Accelerated Formation of H2 Nanobubbles from a Surface Nanodroplet Reaction

The compartmentalization of chemical reactions within droplets has advantages in low costs, reduced consumption of reagents, and increased throughput. Reactions in small droplets have also been shown to greatly accelerate the rate of many chemical reactions. The accelerated growth rate of nanobubbles from nanodroplet reactions is demonstrated in this work. The gaseous products from the reaction at the nanodroplet surface promoted nucleation of hydrogen nanobubbles within multiple organic liquid nanodroplets. The nanobubbles were confined within the droplets and selectively grew and collapsed at the droplet perimeter, as visualized by microscopy with high spatial and temporal resolutions. The growth rate of the bubbles was significantly accelerated within small droplets and scaled inversely with droplet radius. The acceleration was attributed to confinement from the droplet volume and effect from the surface area on the interfacial chemical reaction for gas production. The results of this study provide further understanding for applications in droplet enhanced production of nanobubbles and the on-demand liberation of hydrogen.

Comparative Analysis of Machine Learning Models for Nanofluids Viscosity Assessment

The process of selecting a nanofluid for a particular application requires determining the thermophysical properties of nanofluid, such as viscosity. However, the experimental measurement of nanofluid viscosity is expensive. Several closed-form formulas for calculating the viscosity have been proposed by scientists based on theoretical and empirical methods, but these methods produce inaccurate results. Recently, a machine learning model based on the combination of seven baselines, which is called the committee machine intelligent system (CMIS), was proposed to predict the viscosity of nanofluids. CMIS was applied on 3144 experimental data of relative viscosity of 42 different nanofluid systems based on five features (temperature, the viscosity of the base fluid, nanoparticle volume fraction, size, and density) and returned an average absolute relative error (AARE) of 4.036% on the test. In this work, eight models (on the same dataset as the one used in CMIS), including two multilayer perceptron (MLP), each with Nesterov accelerated adaptive moment (Nadam) optimizer; two MLP, each with three hidden layers and Adamax optimizer; a support vector regression (SVR) with radial basis function (RBF) kernel; a decision tree (DT); tree-based ensemble models, including random forest (RF) and extra tree (ET), were proposed. The performance of these models at different ranges of input variables was assessed and compared with the ones presented in the literature. Based on our result, all the eight suggested models outperformed the baselines used in the literature, and five of our presented models outperformed the CMIS, where two of them returned an AARE less than 3% on the test data. Besides, the physical validity of models was studied by examining the physically expected trends of nanofluid viscosity due to changing volume fraction.

Metals by Micro-Scale Additive Manufacturing: Comparison of Microstructure and Mechanical Properties

Many emerging applications in microscale engineering rely on the fabrication of 3D architectures in inorganic materials. Small-scale additive manufacturing (AM) aspires to provide flexible and facile access to these geometries. Yet, the synthesis of device-grade inorganic materials is still a key challenge toward the implementation of AM in microfabrication. Here, a comprehensive overview of the microstructural and mechanical properties of metals fabricated by most state-of-the-art AM methods that offer a spatial resolution ≤10 μm is presented. Standardized sets of samples are studied by cross-sectional electron microscopy, nanoindentation, and microcompression. It is shown that current microscale AM techniques synthesize metals with a wide range of microstructures and elastic and plastic properties, including materials of dense and crystalline microstructure with excellent mechanical properties that compare well to those of thin-film nanocrystalline materials. The large variation in materials' performance can be related to the individual microstructure, which in turn is coupled to the various physico-chemical principles exploited by the different printing methods. The study provides practical guidelines for users of small-scale additive methods and establishes a baseline for the future optimization of the properties of printed metallic objects-a significant step toward the potential establishment of AM techniques in microfabrication.

Hydroxyapatite as a biomaterial - a gift that keeps on giving

The synthetic analogue to biogenic apatite, hydroxyapatite (HA) has a number of physicochemical properties that make it an attractive candidate for diagnosis, treatment of disease and augmentation of biological tissues. Here we describe some of the recent studies on HA, which may provide bases for a number of new medical applications. The content of this review is divided to different medical application modes utilizing HA, including tissue engineering, medical implants, controlled drug delivery, gene therapies, cancer therapies and bioimaging. A number of advantages of HA over other biomaterials emerge from this discourse, including (i) biocompatibility, (ii) bioactivity, (iii) relatively simple synthesis protocols for the fabrication of nanoparticles with specific sizes and shapes, (iv) smart response to environmental stimuli, (v) facile functionalization and surface modification through noncovalent interactions, and (vi) the capacity for being simultaneously loaded with a wide range of therapeutic agents and switched to bioimaging modalities for uses in theranostics. A special section is dedicated to analysis of the safety of particulate HA as a component of parenterally administrable medications. It is concluded that despite the fact that many benefits come with the usage of HA, its deficiencies and potential side effects must be addressed before the translation to the clinical domain is pursued. Although HA has been known in the biomaterials world as the exemplar of safety, this safety proves to be the function of size, morphology, surface ligands and other structural and compositional parameters defining the particles. For this reason, each HA, especially when it comes in a novel structural form, must be treated anew from the safety research angle before being allowed to enter the clinical stage.

Rapid Intestinal Uptake and Targeted Delivery to the Liver Endothelium Using Orally Administered Silver Sulfide Quantum Dots

Quantum dots (QDs) are used for imaging and transport of therapeutics. Here we demonstrate rapid absorption across the small intestine and targeted delivery of QDs with bound materials to the liver sinusoidal endothelial cells (LSECs) or hepatocytes in vitro and in vivo following oral administration. QDs were radiolabeled with ³H-oleic acid, with a fluorescent tag or ¹⁴C-metformin placed within a drug binding site. Three different biopolymer shell coatings were compared (formaldehyde-treated serum albumin (FSA), gelatin, heparin). Passage across the small intestine into mesenteric veins is mediated by clathrin endocytosis and micropinocytosis. 60% of an oral dose of QDs was rapidly distributed to the liver within 30 min, and this increased to 85% with FSA biopolymer coating. Uptake into LSECs also increased 3-fold with FSA coating, while uptake into hepatocytes was increased from 40% to 85% with gelatin biopolymer coating. Localization of QDs to LSECs was confirmed with immunofluorescence and transmission electron microscopy. 85% of QDs were cleared within 24 h of administration. The bioavailability of ¹⁴C-metformin 2 h post-ingestion was increased 5-fold by conjugation with QD-FSA, while uptake of metformin into LSECs was improved 50-fold by using these QDs. Endocytosis of QDs by SK-Hep1 cells (an LSEC immortal cell line) was via clathrin- and caveolae-mediated pathways with QDs taken up into lysosomes. In conclusion, we have shown high specificity targeting of the LSEC or hepatocytes after oral administration of QDs coated with a biopolymer layer of FSA or gelatin, which improved the bioavailability and delivery of metformin to LSECs.

MALDI Mass Spectrometry of Small Molecules Using Nanometer-sized Clay

Nanometer-sized clay, allophane, was used as the matrix for matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) and applied to the ionization of small molecules. First, the laser desorption ionization mass spectrum of cation-exchanged allophane was measured, and it was found that the cation exchange proceeded smoothly with increasing atomic number of alkali metals in the periodic table. This phenomenon was explained by considering the size of the counter anion on the allophane surface. Then, fructose was measured as the analyte using each alkali-cation-exchanged allophane as the matrix. Contrary to the measurements using allophane itself, the peak intensity of fructose decreased with increasing atomic number of alkali metals in the periodic table. This phenomenon was clarified by considering the stability of alkali cation in the presence of a surface anion, the desorption energy, and the solvation enthalpy of each alkali cation. The applicability of allophane to high molecular weight compounds was also confirmed by measuring cyclodextrin, angiotensin II, and insulin. Finally, a combination of allophane and zeolite was examined by assuming proton relay among allophane, zeolite, and analyte. As a result of proton supply from zeolite to allophane, the peak intensity of the proton sponge (1,8-bis(dimethylamino)naphthalene) was enhanced by almost 2.2 times.

Selenium-Nanoparticles-Loaded Chitosan/Chitooligosaccharide Microparticles and Their Antioxidant Potential: A Chemical and In Vivo Investigation

Selenium nanoparticles (SeNPs) have attracted attention due to their favorable properties, unique bioactivities, and potential for use in nutritional supplements and nanomedicine applications. However, the application of SeNPs in the clinic has been greatly hindered by their poor stability, and their potential to protect against alcohol-induced oxidative stress has not been fully investigated. Herein, SeNPs were synthesized in the presence of chitosan (CS) or chitooligosaccharide (COS), and a mixture of SeNPs, CS, and COS was spray-dried to prepare selenium-nanoparticles-loaded chitosan/chitooligosaccharide microparticles (SeNPs-CS/COS-Ms). Their physicochemical properties, including morphology, elemental state, size distribution, surface potential, and characteristic structure, were investigated. The release of SeNPs from the vehicle and the free radical scavenging ability of SeNPs-CS/COS-Ms were also studied. Furthermore, the safety of SeNPs-CS/COS-Ms and their antioxidant activity against alcohol were evaluated in mice. The results indicate that SeNPs-CS/COS-Ms, with a novel structure characterized by their smooth or wrinkled surface, hollow core, and COS body filled with SeNPs-CS nanobeads, were able to release SeNPs and scavenge DPPH and superoxide anion radicals. SeNPs-CS/COS-Ms were found to be much safer than selenite, and they might protect mice from ethanol-induced oxidative stress by reducing lipid and protein oxidation and by boosting glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT). In conclusion, SeNPs-CS/COS-Ms offer a new way to develop stable SeNPs with higher efficacy and better biosafety, and the antioxidant potential of SeNPs-CS/COS-Ms against ethanol deserves further development.

Corrigendum: Osteoblast-Derived Vesicle Protein Content Is Temporally Regulated During Osteogenesis: Implications for Regenerative Therapies

[This corrects the article DOI: 10.3389/fbioe.2019.00092.].

Facile Synthesis of Uniform Metal Carbide Nanoparticles from Metal-Organic Frameworks by Laser Metallurgy

We report the fast and efficient conversion of metal-organic frameworks (MOFs) to phase pure transition-metal carbide (TMC) nanoparticles with uniform size using laser as the energy source, consuming only 6 W power. Nanoparticles of HfC, ZrC, TiC, V₈C₇, α-MoC, Cr₃C₂, and FeC_x with homogeneous sizes (varied between 6 and 20 nm) were successfully produced, among which HfC and ZrC nanoparticles were obtained, for the first time, with sizes less than 10 nm and in the pure phase. This method was operated directly in air, in stark contrast to traditional furnace heating and laser spray methods, where a protective atmosphere is required. The use of MOFs allowed us to precisely tune the composition of TMC nanoparticles by dialing in the right type and desirable amounts of organic linkers. FeC_x nanoparticles doped with various percentages of nitrogen atoms were synthesized for the Fischer-Tropsch reaction without any pretreatment or activation. Extremely high iron time of yield (FTY) values were observed, 415 and 550 μmol g_Fe^-1 s^-1 (with addition of K), in a 40 h test without any decay in performance. A high olefin to paraffin ratio was achieved for C₂ to C₁₁ products, where the ratio for C₃ was higher than 10.

Western Blotting with Solutions containing Nanoliter Volumes of Antibody

Whether screening small mammal serum during antibody production or attempting to preserve a stock of precious antibody, this protocol's western blotting method using aliquots containing nanoliter volumes of antibody will benefit researchers. Time-tested western blotting workflows allowing separation and analysis of proteins are routinely utilized in clinical and laboratory settings. The necessity for relatively large quantities of antibody is a major limitation to this universal tool. This article provides a step-by-step protocol for detecting proteins of interest with solutions containing nanoliter volumes of antibody without altering the preceding gel electrophoresis and transfer methods. Important considerations, frequently encountered problems, and means of optimizing reproducibility are discussed. Complementary diagrams, images, and videos are provided. The protocol is demonstrated using 0.3 nanoliters of anti-serum to detect fibronectin in a human foreskin fibroblast cell line. Finally, two support protocols detailing methods of extracting proteins from cultured cells are reported. Published 2019. This article is a US Government work and is in the public domain in the USA.

Stainless Steel as A Bi-Functional Electrocatalyst-A Top-Down Approach

For a hydrogen economy to be viable, clean and economical hydrogen production methods are vital. Electrolysis of water is a promising hydrogen production technique with zero emissions, but suffer from relatively high production costs. In order to make electrolysis of water sustainable, abundant, and efficient materials has to replace expensive and scarce noble metals as electrocatalysts in the reaction cells. Herein, we study activated stainless steel as a bi-functional electrocatalyst for the full water splitting reaction by taking advantage of nickel and iron suppressed within the bulk. The final electrocatalyst consists of a stainless steel mesh with a modified surface of layered NiFe nanosheets. By using a top down approach, the nanosheets stay well anchored to the surface and maintain an excellent electrical connection to the bulk structure. At ambient temperature, the activated stainless steel electrodes produce 10 mA/cm² at a cell voltage of 1.78 V and display an onset for water splitting at 1.68 V in 1M KOH, which is close to benchmarking nanosized catalysts. Furthermore, we use a scalable activation method using no externally added electrocatalyst, which could be a practical and cheap alternative to traditionally catalyst-coated electrodes.

Safety assessment of the substance, titanium dioxide surface treated with fluoride-modified alumina, for use in food contact materials

This scientific opinion of the EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP Panel) is a safety assessment of the additive titanium dioxide surface treated with fluoride‐modified alumina, a defined mixture of particles of which ■■■■■% in number have a diameter in the range of 1–100 nm. It is intended to be used as filler and colourant up to 25% w/w in potentially all polymer types. Materials and articles containing the additive are intended to be in contact with all food types for any time and temperature conditions. The data provided demonstrate that the additive particles stay embedded even in swollen polar polymers such as polyamide, and do not migrate. Moreover, the additive particles resisted release by abrasion and did not transfer into a simulant for solid/dry foods. Thus, the additive particles do not give rise to exposure via food and to toxicological concern. Migration of solubilised ionic fluoride and aluminium occurs from the surface of the additive particles and particularly from swollen plastic. The Panel concluded that the substance does not raise safety concern for the consumer if used as an additive up to 25% w/w in polymers in contact with all food types for any time and temperature conditions. However, uses in polar polymers swelling in contact with foodstuffs simulated by 3% acetic acid should be limited to conditions simulated by contact up to 4 h at 100°C. This is due to the fact that when used at 25%, and contact was followed by 10 days at 60°C, the migration of aluminium and fluoride largely exceeded the specific migration limit (SML) of 1 and 0.15 mg/kg food, respectively. The Panel emphasises that the existing SMLs for aluminium and fluoride should not be exceeded in any case.

DNA-Based Photoacoustic Nanosensor for Interferon Gamma Detection

Tracking protein levels in the body is vital in both research and medicine, where understanding their physiological roles provides insight into their regulation in homeostasis and diseases. In medicine, protein levels are actively sampled since they continuously fluctuate, reflecting the status of biological systems and provide insight into patient health. One such protein is interferon gamma, a clinically relevant protein with immunoregulatory functions that play critical roles against infection. New tools for continuously monitoring protein levels in vivo are invaluable in monitoring real-time conditions of patients to allow better care. Here, we developed a DNA-based nanosensor for the photoacoustic detection of interferon gamma. This work demonstrates how we transformed a simple DNA motif, receptors, and a novel phthalocyanine dye into a proof-of-concept photoacoustic nanosensor for protein detection. Surface plasmon resonance kinetic analysis demonstrated that the nanosensor is responsive and reversible to interferon gamma with an affinity in the nanomolar range, K_D1 = 167 nM and K_D2 = 316 nM. As a reporter, our design includes a novel phthalocyanine-based photoacoustic dye that stacks in a J-aggregate, causing a 22.5% increase in signal. Upon receptor binding, the DNA structure bends to induce phthalocyanine dye stacking, resulting in a 55% increase in photoacoustic signal in the presence of 10 μM interferon gamma. This proof-of-concept nanosensor is a novel approach to the development of a photoacoustic sensor and may be adapted for other proteins of interest in the future for in vivo tracking.

Osteoblast-Derived Vesicle Protein Content Is Temporally Regulated During Osteogenesis: Implications for Regenerative Therapies

Osteoblast-derived extracellular vesicles (EV) are a collection of secreted (sEVs) and matrix-bound nanoparticles that function as foci for mineral nucleation and accumulation. Due to the fact sEVs can be isolated directly from the culture medium of mineralizing osteoblasts, there is growing interest their application regenerative medicine. However, at present therapeutic advancements are hindered by a lack of understanding of their precise temporal contribution to matrix mineralization. This study advances current knowledge by temporally aligning sEV profile and protein content with mineralization status. sEVs were isolated from mineralizing primary osteoblasts over a period of 1, 2, and 3 weeks. Bimodal particle distributions were observed (weeks 1 and 3: 44 and 164 nm; week 2: 59 and 220 nm), indicating a heterogeneous population with dimensions characteristic of exosome- (44 and 59 nm) and microvesicle-like (164 and 220 nm) particles. Proteomic characterization by liquid chromatography tandem-mass spectrometry (LC-MS/MS) revealed a declining correlation in EV-localized proteins as mineralization advanced, with Pearson correlation-coefficients of 0.79 (week 1 vs. 2), 0.6 (2 vs. 3) and 0.46 (1 vs. 3), respectively. Principal component analysis (PCA) further highlighted a time-dependent divergence in protein content as mineralization advanced. The most significant variations were observed at week 3, with a significant (p < 0.05) decline in particle concentration, visual evidence of EV rupture and enhanced mineralization. A total of 116 vesicle-localized proteins were significantly upregulated at week 3 (56% non-specifically, 19% relative to week 1, 25% relative to week 2). Gene ontology enrichment analysis of these proteins highlighted overrepresentation of genes associated with matrix organization. Of note, increased presence of phospholipid-binding and calcium channeling annexin proteins (A2, A5, and A6) indicative of progressive variations in the nucleational capacity of vesicles, as well as interaction with the surrounding ECM. We demonstrate sEV-mediated mineralization is dynamic process with variations in vesicle morphology and protein content having a potential influence on developmental changes matrix organization. These findings have implications for the selection and application of EVs for regenerative applications.

Agglomeration of 10 nm amine-functionalized nano-magnetite does not hinder its efficiency as an environmental adsorbent

Amine-functionalized magnetite (nFe₃O₄-NH₂) of two different sizes, 10 nm and 250 nm, were compared as environmental adsorbents. They were synthesized by co-precipitation (10 nm-nFe₃O₄-NH₂) and solvothermal (250 nm-nFe₃O₄-NH₂) methods, respectively. The prepared amine-functionalized magnetite was characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, vibrating sample magnetometer, Fourier transform infrared spectroscopy, size distribution analysis and surface area analysis to compare the properties of different sizes of nFe₃O₄-NH₂. Both nFe₃O₄-NH₂ contained cubic Fe₃O₄ crystalline structure. The 250 nm-nFe₃O₄-NH₂ exhibited higher magnetic saturation value than the 10 nm-nFe₃O₄-NH₂, but both could be separated from an aqueous solution using an external magnet. The surface area and pore volume of the smaller-sized 10 nm-nFe₃O₄-NH₂ was larger than that of 250 nm-nFe₃O₄-NH₂, but stronger aggregation was observed in the 10 nm-nFe₃O₄-NH₂. Batch adsorption of lead indicated that the 10 nm-nFe₃O₄-NH₂ was a better adsorbent than the 250 nm-nFe₃O₄-NH₂. The maximum adsorption capacity of lead for the 10 nm-nFe₃O₄-NH₂ and the 250 nm-nFe₃O₄-NH₂ were 74.48 mg g^-1 and 54.54 mg g^-1, respectively. The stronger aggregation of nanoparticles with a smaller particle size did not affect the superior performance of the 10 nm-nFe₃O₄-NH₂ as an environmental adsorbent.

Performance Improvement of a Nonvolatile UV TD Sensor Using SAHAOS with a High Temperature Annealed, Partially Nano-Crystallized Trapping Layer

This study shows that a silicon⁻aluminum oxide⁻hafnium aluminum oxide-silicon oxide⁻silicon capacitor device with a high temperature pre-metal-anneal-treated and partially-nanocrystallized hafnium aluminum oxide, (hereafter PNC-SAHAOS) can successfully increase the performance of a nonvolatile ultraviolet radiation total dose (hereafter UV TD) sensor. The experimental results show that the UV-induced threshold voltage V_T shift of PNC-SAHAOS was 10 V after UV TD 100 mW·s/cm² irradiation. The UV-induced charge density of PNC-SAHAOS is almost eight times that of amorphous silicon⁻aluminum oxide⁻silicon nitride⁻silicon dioxide⁻silicon SANOS. Moreover, the charge fading rate of ten-years retention on PNC-SAHAOS, even at 85 °C, is below 10%. At 85 °C, the charge fading rate of ten-years retention on amorphous SANOS is almost twice that on PNC-SAHAOS. These results strongly suggest that PNC-SAHAOS could be the most promising candidate for next-generation nonvolatile UV TD sensor technology.

Safety assessment of the substance, montmorillonite clay modified with hexadecyltrimethylammonium bromide, for use in food contact materials

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of montmorillonite clay modified with hexadecyltrimethylammonium bromide (HDTA) when used as an additive at up to ■■■■■ in polylactic acid (PLA) bottles intended for contact with water for long‐term storage at ambient temperature or below. The modified clay, which 90% w/w of the particles have a dimension of 33.1 μm or less and the average size is 9 μm, has a layered structure with layers of a thickness below 100 nm. When incorporated in PLA, nanosized layers can be dispersed in the matrix, but are not expected to migrate. Thermal degradation is not expected at the maximum manufacturing temperature. No loss of integrity of the PLA surface due to interaction with bottled water was observed. The overall migration was very low. No migration of HDTA was detected at the limit of detection ■■■■■. Migration of aluminium was below or at the limit of detection ■■■■■, which would conservatively correspond to approximately ■■■■■. Comparative analysis of bottled water with and without the modified clay did not reveal additional peaks corresponding to impurities identified in the modifier and/or in the modified clay. Moreover, ■■■■■, and the modifier HDTA have been evaluated and authorised. Therefore, the CEP Panel concluded that the substance montmorillonite clay modified with HDTA bromide is not of safety concern for the consumer if the substance is used as an additive at up to ■■■■■ in PLA plastic bottles and other containers intended for long‐term storage of water at ambient temperature or below, as requested by the applicant.

Nanoparticle drug delivery systems: an excellent carrier for tumor peptide vaccines

In the past 40 years, the nanoparticle drug delivery system for tumor peptide vaccines has been widely studied which also reached a splendid result. Nanomaterial can enhance the targeting of vaccines, help vaccines enter the cells and trigger immune response by themselves. They also help in increasing cellular uptake, improving permeability and efficacy. Currently, several categories of nanopreparation, such as liposome, polymeric micelle, polymeric nanoparticle, gold nanoparticle and so on, are proved that they are appropriate for peptide vaccines. This review we discussed the possible mechanisms of nanomaterial's action on the regulation of immunological functions and several major applications of this advanced drug delivery system for tumor peptide vaccine.

Breathable and Flexible Piezoelectric ZnO@PVDF Fibrous Nanogenerator for Wearable Applications

A novel breathable piezoelectric membrane has been developed by growing zinc oxide (ZnO) nanorods on the surface of electrospun poly(vinylidene fluoride) (PVDF) nanofibers using a low-temperature hydrothermal method. Significant improvement in the piezoelectric response of the PVDF membrane was achieved without compromising breathability and flexibility. PVDF is one of the most frequently used piezoelectric polymers due to its high durability and reasonable piezoelectric coefficient values. However, further enhancement of its piezoelectric response is highly desirable for sensor and energy-harvester applications. Previous studies have demonstrated that piezoelectric ceramic and polymer composites can have remarkable piezoelectric properties and flexibility. However, devices made of such composites lack breathability and some present health risks in wearable applications for containing heavy metals. Unlike other piezoelectric ceramics, ZnO is non-toxic material and has been widely used in many applications including cosmetics. The fabrication of ZnO@PVDF porous electrospun membrane involves a simple low-temperature ZnO growth in aqueous solution, which does not weaken the polarization of PVDF created during electrospinning in the high electric field.

Drug delivery across length scales

Over the last century, there has been a dramatic change in the nature of therapeutic, biologically active molecules available to treat disease. Therapies have evolved from extracted natural products towards rationally designed biomolecules, including small molecules, engineered proteins and nucleic acids. The use of potent drugs which target specific organs, cells or biochemical pathways, necessitates new tools which can enable controlled delivery and dosing of these therapeutics to their biological targets. Here, we review the miniaturisation of drug delivery systems from the macro to nano-scale, focussing on controlled dosing and controlled targeting as two key parameters in drug delivery device design. We describe how the miniaturisation of these devices enables the move from repeated, systemic dosing, to on-demand, targeted delivery of therapeutic drugs and highlight areas of focus for the future.

Sol-Gel-Synthesis of Nanoscopic Complex Metal Fluorides

The fluorolytic sol-gel synthesis for binary metal fluorides (AlF₃, CaF₂, MgF₂) has been extended to ternary and quaternary alkaline earth metal fluorides (CaAlF₅, Ca₂AlF₇, LiMgAlF₆). The formation and crystallization of nanoscopic ternary CaAlF₅ and Ca₂AlF₇ sols in ethanol were studied by ¹⁹F liquid and solid state NMR (nuclear magnetic resonance) spectroscopy, as well as transmission electron microscopy (TEM). The crystalline phases of the annealed CaAlF₅, Ca₂AlF₇, and LiMgAlF₆ xerogels between 500 and 700 °C could be determined by X-ray powder diffraction (XRD) and ¹⁹F solid state NMR spectroscopy. The thermal behavior of un-annealed nanoscopic ternary and quaternary metal fluoride xerogels was ascertained by thermal analysis (TG/DTA). The obtained crystalline phases of CaAlF₅ and Ca₂AlF₇ derived from non-aqueous sol-gel process were compared to crystalline phases from the literature. The corresponding nanoscopic complex metal fluoride could provide a new approach in ceramic and luminescence applications.

Nanoformulations of curcumin: an emerging paradigm for improved remedial application

Curcumin is a natural polyphenol and essential curcuminoid derived from the rhizome of the medicinal plant Curcuma longa (L.) is universally acknowledged as “Wonder drug of life”. It is a vital consumable and restorative herb, commonly keened for several ailments such as cancer, arthritis, pain, bruises, gastrointestinal quandaries, swelling and much more. Despite its enormous curative potential, the poor aqueous solubility and consequently, minimal systemic bioavailability with rapid degradation are some of the major factors which restrict the utilization of curcumin at medical perspective. However, to improve its clinically relevant parameters, nanoformulation of curcumin is emerging as a novel substitute for their superior therapeutic modality. It enhances its aqueous solubility and targeted delivery to the tissue of interest that prompts to enhance the bioavailability, better drug conveyance, and more expeditious treatment. Subsequent investigations are endeavored to enhance the bio-distribution of native curcumin by modifying with felicitous nano-carriers for encapsulation. In this review, we specifically focus on the recent nanotechnology based implementations applied for overcoming the innate constraints of native curcumin and additionally the associated challenges which restrict its potential therapeutic applications both in vivo and in-vitro studies, as well as their detailed mechanism of action, have additionally been discussed.

Preparation and antioxidant properties of selenium nanoparticles-loaded chitosan microspheres

Selenium nanoparticles (SeNPs), as a special form of selenium (Se) supplement, have attracted worldwide attention due to their favorable properties and unique bioactivities. Herein, an eco-friendly and economic way to prepare stable SeNPs is introduced. SeNPs were synthesized in aqueous chitosan (CTS) and then embedded into CTS microspheres by spray-drying, forming selenium nanoparticles-loaded chitosan microspheres (SeNPs-M). The physicochemical properties including morphology, elemental state, size distribution and surface potential were investigated. Institute of Cancer Research mice were used as model animal to evaluate the bioactivities of SeNPs-M. Trigonal-phase SeNPs of ~35 nm were synthesized, and SeNPs-M physically embedding those SeNPs were successfully prepared. Amazingly, acute toxicity test indicated that SeNPs-M were much safer than selenite in terms of Se dose, with a LD₅₀ of around 18-fold of that of selenite. In addition, SeNPs-M possessed powerful antioxidant activities, as evidenced by a dramatic increase of both Se retention and the levels of glutathione peroxidase, superoxide dismutase and catalase. The design of SeNPs-M can offer a new way for further development of SeNPs with a higher efficacy and better biosafety. Thus, SeNPs-M may be a potential candidate for further evaluation as an Se supplement with antioxidant properties and be used against Se deficiency in animals and human beings.

Vascular response profiles following a nano polymer-free sirolimus-eluting stent implantation assessed by optical coherence tomography in a porcine model

Optical coherence tomography (OCT) is a high resolution imaging modality and has been considered as the ideal tool for the evaluation of neointimal tissue and vascular responses following stent implantation. However, vascular response profiles following the implantation of a novel nano polymer-free sirolimus-eluting stent (SES) assessed by OCT has not been fully investigated. Therefore, the aim of the present study was to determine the effects of a nano polymer-free SES on neointimal formation using OCT. A total of 16 nano polymer-free SESs were implanted in the coronary arteries of 8 pigs. At 3 (n=4) or 6 months (n=4), the animals were euthanized following OCT evaluation and the stented arterial segments were analyzed by histological analysis. Neointimal area, thickness and burden were evaluated by OCT. In addition, strut-associated inflammation, stent endothelialization and arterial injury were investigated by histomorphological analysis. OCT examination showed that at 6 months, neointimal thickness (193.3±109.5 vs. 167.2±119.7 µm, P=0.023) and neointimal burden (29.3±14.3 vs. 24.8±17.4%, P=0.006) significantly increased compared with at 3 months. Histomorphological analysis indicated that the endothelialization score was significantly greater at 6 months compared with at 3 months (2.85±0.36 vs. 2.52±0.60, P<0.001). However, at 3 months, nano polymer-free SES showed a significantly higher inflammatory score [0 (0, 1) vs. 0 (0, 0), P<0.001] compared with at 6 months. In conclusion, nano polymer-free SES achieves endothelialization at 3 months; however, neointimal proliferation is more significant at 6 months and may be attributed to strut-associated inflammation.

Injection Molding Micro- and Nanostructures in Thermoplastic Elastomers

Flexible polymers such as poly dimethyl siloxane (PDMS) can be patterned at the micro- and nanoscale by casting, for a variety of applications. This replication-based fabrication process is relatively cheap and fast, yet injection molding offers an even faster and cheaper alternative to PDMS casting, provided thermoplastic polymers with similar mechanical properties can be used. In this paper, a thermoplastic polyurethane is evaluated for its patterning ability with an aim to forming the type of flexible structures used to measure and modulate the contractile forces of cells in tissue engineering experiments. The successful replication of grating structures is demonstrated with feature sizes as low as 100 nm and an analysis of certain processing conditions that facilitate and enhance the accuracy of this replication is presented. The results are benchmarked against an optical storage media grade polycarbonate.