Particulate Nanomaterials Research Articles

Bone mineral: A trojan horse for bone cancers. Efficient mitochondria targeted delivery and tumor eradication with nano hydroxyapatite containing doxorubicin

Efficient systemic pharmacological treatment of solid tumors is hampered by inadequate tumor concentration of cytostatics necessitating development of smart local drug delivery systems. To overcome this, we demonstrate that doxorubicin (DOX), a cornerstone drug used for osteosarcoma treatment, shows reversible accretion to hydroxyapatite (HA) of both nano (nHA) and micro (mHA) size. nHA particles functionalized with DOX get engulfed in the lysosome of osteosarcoma cells where the acidic microenvironment causes a disruption of the binding between DOX and HA. The released DOX then accumulates in the mitochondria causing cell starvation, reduced migration and apoptosis. The HA+DOX delivery system was also tested in-vivo on osteosarcoma bearing mice. Locally delivered DOX via the HA particles had a stronger tumor eradication effect compared to the controls as seen by PET-CT and immunohistochemical staining of proliferation and apoptosis markers. These results indicate that in addition to systemic chemotherapy, an adjuvant nHA could be used as a carrier for intracellular delivery of DOX for prevention of tumor recurrence after surgical resection in an osteosarcoma. Furthermore, we demonstrate that nHA particles are pivotal in this approach but a combination of nHA with mHA could increase the safety associated with particulate nanomaterials while maintaining similar therapeutic potential.

Conductive and Elastic TiO2 Nanofibrous Aerogels: A New Concept toward Self‐Supported Electrocatalysts with Superior Activity and Durability

AbstractRecently, various titanium dioxide (TiO2) nanostructures have received increasing attention in the fields of energy conversion and storage owing to their electrochemical properties. However, these particulate nanomaterials exclusively exist in the powder form, which may cause health risks and environmental hazards. Herein we report a novel, highly elastic bulk form of TiO2 for safe use and easy recycling. Specifically, TiO2 nanofibrous aerogels (NAs) consisting of resiliently bonded, flexible TiO2 nanofibers are constructed, which have an ultralow bulk density, ultrahigh porosity, and excellent elasticity. To promote charge transfer, they are subjected to lithium reduction to generate abundant oxygen vacancies, which can modulate the electronic structure of TiO2, resulting in a conductivity up to 38.2 mS cm−1. As a proof‐of‐concept demonstration, the conductive and elastic TiO2 NAs serve as a new type of self‐supported electrocatalyst for ambient nitrogen fixation, achieving an ammonia yield of 4.19×10−10 mol s−1 cm−2 and a Faradaic efficiency of 20.3 %. The origin of the electrocatalytic activity is revealed by DFT calculations.

Conductive and Elastic TiO2 Nanofibrous Aerogels: A New Concept toward Self-Supported Electrocatalysts with Superior Activity and Durability.

Recently, various titanium dioxide (TiO2 ) nanostructures have received increasing attention in the fields of energy conversion and storage owing to their electrochemical properties. However, these particulate nanomaterials exclusively exist in the powder form, which may cause health risks and environmental hazards. Herein we report a novel, highly elastic bulk form of TiO2 for safe use and easy recycling. Specifically, TiO2 nanofibrous aerogels (NAs) consisting of resiliently bonded, flexible TiO2 nanofibers are constructed, which have an ultralow bulk density, ultrahigh porosity, and excellent elasticity. To promote charge transfer, they are subjected to lithium reduction to generate abundant oxygen vacancies, which can modulate the electronic structure of TiO2 , resulting in a conductivity up to 38.2 mS cm-1 . As a proof-of-concept demonstration, the conductive and elastic TiO2 NAs serve as a new type of self-supported electrocatalyst for ambient nitrogen fixation, achieving an ammonia yield of 4.19×10-10 mol s-1 cm-2 and a Faradaic efficiency of 20.3 %. The origin of the electrocatalytic activity is revealed by DFT calculations.

Acoustofluidics Nanomaterial Synthesis: Acoustofluidic Synthesis of Particulate Nanomaterials (Adv. Sci. 19/2019)

In article number 1900913, Tony Jun Huang and co-workers utilize an acoustic-vortex-based active mixing strategy to demonstrate an acoustic-based platform capable of synthesizing particulate nanomaterials in a controllable and reproducible manner. This platform allows dynamic and independent dictation of the mixing process simply by adjusting the strength of the acoustic vortex. Using the platform, the synthesis of nanomaterials is demonstrated such as polymeric nanoparticles, chitosan nanoparticles, organic–inorganic hybrid nanomaterials, metal–organic frameworks biocomposites, and lipid–DNA complexes.

Acoustofluidic Synthesis of Particulate Nanomaterials.

Synthesis of nanoparticles and particulate nanomaterials with tailored properties is a central step toward many applications ranging from energy conversion and imaging/display to biosensing and nanomedicine. While existing microfluidics‐based synthesis methods offer precise control over the synthesis process, most of them rely on passive, partial mixing of reagents, which limits their applicability and potentially, adversely alter the properties of synthesized products. Here, an acoustofluidic (i.e., the fusion of acoustic and microfluidics) synthesis platform is reported to synthesize nanoparticles and nanomaterials in a controllable, reproducible manner through acoustic‐streaming‐based active mixing of reagents. The acoustofluidic strategy allows for the dynamic control of the reaction conditions simply by adjusting the strength of the acoustic streaming. With this platform, the synthesis of versatile nanoparticles/nanomaterials is demonstrated including the synthesis of polymeric nanoparticles, chitosan nanoparticles, organic–inorganic hybrid nanomaterials, metal–organic framework biocomposites, and lipid‐DNA complexes. The acoustofluidic synthesis platform, when incorporated with varying flow rates, compositions, or concentrations of reagents, will lend itself unprecedented flexibility in establishing various reaction conditions and thus enable the synthesis of versatile nanoparticles and nanomaterials with prescribed properties.

Physico-chemical properties of manufactured nanomaterials - Characterisation and relevant methods. An outlook based on the OECD Testing Programme

Identifying and characterising nanomaterials require additional information on physico-chemical properties and test methods, compared to chemicals in general. Furthermore, regulatory decisions for chemicals are usually based upon certain toxicological properties, and these effects may not be equivalent to those for nanomaterials. However, regulatory agencies lack an authoritative decision framework for nanomaterials that links the relevance of certain physico-chemical endpoints to toxicological effects. This paper investigates various physico-chemical endpoints and available test methods that could be used to produce such a decision framework for nanomaterials. It presents an overview of regulatory relevance and methods used for testing fifteen proposed physico-chemical properties of eleven nanomaterials in the OECD Working Party on Manufactured Nanomaterials' Testing Programme, complemented with methods from literature, and assesses the methods' adequacy and applications limits. Most endpoints are of regulatory relevance, though the specific parameters depend on the nanomaterial and type of assessment. Size (distribution) is the common characteristic of all nanomaterials and is decisive information for classifying a material as a nanomaterial. Shape is an important particle descriptor. The octanol-water partitioning coefficient is undefined for particulate nanomaterials. Methods, including sample preparation, need to be further standardised, and some new methods are needed. The current work of OECD's Test Guidelines Programme regarding physico-chemical properties is highlighted.

Thermo-elastic properties of random particulate nano-materials for various models of interphase

A mathematical model based on the method of conditional moments combined with a notion of the energy-equivalent inhomogeneity is adopted here in the investigation of the effective thermo-elastic properties of random nanomaterials. In the proposed model the inhomogeneities and their interphases with the matrix are replaced by energy-equivalent inhomogeneities with mechanical and thermal properties modified so as to incorporate the interphase effects. The effective coefficient of thermal expansion is subsequently determined by the method of conditional moments. Closed-form expression for the effective coefficient of thermal expansion of a composite consisting of a matrix and randomly distributed spherical inhomogeneities is derived for the Gurtin-Murdoch and spring layer model of interphases. Two numerical examples are presented to illustrate the quality of the approach.

The critical role of nanotube shape in cement composites

The growing availability of nanotubes and the increased knowledge about their loading in polymers have prompted the incorporation of nanotubes in cementitious matrices. The effects of loading straight tungsten di-sulfide nanotubes (WS2NT) or waved carbon nanotubes (CNT) in cementitious matrices was explored. Their inclusion in these composites at exceptionally low concentrations (0.063 vol% and 0.15 vol% for WS2NT and CNT, respectively) enhanced the composite’s mechanical properties, including compressive and flexural strengths (25–38%). Thermal analysis and electron microscopy indicated that nanotube incorporation in cementitious matrices also accelerated hydration reaction kinetics. It was shown that straight WS2NTs bridged pores and cracks more effectively than the waved CNTs, which resist crack propagation via an anchoring mechanism. A comparison to representative cement nanocomposite systems shows that nanotubes (aspect ratio≫1), offer better reinforcement efficiencies than particulate nanomaterials, yielding high mechanical properties enhancement at low concentration.

Influence of interfaces on effective properties of nanomaterials with stochastically distributed spherical inclusions

The method of conditional moments is generalized to include evaluation of the effective elastic properties of particulate nanomaterials and to investigate the size effect in those materials. Determining the effective constants necessitates finding a stochastically averaged solution to the fundamental equations of linear elasticity coupled with surface/interface conditions (Gurtin–Murdoch model). To obtain such a solution the system of governing stochastic differential equations is first transformed to an equivalent system of stochastic integral equations. Using statistical averaging, the boundary-value problem is then converted to an infinite system of linear algebraic equations. A two-point approximation is considered and the stress fluctuations within the inclusions are neglected in order to obtain a finite system of algebraic equations in terms of component-average strains. Closed-form expressions are derived for the effective moduli of a composite consisting of a matrix and randomly distributed spherical inhomogeneities. As a numerical example a nanoporous material is investigated assuming a model in which the interface effects influence only the bulk modulus of the material. In that model the resulting shear modulus is the same as for the material without surface effects. Dependence of the bulk moduli on the radius of nanopores and on the pore volume fraction is analyzed. The results are compared to, and discussed in the context of other theoretical predictions.

Emerging roles of engineered nanomaterials in the food industry

Nanoscience is the study of phenomena and the manipulation of materials at the atomic or molecular level. Nanotechnology involves the design, production and use of structures through control of the size and shape of the materials at the nanometre scale. Nanotechnology in the food sector is an emerging area with considerable research and potential products. There is particular interest in the definition and regulation of engineered nanomaterials. This term covers three classes of nanomaterials: natural and processed nanostructures in foods; particulate nanomaterials metabolized or excreted on digestion; and particulate nanomaterials not broken down on digestion, which accumulate in the body. This review describes examples of these classes and their likely status in the food industry.

Developing a Registry of Workers Involved in Nanotechnology

To assist BASF in the establishment of a registry of workers involved in nanotechnology. The initial step was a complete inventory of nanomaterials and sites of use. Guidance was developed to clarify which particulate nanomaterials were to be included in the survey. Site management was then contacted by the medical department to obtain a list of workers. The time line for collecting data ranged from several months to a year, depending on the information needed, and presented challenges based on the lack of global definition and labeling of nanomaterials. Less than 50 nanomaterials are used as raw materials in less than 10% of the sites globally. In North America, less than 5% of sites and 5% workers use nanomaterials. Further work is required to integrate the inventory, registry, and exposure assessments.