Abstract: Polyacrylaimde carboxymethyl starch graft copolymers (PAAm-g-CMS) with different nitrogen contents were prepared using Ultra Violet /photoinitiator system. The as prepared copolymer was further utilized to prepare PAAm-g-CMS silver nanocomposite (PAAm-g-CMS-AgNPs). The latter was prepared using silver nitrate as a precursor and PAAm-g-CMS as both reducing and capping agent under alkaline conditions. The synthesized PAAm-g-CMS-AgNPs were assessed by measuring the absorbance of the colloidal solution using UV-vis spectrophotometer. The size and the shape of AgNPs were assessed by TEM. The morphology of PAAm-g-CMS-AgNPs was evaluated by SEM. Thermal stability was evaluated by TGA. Reproducibility of the synthesis method was also tested. Highest absorbance of the colloidal solution of PAAm-g-CMS-AgNPs was obtained when PAAm-g-CMS (Nitrogen content (%) =7.7) concentration of 0.8% (w/v); AgNO3 concentration of 900 ppm; pH 12; temperature 80oC for 3h were used. TEM showed round shape nanoparticles with size varies from 1-11 nm. The PAAm-g-CMS-AgNPs hydrogel powder was prepared from PAAm-g-CMS-AgNPs colloidal solution. The produced PAAm-g-CMS-AgNPs hydrogel showed swelling capacity of 697%.

Keywords: UV; Photo-grafting; Photo-initiator; Carboxymethyl Starch; Acrylamide; PAAm-g-CMS-AgNPs composite; Silver Nanoparticles; hydrogel.

Abstract: In recent years, the use of renewable biomass has become the focus of research in supplementing and replacing traditional petrochemical products due to growing energy demands and environmental concerns. The utilization of renewable lipid resources has been considered to play a primitive role towards sustainable development due to their large scale availability, built-in-functionality, biodegradability and no net CO2 production. In addition, a broad range of monomers can be obtained from a single feedstock. These attributes make lipids a good fit for the development of renewable biomaterials. This Presentation will focus on the solvent free conversion of lipids, from various sources including waste streams such as waste cooking oil and lipids extracted from spent foul, into monomers and synthesis of biopolymers especially polymers with self-healing and reprocessing attributes which is very challenging when using monomers sourced from biomass especially being reprocessable without degrading mechanical and thermal properties. The healed and reprocessed biopolymer displayed mechanical properties and thermal stabilities comparable to the original after self-healing and reprocessing. Moreover, the developed polymers showed excellent thermal stabilities which make them suitable for different applications. The ability for complete conversion of lipids under solvent free conditions into monomers and different biopolymers is undoubtedly an attractive concept from both an academic and an industrial point of views.

Abstract: With the increase of life expectancy, the risk of infections related to medical devices and/or chronic wounds typical of the elderly, is raising dramatically. Current treatment and prophylaxis of medical device-associated infections are based on systemic and/or local administration of classical antibiotics, and medical device removal in the case of confirmed persistent infection; this is a heavy burden, especially because bacterial resistance to current antibiotics is now widespread [1]. The scenario is similar for chronically infected wounds, particularly those more common to the elderly or bedridden, like venous leg ulcers, pressure ulcers or diabetic foot ulcers [2]. These are major causes for concern, as the decline in the effectiveness of current antibiotic therapies leads to poor prognosis when persistent infection is installed, especially for people with age-aggravated conditions like immune system deficiency, diabetes, venous insufficiency, or osteoarticular impairment, among others. The search for new strategies has been an active field of research for the past decades, but is now becoming a matter of urgency, due to the increasing prevalence of multi-drug resistant pathogens. Antimicrobial peptides (AMP) are amongst the most promising agents to tackle this terrible menace in the post-antibiotic era [3,4]. This talk will address our recent efforts in this regard, with a particular focus on use of click chemistry approaches to develop new peptide-based constructs, from AMP-grafted antibacterial chitosan coatings to enzymatically stable antimicrobial peptide-ionic liquid conjugates with potent antimicrobial activity.

Abstract: Nature provides a seemingly endless varieties of sophisticated materials and materials synthesis strategies where soft materials and soft machines stands out. Researchers have not been late in taking inspiration from nature when it comes to developing novel materials and machines with exciting properties. Starting from trees and their growth that demonstrate an optimal usage of minimum amount of material and highest strength simultaneously down to viruses, bacteriophages or even DNA molecules or the motor bacterial flagellum, nature provides solutions in such diverse fields as computing, car making and motion via rotational propulsion. Here I demonstrate the importance and background of soft matter for novel materials and machines development as well as how nature inherent knowledge can inspire to investigate novel venues in this field. Future per-spectives and challenges in this vibrant area are elucidated.

Abstract: Luminescent nanomaterials doped with lanthanide ions (Ln³⁺) have broad range of applications, e.g. as biomarkers, smart luminescent tracers, light sources, security marks for anti-counterfeiting, optical sensors of pressure and temperature, etc. These various applications are mainly related to the multicolor emission, long-lasting radiative lifetimes, resistance to photobleaching and thermal degradation, as well as ability to formation of stable colloids by the mentioned Ln³⁺ doped nanomaterials.

Alike pressure and temperature are fundamental physical quantities, state functions affecting physicochemical properties of the materials. The conventional methods of their determination require a physical contact with the measured object and/or cannot be used for the exact determination of local pressure/temperature, in the sub-micro sized areas. These issues can be resolved by the use of optical, contactless manometers and thermometers, based on the lanthanide (Ln) doped nanomaterials, i.e. optical nanosensors of pressure and temperature.

Here we show recent advancements in the field of development of luminescent, optical pressure and temperature sensors based on the multi-functional, lanthanide-doped (nano)materials, core/shell type nanostructures, hybrid and composite nanomaterials, including their introduction in the cellulose fibers for anti-counterfeiting purposes[1].This work emphasizes also on combination of different concepts of pressure sensing, and the development of first luminescent pressure sensor working within 9-orders of magnitude (from 10^-4 to 10⁵ bar), allowing alike low (vacuum) and high pressure sensing [2].

Keywords: Nanomaterials, Luminescence, Lanthanides, Optical sensors

References:
[1] M. Runowski, P. Woźny, S. Lis, et al. Adv. Mater. Technol. 5, 1901091 (2020)
[2] M. Runowski, P. Woźny, I. R. Martín, J. Mater. Chem. C. 9, 4643-4651 (2021)

Abstract: Confining polymers in thin films causes significant deviations of their structural and dynamical properties from their bulk phase behaviour. In our presentation, we show the different effect of the substrate on binary polymer blends with linear and cyclic architecture, as well as miktoarm star polymers in the presence of explicit solvent, by means of extensive molecular dynamics simulations. In the first case, we discuss the role of enthalpic and entropic factors of the interfacial free energy of the system in determining which species in the blend preferentially adsorbs at the substrate [1,2]. In the case of miktoarm polymers, we vary the solvent-block interaction to monitor the effect on the morphology and self-assembly of the polymer film [3].

Reference:
[1] G. Pellicane, M. M. Tchoukouegno, G. T. Mola and M. Tsige, 2016. Surface enrichment driven by polymer topology, Physical Review E Rapid Communications, 93, 050501.
[2] F. M. Gaitho and G. Pellicane, 2019. Adsorption of binary polymer mixtures with different topology on a wall, Results in Physics,12, 975.
[3] Z. Workineh, G. Pellicane and M. Tsige, 2020. Tuning solvent quality induces morphological phase transitions in miktoarm star polymer films, Macromolecules, 53(15), 6151.

Abstract: The diffuse and corona discharges are used in different fields, including for modification of surfaces, pumping lasers and exciting excilamps. The report provides a short review of our research data showing the role of runaway electrons (REs) in formation diffuse and corona discharges in an inhomogeneous electric field at high pressures. The generation of runaway electron beams in high-pressure gases is a fundamental physical phenomenon that began to be investigated in the last century. Due to REs, diffuse discharges are formed in various gases without a source of additional preionization. The review is supplemented with respective diagrams and with images captured at high resolution to trace the plasma dynamics of nanosecond gas discharges from early prebreakdown stages until their final diffuse appearance. To obtain runaway beams that can be recorded at atmospheric pressure and more behind the anode foil, cathodes with a small radius of curvature and voltage pulses with an amplitude of about 100 kV and higher with a subnanosecond rise time are usually used. From the data presented can grasp the idea of how such discharges develop at negative and at positive voltage polarity, what setups and conditions are best suited to detect runaway electron beams, and what factors influence their amplitude, duration, and energy. Also analyzed are the streamer mechanisms of diffuse discharges and the generation of runaway electrons in high-pressure gases in an inhomogeneous electric field. In addition, data on cleaning and oxidation of various surfaces using diffuse discharges will be presented.

Keywords: Diffuse discharge, corona discharge, runaway electrons, application for modification

Abstract: The integration of cells and tissues with polymers and other surfaces depends on the pre-coating of the surface as it drives the initial cell adhesion and subsequent protein deposition by the cells to create a viable ECM to enable cells viability and function. Many cultures and cellular integration studies fail due to improper protein modification or post treatment that causes protein degradation. Because in most cases analysis of the surface to determine if the protein is maintained at the interface is not done, many cell cultures or tissue integration studies fail and the fault is proposed to be from the material itself or due to the cells utilized in the culture. We have used a whispering gallery mode (WGM) sensor system and X-ray photoelectron spectroscopy (XPS) to monitor the adsorption of protein to alkysilane self-assembled monolayers (SAMs) at solution concentration levels where measurements were unattainable with other techniques. The adsorption of protein was quantified by monitoring the change in the optical resonance frequency of a silica microsphere as protein accreted to the functionalized sensor surface. The adsorption of dilute solutions (1 µg/ml or less) of fibronectin (FN) on alkylsilane SAMs was studied as a model system, and it was found that FN adsorbed at unexpectedly high and biologically relevant surface densities. Standard adsorption models were then fitted to the experimental data to interpret the kinetics observed. The protein adsorption results, which indicated that an amine containing surface and a fluorinated surface adsorbed the same amount of FN, were then tested by culturing neurons and myocytes on the surfaces. Cells thrived on the amine surface, but didn’t on the fluorinated modified surface. A PEG surface did not adsorb an appreciable amount of FN and did not support cell growth. The combination of WGM sensor measurements for protein adsorption quantitation, modeling, and cell culture studies allowed us to make determinations about the protein confirmation on the surface and its effect on cell survival. XPS analysis was used to determine BSA adsorption and confirmation on modified surfaces and a mechanism was proposed for surface passivation. The high sensitivity and simplicity of the WGM biosensor, combined with its ability to quantify the adsorption of any dilute protein in a label-free assay, establishes the importance of this technology for biomaterial derivitization for implants and surfaces for cell culture.