Magnetic microparticles post-synthetically coated by hyaluronic acid as an enhanced carrier for microfluidic bioanalysis.

Iron oxide based particles functionalized by bioactive molecules have been utilized extensively in biotechnology and biomedicine. Despite their already proven advantages, instability under changing reaction conditions, non-specific sorption of biomolecules on the particles' surfaces, and iron oxide leakage from the naked particles can greatly limit their application. As confirmed many times, surface treatment with an appropriate stabilizer helps to minimize these disadvantages. In this work, we describe enhanced post-synthetic surface modification of superparamagnetic microparticles varying in materials and size using hyaluronic acid (HA) in various chain lengths. Scanning electron microscopy, atomic force microscopy, phase analysis light scattering and laser diffraction are the methods used for characterization of HA-coated particles. The zeta potential and thickness of HA-layer of HA-coated Dynabeads M270 Amine were -50 mV and 85 nm, respectively, and of HA-coated p(GMA-MOEAA)-NH2 were -38 mV and 140 nm, respectively. The electrochemical analysis confirmed the zero leakage of magnetic material and no reactivity of particles with hydrogen peroxide. The rate of non-specific sorption of bovine serum albumin was reduced up to 50% of the naked ones. The coating efficiency and suitability of biopolymer-based microparticles for magnetically active microfluidic devices were confirmed.

Cr(1/3)Zr2P3O12 with unusual tetrahedral coordination of Cr(III): peculiarities of the formation, thermal stability and application as a pigment.

All the known chromium(III) NASICON-related phosphates are considered to be solid solutions. In these compounds chromium atoms share their position in the basic framework of the crystal lattice with other structure forming elements such as zirconium. In our study, we have hypothesised a completely new way of structural organisation of the chromium(III) zirconium(IV) NASICON framework, consisting in the distribution of chromium over the charge-compensating atom sites with tetrahedral oxygen coordination. The possibility of formation of the corresponding phosphate, Cr(1/3)Zr2P3O12, was studied using a classical ceramic route and a sol-gel method. Structural affiliation of the obtained pure phase product was studied using XRD analysis. The results confirmed that the Cr(1/3)Zr2P3O12 phosphate belongs to monoclinic SW-subtype of the NASICON family. In this structure, chromium atoms occupy charge-compensating sites with a strongly distorted tetrahedral oxygen environment. To the best of our knowledge, it is the first example of tetrahedral coordination of chromium(III) in phosphates. Along with the unusual crystallographic characteristics of chromium, special attention in this paper is devoted to the thermal stability of this phosphate and to its performance as an inorganic pigment. The sample was characterised by heating microscopy and DTA study, particle size distribution analysis, and IR- and VIS-spectroscopy. The stability of the obtained powder in a glaze environment, its colouring performance and lightfastness are discussed as well.

Cryogenic grinding of electrospun poly-ε-caprolactone mesh submerged in liquid media.

In this paper, the treatment of poly-ε-caprolactone (PCL) nano/micro-mesh system by cryogenic grinding and subsequent characterization of obtained product is described. The PCL nano/micro-mesh layer submerged in appropriate liquid was cryogenically ground and obtained particles were characterized employing mainly laser diffraction and scanning electron microscopy (SEM). In the ground sample, different types of particles (fibrous particles, fibrous fragments, agglomerates with and without an internal fibrous structure, lamellae and nanoparticles) were identified, described and quantified. Parameters of cryogenic grinding (weight of sample, type of liquid medium, and influence of sample storage) were optimized to maximize the yield of particles with desired features. The potential of the system for cell scaffolding was demonstrated by cultivation of 3T3 fibroblasts on the produced microparticles.