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The major obstacle to developing nanozymes which are considered as promising alternatives to natural enzymes is their moderate performance, including poor affinity for substrates, low catalytic activity, and severe pH-dependence. To address these issues, herein, we synthesize ultrathin layered double hydroxide (LDH) nanosheets with a thickness of 1.4 nm and an average lateral size of 23 nm using a fast-precipitation method. Through the rational design of their compositions, it is found that NiMn LDHs exhibit the optimum peroxidase mimicking performance with excellent substrate affinity, high catalytic activity (a limit of detection (LOD) of 0.04 μM H 2 O 2 ) and robustness in a wide pH range (from 2.6 to 9.0), which is superior to that of natural horseradish peroxidase (HRP). The main active centers are identified as Mn sites because of their strong Lewis acidity and low redox potential. Furthermore, a series of disposable paper bioassays based on NiMn LDH nanozymes are designed and used for the highly sensitive detection of H 2 O 2 and ascorbic acid (AA).

Globally, rapid development of antibiotic resistance amongst pathogens has led to limited treatment options and high indirect costs to health management. There is a need to avoid misuse of available antibiotics and to develop rapid, affordable and accessible diagnostic technologies to detect drug resistance even in resource limited settings. This study reports the development of instrument-free point-of-care devices for detection of antibiotic resistance for rapid diagnosis of drug resistance in the penicillin, cephalosporin and carbapenem groups of antibiotics. The simple paper-based devices for flow through assay determine the presence of resistant bacteria in a sample by a visible colour change within 30 minutes. At the center of this technology is the unique sensing nanomaterial comprising of core-shell nanoparticles layered with specific antibiotics. The core is comprised of chitosan nanoparticles of size ∼15 nm coated with the starch-iodine indicator to form a shell increasing the size to ∼47 nm. The test strip is coated with the nanoparticles, air-dried and overlayed with the required antibiotic. In the presence of penicillin, cephalosporin and carbapenem resistant bacteria, the core-shell nanoparticles undergo a visible colour change from blue to white. The core-shell nanoparticles were deposited on paper to form a point-of-care device. Devices were developed to screen for three main classes of antibiotics namely penicillins, cephalosporins and carbapenems. The devices were validated using standard resistant and susceptible ATCC strains in three different sample types, pure colony, broth culture and saline suspensions. The change of colour from blue to white was considered a positive test. The time of detection was found to be 30 min, while the limit of detection was 10 5 cfu ml -1 . The device exhibited 100% sensitivity and specificity with known resistant and susceptible cultures not only from pure colonies but also from direct samples of spiked saline suspensions with graded confounding factors of albumin, glucose, and urea. The inter-device reproducibility and storage stability of the devices was established. The developed point-of-care devices have potential as screening devices for antimicrobial resistance.

The rapid development of and the large market for medical diagnostics necessitate point-of-care testing (POCT) with superior sensitivity, miniaturization, multiple functionalities and high integration. Thus, flexible substrates with complex structures that provide multiple functions are in demand. Herein, we present multistructured pseudo-papers (MSPs) as a platform for building flexible microfluidics. Flexible and freestanding MSPs are generated by the self-assembly of colloidal silica crystals or core-shell copolymer elastic colloidal crystals on microcavity PDMS molds to form photonic crystals (PCs). Nitrocellulose (NC) multistructured pseudo-papers (NC MSPs) were obtained by etching SiO 2 PCs after NC precursor infiltration, while elastic copolymer (EC) multistructured pseudo-papers (EC MSPs) were directly peeled off the mold; both types of freestanding MSPs have ordered micropillars and nanocrystal structures and presented unique properties such as pumpless liquid transport and fluorescence and chemiluminescence (CL) enhancement. MSPs with designed patterns were fabricated by patterned PDMS molds, and complicated microfluidic chips were used to generate MSPs by utilizing these patterns as liquid channels. The MSPs were used for fabricating microfluidic sensors for human cardiac marker and cancer marker sensing; the features of these bioinspired MSPs indicate their potential for sensitive sensing, which will enable them to find broader applications in many fields.

In this work, a versatile point-of-care assay platform based on a microfluidic paper-based analytic device (μPAD) was developed for the simultaneous detection of multiple targets. The μPAD with a central zone and six test zones is fabricated by a simple and inexpensive wax printing method. A flower-like hybrid nanocomplex synthesized with specific dual enzymes and Cu3(PO4)2 inorganic nanocrystals is spotted in the test zones on the μPAD, followed by the introduction of assay targets. Using dual-enzyme inorganic hybrid nanoflowers in the μPAD as nanobiocatalysts, which preserve the activity and enhance the stability of the enzymes, based on the H2O2-mediated catalytic oxidizing chromogenic reaction produced by glucose/uric acid, the developed multiplex paper-based nanobiocatalytic system is demonstrated to enable simultaneous and sensitive detection of glucose and uric acid with a detection limit of 60 and 25 μM, respectively. More importantly, it has been successfully used for detecting glucose and uric acid levels in human whole blood samples. The developed multiplex paper-based nanobiocatalytic system features very easy fabrication and operation, low cost, and high sensitivity and has promising prospects for a clinical multianalyte point-of-care test.

Microorganisms such as bacteria, fungi, algae and moulds are highly proficient at colonizing artistic and architectural heritage. The irreparable damage they cause to unique artefacts results in immeasurable cultural and societal losses to our shared cultural heritage, which represent an important social and economic resource for Europe. With the overall aim of preventing fungal deterioration of paper artefacts, we report the use of magnesium oxide nanoparticles (MgO NPs) of average diameter 12 nm as potent antifungal agents against fungi commonly found colonising paper heritage: A. niger, C. cladosporioides and T. reesei. Dispersions of MgO NPs on original 18th century paper samples from the Archives of the Spanish Royal Botanic Garden were effective at preventing fungal colonisation without altering the appearance of the paper artefacts. Importantly, MgO NPs also inhibit cellulase activity in the filamentous fungi T. resei and A. niger, two of the principle biodeteriogens of cellulosic materials. In addition, our report provides three simple new procedures for studying the fungal colonisation prevention properties of nanomaterials on paper samples. Overall this opens the door to the use of colourless, low-cost, and scalable nanomaterials for preventing biodeterioration in cellulose-based artefacts.

We report the first use of a paper-based device coated with nanoceria as a simple, low-cost and rapid detection platform for the analysis of organophosphate (OP) pesticides using an enzyme inhibition assay with acetylcholinesterase (AChE) and choline oxidase (ChOX). In the presence of acetylcholine, AChE and ChOX catalyze the formation of H2O2, which is detected colorimetrically by a nanoceria-coated device resulting in the formation of a yellow color. After incubation with OP pesticides, the AChE activity was inhibited, producing less H2O2, and a reduction in the yellow intensity. The assay is able to analyze OP pesticides without the use of sophisticated instruments and gives detection limits of 18 ng mL(-1) and 5.3 ng mL(-1) for methyl-paraoxon and chlorpyrifos-oxon, respectively. The developed method was successfully applied to detect methyl-paraoxon in spiked vegetables (cabbage) and a dried seafood product (dried green mussel), obtaining ∼95% recovery values for both sample types. The spiked samples were also analyzed using LC-MS/MS as a comparison to the developed method and similar values were obtained, indicating that the developed method gives accurate results and is suitable for OP analysis in real samples.

This paper describes a silica nanoparticle-modified microfluidic paper-based analytical device (μPAD) with improved color intensity and uniformity for three different enzymatic reactions with clinical relevance (lactate, glucose, and glutamate). The μPADs were produced on a Whatman grade 1 filter paper and using a CO2 laser engraver. Silica nanoparticles modified with 3-aminopropyltriethoxysilane were then added to the paper devices to facilitate the adsorption of selected enzymes and prevent the washing away effect that creates color gradients in the colorimetric measurements. According to the results herein described, the addition of silica nanoparticles yielded significant improvements in color intensity and uniformity. The resulting μPADs allowed for the detection of the three analytes in clinically relevant concentration ranges with limits of detection (LODs) of 0.63 mM, 0.50 mM, and 0.25 mM for lactate, glucose, and glutamate, respectively. An example of an analytical application has been demonstrated for the semi-quantitative detection of all three analytes in artificial urine. The results demonstrate the potential of silica nanoparticles to avoid the washing away effect and improve the color uniformity and intensity in colorimetric bioassays performed on μPADs.

Airborne particulate matter (PM) pollution significantly impacts human health, but the cellular mechanisms of PM-induced toxicity remain poorly understood. A leading hypothesis on the effects of inhaled PM involves the generation of cellular oxidative stress. To investigate PM-induced oxidative stress, analytical methods have been developed to study the chemical oxidation of dithiothreitol (DTT) in the presence of PM. Although DTT readily reacts with several forms of reactive oxygen species, this molecule is not endogenously produced in biological systems. Glutathione (GSH), on the other hand, is an endogenous antioxidant that is produced throughout the body and is directly involved in combating oxidative stress in the lungs and other tissues. We report here a new method for measuring aerosol oxidative activity that uses silver nanoparticle (AgNP) aggregation coupled to glutathione (GSH) oxidation in a paper-based analytical device. In this assay, the residual reduced GSH from the oxidation of reduced GSH to its disulfide induces the aggregation of AgNPs on a paper-based analytical device, which produces a reddish-brown product. Two methods for aerosol oxidative reactivity are presented: one based on change in color intensity using a traditional paper-based techniques and one based on the length of the color product formed using a distance-based device. These methods were validated against traditional spectroscopic assays for DTT and GSH that employ Elman's reagent. No significant difference was found between the levels measured by all three GSH methods (our two paper-based devices and the traditional method) at the 95% confidence level. PM reactivity towards GSH was less than towards DTT most likely due to the difference in the oxidation potential between the two molecules.

Cu nanoparticles (CuNPs) were successfully synthesized in situ on ZnO whiskers as a selective scaffold, which were supported in a microstructured paper matrix composed of inorganic fibers; as-prepared paper composites were easy to handle in practical use and demonstrated excellent catalytic performance in the methanol reforming process for effective hydrogen production.

MicroRNAs (miRNAs) have emerged as a promising class of biomarkers for early detection of various cancers, including ovarian cancer. However, quantifying miRNAs in human blood samples is challenging owing to the issues of sensitivity and specificity. In this study, hsa-miR-200a-3p of the miR-200a sub-family, which is a biomarker of ovarian cancer, was used as the analyte to demonstrate the analytical capability of an integrated biosensing platform using an extremely sensitive surface-enhanced Raman scattering (SERS) nanotag−nanoaggregate-embedded beads (NAEBs), magnetic nanoparticles (MNPs), a pair of highly specific locked nucleic acid (LNA) probes, and a semi-automated paper-based electrowetting-on-dielectric (pEWOD) device to provide labor-less and thorough sample cleanup and recovery. A sandwich approach where NAEBs are modified by one LNA-1 probe and MNPs are modified by another LNA-2 probe was applied. Then, the target analyte miRNA-200a-3p was introduced to form a sandwich nanocomplex through hybridization with the pair of LNA probes. The pEWOD device was used to achieve short cleanup time and good recovery of the nanocomplex, bringing the total analysis time to less than 30 min. The detection limit of this approach can reach 0.26 fM through SERS detection. The versatility of this method without the need for RNA extraction from clinical samples is expected to have good potential in detecting other miRNAs. [ABSTRACT FROM AUTHOR]

Herein, a simple approach is demonstrated for the fabrication of a paper-based flexible symmetrical supercapacitor as an energy saving device with composite functional materials of nickel nanoparticles (Ni NPs) and polypyrrole (PPy). Specifically, an Ni@PPy nanocomposite was synthesized through a two-step process involving the growth of Ni NPs, followed by pyrrole polymerization on a paper substrate. The paper fabricated with Ni@PPy showed an electrical conductivity of 105 S cm−1. The paper-based flexible supercapacitor device configured with Ni@PPy/electrolyte/Ni@PPy was evaluated for electrochemical performance, and it showed a good specific capacitance of 544 F g−1 at 1 A g−1. A better specific energy of 48 W h kg−1, specific power of 400 W kg−1, and good cycling stability (68.3% capacitance retention after 3000 cycles at 5 A g−1) were obtained for the paper-based flexible supercapacitor compared with other reported polymer-based nanocomposite materials. The obtained results suggest that the fabricated paper-based supercapacitor is inexpensive, sustainable, highly efficient, portable and flexible for a wide range of electronic applications. [ABSTRACT FROM AUTHOR]

Presently, the use of several pesticides has been continuously rising owing to the increase in the production of food materials to meet the requirements of the growing population of the world. The safety of food materials with regards to pesticides is an important health concern for people. With this aim, we have developed a smartphone-assisted paper-based sensor impregnated with citrate capped Cu@Ag core–shell nanoparticles (NPs) for selective determination of phenthoate pesticides in water and food samples. The mechanism for selective detection is based on the high affinity of phenthoate to interact with silver NPs present on the surface of CuNPs, which results in aggregation and a change in the color of the paper device. Furthermore, the proposed mechanism and interaction of phenthoate with Cu@Ag NPs was theoretically investigated by density functional theory (DFT) using Gaussian 16.0 software. The linear range for the determination of phenthoate was found in the range of 50–1500 μg L−1, with a limit of detection of 15 μg L−1, and a 92.6 to 97.4% recovery, and the interference studies demonstrated the selectivity for the determination of the target analyte from complex sample matrices. Finally, paper impregnated with Cu@Ag was exploited for the monitoring of the phenthoate pesticide in different water and food samples. The advantages of this paper-based sensor, coupled with a smartphone readout system, are that is it is user-friendly, easy-to-use, cost-effective, and can be applied at the sample source compared to sophisticated analytical instruments. [ABSTRACT FROM AUTHOR]

A bioactive paper-based colorimetric “dipstick” bioassay is reported that is based on acetylcholinesterase (AChE) catalyzed enlargement of gold nanoparticles that are co-entrapped with the enzyme in a sol–gel based silica material that is coated on a functionalized paper substrate. Test solutions containing acetylthiocholine (ATCh) and a Au(III) salt are spotted over the sensing area of the bioactive test strips containing small (3 nm diameter) primary gold nanoparticles (AuNP). Biocatalyzed hydrolysis of ATCh viaAChE leads to formation of thiocholine, which in turn reduces the Au(III) onto the entrapped nanoparticles, producing particle growth and a concomitant increase in color intensity that can be correlated to the amount of substrate or inhibitor present in test solutions. The entrapped AuNP cannot leach from the silica material, leading to a bioactive paper assay that can utilize visual detection of a color change as a simple readout. Our results show that the dipstick based bioassay is sufficiently sensitive to allow for detection of Paraoxon over the conentration range of 500 nM to ∼ 1 mM. Detection can be made by eye or using a digital camera and image analysis, making the assay suitable for remote analysis. [ABSTRACT FROM AUTHOR]

Point-of-care and in-field technologies for rapid, sensitive and selective detection of molecular biomarkers have attracted much interest. Rugged bioassay technology capable of fast detection of markers for pathogens and genetic diseases would in particular impact the quality of health care in the developing world, but would also make possible more extensive screening in developed countries to tackle problems such as those associated with water and food quality, and tracking of infectious organisms in hospitals and clinics. Literature trends indicate an increasing interest in the use of nanomaterials, and in particular luminescent nanoparticles, for assay development. These materials may offer attributes for development of assays and sensors that could achieve improvements in analytical figures of merit, and provide practical advantages in sensitivity and stability. There is opportunity for cost-efficiency and technical simplicity by implementation of luminescent nanomaterials as the basis for transduction technology, when combined with the use of paper substrates, and the ubiquitous availability of cell phone cameras and associated infrastructure for optical detection and transmission of results. Luminescent nanoparticles have been described for a broad range of bioanalytical targets including small molecules, oligonucleotides, peptides, proteins, saccharides and whole cells (e.g., cancer diagnostics). The luminescent nanomaterials that are described herein for paper-based bioassays include metal nanoparticles, quantum dots and lanthanide-doped nanocrystals. These nanomaterials often have broad and strong absorption and narrow emission bands that improve opportunity for multiplexed analysis, and can be designed to provide emission at wavelengths that are efficiently processed by conventional digital cameras. Luminescent nanoparticles can be embedded in paper substrates that are designed to direct fluid flow, and the resulting combination of technologies can offer competitive analytical performance at relatively low cost. [ABSTRACT FROM AUTHOR]

In this work, microfluidic paper-based analytical device (μ-PAD) was applied in a photoelectrochemical (PEC) method and thus a truly low-cost, simple, portable, and disposable microfluidic PEC origami device (μ-PECOD) was demonstrated. The molecular imprinting technique was introduced into microfluidic paper-based analytical devices (μ-PADs) through electropolymerization of molecular imprinted polyaniline (MPANI) in a novel Au nanoparticle (AuNP)-modified paper working electrode (Au-PWE). This is fabricated through the growth of an AuNP layer on the surfaces of cellulose fibers in the PWE. Under visible light irradiation, MPANI can generate the photoelectric transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), delivering the excited electrons to the AuNPs, and then to the carbon working electrode. Simultaneously, it is believed that a positively charged hole of MPANI that took part in the oxidation process was consumed by ascorbic acid (AA) to promote the amplifying photocurrent response. On the basis of this novel MPANI-Au-PWE and the principle of origami, a microfluidic molecular imprinted polymer (MIP)-based photoelectrochemical analytical origami device (μ-MPECOD), comprised of an auxiliary tab and a sample tab, is developed for the detection of heptachlor in the linear range from 0.03 nmol L−1 to 10.0 nmol L−1 with a low detection limit of 8.0 pmol L−1. The selectivity, reproducibility, and stability of this μ-MPECOD are investigated. This μ-MPECOD would provide a new platform for high-throughput, sensitive, specific, and multiplex assay in public health, environmental monitoring, and the developing world. [ABSTRACT FROM AUTHOR]

In this work, bovine serum albumin (BSA)–Au nanoclusters were used to coat a paper-based microfluidic device. This device acted as a Cu2+ biosensor that showed fluorescence quenching on detection of copper ions. The detection limit of this sensor could be adjusted by altering the water absorbing capacity of the device. Qualitative and semi-quantitative results could be obtained visually without the aid of any advanced instruments. This sensor could test Cu2+ rapidly with high specificity and sensitivity, which would be useful for point-of-care testing (POCT). [ABSTRACT FROM AUTHOR]

Cu nanoparticles (CuNPs) were successfully synthesized in situon ZnO whiskers as a selective scaffold, which were supported in a microstructured paper matrix composed of inorganic fibers; as-prepared paper composites were easy to handle in practical use and demonstrated excellent catalytic performance in the methanol reforming process for effective hydrogen production. [ABSTRACT FROM AUTHOR]

This paper describes the chemistry of green materials synthesized with supercritical fluids. First, the properties and some specific features of supercritical water are summarized. Then, supercritical hydrothermal synthesis of nanoparticles is explained, and various applications of green materials are described. The surface control of nanoparticles in supercritical water is also explained. Green processes involving chemical recycling of waste polymers and a combination of hydrothermal synthesis and supercritical water oxidation are also discussed. Finally, commercialization of supercritical water processes is discussed. [ABSTRACT FROM AUTHOR]

This paper introduces a novel approach to surface bioaffinity sensing based on the adsorption of nanoparticles onto a gold diffraction grating that supports the excitation of planar surface plasmons. A surface enzymatic amplification reaction is also incorporated into the detection scheme to enhance the sensitivity and utility of the nanoparticle-enhanced diffraction grating (NEDG) sensors. As a demonstration, the detection of microRNA is described where a combination of a surface polymerase reaction and DNA-modified nanoparticles is used to detect the bioaffinity adsorption of the target onto the probe-functionalized gold grating surface. The enzymatically-amplified NEDG sensors possess a great potential for a wide range of applications including the detection of biosecurity agents, DNA and RNA viruses, biomarkers, and proteins. [ABSTRACT FROM AUTHOR]

A lack of renewable resources and their inefficient use is a major challenge facing the society. Lignin is a natural biopolymer obtained mainly as a by-product from the pulp- and paper-making industries, and is primarily burned to produce energy. However, interest for using lignin in more advanced applications has increased rapidly. In particular, lignin based nanoparticles could find potential use in functional surface coatings, nanoglue, drug delivery, and microfluidic devices. In this work, a straightforward method to produce lignin nanoparticles from waste lignin obtained from kraft pulping is introduced. Spherical lignin nanoparticles were obtained by dissolving softwood kraft lignin in tetrahydrofuran (THF) and subsequently introducing water into the system through dialysis. No chemical modification of lignin was needed. Water acts as a non-solvent reducing lignin's degrees of freedom causing the segregation of hydrophobic regions to compartments within the forming nanoparticles. The final size of the nanoparticles depended on the pre-dialysis concentration of dissolved lignin. The stability of the nanoparticle dispersion as a function of time, salt concentration and pH was studied. In pure water and at room temperature the lignin nanoparticle dispersion was stable for over two months, but a very low pH or high salt concentration induced aggregation. It was further demonstrated that the surface charge of the particles could be reversed and stable cationic lignin nanoparticles were produced by adsorption of poly(diallyldimethylammonium chloride) (PDADMAC). [ABSTRACT FROM AUTHOR]

In this paper, we report on the development of an 'off–on' fluorescent probe for the detection of hydrogen peroxide (H2O2) and mercury ions (Hg2+) using an in situ synthesized carbon quantum dot and gum Arabic silver nanoparticle composite (CQDs@GA-Ag NPs). Electron microscopy measurement clearly shows that CQDs are attached to the surface of the GA-Ag NPs. The fluorescence intensity of the CQDs was dramatically quenched in the synthesized nanocomposite via the inner filter effect (IFE) mechanism. After adding H2O2 to the nanocomposite system, the Ag NPs got oxidized leading to the formation of Ag+ ions, and the CQDs regained their photoluminescence (PL) property. This facilitates the detection of H2O2 with an extremely low detection limit of 1.02 μM. Furthermore, the as-developed nanocomposite was also tested for the detection of Hg2+ ions, obtaining a remarkably low detection limit of 1.82 μM. The developed probe was extremely selective over a wide range of interfering ions and substances. [ABSTRACT FROM AUTHOR]

Pickering emulsions are considered as promising chemical oil repellents in enhanced oil recovery (EOR). In this paper, an amphiphilic block copolymer poly(ethylene glycol)–poly(dopamine methacrylamide) (mPEG–PDMA, abbreviated as mp) containing catechol adhesion groups was synthesized. The surface modification of A200 and SBA-15 nanoparticles was carried out using the strategy of dip-coating with mp solution, and the emulsification properties of the two modified particles and their stability were comparatively investigated. The results showed that both modified particles could achieve excellent emulsification performance. The best emulsification effect was achieved when the concentration of A200-mp and SBA-15-mp particles was 2.5 mg mL−1 and the oil phase volume fraction was 0.5. The emulsions stabilized by SBA-15-mp tended to be invertible when the volume fraction of the oil phase was 0.7 or pH = 2–3 or when NaCl was added, and O/W emulsions could be inverted into W/O types. Interestingly, the emulsions stabilized by A200-mp particles showed good acid resistance, alkali resistance, high salt resistance, multiple oil phase applicability and centrifugal shear stability. In the simulated rock permeation experiments, the emulsions prepared using A200-mp particles could stably permeate in the silica sand column without an obvious chromatographic separation effect, which is promising for application in tertiary oil recovery. [ABSTRACT FROM AUTHOR]

The biological synthesis of metal nanoparticles from ions has recently emerged as a novel technique for an environmentally benign recovery of heavy metals. Bacteria are known to recover palladium(0) in the form of nanoparticles that are catalytically active. However, the extent of the reactions that can be catalysed by bio-recovered palladium has not been investigated. This study demonstrates that the Suzuki–Miyaura and Mizoroki–Heck reactions can be catalysed by bio-generated palladium nanoparticles formed on the surface of Gram-negative bacteria. The results suggest that the range of applications of this catalyst can be extended to the realm of carbon–carbon bond formation in synthetic organic chemistry. [ABSTRACT FROM AUTHOR]

The loading of pre-treated amorphous silica with platinum or palladium was carried out by using the molecular precursors Pt2(μ-Cl)2Cl2(CO)2, or Pd2(μ-Cl)2Cl2(CO)2, respectively, which contain the required amount of coordinated CO to carry out the formation of the metal particles upon contact with moisture. The reactivity of the well-soluble mononuclear platinum complex cis-PtCl2(CO)2with stoichiometric amounts of water was investigated either under N2or CO. The metal nanoparticles produced on the silica matrix have been characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The catalytic performance of the silica-supported metals thus produced was evaluated in the hydrogenation of cyclohexene. [ABSTRACT FROM AUTHOR]

The preparation and use of tri-functional linkers for surface complexation to both gold and silver nanoparticles is reported. These molecules confer excellent stability towards nanoparticles ensuring particle monodispersity in biological buffers, and also incorporate dyes to allow use of the functionalised nanoparticles as SERRS reporters. Biomolecule conjugation and quantitation has been illustrated using Alexafluor 680 labelled streptavidin. Variation of the chromophore has been introduced, which allows for exquisite control of the SERRS by manipulation of laser wavelength. This demonstrates the potential of SERRS functionalised nanoparticles for multiple, simultaneous monitoring of excitation events, an area of research where the capability of molecular fluorophores and quantum dots is limited. [ABSTRACT FROM AUTHOR]

Although different kinds of film materials and some modification techniques are applied for the development of protein-film electrochemistry, the design of a more ordered adsorption platform with improved sensitivity is still required. Here we employ single-strand DNA (ssDNA)-functionalized gold nanoparticles as scaffolds for the construction of a multilayered uniform self-assembled structure viathe hybridization of complementary ssDNA. After adsorbing with native conformation onto the uniformly built electrode, cytochrome cresponded very well in voltammetry experiments. The peak currents increase with the addition of the number of gold nanoparticle layers, which indicates that the multilayer gold nanoparticles not only provide a compatible microenvironment for the protein to undergo direct electron transfer reactions but also amplify the electrochemical signals by increasing the binding sites for the protein immobilization. Furthermore, ultra-sensitive detection of cytochrome cby using this multilayer gold nanoparticle-modified electrode is carried out. The linear range is from 2 × 10−9to 1 × 10−7M with a detection limit of 6.7 × 10−10M. [ABSTRACT FROM AUTHOR]

A unique multilabeling at a single-site protocol of the Ru(bpy)32+electrochemiluminescence (ECL) system is proposed. Nanoparticles (NPs) were used as assembly substrates to enrich ECL co-reactants of Ru(bpy)32+to construct nanoscale-enhanced ECL labels. Two different kinds of NP substrates [including semiconductor NPs (CdTe) and noble metal NPs (gold)] capped with 2-(dimethylamino)ethanethiol (DMAET) [a tertiary amine derivative which is believed to be one of the most efficient of co-reactants of the Ru(bpy)32+system] were synthesized through a simple one-pot synthesis method in aqueous media. Although both CdTe and gold NPs realized the enrichment of ECL co-reactants, they presented entirely different ECL performances as nanoscale ECL co-reactants of Ru(bpy)32+. The different effects of these two NPs on the ECL of Ru(bpy)32+were studied. DMAET-capped CdTe NPs showed enormous signal amplification of Ru(bpy)32+ECL, whereas DMAET-capped gold NPs showed a slight quenching effect of the ECL signal. DMAET-capped CdTe NPs can be considered to be excellent nanoscale ECL labels of the Ru(bpy)32+system, as even a NP solution sample of 10−18M was still detectable after an electrostatic self-assembly concentration process. DMAET-capped CdTe NPs were further applied in the construction of aptamer-based biosensing system for proteins and encouraging results were obtained. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and magnetic properties of Fe nanoparticles containing an average of 55 and 147 atoms are described. The nanoparticles are prepared using dendrimer templates, and therefore they are nearly size-monodisperse. In the absence of oxygen and water, the Fe nanoparticles are stable, but they decompose quickly when exposed to air. Magnetic analysis indicates that the 55-atom nanoparticles are superparamagnetic, but the 147-atom materials undergo a transition to ferromagnetic at 6 K. Both materials exhibit suppression of the magnetic saturation compared to bulk Fe. [ABSTRACT FROM AUTHOR]

The article presents information on the composites of silicon nanoparticles that are highly dispersed in the graphene sheets aid in the storage capacities and cycling stability of lithium ion batteries. The graphene sheets are supported by a three-dimensional (3-D) network of graphite that is formed by the reconstitution of the regions of graphene stacks. Information on conducting the silicon structure with a carbonaceous layer is also presented.

A surfactant-free synthesis of mesoporous and hollow silica nanoparticles is reported in which boron acts as the templating agent. Using such a simple and mild procedure as a treatment with water, the boron-rich phase is selectively removed, affording mesoporous pure silica nanoparticles with wormhole-like pores or, depending on the synthetic conditions, silica nanoshells. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles with a two-dimensional center-rectangular (plane group c2mm) lattice and coiled elliptical channels have been synthesized; the new synthetic route also allows simple control over the lattice dimensions and the elliptical shape of the channels. [ABSTRACT FROM AUTHOR]

Here it is shown that the chemical nature of outer organic surfactant layers, used to stabilize inorganic nanoparticles (NPs), is a key factor controlling solubility in a mixed liquid CO2—heptane (10% vol) solvent. [ABSTRACT FROM AUTHOR]

The diversity of catalytic activities and antioxidant properties of cerium oxide nanoparticles (CeO2 NPs) makes them promising materials for the theranostics of various diseases, especially those caused by disturbances in free radical homeostasis in living systems. Despite the fact that the functionalisation of nanoparticles' surface plays a critical role in nanomedicine applications, the effect of different coatings on their enzyme-like behaviour and antioxidant properties is still poorly understood, which limits the biomedical application of CeO2 NPs. This paper reports on the effect of low and high molecular weight biocompatible ligands on the SOD-like activity and radical scavenging properties of CeO2 NPs, which was analysed using a phosphate-rich medium resembling a natural environment. The results obtained show that these ligands modulate the SOD-like properties of CeO2 NPs as follows. Citrate and polysaccharide (maltodextrin and dextran) surface coatings increase the SOD-like activity of CeO2 NPs by an average of 2.2 times, and the protein corona (γ-globulin, γ-IgG) increases this activity by an average of 1.8 times. Citrate-coated CeO2 NPs and CeO2 nanoparticles modified with polysaccharide molecules are more effective SOD mimetics than CeO2@γ-IgG NPs. The SOD-like activity of phosphatidylcholine-coated CeO2 and CeO2@γ-IgG NPs is due to the combined action of nanoscale CeO2 and ligands. The antioxidant activity of CeO2 NPs after their modification with different ligands with respect to alkyl peroxyl radicals is multidirectional. Unexpectedly, citrate-, maltodextrin- and dextran-coated CeO2 NPs are more effective antioxidants than bare CeO2 NPs. CeO2 NPs modified with phosphatidylcholine or γ-IgG exhibited less radical-scavenging ability than bare CeO2 nanoparticles. Thus, common biocompatible ligands are able to regulate the biochemical activity of CeO2 NPs. [ABSTRACT FROM AUTHOR]

Cerium vanadate nanoparticles (CeVO 4 NPs), which are members of the rare earth orthovanadate nanomaterial family, have generated considerable interest due to their diverse properties and prospective biomedical applications. The current study, which provides a comprehensive overview of the synthesis and characterization techniques for CeVO 4 NPs, emphasizes the sonochemical method as an efficient and straightforward technique for producing CeVO 4 NPs with tunable size and shape. This paper investigates the toxicity and biocompatibility of CeVO 4 NPs, as well as their antioxidant and catalytic properties, which allow them to modify the redox state of biological systems and degrade organic pollutants. In addition, the most recent developments in the medicinal applications of CeVO 4 NPs, such as cancer treatment, antibacterial activity, biosensing, and drug or gene delivery, are emphasized. In addition, the disadvantages of CeVO 4 NPs, such as stability, aggregation, biodistribution, and biodegradation, are outlined, and several potential solutions are suggested. The research concludes with data and recommendations for developing and enhancing CeVO 4 NPs in the biomedical industry.

Our paper describes the production and characterization of inhalable microparticles loaded with nanoparticles for the lung administration of rapamycin (Rapa). In detail, core-shell lipid/polymer hybrid nanoparticles loaded with Rapa (Rapa@Man-LPHNPs) were produced with mean size of about 128 nm and slightly negative ζ potential (-13.8 mV). A fluorescent graft polyaspartamide-poly(lactic- co -glycolic acid) copolymer (PHEA- g -RhB- g -PLGA) for use as the polymeric core was obtained by nanoprecipitation, while an appropriate mixture of DPPC and mannosylated phospholipid (DSPE-PEG 2000 -Man) was used to provide the macrophage-targeting lipid shell. The successful formation of Rapa@Man-LPHNPs was confirmed by TEM and DSC analyses. The loaded drug (4.3 wt% of the total weight) was slowly released from the polymeric core and protected from hydrolysis, with the amount of intact drug after 24 h of incubation in the medium being equal to 74 wt% (compared to 40% when the drug is freely incubated at the same concentration). To obtain a formulation administrable by inhalation, Rapa@Man-LPHNPs were entrapped inside PVA : LEU microparticles by using the nano into micro (NiM) strategy, specifically by spray drying (SD) in the presence of a pore-forming agent. In this way, NiM particles with geometric and theoretical aerodynamic diameters equal to 4.52 μm and 3.26 μm, respectively, were obtained. Furthermore, these particles showed optimal nebulization performance, having an FPF and an MMAD equal to 27.5% and 4.3 μm, respectively.

Ferroptosis is a new form of non-apoptotic programmed cell death. Due to its effectiveness in cancer treatment, there are increasing studies on the application of nanoparticles based on ferroptosis in cancer therapy. In this paper, we present a summary of the latest progress in nanoparticles based on ferroptosis for effective tumor therapy. We also describe the combined treatment of ferroptosis with other therapies, including chemotherapy, radiotherapy, phototherapy, immunotherapy, and gene therapy. This summary of drug delivery systems based on ferroptosis aims to provide a basis and inspire opinions for researchers concentrating on exploring this field. Finally, we present some prospects and challenges for the application of nanotherapies to clinical treatment by promoting ferroptosis in cancer cells.

The optical properties and potential applications of metal nanostructures are mainly related to the unique surface plasmon resonance (SPR) effects that highly depend on the morphology, composition, assembly style and surrounding medium of metal nanostructures. Compared with monometallic nanoparticles, bimetallic composite nanostructures exhibit improved physicochemical properties. In this paper, the preparation and performance study of core–shell Au@Ag nanocuboids and open Au@Pd nanoframes were carried out based on Au nanorods with different aspect ratios. The co-reduction method was applied to control the deposition of Ag atoms on the surface of Au nanorods to obtain Au@Ag nanocuboids. The nanocuboids have flat surfaces and exhibit an adjustable SPR effect in a wide spectral region. Moreover, they show an ultra-sensitive response to the change of the surrounding medium. The refractive index sensitivity of the Au@Ag nanocuboids is better than that of the Au nanorods. Due to the rich edges and sharp corners, this Au@Ag nanocuboid structure can also be used as a hard template for further growth of highly active nanoframes. Then we controlled the deposition of Pd atoms on the surface, especially the edge parts, of Au@Ag nanocuboids. A new nanostructure of open Au@AgPd nanoframes was constructed after selectively etching the Ag shell. These open nanoframes not only show strong SPR properties similar to Au nanorods, but also exhibit excellent catalytic performance in the electrocatalytic reaction of ethanol. This work provides an idea for designing efficient sensors and nanocatalysts. [ABSTRACT FROM AUTHOR]

In this focus article, we provide a scrutinizing analysis of transmission electron microscopy (TEM) and dynamic light scattering (DLS) as the two common methods to study the sizes of nanoparticles with focus on the application in pharmaceutics and drug delivery. Control over the size and shape of nanoparticles is one of the key factors for many biomedical systems. Particle size will substantially affect their permeation through biological membranes. For example, an enhanced permeation and retention effect requires a very narrow range of sizes of nanoparticles (50-200 nm) and even a minor deviation from these values will substantially affect the delivery of drug nanocarriers to the tumour. However, amazingly a great number of research papers in pharmaceutics and drug delivery report a striking difference in nanoparticle size measured by the two most popular experimental techniques (TEM and DLS). In some cases, this difference was reported to be 200-300%, raising the question of which size measurement result is more trustworthy. In this focus article, we primarily focus on the physical aspects that are responsible for the routinely observed mismatch between TEM and DLS results. Some of these factors such as concentration and angle dependencies are commonly underestimated and misinterpreted. We convincingly show that correctly used experimental procedures and a thorough analysis of results generated using both methods can eliminate the DLS and TEM data mismatch completely or will make the results much closer to each other. Also, we provide a clear roadmap for drug delivery and pharmaceutical researchers to conduct reliable DLS measurements.

The main emphasis of the present Highlight paper is to summarise reported works aiming to understand the effect of sulfur and nitrogen doping on graphene nanoplatelets for high capacity electrodes in solid-state rechargeable energy storage devices. Lithium-ion batteries are considered to be one of the most promising energy storage devices which have the potential of integrating the high energy granted by lithium-ion batteries and long cycling life of supercapacitors in the same system. However, the present Li-ion batteries provide only high power density due to the low electrical conductivity of the anode materials. Moreover, there is a need to increase the capacity and kinetic imbalances between the anode and cathode by designing high-power and stable structures for the anode and cathode materials. Graphene nanoplatelets (GnPs) have been intensively explored as anode materials in lithium ion batteries due to their unique structure and outstanding electrochemical properties. The synthesis procedure, structure and electrochemical performance of such materials are discussed extensively in this manuscript. [ABSTRACT FROM AUTHOR]

Crocin, the main component of the gardenia yellow pigment, is a rare natural water-soluble carotenoid that is effective in treating many diseases owing to its excellent anti-oxidant properties. Developing simple methods for the sensitive detection of crocin is thus of great significance. In this study, green fluorescent silicon nanoparticles (SiNPs) with good water dispersibility were synthesized via a one-pot hydrothermal method by using N-[3-(trimethoxysilyl)propyl]-ethylenediamine (DAMO) as a silicon source and 4,6-diaminoresorcinol dihydrochloride as a reducing agent. Under excitation at 437 nm, the SiNPs emitted bright green fluorescence at 513 nm. The SiNPs revealed robust photo-stability, as well as excellent salt and temperature stability. Interestingly, the fluorescence of the SiNPs was positively sensitive to the solution pH, making them a promising probe for pH sensing. Moreover, the fluorescence of the SiNPs could be dramatically quenched by crocin. Employing the SiNPs as a fluorescent probe, a novel fluorescence method for the accurate and quantitative detection of crocin was established with a linear range of 0.01–17 μM and a limit of detection (LOD) of 3.3 nM. In addition, the quenching mechanism was also discussed. The proposed method was successfully utilized for the accurate detection of the gardenia yellow pigment in three traditional Chinese herbs. In addition, a paper sensor based on the SiNPs was also developed for rapid and convenient detection of crocin by the naked eye. [ABSTRACT FROM AUTHOR]

Easy movement of oxidized Galinstan in microfluidic channels is a promising way for the wide application of the non-toxic liquid metal. In this paper, two different surface modification techniques (physical and chemical) are reported, which dramatically improve the non-wetting characteristics of oxidized Galinstan in the microfluidic channel. In the physical technique, normal paper textures are transferred to the inner wall of polydimethylsiloxane (PDMS) channels and four types of nanoparticles are then coated on the surface of the wall for further improvement of the non-wetting characteristics. Highest advancing angle of 167° and receding angle of 151° are achieved on the paper-textured PDMS with titanium oxide (TiO2) nanoparticles. In the chemical technique, three types of inorganic acids are employed to generate dual-scale structures on the PDMS surface. The inner wall surface treated with sulfuric acid (H2SO4) shows the highest contact angle of 167° and a low hysteresis of ~14° in the dynamic measurement. Creating, transporting, separating and merging of oxidized Galinstan droplets are successfully demonstrated in the fabricated PDMS microfluidic channels. After optimization of these modification techniques, the potential application of tunable capacitors and electronic filters is realized by using liquid metal-based microfluidic devices. [ABSTRACT FROM AUTHOR]

Photocatalytic reduction of CO2 to valuable carbon fuel is a prospective technique to decrease CO2 emissions and simultaneously generate efficient chemical energy. In this paper, a novel high-efficiency photocatalyst ZIF-8@CeO2 heterogeneous composite (ZIF = zeolitic imidazolate framework) was prepared by the hydrothermal method, where CeO2 nanospheres were uniformly grown on the surface of ZIF-8. Compared to pristine ZIF-8 or CeO2 nanoparticles (NPs), the ZIF-8@CeO2 composite shows significantly better efficiency in the reduction of CO2 into CO and CH4 under light irradiation, that is the CO evolution rate can reach 465.01 μmol g−1 h−1 and the CH4 evolution rate can reach 181.27 μmol g−1 h−1. Analyses indicated that the addition of CeO2 in the composites will expand the photoresponse region; the formation of the ZIF-8/CeO2 heterojunction significantly promoted the separation of photogenerated electron–hole pairs within the composite. This work provided an effective method to further improve the catalytic activity of ZIF-based materials, which paved a new way for eco-friendly conversion of carbon dioxide into clean fuels and they could also have huge potential for application in energy and environmental science. [ABSTRACT FROM AUTHOR]

In this paper, using a molten salt process, nickel cobaltite nanoparticles were successfully synthesized for the first time from non-standard reagents. Diverse techniques were applied for the characterization of this multifunctional nanomaterial. TGA shows the thermal behavior of the mixed non-annealed powder. XRD, FTIR, TEM, EDS, XPS, and MPMS were used to characterize the composition, structural properties, morphology, oxidation states, and magnetic measurements of the prepared samples, respectively. All the analyzed results indicated that the NiCo2O4 nanoparticles were successfully obtained with a spinel structure and a high purity at 300 1C. The two M-O absorption bands characteristic of the NiCo2O4 spinel structure are detected. The nanoparticles have a hexagonal and spherical morphology with an average size close to 7 nm. EDS spectra confirm the purity of the nickel cobaltite. The magnetic measurements illustrate a ferrimagnetic behavior of NiCo2O4 at room temperature. This work presents a very promising approach for the first-time synthesis of multifunctional nickel cobaltite nanoparticles from non-standard reagents that are very competitive in many electrochemical applications as supercapacitors. [ABSTRACT FROM AUTHOR]

Hyperlipidemia is a lipid metabolism disorder that requires long-term and daily medication. Leonurine (Leo), an active alkaloid derived from Herba leonuri , can effectively ameliorate lipid profiles in mammals and serve as a candidate antihyperlipidemic agent for clinical applications. In this paper, poly(lactic- co -glycolic acid) (PLGA) microsphere (MP)-based drug delivery platforms were for the first time employed for hyperlipidemia management by encapsulating leonurine nanocrystals (Leo-nano) by a modified solid-in-oil-in-water (S/O/W) double emulsion-solvent emulsion technique. The optimal formulation (Leo-nano@MP) was characterized by a high drug loading and encapsulation efficiency of 19.90 ± 0.82% and 79.62 ± 3.57%, respectively, which followed first-order drug release kinetics over 20 days in vitro . Interestingly, Leo-nano@MP exhibited a unique morphology with a condensed surface yet a porous internal structure, which potentially contributed to the enhanced drug loading and release properties. Furthermore, subcutaneous injection of Leo-nano@MP every two weeks significantly ameliorated the lipid profiles and alleviated liver and kidney injury in HFD-fed rats in comparison with daily administration of free Leo. Besides, no abnormalities in the heart, lung, spleen, and skin tissues at injection sites were observed. In summary, Leo-nano@MP with enhanced therapeutic efficacy, reduced administration frequency, and good biosafety constitutes a promising sustained-release platform for hyperlipidemia management.

White light emission from a pristine, solid material is currently the biggest challenge in the lighting industry. In this paper we report for the first time highly reproducible, stable, and intense white phosphorescence (∼4–32 μs) from phase-pure zinc oxide (ZnO) nanopowder synthesized by a simple, low temperature process. The structure and morphology were studied by XRD, FESEM, and TEM. The white light consisted of narrow blue (centered at ∼425 nm) and broad yellow-orange (centered at ∼625 nm) photoluminescence and the best result was observed at (0.36,0.33) in the CIE plot. The presence of zinc interstitial (Zni) and oxygen interstitial (Oi) defects responsible for such white phosphorescence was confirmed by EDX, XPS, and Raman studies. The visibly bright white emission has appreciable quantum yield (∼12–14%) and cool/near cool correlated color temperature, rendering it suitable for W-LED applications. Further, a defect chemistry-based thermodynamic interpretation was invoked to adequately explain the white emission. [ABSTRACT FROM AUTHOR]

This paper describes the preparation of poly(succinimide) nanoparticles (PSI NPs) and investigates their properties and characteristics. Employing direct and inverse precipitation methods, stable PSI NPs with tunable size and narrow dispersity were prepared without the use of any stabilizer or emulsifier. It was demonstrated that PSI NPs convert to poly(aspartic acid) (PASP) gradually under physiological conditions (37 °C, pH 7.4), while remaining stable under mildly acidic conditions. The dissolution profile was tuned and delayed by chemical modification of PSI. Through grafting a fluorophore to the PSI backbone, it was also demonstrated that such a spontaneous conversion could offer great potential for oral delivery of therapeutic agents to the colon. Sustained PASP synthesis also contributed to a sustained reduction of reactive oxygen species induced by iron. Furthermore, PSI NPs effectively prevented in vitro calcification of smooth muscle cells. This was attributed to the chelation of calcium ions to PASP, thereby inhibiting calcium deposition, because under cell culture conditions PSI NPs serve as reservoirs for the sustained synthesis of PASP. Overall, this study sheds light on the preparation and features of biocompatible and biodegradable PSI-based NPs and paves the way for further research to discover as-yet unfulfilled potential of this polymer in the form of nanoparticles.

In recent years, titanium(IV) dioxide nanoparticles (TiO 2 NPs) have shown promising potential in various biological applications such as antimicrobials, drug delivery, photodynamic therapy, biosensors, and tissue engineering. For employing TiO 2 NPs in these fields, their nanosurface must be coated or conjugated with organic and/or inorganic agents. This modification can improve their stability, photochemical properties, biocompatibility, and even surface area for further conjugation with other molecules such as drugs, targeting molecules, polymers, etc. This review describes the organic-based modification of TiO 2 NPs and their potential applications in the mentioned biological fields. In the first part of this review, around 75 recent publications (2017-2022) are mentioned on the common TiO 2 NP modifiers including organosilanes, polymers, small molecules, and hydrogels, which improve the photochemical features of TiO 2 NPs. In the second part of this review, we presented 149 recent papers (2020-2022) about the use of modified TiO 2 NPs in biological applications, in which specific bioactive modifiers are introduced in this part with their advantages. In this review, the following information is presented: (1) the common organic modifiers for TiO 2 NPs, (2) biologically important modifiers and their benefits, and (3) recent publications on biological studies on the modified TiO 2 NPs with their achievements. This review shows the paramount significance of the organic-based modification of TiO 2 NPs to enhance their biological effectiveness, paving the way toward the development of advanced TiO 2 -based nanomaterials in nanomedicine.

It is very important to reduce the oxidation of free radicals in organic membrane materials for the stability and safety of drinking water production treatment processes. This paper presents a new method for the qualitative and quantitative determination of free radicals in sodium hypochlorite solution by electron spin resonance (ESR) and salicylic acid spectrophotometry. Experiments show that the free radical scavenging rate reaches over 86% after the addition of 0.5 wt% nano-particles. PVDF–PVP/TiO2 and PVDF–PVP/CNT modified membranes are prepared by blending polyvinylidene fluoride (PVDF) with nano titanium dioxide (nano-TiO2) and carboxyl-modified multi-wall carbon nanotubes (MWCNTs-COOH), and are treated in 2000 ppm sodium hypochlorite solution for 30 days. Through surface chemistry (FTIR, XRD), surface morphology (SEM), surface hydrophilicity (contact angle), surface electronegative (zeta potential) and mechanical properties tests, the changes of membrane properties are analyzed during aging. The experimental results show that the nano-particles have a quenching effect on free radicals and inhibit defluorination. It has been proved that under the action of nano-additives, the erosion of free radicals on the membrane material is reduced, the aging rate of the membrane material is decreased, and the chemical stability of the membrane material is improved. In this paper, the reason and mechanism of anti-aging of the nano-particle modified membrane are analyzed, which provides theoretical support for future membrane cleaning technology and prolonging the service life of the membrane. [ABSTRACT FROM AUTHOR]