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The engineering of advanced materials capable of mimicking the cellular micro-environment while providing cells with physicochemical cues is central for cell culture applications. In this regard, paper meets key requirements in terms of biocompatibility, hydrophilicity, porosity, mechanical strength, ease of physicochemical modifications, cost, and ease of large-scale production, to be used as a scaffold material for biomedical applications. Most notably, paper has demonstrated the potential to become an attractive alternative to conventional biomaterials for creating two-dimensional (2D) and three-dimensional (3D) biomimetic cell culture models that mimic the features of in vivo tissue environments for improving our understanding of cell behavior (e.g. growth, cell migration, proliferation, differentiation and tumor metastasis) in their natural state. On the other hand, integration of plasmonic nanomaterials (e.g. gold nanoparticles) within the fibrous structure of paper opens the possibility to generate multifunctional scaffolds equipped with biosensing tools for monitoring different cell cues through physicochemical signals. Among different plasmonic based detection techniques, surface-enhanced Raman scattering (SERS) spectroscopy emerged as a highly specific and sensitive optical tool for its extraordinary sensitivity and the ability for multidimensional and accurate molecular identification. Thus, paper-based plasmonic substrates in combination with SERS optical detection represent a powerful future platform for monitoring cell cues during cell culture processes. To this end, in this review, we will describe the different methods for fabricating hybrid paper-plasmonic nanoparticle substrates and their use in combination with SERS spectroscopy for biosensing and, more specifically, in cell culture applications., Graphical abstract Image 1

Silver nanoparticles (AgNPs) are in situ synthesized for the first time on microfibrillated silk (MFS) exfoliated from domesticated Philosamia cynthia ricini (eri) and Bombyx mori (mulberry) silkworm silk fibers. The process is rapid (hours time), does not rely on harmful chemicals, and produces robust and flexible AgNPs coated MFS (MFS-AgNPs) protein papers with excellent handling properties. None of these can be achieved by approaches used in the past to fabricate AgNPs silk systems. MFS bonds the AgNPs strongly, providing good support and stabilization for the NPs, leading to strong wash fastness. The mechanical properties of the MFS-AgNPs papers largely do not change compared to the MFS papers without nanoparticles, except for some higher concentration of AgNPs in the case of mulberry silk. The improved tensile properties of eri silk papers with or without AgNPs compared to mulberry silk papers can be attributed to the higher degree of fibrillation achieved in eri silk and its inherent higher ductility. MFS-AgNPs from eri silk also exhibit strong antibacterial activity. This study provides the basis for the development of smart protein papers based on silk fiber and functional nanomaterials.

Smart and green construction of noble metal nanostructures on two-dimensional nanomaterials-based flexible paper-like materials have gained extensive attention due to the formed hybrid papers have shown great promise in the applications of energy devices, sensing electronics, actuators, and chemical filters. Herein, a cost-effective and environment-friendly strategy to realize the spontaneous growth of noble metal nanoparticles (Au, Pd, and Pt) on flexible biomimetic MXene paper was proposed. The self-defined regulation of formed noble metal nanoparticles could be easily achieved, and the bimetallic (AuPt, PdPt) nanoparticles decorated MXene paper could be obtained at the mean time. These findings bring a simple, efficient and green way for constructing various hybrid MXene paper with outperforming electrocatalytic activities, which was demonstrated by the sensitive detection of superoxide (O2•-) and the good stability and reproducibility after a long-term usage. The outstanding analytical performance of the obtained AuPtNPs/MXene paper in O2•- monitoring leads to a satisfactory application in real-time extracellular biosensing. The investigation for spontaneous growth and regulation of noble metal nanoparticles on flexible biomimetic MXene paper exhibits a huge application potential for constructing high-performance flexible bioelectronics and energy-related devices.

Lab-on-paper (LOP) devices are urgently required for the rapid development of point-of-care diagnoses and environmental assays. Herein, an all-sealed paper-based electrochemiluminescence (ECL) platform was developed to achieve lead ions (Pb2+) sensitive analysis via incorporating convenient plastic package technology. Benefiting from transparent plastic encapsulation, the sealed devices effectively avoided the interference of O2. Meanwhile, myrica rubra-like Pt nanomaterials (MPNs) prepared by an economical and easy-to-operate ultrasound method were employed to catalyze H2O2 decomposition. With the help of Pb2+-specific DNAzymes, the oligonucleotide probe functionalized via MPNs could be detached from the device in the presence of target, resulting in the reduced ECL intensity. Moreover, the combination of modified paper electrode with functional regions separated by multiple layers of wax enhanced the practicability of the LOP device for rapid detection. Under the optimal conditions, the all-sealed platform achieved wide linear relationship ranging from 0.01 nM to 0.05 μM with a low detection limit of 0.004 nM for sensitive detecting Pb2+. It is believed that this platform could provide a robust, simple and versatile strategy for sensitive determination of heavy metal ions, and be applied in on-site contamination analysis in the future.

In this study, a low-cost and robust impedimetric immunosensor based on gold nanoparticles modified free-standing graphene paper electrode for rapid and sensitive detection of Escherichia coli O157:H7 (E. coli O157:H7) was developed. Graphene paper was prepared by chemical reduction of graphene oxide paper obtained from vacuum filtration method. Scanning electron microscope, Raman spectroscopy and X-ray diffraction techniques were employed to investigate the surface morphology and crystal structure of the prepared graphene paper. The gold nanoparticles were grown on the surface of graphene paper electrode by one-step electrodeposition technique. The immobilization of anti-E. coli O157:H7 antibodies on paper electrode were performed via biotin-streptavidin system. Electrochemical impedance spectroscopy was used to detect E. coli O157:H7 captured on the paper electrode. Results show that the developed paper immunosensor possesses greatly enhanced sensing performance, such as wide linear range (1.5 × 10(2)-1.5 × 10(7) cfu mL(-1)), low detection limit (1.5 × 10(2) cfu mL(-1)), and excellent specificity. Furthermore, flexible test demonstrate the graphene paper based sensing device has high tolerability to mechanical stress. The strategy of structurally integrating metal nanomaterials, graphene paper, and biorecognition molecules would provide new insight into design of flexible immunosensors for routine sensing applications.

Lateral flow biosensors are paper-based devices that allow the detection of different types of analytes with quickness, robustness and selectivity, without leaving behind paper sensors benefits as low-cost, recyclability and sustainability. Nanomaterials have been widely reported in lateral flow biosensors, offering new sensing strategies based on optical or electrical detection techniques. Looking for other advantageous nanomaterials, we propose for the first time the use of iridium oxide (IV) nanoparticles in lateral flow assays for the detection of human immunoglobulin as a model protein. These nanoparticles can be easily prepared and conjugated with biomarkers. Their dark blue color gives a high contrast against the white background of the strips being in this way excellent labels., We acknowledge support from MINECO (Spain) MAT2017-87202-P and project PCIN-2016-066 (program Euronanomed 2). This work is also funded by the CERCA Programme / Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706). Daniel Quesada-González and Amadeo Sena-Torralba acknowledge Autonomous University of Barcelona (UAB) for the possibility of performing this work inside the framework of Chemistry and Biotechnology Ph.D. Programmes, respectively.

During the last few years, for therapeutic purposes in oncology, considerable attention has been focused on a method called magnetic fluid hyperthermia (MFH) based on local heating of tumor cells. In this paper, an innovative, promising nanomaterial, M48 composed of iron oxide-based phases has been tested. M48 shows self-regulating temperature due to the observable second order magnetic phase transition from ferromagnetic to paramagnetic state. A specific hydrophilic coating based on both citrate ions and glucose molecules allows high biocompatibility of the nanomaterial in biological matrices and its use in vivo. MFH mediator efficiency is demonstrated in vitro and in vivo in breast cancer cells and tumors, confirming excellent features for biomedical application. The temperature increase, up to the Curie temperature, gives rise to a phase transition from ferromagnetic to paramagnetic state, promoting a shortage of the r2 transversal relaxivity that allows a switch in the contrast in Magnetic Resonance Imaging (MRI). Combining this feature with a competitive high transversal (spin-spin) relaxivity, M48 paves the way for a new class of temperature sensitive T2 relaxing contrast agents. Overall, the results obtained in this study prepare for a more affordable and tunable heating mechanism preventing the damages of the surrounding healthy tissues and, at the same time, allowing monitoring of the temperature reached.

Advances in cutting-edge technologies including nanotechnology, micmfluidics, electronic engineering, and material science have boosted a new era in the design of robust and sensitive biosensors. In recent years, carbon black has been re-discovered in the design of electrochemical (bio)sensors thanks to its interesting electroanalytical properties, absence of treatment requirement, cost-effectiveness (c.a. 1 (sic)/Kg), and easiness in the preparation of stable dispersions. Herein, we present an overview of the literature on carbon black-based electrochemical (bio)sensors, highlighting current trends and possible challenges to this rapidly developing area, with a special focus on the fabrication of carbon black-based electrodes in the realisation of sensors and biosensors (e.g. enzymatic, immunosensors, and DNA-based).

Extensive production of nanomaterials of various properties needs to be coupled with rapid toxicity testing in order to provide information about their potential risks to the environment and human health. Miniaturization of toxicity tests may accelerate economical testing of nanomaterials, but is not a common practice. We describe a case study to miniaturize a commonly used toxicity test with plant duckweed Lemna minor. 6-well, 12-well and 24-well culture plates were used to assess their potential use for the duckweed toxicity test with potassium chloride as reference material. The results were compared to the standard test design using 100 mL glass beakers. The comparison showed that the best agreement was with the 6-well vessels. This set-up was further used for toxicity testing of zinc oxide nanoparticles (ZnO NP) and zinc chloride. Zinc was not adsorbed onto either glass or plastic walls of the miniaturized system. We assume that in both vessels a fast agglomeration and settling of ZnO NP took place. Linear regression and statistical testing indicated a good correlation between the toxicity results obtained in the standard test and miniaturized 6-well vessels. The miniaturization of the test system for assessing the biological effect of nanomaterials on Lemna minor could become an appropriate alternative to the traditionally used high volume vessels.

Development of biopolymer-based imaging agents which can access rapidly and provide detailed information about the diseases has received much attention as an alternative to conventional imaging agents. However, development of biopolymer-based nanomaterials for tumor imaging still remains challenging due to their low sensitivity and image resolution. To surmount of these limitations, multimodal imaging agents have been developed, and they were widely utilized for theranostic applications. Herein, iodine containing echogenic glycol chitosan nanoparticles are developed for x-ray computed tomography (CT) and ultrasound (US) imaging of tumor diagnosis. X-ray CT/US dual-modal imaging probe was prepared by following below two steps. First, iodine-contained diatrizoic acid (DTA) was chemically conjugated to the glycol chitosan (GC) for the CT imaging. DTA conjugated GC (GC-DTA NPs) formed stable nanoparticles with an average diameter of 315 nm. Second, perfluoropentane (PFP), a US imaging agent, was physically encapsulated into GC-DTA NPs by O/W emulsion method yielding GC-DTA-PFP nanoparticles (GC-DTA-PFP NPs). The GC-DTA-PFP NPs formed nanoparticles in physiological condition, and they presented the strong x-ray CT, and US signals in phantom test in vitro. Importantly, GC-DTA-PFP NPs were effectively accumulated on the tumor site by enhanced permeation and retention (EPR) effects. Moreover, GC-DTA-PFP NPs showed x-ray CT, and US signals in tumor tissues after intratumoral and intravenous injection, respectively. Therefore, GC-DTA-PFP NPs indicated that x-ray CT/US dual-modal imaging using iodinated echogenic nanoparticles could be provided more comprehensive and accurate diagnostic information to diagnosis of tumor.

Near-infrared (NIR)-based nanomaterials that provide efficient tumor ablation for cancer therapy have been reported. However, the issues of biocompatibility of metals or ions in inorganic nanoparticles systems such as copper and gold nanoparticles are still a matter of concern. In this study, we developed a facile and ligand-assisted co-precipitation method to synthesize biocompatible iron oxide (IO) nanocrystals with NIR absorption that provided T2-weighted magnetic resonance (MR) images and photothermal ablation characteristics suitable for cancer theranostics. Our results showed that 150-nm particles can be synthesized and optimized by using different amounts of ligand. NIR-IO nanocrystals of this size showed high photothermal conversion efficiency (21.2%) and T2-weighted MR contrast (transverse relaxivity value approximately 141 S-1 mM-1). The NIR-IO nanocrystals showed no cytotoxicity in HT-29 colorectal cancer cells without irradiation, whereas the viability of cells that received NIR-IO nanocrystals decreased significantly after 808-nm laser irradiation. The mechanism of cell death may involve alterations in protein secondary structure and membrane permeability. For in vivo studies, 4-fold enhanced tumor accumulation was significantly observed of NIR-IO nanocrystals with a magnetic field (MF) application, resulting in a 3-fold higher T2-weighted MR signal than that produced by a commercial T2-weighted MR contrast agent (Resovist®) and excellent photothermal efficacy (approximately 53 °C) for cancer treatment. The innovative NIR-IO nanocrystals showed excellent biocompatibility and have great potential as a theranostic agent against cancer.

Graphene is a two dimensional (2D) planar and hexagonal array of carbon atoms and has been studied extensively as advanced nanomaterials for important technological applications. This review summarizes the recent developments in chemistry, materials and energy applications of graphene, doped graphene and their composites with nanoparticles (NPs). It first highlights the new chemistry used to synthesize high quality graphene. It then outlines the methodologies developed to dope graphene with heteroatoms to modify and control graphene properties. It further describes the general approaches to graphene–NP composites via either direct NP growth onto graphene or self-assembly of the pre-formed NPs on graphene surface. These graphene–NP composites provide some ideal systems for studying synergistic effects between graphene and NPs on catalysis. The review focuses on applications of graphene–NP composites in increasing electrochemical energy storage density and in catalyzing chemical reactions with much desired electrochemical efficiencies.

A series of highly dispersed bimetallic PtPd alloy nanoparticles (NPs) anchored on reduced graphene oxide (RGO) have been synthesized with the assistance of ionic liquid (IL: [VEIM]BF 4 ). Different ratios of (PtCl 6 ) 2− and (PdCl 4 ) 2− ions were firstly attached to IL functionalized graphene oxide (GO) sheets in ethylene glycol (EG), and then the encased metal ions and graphene oxide sheets were reduced simultaneously by EG with the assistance of microwave. The characterization results of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and X-ray diffraction (XRD) demonstrate that PtPd alloy NPs with small particle sizes are uniformly dispersed on RGO. Electrochemical measurements reveal that PtPd–IL–RGO modified electrode can directly catalyze glucose oxidation and display enhanced current response compared with PtPd–RGO (such as: a response time within 3 s, a linear range from 0.1 to 22 mM at 0 V, good reproducibility, considerable stability, and excellent anti-interference to electroactive molecules and Cl − ). The superior catalytic activity and selectivity make PtPd–IL–RGO nanomaterials very promising for applications in direct detection of glucose.

The demands to examine components serving as one of the active layers in heterostructures of 2D materials have been recently increasing. Nanomaterials synthesized from a solution process and their self-assembly can provide a promising route to build a new type of mixed dimensional heterostructures, and several methodologies have been reported previously to construct 2D assemblies from colloidal nanostructures in solution. Graphene quantum dots (GQDs), receiving much interest due to the tunable optical band gap and the capability of chemical functionalization, are considered as emerging nanomaterials for various optoelectronic and biological applications. This study fabricates a closely packed GQDs film (GQDF) from colloidal solutions using a solvent-assisted Langmuir Blodgett method, and investigates the optical and electrical characteristics of the heterostacked graphene/GQD film (G/GQDF) structures. It is observed that the GQDF plays a role not only as a buffer layer that isolates Chemical Vapor Deposited graphene (CVD graphene) from undesired p-doping but also as a photoactive layer that triggers n-doping of the heterostacked CVD graphene film. The n-doping density of the G/GQDF device is proportional to UV irradiation time, but its carrier mobility remains constant regardless of doping densities, which are unique characteristics that have not been observed in other doping methods.

Nanotubular shaped α-MnO2/graphene oxide nanocomposites were synthesized via a simple, cost and time efficient hydrothermal method. The growth of hollow structured MnO2 nanotubes preferentially occurred along the [001] direction as evidenced from the morphological and structural characterizations. The tunnels of α-MnO2 nanotubes easily accommodated the molecular oxygen and exhibited excellent catalytic activity towards the oxygen reduction reaction over the rod structure and was further enhanced with the effective carbon support graphene oxide. The MnO2 nanotubes/graphene oxide nanocomposite modified electrode exhibited a maximum power density of 3359 mW m(-2) which is 7.8 fold higher than that of unmodified electrode and comparable with the Pt/C modified electrode. The microbial fuel cell equipped with MnO2 nanotubes/graphene oxide nanocomposite modified cathode exhibited quick start up and excellent durability over the studied electrodes and is attributed to the high surface area and number of active sites. These findings not only provide the fundamental studies on carbon supported low-dimensional transition-metal oxides but also open up the new possibilities of their applications in green energy devices.

Graphene nanosheet is a one-atom thick planar sheet of sp2-bonded carbon atoms, which are densely packed in a honeycomb crystal lattice, attracting tremendous attention from both fundamental research and industrial applications. The synthesis of graphene from graphene oxide (GO) using a biological method is one of the important topics in the areas of nanotechnology, because graphene-based nanomaterials have potential applications. A green, simple and non-toxic method for preparing graphene using biomass of Pseudomonas aeruginosa as the reducing reagent is proposed. The resulting microbially reduced graphene oxide (M-rGO) was characterized using a range of analytical techniques. UV–visible spectroscopy confirms the transition of graphene oxide to graphene. Fourier transform infrared spectroscopy (FT-IR) was used to study the changes in surface functionalities. X-ray diffraction (XRD) and high resolution scanning electron microscopy (SEM) were used to investigate the crystalline nature and the morphologies of prepared graphene respectively. Furthermore, the biocompatibility of the M-rGO was investigated using primary mouse embryonic fibroblast (PMEF) cells. The present study suggests that the M-rGO has significant biocompatibility for PMEF cells, even at a high concentration of 100 μg ml−1. Therefore, the proposed safe and green method confers the M-rGO with a great potential for various biomedical applications.

Both graphene oxide (GO) and DNA can be used as building blocks for nano/micro devices or hybrid structures. Reversible assembly of these nanomaterials is highly desirable because of their promising applications in chemical sensors, energy storage, catalysis, and optoelectronic applications. However, reversible assembly of GO-DNA hybrid materials has not been achieved based on specific DNA hybridization and conformational transition. Here we report a general pH-responsive, DNA-directed assay for the design of a reversible assembly of GO-GO and GO-AuNPs hybrid using human telomeric G-quadruplex and i-motif DNA.

Directed self-assembly of nano or microsized materials as building blocks is a very exciting research topic to construct large-scale but still uniform 2D or 3D architectures. Graphene shows great potential as an advanced building block for fabricating varied graphene-based functional films or architectures together with other metal, metal oxide and semiconductor nanomaterials. In our work, we demonstrated an approach to fabrication of flexible, transparent conductive thin films via layer-by-layer (LbL) assembly of oppositely charged reduced graphene oxides (RGOs). The graphene thin films showed remarkable optical–electronic properties. Inspired by this, we further fabricated transparent conductive hybrid thin film via LbL assembly of oppositely charged RGO nanosheets and Pt nanoparticles. The graphene– Pt hybrid thin film showed transient optical property as well as appropriate conductive and wetting properties. Moreover, we demonstrated graphene wrapped- MnO2 (GW- MnO2 ) nanocomposites by self-assembly of honeycomb MnO2 nanospheres and graphene sheets via an electrostatic co-precipitation method. The hybrid materials had a good electrochemical performance.

Poor crack resistance, high brittleness, and poor toughness are inherent limitations of traditional cement-based materials. Besides, cement-based materials have certain shortcomings in energy consumption and environmental protection. Therefore, improving the performance of cement-based materials becomes a hot topic in related research. At the same time, the development of nanomaterials and technologies provides researchers with a new research idea: to enhance the performance of cement-based materials at the nanoscale level. Graphene oxide (GO) is one of the most representative nano-reinforcements. Due to its high surface area and excellent physical properties, GO has a surprising effect on improving the performance of cement-based materials. In addition, nanosilica (NS) and carbon nanotubes (CNTs) have excellent improvement on cement-based materials, and people also hope to further improve the performance of cement-based materials through the interaction of various nanomaterials. In this paper, the influence of GO on cement-based materials is reviewed by consulting a lot of correlative literature, mainly focusing on the following aspects: (i) The dispersion of GO in cement paste. (ii) The influence of GO on the properties of cement-based materials, including working performance, mechanical strength, microstructural characteristics, and durability. (iii) The effect of nanohybrid materials of GO, NS, and CNTs on cement-based materials, and the synergistic effects of various nanomaterials are reviewed for the first time. (iv) Evaluation of current progress. This paper aims to provide guidance for the study and application of GO-modified cement-based materials and nanohybrid materials.

Buildings contribute to 40% of total global energy consumption, which is responsible to 38% of greenhouse gas emissions. It is critical to enhance the energy efficiency of buildings to mitigate global warming. In the last decade, advances in thermal energy storage (TES) techniques using phase change material (PCM) have gained much attention among researchers, mainly to reduce energy consumption and to promote the use of renewable energy sources such as solar energy. PCM technology is one of the most promising technologies available for the development of high performance and energy-efficient buildings and, therefore, considered as one of the most effective and on-going fields of research. The main limitation of PCM is its leakage problem which limits its potential use in building construction and other applications such as TES and textiles, which can be overcome by employing nano-/micro-encapsulation technologies. This paper comprehensively overviews the nano-/micro-encapsulation technologies, which are mainly classified into three categories including physical, physiochemical and chemical methods, and the properties of microcapsules prepared. Among all encapsulation technologies available, the chemical method is commonly used since it offers the best technological approach in terms of encapsulation efficiency and better structural integrity of core material. There is a need to develop a method for the synthesis of nano-encapsulated PCMs to achieve enhanced structural stability and better fracture resistance and, thus, longer service life. The accumulated database of properties/performance of PCMs and synthesised nano-/micro-capsules from various techniques presented in the paper should serve as the most useful information for the production of nano-/micro-capsules with desirable characteristics for building construction application and further innovation of PCM technology.

Experimental research on circular nano-silica concrete filled stainless steel tube (C-CFSST) stub columns after being exposed to freezing and thawing is carried out in this paper. All of forty specimens were tested in this paper, including nine C-CFSST specimens at normal temperature, 28 short columns of C-CFSST for freeze-thaw treatment and three circular hollow stainless steel stub columns. The failure mode, load-displacement curves, load-strain curves and load-bearing capacity were obtained and analyzed in this paper. The main parameters explored in the test include the number of freeze-thaw cycles (N=0, N=50, N=75, and N=100), wall thickness (T=1.0mm, T=1.2mm, T=1.5mm) andnano-silica concrete strength (fc=20MPa, fc=30MPa, fc=40MPa). The result shows that C-CFSST short columns at normal temperature and subjected to freezing and thawing follow similar failure mode. The effect of freeze-thaw cycles (N) of 50 on bearing capacity of C-CFSST column was maximal, and then the influence of N on the bearing capacity of specimens was small when N reached to 75, finally the effect of N on bearing capacity of C-CFSST column was large when N reached to 100. The bearing capacity of C-CFSST columns increases with increasing wall thickness. In addition, the loss percentage of bearing capacity of specimens (fc=40MPa) for freeze-thaw treatment is maximal, and the loss percentage of bearing capacity of specimens (fc=30MPa) for freeze-thaw treatment is minimal. According to the test results, this paper proposed a formula to calculate the bearing capacity of C-CFSST short columns for freeze-thaw treatment.

The nanoscratch test has been identified as one of the important tools for evaluating the mechanical and tribological properties of materials. This paper reviews the current researches on the nanoscratch test using to characterise the mechanical properties of three typical materials, including thin film, polymer composite and concrete, from the perspectives of the Berkovich indenter, parameter selection, mode selection, and analysis of resulting data. In addition, to provide a deep understanding on the test from different magnitude, a comparison between the microscratch test and nanoscratch test on the evaluation of tribological performance is also provided in this paper. The characterisation by nanoscratch test of two structural samples, in terms of layered film structures (thin film and coating sample) and single layer block structure (polymer composite sample and concrete samples) are also described in this paper, which aims to provides a deep understand on the evaluation the adhesion, tribological and interfacial properties of the typical materials samples by nanoscratch test. Finally, the coefficient of friction and critical load are discussed, which are two important parameters in tribological properties and adhesion properties.

Two-dimensional (2D) materials were widely used in sensing owing to the tunable physical or chemical properties. For years, optical sensing attracted a massive amount of attention on account of high accuracy, high security, non-invasive measurement, and strong anti-interference ability. Among the various optical sensing schemes, multi-wavelength optical sensing (MWOS) is an important branch and widely adopted in optical image, spectroscopy, or bio/chemical research. However, no spectral selectivity, limited working wavelength range, or intrinsic instability makes conventional 2D materials unsuitable for MWOS. A new class of 2D materials, known as MXene, exhibits outstanding electronic, optical, and thermal properties, leading to new applications in optical sensing. In this paper, we propose an integrated photothermal optical sensor (PHOS) using Ti3C2Tx MXene films. Thanks to the inherent spectral dependence of Ti3C2Tx MXene over a broadband range, the proposed PHOS can respond to different wavelengths from visible to short-wavelength infrared. Because of the efficient photothermal conversion, the PHOS has a control efficiency up to 0.19 π · mW−1 · mm−1 under 980-nm laser pumping and shows a higher control efficiency under red light (690 nm) irradiation. The measured response time of the proposed PHOS is 23.4 μs. This paper brings MXene into chip-integrated optical sensing fields for the first time and shows the potential applications.

Rare earth upconversion nanoparticles (UCNPs) with the superior performance in the biomedical field have attracted great attention. Due to the good light stability, low toxicity, deep tissue penetration and excellent bio-compatibility, UCNPs display great potential for development in the biomedical field. Excellent related reports are increasing year by year, like molecular sensing, bioimaging and therapeutics. In this paper, the preparation, modification, application of upconversion fluorescent nanoparticles and the latest research results in the field of biomedical materials have been reported in detail. Graphical abstract: In this paper, we systematically summarize and describe the preparation, modification, application and latest discovery in biomedical field of rare earth upconversion nanoparticles (UCNP). Due to the good light stability, low toxicity, deep tissue penetration and excellent biocompatibility, UCNPs display superior performance for the development of biomedical field in cancer therapy. Our work will certainly inspire researchers in related fields to create more meaningful upconversion nanomaterials and do more contributions to human cancer treatment research.

In recent years, sub-wavelength metamaterials-based light perfect absorbers have been the subject of many studies. The most frequently utilized absorber configuration is based on nanostructured plasmonic metals. However, two main drawbacks were raised for this design architecture. One is the fabrication complexity and large scale incompatibility of these nano units. The other one is the inherent limitation of these common metals which mostly operate in the visible frequency range. Recently, strong interference effects in lithography-free planar multilayer designs have been proposed as a solution for tackling these drawbacks. In this paper, we reveal the extraordinary potential of bismuth (Bi) metal in achieving light perfect absorption in a planar design through a broad wavelength regime. For this aim, we adopted a modeling approach based on the transfer matrix method (TMM) to find the ideal conditions for light perfect absorption. According to the findings of our modeling and numerical simulations, it was demonstrated that the use of Bi in the metal-insulator-metal-insulator (MIMI) configuration can simultaneously provide two distinct functionalities; a narrow near unity reflection response and an ultra-broadband near perfect absorption. The reflection behavior can be employed to realize additive color filters in the visible range, while the ultra-broadband absorption response of the design can fully harvest solar irradiation in the visible and near infrared (NIR) ranges. The findings of this paper demonstrate the extraordinary potential of Bi metal for the design of deep sub-wavelength optical devices.

Electrochemical biointerfaces are constructed with a wide range of nanomaterials and conducting polymers that strongly affect the analytical performance of biosensors. The analysis of progress toward electrochemical sensing platforms offers opportunities to provide devices for commercial use. The investigation of different methods for the synthesis of phenol biointerfaces leads to design challenges in the field of monitoring phenolic compounds. This paper review the innovative strategies and feature techniques in the construction of phenolic compound biosensors. The focus was made on the preparation methods of nanostructures and nanomaterials design for catalytic improvements of sensing interfaces. The paper also provides a comprehensive overview in the field of enzyme immobilization approaches at solid supports and technical formation of polymer nanocomposites, as well as applications of hybrid organic-inorganic nanocomposites in phenolic biosensors. This review also highlights the recent progress in the electrochemical detection of phenolic compounds and summarizes analytical performance parameters including sensitivity, storage stability, limit of detection, linear range, and Michaelis-Menten kinetic analysis. It also emphasizes advances from the past decade including technical challenges for the construction of suitable biointerfaces for monitoring phenolic compounds.

An all-carbon pressure sensor is designed and fabricated based on reduced graphene oxide (rGO) nanomaterials. By sandwiching one layer of superelastic rGO aerogel between two freestanding high-conductive rGO thin papers, the sensor works based on the contact resistance at the aerogel-paper interfaces, getting rid of the alien materials such as polymers and metals adopted in traditional sensors. Without the limitation of alien materials, the all-carbon sensors demonstrate an ultrawide detecting range (0.72 Pa-130 kPa), low energy consumption (≈0.58 µW), ultrahigh sensitivity (349-253 kPa-1 ) at low-pressure regime (

This paper deals with the possibilities of applying modern technologies in biomedicine. The paper discussed a theoretical model, which enables a more detailed explanation of the processes that occour upon impact of laser beam on nanoparticles. The paper has presented a method that makes it possible to more effectively deal with the pathological formations. The paper also considers a relevant physic-mathematical model.

A passively pulsed fiber laser using saturable absorbers such as graphene has been increased dramatically in recent years. Up to now, researchers have been proposed many methods to fabricate graphene saturable absorber such as (evanescent coupling structure, electrochemical exfoliation, and mechanical exfoliation) for light pulse generation in a fiber laser. However, each of these methods has got some limitations which reduce the saturable absorber performance and restrict its range of applications. In this paper, we propose a simple but very efficient fabrication way of graphene saturable absorber by converting graphene Nano powder into a thin film using polyvinyl alcohol (PVA) as a host material. The fabricated film can then be easily sandwiched between two fiber pigtails and inserted inside the laser cavity to form the saturable absorber. when compared with other methods, this method is much preferable because it provides saturable absorber with combat structure, maximum interaction area, reasonable insertion loss, polarization insensitive, controllable concentration, and safe to handle. The fabricated graphene saturable absorber in this paper was characterized and found to have a uniform distribution of the graphene nanomaterial in the PVA and have a modulation depth of 6.1% which make it a very promising saturable absorber for ultra-fast fiber laser demonstration.

Cooling is one of the most important technique challenges faced by a range of diverse industries and military needs. There is an urgent need for the innovative heat transfer fluids with improved thermal properties over the currently available. This review paper discusses the concept of using phase-changeable nanoparticles to increase the effective heat capacity and the heat transfer rate of the fluid. A large amount of heat can be absorbed or released when these nanoparticles undergo phase transition from solid to liquid or liquid to gas or vice versa and, thus, enhancing the heat transfer rate. Two types of phase-change fluids are introduced: one contains liquid nanodroplets that will evaporate at elevated temperatures or solidifies at reduced temperatures, called “nanoemulsion fluids”; the other is suspensions of solid-liquid metallic phase-change nanoparticles. The material synthesis and property characterizations of these phase-changeable fluids are two main aspects of this paper. The explosive vaporization of the dispersed nanodroplets would significantly improve the heat transfer in the nanoemulsion fluid. The solid-liquid metallic phase-change nanoparticles will increase the effective heat capacity and thermal conductivity of the base fluids simultaneously. This paper also identifies the several critical issues in the phase-changeable fluids to be solved in the future.

The last decade has seen an extensive development of the field of nanomaterials which are currently being used in their first commercial applications. This rapid development is necessarily connected with certain technological demands. This paper describes a technology for the manufacture of nanomaterials from solutions by electrostatic spinning or spraying. Although this method has been well known since the last century, there are still only a few high-quality devices that can be used for the research of new nanomaterials. The main reason for this is that the process of nanomaterials manufacturing is influenced by numerous processing parameters which need to be properly regulated, and furthermore all device components must be resistant to interference from high voltage. The technological requirements are thus stringent. Moreover, such a device must be multifunctional, compact and affordable. This paper describes the technical aspects of a unique laboratory device, i.e., device modules and central control, measured processing parameters, and their effect on the produced materials. The developed laboratory device meets the most demanding criteria for a nanotechnological laboratory device and helps facilitate and speed up the research and development of new nanomaterials produced in high electrostatic field.

The raw materials of geopolymer come from industrial wastes, which have the advantages of lower carbon emissions and less energy consumption compared with traditional cement products. However, it still has the disadvantages of low strength, easy cracking, and low production efficiency, which limit its engineering application and development. At present, with the application and development of nanotechnology in the field of materials, it is found that nanomaterials have a good filling effect on composites, which greatly improves the integrity of the composites. It has become a very popular research direction to optimize and improve the engineering application performance of geopolymer concrete (GPC) by nanomaterials. The modification of nanomaterials can further improve the properties of GPC and expand its application fields in engineering and life. Based on people’s strong interest in nanomaterial-modified GPC and providing the latest and complete research status for further related work, this paper summarized the key technical problems in the field of nanomaterials-modified GPC in the past decade. Those include the modification mechanism, dispersion mode, and mechanical properties of nanomaterials. At the same time, the application bottlenecks and key problems of nanomaterials-modified GPC are comprehensively analyzed. Finally, the prospects and challenges of future work in this field are discussed.

Critical-sized bone defects have, in many cases, posed challenges to the current gold standard treatments. Bioactive glasses are reported to be able to stimulate more bone regeneration than other bioactive ceramics; however, the difficulty in producing porous scaffolds made of bioactive glasses has limited their extensive use in bone regeneration. On the other hand, calcium phosphate ceramics such as synthetic hydroxyapatite and tricalcium phosphate are widely used in the clinic, but they stimulate less bone regeneration. This paper gives an overview of the recent developments in the field of bioactive nanoparticles, with a focus on nanohydroxyapatite and bioactive glasses for bone repair and regeneration. First, a brief overview of the chemical structure and common methods used to produce synthetic nanohydroxyapatite and bioactive glasses has been presented. The main body of the paper covers the physical and biological properties of these biomaterials, as well as their composites with biodegradable polymers used in bone regeneration. A summary of existing challenges and some recommendations for future directions have been brought in the concluding section of this paper.

Creation of various photoluminescent nanomaterials has significantly expanded the arsenal of approaches used in modern biomedicine. Their unique photophysical properties can significantly improve the sensitivity and specificity of diagnostic methods, increase therapy effectiveness, and make a theranostic approach to treatment possible through the application of nanoparticle conjugates with functional macromolecules. The most widely used nanomaterials to date are semiconductor quantum dots; gold nanoclusters; carbon dots; nanodiamonds; semiconductor porous silicon; and up-conversion nanoparticles. This paper considers the promising groups of photoluminescent nanomaterials that can be used in medical biotechnology: in particular, for devising agents for optical diagnostic methods, sensorics, and various types of therapy.

Background: Currently, solution combustion synthesis (SCS) is considered a reproducible, flexible, and low-cost synthesis method for the preparation of nanomaterials. A new trend in the SCS method is the use of less polluting fuels, such as starch. The use of starch as fuel in SCS is very interesting for green chemistry, as it is renewable and has several advantages, including its abundance, low-cost, and non-toxicity. Objective: This paper provides a comprehensive review of the SCS method using starch as fuel. The main advantages of using starch as fuel will be illustrated with a wide variety of examples, highlighting its impact on the preparation of nanomaterials for energy and environmental applications. Conclusion: In a combustion reaction using starch as fuel, several positive effects are expected, such as non-violent propagation, combustion with the production of non-toxic gases (mainly CO2 and H2O), and development of pores during the release of gases. For example, several macroporous metal oxide foams were prepared using the SCS method, through an appropriate combination of urea and starch fuels. With this approach, it is possible to control the structure, lattice defects, crystallite size, specific surface area, porosity, and other characteristics of the synthetized nanomaterial. For example, by combining starch with other fuels, it is possible to control the concentration of lattice defects in metal oxides and modify the optical properties of these materials. These properties are of fundamental importance for the performance of these materials and their subsequent application in electrodes, electrocatalysts, and photocatalysts in the areas of energy and environment.

Nanomaterials and nanotechnology have been widely used in various fields, such as materials, chemical engineering, optics, and other disciplines. In this paper, gold nanoparticles are prepared by the hydrothermal method and treated with polypyrrole coating (PPy-GNPs). Then, the anti-HER2 protein was conjugated to polypyrrole coated gold nanoparticles, and the nanomaterials are named anti-HER2-PPy@GNPs (anti-PPy@GNPs). Their diameter is about 80–90 nm, and they show a strong absorption peak in the near-infrared band, especially under 808 nm laser irradiation. In the MTT test experiment, anti-HER2-PPy@GNPs show a significant inhibitory effect on the SKOV-3 cell. Fluorescent cytoskeletal analysis of SKOV-3 cells and atomic force microscopy (AFM) of the mechanical characteristics of the cell surface revealed that the cell micro-structure, adhesion, and Young's modulus of anti-HER2-PPy@GNPs have changed under the near-infrared illumination. These results indicate anti-HER2-PPy@GNPs has an inhibitory effect on SKOV-3 cells. AFM detects the mechanical characteristics of SKOV-3 cells. Compared with the control group, Young's modulus is increased 52.7%, while the adhesion force is decreased 14.47%.

In this study, we report the formation of laser-induced periodic surface nanometric concentric ring structures on silicon surfaces through single-spot irradiation with orthogonally polarized femtosecond laser double-pulse sequences (OP pulses). The period of the ring structures is marginally smaller than the irradiated laser’s wavelength, which indicates that the structures are a type of low-spatial-frequency laser-induced periodic surface structures. Regular nanometric concentric ring structures can be formed when the time delay between two subpulses is approximately 1 ps (roughly from 500 fs to 1.5 ps) and the number of laser bursts is approximately 4. The formation mechanism of the concentric ring structures is attributed to the surface wave (i.e., cylindrical wave) stimulated by OP pulses through single-spot irradiation is radially distributed. Large area of concentric ring structures eliminating anisotropy in the generation of structural colors was shown in this paper.