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Effect of physicochemical properties including dissociation constant (pKa) and partition coefficient (log P) of the compounds on their extraction efficiency in sample preparation using fibrous polymer sorbents has been demonstrated. Poly-ε-caprolactone as meltblown/electrospun composite fibers, and polypropylene, polyethylene, poly(3-hydroxybutyrate), poly(lactic acid), and polyamide 6 in the meltblown fiber format were used as sorbents in solid-phase extraction. In addition, the polycaprolactone fibers were coated with dopamine, dopamine combined with heparin, and tannin, respectively, to modify their extraction properties. These fibers that were not yet used for extractions and the unique combination of sorbents and analytes significantly extends the scope of nanofibrous extraction. The extraction efficiency was determined using model pharmaceuticals including acetylsalicylic acid, moxonidine, metoprolol, propranolol, propafenone, diltiazem, atorvastatin, and amiodarone. These model compounds displayed the widest differences in both pKa and log P values. The extraction efficiency of some of the fibers reached 96.64%. Coating of polycaprolactone fibers with dopamine significantly improved extraction efficiency of slightly retained metoprolol while moxonidine was not retained on any sorbent. The fibrous sorbents were also tested for extraction of pharmaceuticals in bovine serum albumin and human serum, respectively, to demonstrate their capability to extract them from a complex protein-containing matrix. The clean-up efficiency of our fibers was compared with that of a commercial restricted access media (RAM) C-18 alkyl-diol silica column. Our technique is in accordance with the requirements of modern sample preparation techniques., (Copyright © 2021 Elsevier B.V. All rights reserved.)

This study presents the advantages of combining three-dimensional biodegradable scaffolds with the injection bioprinting of hydrogels. This combination takes advantage of the synergic effect of the properties of the various components, namely the very favorable mechanical and structural properties of fiber scaffolds fabricated from polycaprolactone and the targeted injection of a hydrogel cell suspension with a high degree of hydrophilicity. These properties exert a very positive impact in terms of promoting inner cell proliferation and the ability to create compact tissue. The scaffolds were composed of a mixture of microfibers produced via meltblown technology that ensured both an optimal three-dimensional porous structure and sufficient mechanical properties, and electrospun nanofibers that allowed for good cell adhesion. The scaffolds were suitable for combination with injection bioprinting thanks to their mechanical properties, i.e., only one nanofibrous scaffold became deformed during the injection process. A computer numerical-control manipulator featuring a heated printhead that allowed for the exact dosing of the hydrogel cell suspension into the scaffolds was used for the injection bioprinting. The hyaluronan hydrogel created a favorable hydrophilic ambiance following the filling of the fiber structure. Preliminary in vitro testing proved the high potential of this combination with respect to the field of bone tissue engineering. The ideal structural and mechanical properties of the tested material allowed osteoblasts to proliferate into the inner structure of the sample. Further, the tests demonstrated the significant contribution of printed hydrogel-cell suspension to the cell proliferation rate. Thus, the study led to the identification of a suitable hydrogel for osteoblasts.

Melt blowing is the most common technique to directly produce nonwovens from polymeric resins without any demand for extra bonding steps. The relatively low diameter of meltblown fibers, 1–2 μm, makes them superior in separations performance to the competing melt processing technique, spun-bonding. To further decrease meltblown fiber diameter, the islands-in-the-sea approach was investigated in this study. Immiscible blends of a water-soluble polymer, sulfonated poly(ethylene terephthalate) (SP), and hydrophilic polybutylene terephthalate (PBT) and hydrophobic polyvinylidene fluoride (PVDF) were meltblown and the SP washed away to produce nanofibers of less than 200 nm diameter. Despite a significant increase in blend drop size upon increasing the minor phase fraction, ϕ , the nanofiber diameter increased only slightly. Thus, we conjecture that nanofiber diameter is mainly controlled by fiber pinch-off, induced by quick stretching during the melt blowing process, rather than being affected by initial drop size. At a high shear viscosity ratio, η minor /η matrix  > 3, nanofibers showed a higher level of irregularities, particularly when the polymer flow rate decreased. At ϕ  ≥ 0.2 fiber bundling was observed but with nanofibers from PVDF, due to its lower surface energy, compared with PBT, bundling decreased. Our work shows that using polymers with relatively low surface energy, and thus low tendency for coalescence, coupled with low viscosity can result in nonwoven mats of fibers with very low average diameter, low bundling, and an acceptable fiber regularity. With PVDF we achieved a record low average diameter of 36 nm. By using a water-soluble polymer matrix, such as sulfonated poly(ethylene terephthalate), concerns about cost and environmental problems related to chemical solvents are alleviated. [ABSTRACT FROM AUTHOR]