Filippo Pierini, Ph.D.

Department of Biosystems and Soft Matter (ZBiMM)
Division of Modelling in Biology and Medicine (PMBM)
position: assistant professor
telephone: (+48) 22 826 12 81 ext.: 423
room: 328
e-mail: fpierini

Doctoral thesis
2013-04-22Conductive Polymer Composites  (UB)
supervisor -- Norberto Roveri, UB
1241 
Recent publications
1.Pierini F., Lanzi M., Nakielski P., Pawłowska S., Urbanek O., Zembrzycki K., Kowalewski T.A., Single-Material Organic Solar Cells Based on Electrospun Fullerene-Grafted Polythiophene Nanofibers, Macromolecules, ISSN: 0024-9297, DOI: 10.1021/acs.macromol.7b00857, pp.1-10, 2017
Pierini F., Lanzi M., Nakielski P., Pawłowska S., Urbanek O., Zembrzycki K., Kowalewski T.A., Single-Material Organic Solar Cells Based on Electrospun Fullerene-Grafted Polythiophene Nanofibers, Macromolecules, ISSN: 0024-9297, DOI: 10.1021/acs.macromol.7b00857, pp.1-10, 2017

Abstract:
Highly efficient single-material organic solar cells (SMOCs) based on fullerene-grafted polythiophenes were fabricated by incorporating electrospun one-dimensional (1D) nanostructures obtained from polymer chain stretching. Poly(3-alkylthiophene) chains were chemically tailored in order to reduce the side effects of charge recombination which severely affected SMOC photovoltaic performance. This enabled us to synthesize a donor–acceptor conjugated copolymer with high solubility, molecular weight, regioregularity, and fullerene content. We investigated the correlations among the active layer hierarchical structure given by the inclusion of electrospun nanofibers and the solar cell photovoltaic properties. The results indicated that SMOC efficiency can be strongly increased by optimizing the supramolecular and nanoscale structure of the active layer, while achieving the highest reported efficiency value (PCE = 5.58%). The enhanced performance may be attributed to well-packed and properly oriented polymer chains. Overall, our work demonstrates that the active material structure optimization obtained by including electrospun nanofibers plays a pivotal role in the development of efficient SMOCs and suggests an interesting perspective for the improvement of copolymer-based photovoltaic device performance using an alternative pathway.

2.Urbanek O., Sajkiewicz P., Pierini F., Czerkies M., Kołbuk D., Structure and properties of polycaprolactone/chitosan nonwovens tailored by solvent systems, Biomedical Materials, ISSN: 1748-6041, DOI: 10.1088/1748-605X/aa5647, Vol.12, No.1, pp.015020-1-12, 2017
Urbanek O., Sajkiewicz P., Pierini F., Czerkies M., Kołbuk D., Structure and properties of polycaprolactone/chitosan nonwovens tailored by solvent systems, Biomedical Materials, ISSN: 1748-6041, DOI: 10.1088/1748-605X/aa5647, Vol.12, No.1, pp.015020-1-12, 2017

Abstract:
Electrospinning of chitosan blends is a reasonable idea to prepare fibre mats for biomedical applications. Synthetic and natural components provide, for example, appropriate mechanical strength and biocompatibility, respectively. However, solvent characteristics and the polyelectrolyte nature of chitosan influence the spinnability of these blends. In order to compare the effect of solvent on polycaprolactone/chitosan fibres, two types of the most commonly used solvent systems were chosen, namely 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and acetic acid (AA)/formic acid (FA). Results obtained by various experimental methods clearly indicated the effect of the solvent system on the structure and properties of electrospun polycaprolactone/chitosan fibres. Viscosity measurements confirmed different polymer–solvent interactions. Various molecular interactions resulting in different macromolecular conformations of chitosan influenced its spinnability and properties. HFIP enabled fibres to be obtained whose average diameter was less than 250 nm while maintaining the brittle and hydrophilic character of the nonwoven, typical for the chitosan component. Spectroscopy studies revealed the formation of chitosan salts in the case of the AA/FA solvent system. Chitosan salts visibly influenced the structure and properties of the prepared fibre mats. The use of AA/FA caused a reduction of Young's modulus and wettability of the proposed blends. It was confirmed that wettability, mechanical properties and the antibacterial effect of polycaprolactone/chitosan fibres may be tailored by selecting an appropriate solvent system. The MTT cell proliferation assay revealed an increase of cytotoxicity to mouse fibroblasts in the case of 25% w/w of chitosan in electrospun nonwovens.

Keywords:
chitosan, electrospinning, PCL/chitosan fibres, solvent system, chitosan salts

3.Lanzi M., Salatelli E., Di-Nicola F.P., Zuppiroli L., Pierini F., A new photocrosslinkable oligothiophene for organic solar cells with enhanced stability, MATERIALS CHEMISTRY AND PHYSICS, ISSN: 0254-0584, DOI: 10.1016/j.matchemphys.2016.10.034, Vol.186, pp.98-107, 2017
Lanzi M., Salatelli E., Di-Nicola F.P., Zuppiroli L., Pierini F., A new photocrosslinkable oligothiophene for organic solar cells with enhanced stability, MATERIALS CHEMISTRY AND PHYSICS, ISSN: 0254-0584, DOI: 10.1016/j.matchemphys.2016.10.034, Vol.186, pp.98-107, 2017

Abstract:
A novel thiophenic tetramer containing a cinnamate group in the side chain with a functionalization degree of 50% is reported. The tetramer was obtained by means of a simple and straightforward procedure involving the functionalization of a p-methoxyphenoxy substituted thiophenic precursor, which led to a soluble product with a good yield. The oligomer was fully characterized from a structural and chemical point of view and employed for the fabrication of small molecule organic solar cells exploiting the bulk heterojunction (BHJ) architecture. The presence of an UV-light sensitive group in the tetramer allowed the photocrosslinking of tetramer/PCBM blends, giving high values of photocurrent and conversion efficiency for the exposed samples. Moreover, the UV-treated devices showed improved stability, even upon heating for three days at 130 °C, thus confirming that photocrosslinking can strongly reduce phase segregation under severe operational conditions.

Keywords:
Electronic materials, Polymers, Fullerenes, Nanostructures, Electrical characterization, Semiconductors

4.Urbanek O., Pierini F., Choińska E., Sajkiewicz P., Bil M., Święszkowski W., Effect of hydroxyapatite nanoparticles addition on structure properties of poly(L-lactide-co-glycolide) after gamma sterilization, Polymer Composites, ISSN: 0272-8397, DOI: 10.1002/pc.24028, Vol.1, pp.1-9, 2016
Urbanek O., Pierini F., Choińska E., Sajkiewicz P., Bil M., Święszkowski W., Effect of hydroxyapatite nanoparticles addition on structure properties of poly(L-lactide-co-glycolide) after gamma sterilization, Polymer Composites, ISSN: 0272-8397, DOI: 10.1002/pc.24028, Vol.1, pp.1-9, 2016

Abstract:
Physical and chemical factors resulting from the sterilization methods may affect the structure and properties of the materials which undergo this procedure. Poly(l-lactide-co-glicolide) (PLGA) is commonly used for medical applications, but, due to its inadequate mechanical properties, it is not recommended for load-bearing applications. One of the methods for improving PLGA mechanical properties is addition of hydroxyapatite nanoparticles (nHAp). The aim of this study was to evaluate the effect of nanoparticles addition on PLGA structure and properties after gamma radiation. According to our results, reduction of the molecular mass caused by gamma radiation was lower for PLGA with nHAp addition. Differential scanning calorimetry (DSC) analysis indicates an increase of crystallinity caused both by nHAp and gamma radiation. The first phenomenon can be explained by heteronucleation, while the second one is most probably related to higher molecular mobility of degrading polymer. Moreover, addition of nanoparticles increases thermal stability and affects the Young's modulus changes after gamma radiation.

5.Pierini F., Lanzi M., Nakielski P., Pawłowska S., Zembrzycki K., Kowalewski T.A., Electrospun poly(3-hexylthiophene)/poly(ethylene oxide)/graphene oxide composite nanofibers: effects of graphene oxide reduction, Polymers for Advanced Technologies, ISSN: 1042-7147, DOI: 10.1002/pat.3816, Vol.27, No.11, pp.1465-1475, 2016
Pierini F., Lanzi M., Nakielski P., Pawłowska S., Zembrzycki K., Kowalewski T.A., Electrospun poly(3-hexylthiophene)/poly(ethylene oxide)/graphene oxide composite nanofibers: effects of graphene oxide reduction, Polymers for Advanced Technologies, ISSN: 1042-7147, DOI: 10.1002/pat.3816, Vol.27, No.11, pp.1465-1475, 2016

Abstract:
In this article, we report on the production by electrospinning of P3HT/PEO, P3HT/PEO/GO, and P3HT/PEO/rGO nanofibers in which the filler is homogeneously dispersed and parallel oriented along the fibers axis. The effect of nanofillers' presence inside nanofibers and GO reduction was studied, in order to reveal the influence of the new hierarchical structure on the electrical conductivity and mechanical properties. An in-depth characterization of the purity and regioregularity of the starting P3HT as well as the morphology and chemical structure of GO and rGO was carried out. The morphology of the electrospun nanofibers was examined by both scanning and transmission electron microscopy. The fibrous nanocomposites are also characterized by differential scanning calorimetry to investigate their chemical structure and polymer chains arrangements. Finally, the electrical conductivity of the electrospun fibers and the elastic modulus of the single fibers are evaluated using a four-point probe method and atomic force microscopy nanoindentation, respectively. The electrospun materials crystallinity as well as the elastic modulus increase with the addition of the nanofillers while the electrical conductivity is positively influenced by the GO reduction.

Keywords:
electrospun composite nanofibers, poly(3-hexylthiophene), graphene oxide, electrical conductivity, mechanical properties

6.Pierini F., Zembrzycki K., Nakielski P., Pawłowska S., Kowalewski T.A., Atomic force microscopy combined with optical tweezers (AFM/OT), MEASUREMENT SCIENCE AND TECHNOLOGY, ISSN: 0957-0233, DOI: 10.1088/0957-0233/27/2/025904, Vol.27, pp.025904-1-11, 2016
Pierini F., Zembrzycki K., Nakielski P., Pawłowska S., Kowalewski T.A., Atomic force microscopy combined with optical tweezers (AFM/OT), MEASUREMENT SCIENCE AND TECHNOLOGY, ISSN: 0957-0233, DOI: 10.1088/0957-0233/27/2/025904, Vol.27, pp.025904-1-11, 2016

Abstract:
The role of mechanical properties is essential to understand molecular, biological materials, and nanostructures dynamics and interaction processes. Atomic force microscopy (AFM) is the most commonly used method of direct force evaluation, but due to its technical limitations this single probe technique is unable to detect forces with femtonewton resolution. In this paper we present the development of a combined atomic force microscopy and optical tweezers (AFM/OT) instrument. The focused laser beam, on which optical tweezers are based, provides us with the ability to manipulate small dielectric objects and to use it as a high spatial and temporal resolution displacement and force sensor in the same AFM scanning zone. We demonstrate the possibility to develop a combined instrument with high potential in nanomechanics, molecules manipulation and biological studies. AFM/OT equipment is described and characterized by studying the ability to trap dielectric objects and quantifying the detectable and applicable forces. Finally, optical tweezers calibration methods and instrument applications are given.

Keywords:
optical trap, nanomanipulation, nanomechanics, femtonewton forces

7.Nakielski P., Pawłowska S., Pierini F., Liwińska W., Hejduk P., Zembrzycki K., Zabost E., Kowalewski T.A., Hydrogel nanofilaments via core-shell electrospinning, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0129816, Vol.10, No.6, pp.e0129816-1-16, 2015
Nakielski P., Pawłowska S., Pierini F., Liwińska W., Hejduk P., Zembrzycki K., Zabost E., Kowalewski T.A., Hydrogel nanofilaments via core-shell electrospinning, PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0129816, Vol.10, No.6, pp.e0129816-1-16, 2015

Abstract:
Recent biomedical hydrogels applications require the development of nanostructures with controlled diameter and adjustable mechanical properties. Here we present a technique for the production of flexible nanofilaments to be used as drug carriers or in microfluidics, with deformability and elasticity resembling those of long DNA chains. The fabrication method is based on the core-shell electrospinning technique with core solution polymerisation post electrospinning. Produced from the nanofibers highly deformable hydrogel nanofilaments are characterised by their Brownian motion and bending dynamics. The evaluated mechanical properties are compared with AFM nanoindentation tests.

Correction: Hydrogel Nanofilaments via Core-Shell Electrospinning, Nakielski P., Pawłowska S., Pierini F., Liwińska W., Hejduk P., Zembrzycki K., Zabost E., Kowalewski T.A., PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0133458, Vol.10, No.7, pp.e0133458-1-2, 2015

Keywords:
Gels, Nanomaterials, Atomic force microscopy, Polymerization, Bending, Mass diffusivity, Mechanical properties, Hydrodynamics

8.Pierini F., Lanzi M., Lesci I.G., Roveri N., Comparison between Inorganic Geomimetic Chrysotile and Multiwalled Carbon Nanotubes in the Preparation of One-dimensional Conducting Polymer Nanocomposites, Fibers and Polymers, ISSN: 1229-9197, DOI: 10.1007/s12221-015-0426-x, Vol.16, No.2, pp.426-433, 2015
Pierini F., Lanzi M., Lesci I.G., Roveri N., Comparison between Inorganic Geomimetic Chrysotile and Multiwalled Carbon Nanotubes in the Preparation of One-dimensional Conducting Polymer Nanocomposites, Fibers and Polymers, ISSN: 1229-9197, DOI: 10.1007/s12221-015-0426-x, Vol.16, No.2, pp.426-433, 2015

Abstract:
The aim of this study was to examine the role of the nanofillers spatial arrangement in the electrical properties of hybrid organic-inorganic fibers. In this paper, we have presented experimental results for preparation of fibers with a nanometric diameter based on a polyaniline/poly(ethylene oxide) doped blend and geomimetic chrysotile nanotubes. The nanostructured material was prepared using electrospinning techniques. Electrospun fibers made by pristine polymers and by the same blend loaded with carbon nanotubes were used as reference materials to compare the structural, and electrical properties of the novel organic-inorganic material. Generally, electrical properties were improved by the addition of materials that have high conductivity. Electrospun fibers filled with a traditional insulator like chrysotile have shown higher electrical conductivity than the pristine materials. In order to fully understand how structural variations impact upon the electrical conductivity the materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), differential scanning calorimetry (DSC) and four-point probe method. The results suggest that the occurred electrical conductivity gain could be attributed to parallel orientation of the chrysotile nanotubes and higher crystallinity induced by the one-dimensional nanostructured filler materials. The obtained results bring us one step closer to using intrinsically conducting polymers (ICPs) in the creation of functionalized polymeric nanocomposites for nanotechnology.

Keywords:
Nanocomposites, Conductive polymer, Electrospinning, Chrysotile, Carbon nanotubes

9.Lesci I.G., Balducci G., Pierini F., Soavi F., Roveri N., Surface features and thermal stability of mesoporous Fe doped geoinspired synthetic chrysotile nanotubes, Microporous and Mesoporous Materials, ISSN: 1387-1811, DOI: 10.1016/j.micromeso.2014.06.002, Vol.197, pp.8-16, 2014
Lesci I.G., Balducci G., Pierini F., Soavi F., Roveri N., Surface features and thermal stability of mesoporous Fe doped geoinspired synthetic chrysotile nanotubes, Microporous and Mesoporous Materials, ISSN: 1387-1811, DOI: 10.1016/j.micromeso.2014.06.002, Vol.197, pp.8-16, 2014

Abstract:
Synthetic mesoporous Fe doped geoinspired nanotubes have been utilized to evaluate the modification of the surface composition, morphology charge distribution and thermal stability as functions of the Fe doping extent and Fe prevalent substitution into the octahedral or tetrahedral sites. FTIR-ATR spectroscopy analysis has allowed to highlight the chrysotile structure modification by the Fe substitution to Mg or Si and to underline clearly the crucial role of the Fe doping in the octahedral sheet in modifying chrysotile structure and morphology. XPS analysis, ζ-potentials and porosity characterization have allowed to define the propriety of the chrysotile surface structure when iron replaces Mg in octahedral or Si in tetrahedral sites. DTA analysis has allowed to relate the effect of Fe doping on the chemical–physical characteristics of both synthetic and mineral chrysotile. We have observed that the simultaneous decrease in dehydroxylation and recrystallization temperature occurs when the Fe increases on surface and this is due to the increased substitution of Fe in octahedron. The results highlight the relevance to estimate the health hazard of the natural asbestos fibres by valuating the role of Fe surface throughout the use of geoinspired chrysotile synthesised under controlled stoichiometry and structure utilizing it as a selected reference standard.

Keywords:
Asbestos, Mesoporous synthetic chrysotile, Geoinspired inorganic nanotubes, Fe doped chrysotile, Surface functionalities

10.Lanzi M., Paganin L., Pierini F., Errani F., Di-Nicola F.P., Use of poly(3-methylthio)thiophene blends for direct laser tracing and bulck heterojunction solar cells, REACTIVE AND FUNCTIONAL POLYMERS, ISSN: 1381-5148, DOI: 10.1016/j.reactfunctpolym.2014.07.007, Vol.83, pp.33-41, 2014
Lanzi M., Paganin L., Pierini F., Errani F., Di-Nicola F.P., Use of poly(3-methylthio)thiophene blends for direct laser tracing and bulck heterojunction solar cells, REACTIVE AND FUNCTIONAL POLYMERS, ISSN: 1381-5148, DOI: 10.1016/j.reactfunctpolym.2014.07.007, Vol.83, pp.33-41, 2014

Abstract:
In this article we demonstrate the use of a blend made of two regioregular polythiophenic derivatives, namely poly(3-methylthio)thiophene and poly(3-hexyl)thiophene, to obtain conductive traces by the simple laser exposure of their thin films to a suitable laser source. The polymeric blend was also tested as a photoactive layer for BHJ solar cells, showing an improved surface morphology and a wider absorption spectrum, thus resulting in an enhanced photovoltaic performance. In the standard condition normally used for the cell preparation, we obtained a 3.16% power conversion efficiency. The device showed good reproducibility and stability over time.

Keywords:
Electrical conductivity, Laser tracing, Bulk heterojunction polymeric solar cells, Regioregular polyalkylthiophenes, Polymer blends

11.Lanzi M., Di-Nicola F.P., Livi M., Paganin L., Cappelli F., Pierini F., Synthesis and characterization of conjugated polymers for the obtainment of conductive patterns through laser tracing, JOURNAL OF MATERIALS SCIENCE, ISSN: 0022-2461, DOI: 10.1007/s10853-013-7204-1, Vol.48, pp.3877-3893, 2013
Lanzi M., Di-Nicola F.P., Livi M., Paganin L., Cappelli F., Pierini F., Synthesis and characterization of conjugated polymers for the obtainment of conductive patterns through laser tracing, JOURNAL OF MATERIALS SCIENCE, ISSN: 0022-2461, DOI: 10.1007/s10853-013-7204-1, Vol.48, pp.3877-3893, 2013

Abstract:
This article describes the preparation of thin films of conjugated polymers which can enhance their specific electrical conductivity by several orders of magnitude by changing their state from insulating to conducting materials. The examined polymers, i.e., a polyacetylenic and a polythiophenic derivative, are functionalized with thioalkylic side chains and are soluble in common organic solvents from which they lead to thick homogeneous films. The films can be deposited on different substrates, either rigid or flexible, and can be easily exposed to laser radiation to make them conductive. The process is irreversible, and the final conductivity is stable over time, even in the presence of high temperatures (up to 180°C), moisture, and air. The high stability of treated samples, easy polymer synthesis and quick and inexpensive suitably tailored laser tracing procedure make these materials very promising for applications in organic electronics and in the development of new electronic circuitry.

12.Pierini F., Foresti E., Fracasso G., Lesci I.G., Roveri N., Potential Technological Applications of Synthetic Geomimetic Nanotubes, ISRAEL JOURNAL OF CHEMISTRY, ISSN: 0021-2148, DOI: 10.1002/ijch.201000062, Vol.50, pp.484-499, 2010
Pierini F., Foresti E., Fracasso G., Lesci I.G., Roveri N., Potential Technological Applications of Synthetic Geomimetic Nanotubes, ISRAEL JOURNAL OF CHEMISTRY, ISSN: 0021-2148, DOI: 10.1002/ijch.201000062, Vol.50, pp.484-499, 2010

Abstract:
Geomimetic chrysotile nanotubes have a high potentiality in nanotechnological applications. These synthetic inorganic nanotubes can be used to prepare quantum wires with interesting electrical and optical properties. In fact, they behave as host systems, exhibiting a constant inner diameter inferior to 7 nm, a low tendency to aggregate and large inter-channel separation, preventing the interaction between individual guest filled nanomaterial acting as an unisosotropic confining structure. The chemical-physical properties of undoped and differently Fe doped geoinspired chrysotile synthetic nanotubes have been reviewed confirming that these characteristic features make synthetic chrysotile nanotubes excellent candidates to prepare innovative inorganic nanowires. Furthermore, the possibility to synthesize undoped geomimetic chrysotile nanotubes with high reproducibility and crystallinity avoids cytotoxicity, making them safe for human health.

Keywords:
chrysotile, geomimetic nanostructures, inorganic nanotubes, nanotechnology, nanowires


List of recent monographs
1.
471
Zembrzycki K., Pawłowska S., Nakielski P., Pierini F., Development of a hybrid Atomic Force microscope and Optical Tweezers apparatus , IPPT Reports on Fundamental Technological Research, 2, pp.1-58, 2016
List of chapters in recent monographs
1.
467
Kowalewski T.A., Nakielski P., Pierini F., Zembrzycki K., Pawłowska S., Advances in Mechanics: Theoretical, Computational and Interdisciplinary Issues, rozdział: Micro and nano fluid mechanics, CRC Press/Balkema, Taylor & Francis Group, M. Kleiber et al. (Eds.), pp.27-34, 2016

Conference abstracts
1.Pawłowska S., Nakielski P., Pierini F., Zembrzycki K., Piechocka I.K., Kowalewski T.A., Tumbling, rotating and coiling of nanofilaments in an oscillating microchannel flow, BioNano6, Biomolecules and Nanostructures 6, 2017-05-10/05-14, Podlesice (PL), No.41E, pp.60, 2017
2.Nakielski P., Pierini F., Piechocka I.K., Blood clotting in the contact with nanofibers, NanoTech, NanoTech Poland International Conference & Exhibition, 2017-06-01/06-03, Poznań (PL), pp.178-178, 2017
Nakielski P., Pierini F., Piechocka I.K., Blood clotting in the contact with nanofibers, NanoTech, NanoTech Poland International Conference & Exhibition, 2017-06-01/06-03, Poznań (PL), pp.178-178, 2017

Abstract:
Nanofibers have received considerable attention in the past years, mainly due to their vast application in medicine [1]. One of the fastest growing areas of application are wound dressings and hemostats. Among the major causes of death from trauma, massive bleeding is responsible for 30 – 40% of mortality. In the hospital, massive bleeding are the second most common cause of death (22%) just after cardiac factors (33%) [2].
Despite a large number of experiments done in the topic of blood-biomaterial interactions, coagulation mechanisms are still not fully understood. Therefore, the main objective of our work is the analysis of protein adsorption, platelet adhesion and aggregation, and blood plasma coagulation in the contact with polymer nanofibers. Various synthetic polymers, their blends with natural polymers of confirmed hemostatic effect e.g. collagen and gelatine, and additionally nanofibers made of chitosan are investigated for their potential to stop bleeding. In the final, controlled release of drugs affecting coagulation cascade will be an important step providing accelerated blood clot formation.

3.Pawłowska S., Nakielski P., Pierini F., Zembrzycki K., Kowalewski T.A., Mobility of highly deformable nanofilaments, ICTAM XXIV, 24th International Congress of Theoretical and Applied Mechanics, 2016-08-21/08-26, Montréal (CA), pp.1196-1197, 2016
Pawłowska S., Nakielski P., Pierini F., Zembrzycki K., Kowalewski T.A., Mobility of highly deformable nanofilaments, ICTAM XXIV, 24th International Congress of Theoretical and Applied Mechanics, 2016-08-21/08-26, Montréal (CA), pp.1196-1197, 2016

Abstract:
Mobility of hydrogel nanofilaments suspended in liquid is investigated to gain basic knowledge on hydrodynamic interactions biased by Brownian fluctuations. Typical for long macromolecules effects like spontaneous conformational changes and cross-flow migration are observed and evaluated. The collected experimental data can be used to validate assumptions present in numerical models describing intercellular transport of long biomolecules.

Keywords:
persistence length, macromolecules, electrospinning, DNA, Brownian motion

4.Pierini F., Nakielski P., Pawłowska S., Zembrzycki K., Kowalewski T.A., Particles double layer evaluation by atomic force microscopy - optical tweezers, ICTAM XXIV, 24th International Congress of Theoretical and Applied Mechanics, 2016-08-21/08-26, Montréal (CA), pp.1204-1205, 2016
Pierini F., Nakielski P., Pawłowska S., Zembrzycki K., Kowalewski T.A., Particles double layer evaluation by atomic force microscopy - optical tweezers, ICTAM XXIV, 24th International Congress of Theoretical and Applied Mechanics, 2016-08-21/08-26, Montréal (CA), pp.1204-1205, 2016

Abstract:
Atomic force microscopy (AFM) is the most commonly used method of direct force evaluation, but due to its technical limitations this single probe technique is unable to detect forces with femtonewton resolution. We present the development of a combined atomic force microscopy and optical tweezers (AFM/OT) instrument. The optical tweezers system provides us the ability to manipulate small dielectric objects and to use it as a high spatial and temporal resolution displacement and force sensor in the same AFM scanning zone. We demonstrate the possibility to develop a combined instrument with high potential in nanomechanics, molecules manipulation and biologic al studies. The presented study is aimed to quantify the interaction forces between two single polystyrene particles in the femtonewton scale by using the developed AFM/OT equipment.

Keywords:
optical trap, nanomanipulation, femtonewtons

5.Pawłowska S., Nakielski P., Pierini F., Zembrzycki K., Kowalewski T.A., Highly Deformable Hydrogel Nanofilaments in Poiseuille Flow, MNF 2016, 5th Micro and Nano Flows Conference, 2016-09-11/09-14, Milan (IT), pp.50, 2016
Pawłowska S., Nakielski P., Pierini F., Zembrzycki K., Kowalewski T.A., Highly Deformable Hydrogel Nanofilaments in Poiseuille Flow, MNF 2016, 5th Micro and Nano Flows Conference, 2016-09-11/09-14, Milan (IT), pp.50, 2016

Keywords:
Hydrogel Nanofilaments, Bending Dynamics, Poiseuille Flow, Electrospinning

6.Pierini F., Zembrzycki K., Nakielski P., Pawłowska S., Kowalewski T.A., Nanomanipulating and sensing single particles interactions with combined atomic force microscopy optical tweezers (AFM/OT), MNF 2016, 5th Micro and Nano Flows Conference, 2016-09-11/09-14, Milan (IT), pp.40-41, 2016
Pierini F., Zembrzycki K., Nakielski P., Pawłowska S., Kowalewski T.A., Nanomanipulating and sensing single particles interactions with combined atomic force microscopy optical tweezers (AFM/OT), MNF 2016, 5th Micro and Nano Flows Conference, 2016-09-11/09-14, Milan (IT), pp.40-41, 2016

Keywords:
Atomic force microscopy/optical tweezers, Nanomanipulation, Single particles analysis, Interaction force measurement, DLVO theory

7.Urbanek O., Pierini F., Kołbuk D., Sajkiewicz P., Effect of positive and negative charge applied during electrospinning on surface chemistry and selected properties of chitosan nanofibers, COST MP1206 Workshop on Electrospinning of Chitosan, 2015-09-02/09-03, Münster (DE), pp.7-8, 2015
Urbanek O., Pierini F., Kołbuk D., Sajkiewicz P., Effect of positive and negative charge applied during electrospinning on surface chemistry and selected properties of chitosan nanofibers, COST MP1206 Workshop on Electrospinning of Chitosan, 2015-09-02/09-03, Münster (DE), pp.7-8, 2015

Keywords:
electrospinning, fibres, surface, chitosan

8.Nakielski P., Pawłowska S., Pierini F., Hejduk P., Zembrzycki K., Kowalewski T.A., Novel hydrogel nanofilaments based on electrospun core-shell fibers, Europhysics Conference Biomolecules and Nanostructures 5, 2015-05-13/05-17, Jaroszowice (PL), Vol.39C, pp.101, 2015
Nakielski P., Pawłowska S., Pierini F., Hejduk P., Zembrzycki K., Kowalewski T.A., Novel hydrogel nanofilaments based on electrospun core-shell fibers, Europhysics Conference Biomolecules and Nanostructures 5, 2015-05-13/05-17, Jaroszowice (PL), Vol.39C, pp.101, 2015

Keywords:
nanofilaments, hydrogel, long molecules flexibility

9.Pawłowska S., Nakielski P., Pierini F., Zembrzycki K., Kowalewski T.A., Mobility of nanofilaments, Experiments in Fluid Mechanics 2015, 2015-10-26/10-27, Warszawa (PL), pp.1, 2015
Pawłowska S., Nakielski P., Pierini F., Zembrzycki K., Kowalewski T.A., Mobility of nanofilaments, Experiments in Fluid Mechanics 2015, 2015-10-26/10-27, Warszawa (PL), pp.1, 2015

Abstract:
We propose a microscale experimental model in form of highly deformable nanofilaments, which permits for precise optical measurements and to evaluate hydrodynamic interactions (mobility). The conducted research includes determination of the mechanical properties of elastic hydrogel nanofilaments obtained by electrospinning that can serve as experimental benchmark to validate theoretical and numerical models describing dynamics of long biological molecules (e.g. proteins, DNA). Nanofilaments mechanical properties are determined by studying their dynamic bending. in shear flow and deformations due to the thermal fluctuations (Brownian motion). These results are compared with AFM nanoindentation measurements. Data obtained from this research project will be a base to crea te biocompatible nanoobjects that can become tools for the regeneration of tissue (e.g. neural tissue).

Keywords:
Biocompatible nanoobjects, highly deformable nanofilaments, regeneration of tissue

10.Nakielski P., Pawłowska S., Pierini F., Hejduk P., Zembrzycki K., Kowalewski T.A., Processing and mechanical properties relationships in hydrogel nanofilamets for biological application, ICMCSF, International Conference on Mechanics of Complex Solids and Fluids, 2015-05-17/05-22, Lille (FR), pp.1, 2015
Nakielski P., Pawłowska S., Pierini F., Hejduk P., Zembrzycki K., Kowalewski T.A., Processing and mechanical properties relationships in hydrogel nanofilamets for biological application, ICMCSF, International Conference on Mechanics of Complex Solids and Fluids, 2015-05-17/05-22, Lille (FR), pp.1, 2015

Keywords:
Nanofilaments, hydrogel filaments, nanofibres, long nanoobjects deformability

11.Pierini F., Nakielski P., Pawłowska S., Zembrzycki K., Kowalewski T.A., Hydrogel nanofilaments via core-shell electrospinning, NanoItaly, Nanotechnology meeting forum for research and market, 2015-09-21/09-24, Roma (IT), pp.1, 2015
Pierini F., Nakielski P., Pawłowska S., Zembrzycki K., Kowalewski T.A., Hydrogel nanofilaments via core-shell electrospinning, NanoItaly, Nanotechnology meeting forum for research and market, 2015-09-21/09-24, Roma (IT), pp.1, 2015

Abstract:
Controlled drug delivery systems are used to improve the conventional administration of drugs. One of the main challenges is to synthesize materials able to find a defined target and to release drugs in a controlled manner [1]. Several research tasks have been focused on developing ideal drug delivery systems made by hydrogel due to their unique properties [2]. The present study is based on the idea that soft and flexible nanomaterials can easily travel in crowed environments of body fluids and biological tissues. Modification of their mechanical properties obtained by changing of the cross-linker amount may give us the possibility to tune the material rigidity according to desired application. Here, we describe a novel method based on coaxial electrospinning for obtaining highly flexible hydrogel nanofilaments able to transport and release dedicated molecules. Two different types of hydrogels (poly(N,Nisopropyl acrylamide) and polyacrylamide) with three polymer/cross-linker ratios were produced and deeply studied. The nanofilaments morphology was characterized and the release of bovine serum albumin as a function of time was quantified. Mechanical properties of highly deformable hydrogel nanofilaments were evaluated by bending dynamics and Brownian motion observation techniques. The calculated mechanical properties were compared with data obtained by nanoindention. The results highlight the crucial role of morphology and stiffness on mobility of nanofilaments colloid systems. The information gained are fundamental to design nanoobjects with well-defined chemical and physical behaviour.

Keywords:
Nanofilaments, electrospinning, core-shell method, hydrogel

12.Kowalewski T.A., Nakielski P., Pierini F., Zembrzycki K., Pawłowska S., Nanoscale challenges of fluid mechanics, PCM-CMM-2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.11-16, 2015
Kowalewski T.A., Nakielski P., Pierini F., Zembrzycki K., Pawłowska S., Nanoscale challenges of fluid mechanics, PCM-CMM-2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.11-16, 2015

Abstract:
In this talk we would like to tackle general question of contemporary fluid dynamics, how far its assumption of a continuous, smooth medium remains useful when size and time scales start to approach molecular ones. The question is not trivial and seems to depend on several additional factors usually minored. For example, when full Navier-Stokes equations are replaced by their linear approximation we are loosing basic characteristics of convective motion, and still we use such approach. Once our fluid becomes granular matter with its own internal properties, proper interpretation of flow interactions with other molecular structures probably needs deeper physics. But still we try to convert such problem to the classical macro/micro scale description. Hence a general question arises, how small does a fluid have to be before it is not a fluid anymore?

Keywords:
microfluidics, nanofluids, Brownian motion, nanofilaments

13.Zembrzycki K., Pierini F., Kowalewski T.A., Optical tweezers to interrogate nano-objects in fluid, KKNM, 4th National Conference on Nano- and Micromechanics, 2014-07-08/07-10, Wrocław (PL), pp.25-26, 2014
Zembrzycki K., Pierini F., Kowalewski T.A., Optical tweezers to interrogate nano-objects in fluid, KKNM, 4th National Conference on Nano- and Micromechanics, 2014-07-08/07-10, Wrocław (PL), pp.25-26, 2014

Keywords:
nanomanipulation, optical trap, optical tweezers

14.Pawłowska S., Nakielski P., Hejduk P., Pierini F., Zembrzycki K., Kowalewski T.A., Brownian motion of nanofibers, KKNM, 4th National Conference on Nano- and Micromechanics, 2014-07-08/07-10, Wrocław (PL), pp.162-163, 2014
Pawłowska S., Nakielski P., Hejduk P., Pierini F., Zembrzycki K., Kowalewski T.A., Brownian motion of nanofibers, KKNM, 4th National Conference on Nano- and Micromechanics, 2014-07-08/07-10, Wrocław (PL), pp.162-163, 2014

Keywords:
electrospinning, flexible nanorods, Brownian motion

15.Pierini F., Hejduk P., Nakielski P., Pawłowska S., Zembrzycki K., Kowalewski T.A., Study of surface interaction forces in polystyrene colloidal nanoparticles systems, XXI FMC, XXI Fluid Mechanics Conference, 2014-06-15/06-18, Kraków (PL), pp.115, 2014
Pierini F., Hejduk P., Nakielski P., Pawłowska S., Zembrzycki K., Kowalewski T.A., Study of surface interaction forces in polystyrene colloidal nanoparticles systems, XXI FMC, XXI Fluid Mechanics Conference, 2014-06-15/06-18, Kraków (PL), pp.115, 2014

Keywords:
Nanoparticles, polystyrene beads, surface properties, atomic force microscopy, hydrodynamic properties

16.Pawłowska S., Hejduk P., Nakielski P., Pierini F., Zembrzycki K., Kowalewski T.A., Analysis of nanoparticles hydrodynamic diameters in Brownian motion, XXI FMC, XXI Fluid Mechanics Conference, 2014-06-15/06-18, Kraków (PL), pp.116, 2014
Pawłowska S., Hejduk P., Nakielski P., Pierini F., Zembrzycki K., Kowalewski T.A., Analysis of nanoparticles hydrodynamic diameters in Brownian motion, XXI FMC, XXI Fluid Mechanics Conference, 2014-06-15/06-18, Kraków (PL), pp.116, 2014

Keywords:
Nanoparticles, Brownian motion, hydrodynamic diameter