Spray-Dried Hierarchical Aggregates of Iron Oxide Nanoparticles and Their Functionalization for Downstream Processing in Biotechnology

Influence of cation concentration and valence on the structure and texture of spray-dried supraparticles from colloidal silica dispersions

The structure and texture of supraparticles determine their properties and performance, thus playing a critical role in research studies as well as industrial applications. The addition of salts is a well-known strategy to manipulate the colloidal stability of nanoparticles. In this study, this approach is used to tune the structure of spray-dried supraparticles. Three different salts (NaCl, CaCl2, and AlCl3) were added to binary silica (SiO2) nanoparticle dispersions (of 40 and 400 nm in size) to change their colloidal stability by lowering the electrostatic repulsion or enhancing the cation bridging. Dependent on the cation valence of the added salt and the nanoparticle size, the critical salt concentration, which yields nanoparticle agglomeration, is reached at different salt amounts. This phenomenon is exploited to tune the final structure of supraparticles - obtained by spray-drying binary dispersions - from core-shell to Janus-like to well-mixed structures. This consequently also tunes textural properties, like surface roughness and the pore system of the obtained supraparticles. Our results provide insights for controlling the structure of spray-dried supraparticles by manipulating the stability of binary nanoparticle dispersions, and they establish a framework for composite particle design.

Sustainable gliadin - Metal oxide composites for efficient inactivation of Escherichia coli and remediation of cobalt (II) from water

Bio-based materials facilitate greener approach to engineering novel materials with multifunctional properties for various applications including water treatment. In this study, we extracted gliadin from wheat gluten using alcoholic solvent. The aggregation limitations of gliadin protein were overcome by functionalisation with metal oxides (MOs) TiO2, AgFe2O3 and AgFe-TiO2 prepared by chemical precipitations. The novel composites were characterised by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), thermogravimetry analysis (TGA), Brunauer Emmet-Teller (BET), and zeta potential. The multifunctionality of MOs-gliadin composites was tested through toxic Escherichia coli (E. coli) inactivation and Co2+ adsorption from water. The antibacterial results showed excellent inhibition under both dark and light conditions. The maximum Co2+ uptake, 101 mg/g was reached with TiO2@gliadin after 24 h and best fitted the Langmuir isotherm model. The adsorption process followed pseudo-second order model with an equilibrium adsorption capacity, qe2= 89.86 mg/g closer to the experimental data. Thermodynamic investigations indicated that ΔG°=-9.677kJ/mol,ΔH°=-123kJ/mol,and ΔS°=0.490J.K/mol, respectively, suggesting that adsorption was spontaneous and endothermic. The regenerated TiO2@gliadin composite was still efficient after five consecutive cycles. This study demonstrates that MOs-gliadin blended composites are sustainable for water purification.

Low-Gradient Magnetophoresis of Nanospheres and Nanorods through a Single Layer of Paper

The possible magnetophoretic migration of iron oxide nanoparticles through the cellulosic matrix within a single layer of paper is challenging with its underlying mechanism remained unclear. Even with the recent advancements of theoretical understanding on magnetophoresis, mainly driven by cooperative and hydrodynamics phenomena, the contributions of these two mechanisms on possible penetration of magnetic nanoparticles through cellulosic matrix of paper have yet been proven. Here, by using iron oxide nanoparticles (IONPs), both nanospheres and nanorods, we have investigated the migration kinetics of these nanoparticles through grade 4 Whatman filter paper with a particle retention of 20-25 μm. By performing droplet tracking experiments, the real-time stained area growth of the particle droplet on the filter paper, under the influences of a grade N40 NdFeB magnet, were recorded. Our results show that the spatial and temporal expansion of the IONP stain is biased toward the magnet and such an effect is dependent on (i) particle concentration and (ii) particle shape. The kinetics data were first analyzed by treating it as a radial wicking fluid, and later the IONP distribution within the cellulosic matrix was investigated by optical microscopy. The macroscopic flow front velocities of the stained area ranged from 259 μm/s to 16 040 μm/s. Moreover, the microscopic magnetophoretic velocity of nanorod cluster was also successfully measured as ∼214 μm/s. Findings in this work have indirectly revealed the strong influence of cooperative magnetophoresis and the engineering feasibility of paper-based magnetophoretic technology by taking advantage of magnetoshape anisotropy effect of the particles.

From Meso to Macro: Controlling Hierarchical Porosity in Supraparticle Powders

A drying droplet containing colloidal particles can consolidate into a spherical assembly called a supraparticle. Such supraparticles are inherently porous due to the spaces between the constituent primary particles. Here, the emergent, hierarchical porosity in spray-dried supraparticles is tailored via three distinct strategies acting at different length scales. First, mesopores (<10 nm) are introduced via the primary particles. Second, the interstitial pores are tuned from the meso- (35 nm) to the macro scale (250 nm) by controlling the primary particle size. Third, defined macropores (>100 nm) are introduced via templating polymer particles, which can be selectively removed by calcination. Combining all three strategies creates hierarchical supraparticles with fully tailored pore size distributions. Moreover, another level of the hierarchy is added by fabricating supra-supraparticles, using the supraparticles themselves as building blocks, which provide additional pores with micrometer dimensions. The interconnectivity of the pore networks within all supraparticle types is investigated via detailed textural and tomographic analysis. This work provides a versatile toolbox for designing porous materials with precisely tunable, hierarchical porosity from the meso- (3 nm) to the macroscale (≈10 µm) that can be utilized for applications in catalysis, chromatography, or adsorption.

Functional Nanomaterials in Biomedicine: Current Uses and Potential Applications

Nanomaterials, that is, materials made up of individual units between 1 and 100 nanometers, have lately involved a lot of attention since they offer a lot of potential in many fields, including pharmacy and biomedicine, owed to their exceptional physicochemical properties arising from their high surface area and nanoscale size. Smart engineering of nanostructures through appropriate surface or bulk functionalization endows them with multifunctional capabilities, opening up new possibilities in the biomedical field such as biosensing, drug delivery, imaging, medical implants, cancer treatment and tissue engineering. This article highlights up-to-date research in nanomaterials functionalization for biomedical applications. A summary of the different types of nanomaterials and the surface functionalization strategies is provided. Besides, the use of nanomaterials in diagnostic imaging, drug/gene delivery, regenerative medicine, cancer treatment and medical implants is reviewed. Finally, conclusions and future perspectives are provided.

Surface Engineering of Nanomaterials with Polymers, Biomolecules, and Small Ligands for Nanomedicine

Nanomedicine is a speedily growing area of medical research that is focused on developing nanomaterials for the prevention, diagnosis, and treatment of diseases. Nanomaterials with unique physicochemical properties have recently attracted a lot of attention since they offer a lot of potential in biomedical research. Novel generations of engineered nanostructures, also known as designed and functionalized nanomaterials, have opened up new possibilities in the applications of biomedical approaches such as biological imaging, biomolecular sensing, medical devices, drug delivery, and therapy. Polymers, natural biomolecules, or synthetic ligands can interact physically or chemically with nanomaterials to functionalize them for targeted uses. This paper reviews current research in nanotechnology, with a focus on nanomaterial functionalization for medical applications. Firstly, a brief overview of the different types of nanomaterials and the strategies for their surface functionalization is offered. Secondly, different types of functionalized nanomaterials are reviewed. Then, their potential cytotoxicity and cost-effectiveness are discussed. Finally, their use in diverse fields is examined in detail, including cancer treatment, tissue engineering, drug/gene delivery, and medical implants.

In-Vitro Application of Magnetic Hybrid Niosomes: Targeted siRNA-Delivery for Enhanced Breast Cancer Therapy

Even though the administration of chemotherapeutic agents such as erlotinib is clinically established for the treatment of breast cancer, its efficiency and the therapy outcome can be greatly improved using RNA interference (RNAi) mechanisms for a combinational therapy. However, the cellular uptake of bare small interfering RNA (siRNA) is insufficient and its fast degradation in the bloodstream leads to a lacking delivery and no suitable accumulation of siRNA inside the target tissues. To address these problems, non-ionic surfactant vesicles (niosomes) were used as a nanocarrier platform to encapsulate Lifeguard (LFG)-specific siRNA inside the hydrophilic core. A preceding entrapment of superparamagnetic iron-oxide nanoparticles (FexOy-NPs) inside the niosomal bilayer structure was achieved in order to enhance the cellular uptake via an external magnetic manipulation. After verifying a highly effective entrapment of the siRNA, the resulting hybrid niosomes were administered to BT-474 cells in a combinational therapy with either erlotinib or trastuzumab and monitored regarding the induced apoptosis. The obtained results demonstrated that the nanocarrier successfully caused a downregulation of the LFG gene in BT-474 cells, which led to an increased efficacy of the chemotherapeutics compared to plainly added siRNA. Especially the application of an external magnetic field enhanced the internalization of siRNA, therefore increasing the activation of apoptotic signaling pathways. Considering the improved therapy outcome as well as the high encapsulation efficiency, the formulated hybrid niosomes meet the requirements for a cost-effective commercialization and can be considered as a promising candidate for future siRNA delivery agents.