermal synergistic therapy of cancer.

PURPOSE: Gemcitabine's clinical application is limited due to its short plasma half-life and poor uptake by cells. To address this problem, a drug delivery three-component composite, multiwalled carbon nanotubes (MWNTs)/gemcitabine (Ge)/lentinan (Le; MWNTs-Ge-Le), was fabricated in our study. Moreover, the combination of chemotherapy and photothermal therapy was employed to enhance antitumor efficacy. METHODS: In this study, we conjugated gemcitabine and lentinan with MWNTs via a covalent and noncovalent way to functionalize with MWNTs, and the chemical structure of MWNTs-Ge-Le was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis and transmission electron microscopy. Using the composite and an 808 nm laser, we treated tumors, both in vitro and in vivo, and investigated the photothermal responses and the anticancer efficacy. RESULTS: The MWNTs-Ge-Le composite could efficiently cross cell membrane, having a higher antitumor activity than MWNTs, gemcitabine and MWNTs-Ge in vitro and in vivo. Our study on the MWNTs-Ge-Le composite with an 808 nm laser radiation showed the combination of drug therapy and near-infrared photothermal therapy possesses great synergistic antitumor efficacy. CONCLUSION: The MWNTs-Ge-Le three-component anticancer composite can serve as a promising candidate for cancer therapy in the combination of chemotherapy and photothermal therapy.

Enhanced Response of Metformin towards the Cancer Cells due to Synergism with Multi-walled Carbon Nanotubes in Photothermal Therapy.

Converging evidence from laboratory models pointed that the widely used antidiabetic drug metformin has direct effects on cancer cells. Thus far, relatively little attention has been addressed to the drug exposures used experimentally relative to those achievable clinically. Here, we demonstrated that metformin loaded on carbon nanotubes under near-infrared (NIR) irradiation led to the remarkably enhancement in response towards cancer cells. The dose of metformin has reduced to only 1/280 of typical doses in monotherapy (35: 10 000-30 000 µM) where the realization of metformin in conventional antidiabetic doses for cancer therapies becomes possible. The heat generated from carbon nanotubes upon NIR irradiation has mediated a strong and highly localized hyperthermia-like condition that facilitated the enhancement. Our work highlight the promise of using highly localized heating from carbon nanotubes to intensify the efficacy of metformin for potential cancer therapies.

[Photothermal effects of metallic carbon nanotubes on human breast cancer cells].

SWNTs are a mixture of 1/3 metallic SWNTs (m-SWNTs) and 2/3 semiconducting SWNTs (s-SWNTs). It is desirable to separate the metallic SWNTs from the semi-conducting ones. In this study m-SWNTs was separated by using a poly[(m-phenylenevinylene)-alt-(p-phenylenevinylene)] (PmPV) derivative and used as photo-thermal media instead of SWNTs. The separation effects of m-SWNTs were evaluated by Raman spectra, molecular modeling and TEM images. The effects of m-SWNTs on MCF-7 cell proliferation and apoptosis were evaluated with MTT assay and flow cytometry, respectively. m-SWNTs were separated with high purity. A strong inhibition of MCF-7 cell growth was observed with the m-SWNTs under near-infrared (NIR) light irradiation. Our results will be helpful for the potential applications of m-SWNTs in clinical photothermal cancer therapy.

Optical limiting properties and mechanisms of single-layer graphene dispersions in heavy-atom solvents.

The optical limiting (OL) properties of single-layer graphene dispersions in different solvents were studied using a nanosecond pulse laser. The graphene dispersions, especially in heavy-atom solvents, showed much better OL properties compared with referenced C60-toluene solution. The dependences of OL thresholds and nonlinear scattering (NLS) intensities on the solvent surface tensions indicated that, NLS effect played an important role in the OL process of graphene dispersions, while nonlinear absorption (NLA) effect might also contribute in solvents with heavy atoms. The NLA measurements further demonstrated the contribution of NLA effect to the excellent OL property of graphene dispersions in heavy-atom solvents.

Low threshold power density for the generation of frequency up-converted pulses in bismuth glass by two crossing chirped femtosecond pulses.

We investigated the generation of frequency up-converted femtosecond laser pulses by nondegenerate cascaded four-wave mixing (CFWM) in a bismuth-oxide glass (BI glass). Broad-bandwidth light pulses with different propagation directions were simultaneously obtained by using two small-angle crossing femtosecond laser pulses in BI glass. Experimental results show that the threshold power density for the generation of broad-bandwidth femtosecond pulses in BI glass is one order of magnitude lower than that in fused silica.

Wrapping of single-walled carbon nanotubes by a pi-conjugated polymer: the role of polymer conformation-controlled size selectivity.

Wrapping of a single-walled carbon nanotube (SWNT) was examined by using a poly[( m-phenylenevinylene)- alt-( p-phenylenevinylene)] (PmPV) derivative. The polymer's intrinsic ability in forming a helical conformation was found to play an essential role in the separation of nanotubes. Among about 15 tubes present in the pure SWNT (HiPcoTM) sample, the polymer was found to selectively pick up the tubes (11,6), (11,7) and (12,6), which correspond to tube diameters of 1.19, 1.25 and 1.24 nm, respectively. The SWNTs of smaller diameters were held loosely by the PmPV, and were gradually dropped out under centrifugation. The suspension solution prepared from the SWNT and PmPV was not permanently stable, with precipitation occurring after a few weeks. Irradiation in the UV-vis region exhibited a catalytic effect to shorten the precipitation time to hours. Those tubes, which were held loosely by PmPV, were quickly separated from the suspension during the irradiation process.

[FTIR analysis of benign and malignant pleomorphic adenoma tissues].

The FTIR (Fourier transform infrared) spectra of benign pleomorphic adenoma tissues and malignant ones were investigated using the spectrometer GX FTIR Spectroscopy. The results indicated that there were infrared spectra difference between the benign adenoma tissues and the malignant ones in some bands. Compared to the benign adenoma tissues, the contents of nucleic acid relative to the collagen protein and the adipose relative to the protein both increase in malignant ones.

Photochemical-controlled switching based on azobenzene monolayer modified silicon (111) surface.

Azobenzene-containing compounds were covalently attached onto Si(111) surfaces via Si-O linkages using a two-step procedure. The modified Si(111) surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy measurements. The monolayer surface showed preferably chemical stability. Switchable photoisomerizability of azobenzene molecules on these modified surfaces was observed in response to alternating UV and visible light exposure. The measured conductivity showed distinct difference with trans and cis forms of azobenzene compounds on as-modified Si(111) surfaces.