In metal-enhanced fluorescence (MEF), the localized surface plasmon resonances of metallic nanostructures amplify the absorption of excitation light and assist in radiating the consequent fluorescence of nearby molecules to the far-field. This effect is at the base of various technologies that have strong impact on fields such as optics, medical diagnostics, and biotechnology. Among possible emission bands, those in the near-infrared (NIR) are particularly intriguing and widely used in proteomics and genomics due to its noninvasive character for biomolecules, living cells, and tissues, which greatly motivates the development of effective and, eventually, multifunctional NIR-MEF platforms. Here, we demonstrate NIR-MEF substrates based on Au nanocages micropatterned with a tight spatial control. The dependence of the fluorescence enhancement on the distance between the nanocage and the radiating dipoles is investigated experimentally and modeled by taking into account the local electric field enhancement and the modified radiation and absorption rates of the emitting molecules. At a distance around 80 nm, a maximum enhancement up to 2–7 times with respect to the emission from pristine dyes (in the region 660–740 nm) is estimated for films and electrospun nanofibers. Due to their chemical stability, finely tunable plasmon resonances, and large light absorption cross sections, Au nanocages are ideal NIR-MEF agents. When these properties are integrated with the hollow interior and controllable surface porosity, it is feasible to develop a nanoscale system for targeted drug delivery with the diagnostic information encoded in the fluorophore. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b03624

Two-dimensional (2D) materials present many unique materials concepts, including material properties that sometimes differ dramatically from those of their bulk counterparts. One of these properties, piezoelectricity, is important for micro- and nanoelectromechanical systems applications. Using symmetry analysis, we determine the independent piezoelectric coefficients for four groups of predicted and synthesized 2D materials. We calculate with density-functional perturbation theory the stiffness and piezoelectric tensors of these materials. We determine the in-plane piezoelectric coefficient d11 for 37 materials within the families of 2D metal dichalcogenides, metal oxides, and III–V semiconductor materials. A majority of the structures, including CrSe2, CrTe2, CaO, CdO, ZnO, and InN, have d11 coefficients greater than 5 pm/V, a typical value for bulk piezoelectric materials. Our symmetry analysis shows that buckled 2D materials exhibit an out-of-plane coefficient d31. We find that d31 for 8 III–V semiconductors ranges from 0.02 to 0.6 pm/V. From statistical analysis, we identify correlations between the piezoelectric coefficients and the electronic and structural properties of the 2D materials that elucidate the origin of the piezoelectricity. Among the 37 2D materials, CdO, ZnO, and CrTe2 stand out for their combination of large piezoelectric coefficient and low formation energy and are recommended for experimental exploration. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b03394

We report on the facile fabrication of a stretchable array of highly sensitive pressure sensors. The proposed pressure sensor consists of the top layer of Au-deposited polydimethylsiloxane (PDMS) micropillars and the bottom layer of conductive polyaniline nanofibers on a polyethylene terephthalate substrate. The sensors are operated by the changes in contact resistance between Au-coated micropillars and polyaniline according to the varying pressure. The fabricated pressure sensor exhibits a sensitivity of 2.0 kPa–1 in the pressure range below 0.22 kPa, a low detection limit of 15 Pa, a fast response time of 50 ms, and high stability over 10000 cycles of pressure loading/unloading with a low operating voltage of 1.0 V. The sensor is also capable of noninvasively detecting human-pulse waveforms from carotid and radial artery. A 5 × 5 array of the pressure sensors on the deformable substrate, which consists of PDMS islands for sensors and the mixed thin film of PDMS and Ecoflex with embedded liquid metal interconnections, shows stable sensing of pressure under biaxial stretching by 15%. The strain distribution obtained by the finite element method confirms that the maximum strain applied to the pressure sensor in the strain-suppressed region is less than 0.04% under a 15% biaxial strain of the unit module. This work demonstrates the potential application of our proposed stretchable pressure sensor array for wearable and artificial electronic skin devices. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b03510

Despite numerous applications, the cellular-clearance mechanism of multiwalled carbon nanotubes (MWCNTs) has not been clearly established yet. Previous in vitro studies showed the ability of oxidative enzymes to induce nanotube degradation. Interestingly, these enzymes have the common capacity to produce reactive oxygen species (ROS). Here, we combined material and life science approaches for revealing an intracellular way taken by macrophages to degrade carbon nanotubes. We report the in situ monitoring of ROS-mediated MWCNT degradation by liquid-cell transmission electron microscopy. Two degradation mechanisms induced by hydroxyl radicals were extracted from these unseen dynamic nanoscale investigations: a non-site-specific thinning process of the walls and a site-specific transversal drilling process on pre-existing defects of nanotubes. Remarkably, similar ROS-induced structural injuries were observed on MWCNTs after aging into macrophages from 1 to 7 days. Beside unraveling oxidative transformations of MWCNT structure, we elucidated an important, albeit not exclusive, biological pathway for MWCNT degradation in macrophages, involving NOX2 complex activation, superoxide production, and hydroxyl radical attack, which highlights the critical role of oxidative stress in cellular processing of MWCNTs. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b03708

Water disinfection materials should ideally be broad-spectrum-active, nonleachable, and noncontaminating to the liquid needing sterilization. Herein, we demonstrate a high-performance capacitive deionization disinfection (CDID) electrode made by coating an activated carbon (AC) electrode with cationic nanohybrids of graphene oxide-graft-quaternized chitosan (GO-QC). Our GO-QC/AC CDID electrode can achieve at least 99.9999% killing (i.e., 6 log reduction) of Escherichia coli in water flowing continuously through the CDID cell. Without the GO-QC coating, the AC electrode alone cannot kill the bacteria and adsorbs a much smaller fraction (<82.8 ± 1.8%) of E. coli from the same biocontaminated water. Our CDID process consists of alternating cycles of water disinfection followed by electrode regeneration, each a few minutes duration, so that this water disinfection process can be continuous and it only needs a small electrode voltage (2 V). With a typical brackish water biocontamination (with 104 CFU mL–1 bacteria), the GO-QC/AC electrodes can kill 99.99% of the E. coli in water for 5 h. The disinfecting GO-QC is securely attached on the AC electrode surface, so that it is noncontaminating to water, unlike many other chemicals used today. The GO-QC nanohybrids have excellent intrinsic antimicrobial properties in suspension form. Further, the GO component contributes toward the needed surface conductivity of the CDID electrode. This CDID process offers an economical method toward ultrafast, contaminant-free, and continuous killing of bacteria in biocontaminated water. The proposed strategy introduces a green in situ disinfectant approach for water purification. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b03763

Photodynamic therapy faces the barrier of choosing the appropriate irradiation region and time. In this paper, a matrix metalloproteinase-2 (MMP-2) responsive ratiometric biosensor was designed and synthesized for aggregation-induced emission (AIE)-guided precise photodynamic therapy. It was found that the biosensor presented the MMP-2 responsive AIE behavior. Most importantly, it could accurately differentiate the tumor cells from the healthy cells by the fluorescence ratio between freed tetraphenylethylene and protoporphyrin IX (PpIX, internal reference). In vivo study demonstrated that the biosensor could preferentially accumulate in the tumor tissue with a relative long blood retention time. Note that the intrinsic fluorescence of PpIX and MMP-2-triggered AIE fluorescence provided a real-time feedback which guided precise photodynamic therapy in vivo efficiently. This strategy demonstrated here opens a window in the precise medicine, especially for phototherapy. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b04243

Chemotherapeutic drugs frequently encounter multiple drug resistance in the field of cancer therapy. The strategy has been explored with limited success for the ablation of drug-resistant tumor via intravenous administration. In this work, the rationally designed light-triggered nanoparticles with multipronged physicochemical and biological features are developed to overcome cisplatin resistance via the assembly of Pt(IV) prodrug and cyanine dye (Cypate) within the copolymer for efficient ablation of cisplatin-resistant tumor. The micelles exhibit good photostability, sustained release, preferable tumor accumulation, and enhanced cellular uptake with reduced efflux on both A549 cells and resistant A549R cells. Moreover, near-infrared light not only triggers the photothermal effect of the micelles for remarkable photothermal cytotoxicity, but also leads to the intracellular translocation of the micelles and reduction-activable Pt(IV) prodrug into cytoplasm through the lysosomal disruption, as well as the remarkable inhibition on the expression of a drug-efflux transporter, multidrug resistance-associated protein 1 (MRP1) for further reversal of drug resistance of A549R cells. Consequently, the multipronged effects of light-triggered micelles cause synergistic cytotoxicity against both A549 cells and A549R cells, and thus efficient ablation of cisplatin-resistant tumor without regrowth. The multipronged features of light-triggered micelles represent a versatile synergistic approach for the ablation of resistant tumor in the field of cancer therapy. @nanotech1 http://pubs.acs.org/doi/abs/10.1021/acsnano.5b05097

Semiconductor–Insulator–Semiconductor Diode Consisting of Monolayer MoS2, h-BN, and GaN Heterostructure. @nanotech1

Metal-Enhanced Near-Infrared Fluorescence by Micropatterned Gold Nanocages. @nanotech1

Ab Initio Prediction of Piezoelectricity in Two-Dimensional Materials. @nanotech1

Stretchable Array of Highly Sensitive Pressure Sensors Consisting of Polyaniline Nanofibers and Au-Coated Polydimethylsiloxane Micropillars.

Carbon Nanotube Degradation in Macrophages: Live Nanoscale Monitoring and Understanding of Biological Pathway. @nanotech1

High-Performance Capacitive Deionization Disinfection of Water with Graphene Oxide-graft-Quaternized Chitosan Nanohybrid Electrode Coating.

Ratiometric Biosensor for Aggregation-Induced Emission-Guided Precise Photodynamic Therapy. @nanotech1

Multipronged Design of Light-Triggered Nanoparticles To Overcome Cisplatin Resistance for Efficient Ablation of Resistant Tumor. @nanotech1

سنندج: اندازه‌گیری گونه‌ای پروتئین در نمونه‌های حقیقی به کمک نانوزیست حسگر آزمایشگاهی


پژوهشگران دانشگاه کردستان در تحقیقات خود نمونه‌ی آزمایشگاهی نانوزیست‌حسگری طراحی کرده‌اند که قادر است با دقت بالایی گونه‌ای پروتئین را در نمونه‌های حقیقی اندازه‌گیری کند. حسگر طراحی شده حد تشخیص پایینی دارد. پروتئین مورد بررسی در این تحقیق نقش ضدباکتری داشته و میزان غیرطبیعی آن در بدن نشانگر بیماری‌های خاصی است.
لیزوزیم پروتئینی است که در بافت‌ها و ترشحات بدن پستانداران و سفیده‌ی تخم پرندگان به وفور یافت می‌شود. نقش بارز لیزوزیم خاصیت ضد میکروبی آن است. در واقع این ماده یک آنتی بیوتیک طبیعی است که به درمان بسیاری از بیماری‌ها کمک می‌کند.@nanotech1
به گفته‌ی دکتر عبدلله سلیمی، غلظت غیر طبیعی لیزوزیم در سرم خون و ادرار می‌تواند نشان دهنده‌ی انواع بیماری‌ها از قبیل لوسمی، بیماری‌های کلیوی و مننژیت باشد. همچنین لیزوزیم به دلیل داشتن فعالیت علیه سلول‌های باکتریایی، ساختار مشخص و وزن مولکولی کم، نسبت به سایر پروتئین‌ها کاربرد گسترده‌تری در صنایع غذایی و پزشکی نیز دارد. بنابراین اندازه‌گیری آن از اهمیت قابل توجهی برخوردار است. لذا در این پژوهش یک نانو زیست حسگر بر پایه‌ی نانو ذرات طلا برای اندازه‌گیری لیزوزیم طراحی و ساخته شده است.
سلیمی در ادامه در خصوص ویژگی‌های حسگر ساخته شده افزود: «طراحی و ساخت این زیست حسگر به گونه‌ای صورت گرفته که نمونه‌ی سنتز شده از حساسیت بالا با گستره‌ی خطی بسیار وسیع و تکرارپذیری مناسب برخوردار است. از طرفی گزینش‌پذیری بالا و حد تشخیص بسیار پایین و همچنین کارایی آن در بررسی نمونه‌های حقیقی از دیگر ویژگی‌های این حسگر است.»
طبق بررسی‌های صورت گرفته، به کمک این حسگر امکان سنجش دقیق و نسبتاً سریع پروتئین لیزوزیم در نمونه‌های حقیقی و زیستی از جمله سفیده‌ی تخم پرندگان وجود دارد که اهمیت بسیار بالایی در صنایع غذایی، دارویی و درمانی دارد.
این روش سنجش کم هزینه بوده و بدون استفاده از معرف‌های خاص انجام میگیرد و و به راحتی می‌توان آنرا برای تشخیص مقادیر بسیار جزیی لیزوزیم بکار برد.
سلیمی نحوه‌ی ساخت این نانوزیست حسگر را بدین شرح بیان کرد: «برای ساخت این حسگر، نانو ذرات طلا توسط روش الکترو انباشت بر روی سطح الکترود کربن شیشه‌ای تثبیت گردید. نانو ذرات طلا بستر بسیار مناسبی برای تثبیت مولکول‌های هدف بر روی سطح الکترود را فراهم می‌کند. همچنین با تثبیت ترکیب تمایلی مس- ایمینودی استیک اسید بر روی سطح نانوذرات طلا، امکان سنجش لیزوزیم در نمونه‌های حقیقی فراهم می‌شود. در روند مطالعات از روش‌های SEM، طیف بینی امپدانس الکتروشیمیایی، ولتامتری چرخه‌ای و ولتامتری پالس تفاضلی برای شناسایی و بررسی مراحل ساخت زیست حسگر استفاده شده است.»
دکتر عبدلله سلیمی- عضو هیأت علمی دانشگاه کردستان و عباس عرب زاده- دانشجوی دکترای شیمی تجزیه از این دانشگاه در انجام این طرح همکاری داشته‌اند و نتایج آن در مجله‌ی Biosensors and Bioelectronics (جلد 74، سال 2015، صفحات 270 تا 276) به چاپ رسیده است. http://news.nano.ir/51547/1

Scanning electron microscope (SEM) image of quantum dots fabricated through electron beam lithography and subsequent dry-chemical etching on a quasi bidimensional layer (GaAl heterostructure). These structures are used to study the behavior of electrons, which are confined into tiny spaces – approximate. 10 electrons per dot. The diameter of each quantum dot is 200 nm (which means that a billion of these structure easily fit on the tip of your finger).

Read more: Blow-up: The startling landscapes of nanotechnology
@nanotech1

SEM image of a micron sized trench (10 x 20 x14 µm3) in a Cu/SiO2/Si multilayer, obtained through FIB milling. The precision of this technique allows the visualization of ultrathin (tens of nanometers) layers
@nanotech1