New SiO2/Caffeic Acid Hybrid Materials: Synthesis, Spectroscopic Characterization, and Bioactivity

Chitosan-grafted folic acid decorated one-dimensional GONS: A biocompatible drug cargo for targeted co-delivery of anticancer agents

In conventional chemotherapy, the cancer cells can become highly resilient due to a phenomenon known as multi-drug resistance (MDR). The co-delivery of chemotherapeutic agents assisted with novel nanocarrier-based targeted DDS may counter the MDR issues and subsequently improve their therapeutic efficacy. In line with this, the present work deals with the development of 1D graphene oxide nanoscrolls (GONS)-based nano delivery system for co-delivery of chemosensitizer along with the chemotherapeutic agent. Herein, the 1D GONS nanocarrier was initially functionalized with chitosan (CS) biopolymer and folic acid (FA) further to enhance their biocompatibility and target-specific co-delivery. The resultant GONS-CS-FA (GCF) nanocarriers were co-loaded with doxorubicin (DOX) and caffeic acid (CA) at different weight proportions with respect to nanocarrier and drug composition. The optimum loading efficiency of 51.14 ± 1.47 % (DOX) and 49.70 ± 1.19 % (CA) was observed for GCF: drug ratio of 2.5 with drug composition of 1:1. In vitro release at pH 5 yielded ~83 % DOX and 75 % CA, compared to ~71 % DOX and 61 % CA at pH 7.4 over 7 days, suggesting a higher and targeted drug release in the cancer microenvironment. Cytotoxicity tests revealed selective apoptosis in cancer cells (A549) while maintaining cytocompatibility with normal cells (HEK293).

Effect of pine bark extract and its phenolic compounds on selected pathogenic and probiotic bacterial strains

Introduction

Inflammatory bowel disease (IBD) comprises a heterogeneous group of chronic diseases as ulcerative colitis (UC) and Crohn's disease (CD). IBD is the result of a dysregulation of intestinal homeostasis with a host's loss of tolerance toward normal enteric microflora. Plant-based extracts as phenolic compounds can play a role by modulating the intestinal inflammation response.

Methods

The in vitro antimicrobial activity of French maritime pine bark extract (PBE) and its phenolic constituents has been investigated in this study. Furthermore, the ability of PBE and phenolic compounds (caffeic acid, chlorogenic acid, ferulic acid, gallic acid and taxifolin) to modulate the microbiota has been assessed.

Results

Phenolic compounds and PBE showed a great inhibitory effect on the pathogens growth at the highest concentration assessed (1.25 mg/mL). The growth of E. sakazakii and E. faecalis were affected by the effect of caffeic acid and ferulic acid. Taxifolin showed a very strong activity against Listeria sp. (with a reduction ~98%). Gallic acid revealed antibacterial effect on S. aureus at different concentrations. The inhibitory effect of PBE was highly significant on the growth of E. coli O157:H7. PBE, caffeic acid and chlorogenic acid seem to provide the greatest beneficial effect on the probiotic bacteria. However, the highest concentrations of taxifolin may have impaired the growth of beneficial microbiota.

Conclusion

Present findings could be of interest for considering PBE and/or its phenolic constituents as protectors against gastrointestinal disturbances which lead to ulcerative colitis and Crohn's disease.

Development of Antioxidant and Antimicrobial Membranes Based on Functionalized and Crosslinked Chitosan for Tissue Regeneration

Tissue engineering is an interdisciplinary field that develops new methods to enhance the regeneration of damaged tissues, including those of wounds. Polymer systems containing bioactive molecules can play an important role in accelerating tissue regeneration, mitigating inflammation process, and fighting bacterial infection. Chitosan (CS) has attracted much attention regarding its use in wound healing system fabrication thanks to its biocompatibility, biodegradability, and the presence of functional groups in its structure. In this work, bioactive chitosan-based membranes were obtained by both chemical and physical modifications of the polymer with glycidyl methacrylate and glycerol (GLY), respectively. The most suitable GLY concentration to obtain wound healing systems with good elongation at break, a good water vapor transmission rate (WVTR), and good wettability values was 20% (w/w). Afterwards, the membranes were crosslinked with different concentrations of ethylene glycol dimethacrylate (EGDMA). By using a concentration of 0.05 mM EGDMA, membranes with a contact angle and WVTR values suitable for the application were obtained. To make the system bioactive, 3,4-dihydrocinnamic acid (HCAF) was introduced into the membranes, either by imbibition or chemical reaction, using laccase as a catalyst. Thermal and mechanical analyses confirmed the formation of a cohesive network, which limited the plasticizing effect of GLY, particularly when HCAF was chemically bound. The HCAF-imbibed membrane showed a good antioxidant and antimicrobial activity, highlighting the potential of this system for the treatment of wound healing.

Waste to value: Enhancing xanthan gum hydrogel with wine lees extract for optimal performance

The current study investigated the potential of utilizing wine lees extract (WLE) from red wine to enhance the sustainability and cost-effectiveness of xanthan gum (XG). A novel hydrogel system was successfully generated by cross-linking WLE and XG. Response surface methodology (RSM) was used to thoroughly analyze the characteristics of this novel hydrogel to understand its behavior and possible applications. Consistency index (K), flow behavior index (n), water holding capacity (%), and oil binding capacity (%) of the cross-linked hydrogels were optimized, and the best formulation was determined to be 0.81 % XG + 0.67 % WLE and crosslink temperature of 47 °C. The addition of WLE (0-1 % w/v) to different concentrations of XG (0-1 % w/v) was found to have a notable impact on the rheological properties, but changes in cross-link temperature (45-65 °C) did not have a significant effect. The activation energy was increased by incorporating WLE at XG concentration above 0.5 %, indicating a more robust and stable structure. FTIR and SEM analyses confirmed the chemical bonding structure of the optimum hydrogel. Incorporating WLE could significantly improve the functional properties of XG hydrogels, allowing the development of healthier product formulations.

Combined Experimental and Theoretical Insights: Spectroscopic and Molecular Investigation of Polyphenols from Fagonia indica via DFT, UV-vis, and FT-IR Approaches

This review deals with computational study of polyphenolic compounds of medicinal importance and interest for drug development. Herein, four polyphenolic compounds comprising catechol (1), caffeic acid (II), gallic acid (III), and pyrogallol (IV) have been isolated from a medicinal specie, Fagonia indica, by applying silica gel column chromatography. These compounds were identified by using gas chromatography-mass spectrometry (GC-MS) analysis and confirmed by geometric computational analysis. According to computational results, caffeic acid has shown the highest biological activation due to higher chemical softness, electronegativity (χ (eV) = -648.644), and electrostatic potential value (-8.424 × 10-2 to +8.424 × 10-2), while smaller values of chemical potential (-0.269), ELUMO (-0.080), and energy gap (ΔE = 0.149). The Mulliken atomic charges were calculated by using DFT/B3LYP with basis set 6-311G for the determination of active sites. The oxygen atom of catechol showed highest nucleophilic characteristic with a more negative charge (08 = -0.695), and pyrogallol indicated a strong electrophilic center at C14 = 0.415 with a higher positive charge. Moreover, UV-visible absorption spectra and a detailed study of vibrational frequencies for all phenolic compounds by employing the DFT approach with 3-21G, 6-31G, and 6-311G basis sets at the ground-state level showed the great agreement with experimental results. ANOVA has been applied to validate the theoretical data. Results suggest that compounds I-IV are suitable in diverse fields.

Plasmonic and Photothermal Effects of CuS Nanoparticles Biosynthesized from Acid Mine Drainage with Potential Drug Delivery Applications

In this work, the plasmonic and photothermal effects of CuS nanoparticles biosynthesized from acid mine drainage (AMD) were studied. CuS were formed by delivering the H2S generated by a sulfidogenic bioreactor to an off-line system containing the AMD. The precipitates collected after contact for an hour were washed and physico-chemically characterized, showing a nanoparticle with a mean diameter of 33 nm, crystalline nature and semiconductor behavior with a direct band gap of 2.2 eV. Moreover, the CuS nanoparticles exhibited localized surface plasmonic resonance in the near infrared range, with a high absorption band centered at 973 nm of wavelength, which allowed an increase in the temperature of the surrounding media under irradiation. Finally, the cytotoxicity of the CuS nanoparticles as well as their potential use as part of drug delivery platforms were investigated.

Caffeic acid recarbonization: A green chemistry, sustainable carbon nano material platform to intervene in neurodegeneration induced by emerging contaminants

Environmental agents such as pesticides, weedicides and herbicides (collectively referred to as pesticides) are associated with the onset and pathogenesis of neurodegenerative disorders such as Parkinson's (PD) and Alzheimer's (AD) diseases. The development of blood-brain barrier (BBB)-penetrating therapeutic candidates to both prevent and treat the aforementioned xenotoxicant-induced neurodegenerative disorders remains an unmet need. Here, we examine whether caffeic-acid based Carbon Quantum Dots (CACQDs) can intervene in pesticide-associated onset and progress of the PD phenotype. Pulse-chase fluorescence analyses revealed that CACQDs intervene in the soluble-to-toxic transformation of the amyloid-forming protein model Hen Egg White Lysozyme (HEWL). The sp2-rich CACQDs also scavenged free radicals, a milestone along the PD trajectory. In-vitro, CACQDs introduced into a human neuroblastoma-derived cell line (SH-SY5Y) demonstrated negligible cytotoxicity up to 5 mg/mL and protected the cell line against oxidative stress-induced neuronal injury induced by the pesticide and potent neurotoxin, paraquat. Our findings suggest that the potentially BBB-penetrating CACQDs derived from caffeic acid hold promise for mitigating neurodegenerative disorders associated with environmental pesticides and xenobiotic neurotoxicants. Importantly, CACQDs sourced from coffee, coupled with their facile synthesis, represent a sustainable, green chemistry platform for generating interventional candidates in neurodegeneration.

A comparative study between two carboxymethylated polysaccharides/protein electrostatic and cross-linked nanogels constructed for caffeic acid and eugenol delivery

In response to the pressing demand for functional nanomaterials synthesis and applications, two polyelectrolyte complexes (PECs) [electrostatic and cross-linked nanogels (NGs)] loaded individually with caffeic acid (CafA) and eugenol (Eug) demonstrating multifunctionalities were proposed for the first time. Curdlan (Curd) and glucomannan (GM) were carboxymethylated (CMCurd and CMGM) successfully and polymeric ratios of 1:1 and 4:1 (v/v) for chitosan (Cs): CMCurd and lactoferrin (Lf): CMGM were selected for the synthesis of Cs/CMCurd and Lf/CMGM NGs. Due to the use of EDC/NHS, Cs/CMCurd/CafA and Lf/CMGM/Eug NGs possessed very uniform particles sizes of 177 ± 18 and 230 ± 17 nm with marked encapsulation efficiencies (EEs) of 76 ± 4 and 88 ± 3 %, respectively. The formation of a carbonyl-amide linkage in both cross-linked NGs was confirmed by FTIR. It should be noted, the self-assembly was not reliable in retaining enough of the encapsulated compounds. Owing to the excellent physicochemical characteristics of the loaded cross-linked NGs, they were prioritized over the electrostatic ones. Both Cs/CMCurd/CafA and Lf/CMGM/Eug NGs exhibited high colloidal stability over 12 weeks, elevated hemocompatibility, and in vitro serum stability. The generated NGs were also tailored to possess controlled release profiles for CafA and Eug over 72 h. Cs/CMCurd/CafA and Lf/CMGM/Eug NGs had promising antioxidant efficacies and could remarkably inhibit 4 bacterial pathogens at low 2-16 μg/mL concentration of encapsulated NGs compared to their unencapsulated counterparts. Interestingly, the respective NGs could significantly decline the IC₅₀ against colorectal cancer HCT-116 than conventional drugs. Based on these data, it was conferred that the investigated NGs could be promising candidates for functional foods and pharmaceutics.

The Development of Alginate/Ag NPs/Caffeic Acid Composite Membranes as Adsorbents for Water Purification

Since the water pollution problem still affects the environmental system and human health, the need to develop innovative membranes has become imperious. Lately, researchers have focused on developing novel materials to help diminish the contamination problem. The aim of present research was to obtain innovative adsorbent composite membranes based on a biodegradable polymer, alginate, to remove toxic pollutants. Of all pollutants, lead was chosen due to its high toxicity. The composite membranes were successfully obtained through a direct casting method. The silver nanoparticles (Ag NPs) and caffeic acid (CA) from the composite membranes were kept at low concentrations, which proved enough to bestow antimicrobial activity to the alginate membrane. The obtained composite membranes were characterised by Fourier transform infrared spectroscopy and microscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TG-DSC). Swelling behaviour, lead ion (Pb²⁺) removal capacity, regeneration and reusability were also determined. Further, the antimicrobial activity was tested against selected pathogenic strains (S. aureus, E. faecalis sp., P. aeruginosa, E. coli and C. albicans). The presence of Ag NPs and CA improves the antimicrobial activity of the newly developed membranes. Overall, the composite membranes are suitable for complex water treatment (removal of heavy metal ions and antimicrobial treatment).

Pullulan/Poly(vinyl alcohol) Hydrogels Loaded with Calendula officinalis Extract: Design and In Vitro Evaluation for Wound Healing Applications

The therapeutic efficiency of plant extracts has been limited by their poor pharmaceutical availability. Hydrogels have promising potential to be applied as wound dressings due to their high capacity to absorb exudates and their enhanced performance in loading and releasing plant extracts. In this work, pullulan/poly (vinyl alcohol) (P/PVA) hydrogels were first prepared using an eco-friendly method based on both a covalent and physical cross-linking approach. Then, the hydrogels were loaded with the hydroalcoholic extract of Calendula officinalis by a simple post-loading immersion method. Different loading capacities were investigated in terms of the physico-chemical properties, chemical composition, mechanical properties, and water absorption. The hydrogels exhibited high loading efficiency due to the hydrogen bonding interactions between polymer and extract. The water retention capacity as well as the mechanical properties decreased with the increase in the extract amount in hydrogel. However, higher amounts of extract in the hydrogel improved the bioadhesiveness. The release of extract from hydrogels was controlled by the Fickian diffusion mechanism. Extract-loaded hydrogels expressed high antioxidant activity, reaching 70% DPPH radical scavenging after 15 min immersion in buffer solution at pH 5.5. Additionally, loaded hydrogels showed a high antibacterial activity against Gram-positive and Gram-negative bacteria and were non-cytotoxic against HDFa cells.

Application of Poly(caffeic acid) for the Extraction of Critical Rare Earth Elements

Poly(caffeic acid) was synthesized and utilized for the extraction and determination of rare earth elements (REEs), thorium, and uranium. Oxidative polymerization of caffeic acid, a low-cost plant-based material, in the presence of ethylenediamine produced a granular, air-stable, and cross-linked polymer. The polymer is highly oxygenated and together with the amino group from ethylenediamine efficiently coordinates and preconcentrates these critical elements from aqueous media. Extraction was dependent on solution pH, amount of sorbent, and extraction time, while the concentration and flow rate of the desorption solution governed the recovery efficiency. Removal and recovery efficiencies greater than 98 and 90%, respectively, and low levels of detection ranging from 0.1 to 2.9 ng/L were achieved. Determination of these strategic elements in the presence of potentially interfering ions as well as in complex matrices such as well water and produced water samples also was demonstrated. The capacity of poly(caffeic acid) was determined with lanthanum as a representative REE to be 161.7 mg/g, establishing the promise of poly(caffeic acid) for larger-scale extractions in addition to the ability to screen sources for the presence of REEs.

Hydroxycinnamic acid derivatives for UV-selective and visibly transparent dye-sensitized solar cells

Naturally abundant dyes are very attractive for the development of dye-sensitized solar cells (DSSCs). Hydroxycinnamic acid derivatives, such as caffeic acid (CA), ferulic acid (FA), and p-coumaric acid (PA), were considered for the selective harvesting of ultraviolet A (UVA) (315-400 nm) photons. Their spectroscopic and electrochemical properties were investigated both theoretically and experimentally. They were further successfully adopted as photosensitizers in UV-selective and visibly transparent DSSCs, which exhibited a power conversion efficiency of 0.22-0.38% under AM (air mass) 1.5G (global) illumination (100 mW/cm²) and 3.40-3.62% under UVA irradiation (365 nm, 115.22 mW/cm²), with a corresponding visible light transmittance (VLT) of 49.07-43.72% and a general color rendering index (R_a) of 93-90.

Thermal Treatment to Obtain 5-Hydroxymethyl Furfural (5-HMF), Furfural and Phenolic Compounds from Vinasse Waste from Agave

Vinasses represent important final disposal problems due to their physical-chemical composition. This work analyzed the composition of tequila vinasses and increased 5-hydroxymethylfurfural, furfural, and phenolic compounds using thermal hydrolysis with hydrogen peroxide as a catalyst. A statistical Taguchi design was used, and a UPLC-MS (XEVO TQS Micro) analysis determined the presence and increase of the components. The treatment at 130 °C, 40 min, and 0.5% of catalyst presented the highest increase for 5-HMF (127 mg/L), furfural (3.07 mg/L), and phenol compounds as chlorogenic (0.36 mg/L), and vanillic acid (2.75 mg/L). Additionally, the highest removal of total sugars (57.3%), sucrose (99.3%), and COD (32.9%). For the treatment T130:30m:0P the syringic (0.74 mg/L) and coumaric (0.013 mg/L) acids obtained the highest increase, and the treatment T120:30m:1P increased 3-hydroxybenzoic (1.30 mg/L) and sinapic (0.06 mg/L) acid. The revaluation of vinasses through thermal treatments provides guidelines to reduce the impact generated on the environment.

Chitooligosaccharide Conjugates Prepared Using Several Phenolic Compounds via Ascorbic Acid/H2O2 Free Radical Grafting: Characteristics, Antioxidant, Antidiabetic, and Antimicrobial Activities

Chitooligosaccharide (COS)-polyphenol (PPN) conjugates prepared using different PPNs, including gallic, caffeic, and ferulic acids, epigallocatechin gallate, and catechin, at various concentrations were characterized via UV-visible, FTIR, and 1H-NMR spectra and tested for antioxidant, antidiabetic, and antimicrobial activities. Grafting of PPNs with COS was achieved. The highest conjugation efficiency was noticed for COS-catechin (COS-CAT), which was identified to have the highest total phenolic content (TPC) out of all the conjugates (p < 0.05). For antioxidant activities, DPPH and ABTS radical scavenging activities (DPPH-RSA and ABTS-RSA, respectively), oxygen radical absorbance capacity (ORAC), ferric reducing antioxidant power (FRAP), and metal chelating activity (MCA) of all the samples were positively correlated with the TPC incorporated. COS-CAT had higher DPPH-RSA, ABTS-RSA, ORAC, and FRAP than COS and all other COS-PPN conjugates (p < 0.05). In addition, COS-CAT also showed the highest antidiabetic activity of the conjugates, as determined by inhibitory activity toward α-amylase, α-glucosidase, and pancreatic lipase (p < 0.05). COS-CAT also had the highest antimicrobial activity against all tested Gram-negative and Gram-positive bacteria (p < 0.05). Overall, grafting of PPNs, especially CAT on COS, significantly enhanced bioactivities, including antioxidant and antimicrobial, which could be used to retard spoilage and enhance shelf-life of various food systems. Moreover, the ability of COS-CAT to inhibit digestive enzymes reflects its preventive effect on diabetes mellitus and its complications.

Water-soluble caffeic acid-dopamine acid-base complex exhibits enhanced bactericidal, antioxidant, and anticancer properties

Despite the highly potent biological characteristics, the poor water-solubility of caffeic acid (CA) limits its applications in various domains. Here, we present a facile approach, wherein CA has been treated with dopamine hydrochloride (Dopa.HCl) to obtain a water-soluble acid-base complex, which does not possess any covalent bond between the individual components and thus retains their nativity. Simple mixing of CA and Dopa.HCl did not provide water solubility to CA, but the complex became readily soluble in water when the mineral acid was scavenged using sodium bicarbonate. The obtained CA-Dopa complex had been characterized using FT-IR, ¹H NMR, ¹³C NMR, 2D ¹H-¹H NOESY NMR, XPS, and DSC techniques. The complex was found to exhibit excellent bactericidal, antibiofilm, antioxidant, and anticancer properties in the physiologically relevant pH range of 5.5 to 7.5. The results have revealed the high potential of the simple acid-base complex of CA in diverse domains.

Effects of Sargassum thunbergii Extract on Skin Whitening and Anti-Wrinkling through Inhibition of TRP-1 and MMPs

Sargassum thunbergii has been traditionally used as an edible and medicinal material in oriental countries. However, the skin-whitening and anti-wrinkling effects of S. thunbergii have not yet been investigated. This study was conducted to establish optimal extraction conditions for the production of bioactive compounds with antioxidant activity as well as skin-whitening and anti-wrinkle effects using ultrasound-assisted extraction (UAE) in S. thunbergii. The extraction time (5.30~18.7 min), extraction temperature (22.4~79.6 °C), and ethanol concentration (0.0~99.5%), which are the main variables of the UAE, were optimized using a central composite design. Quadratic regression equations were derived based on experimental data and showed a high coefficient of determination (R2 > 0.85), demonstrating suitability for prediction. The optimal UAE condition for maximizing all dependent variables, including radical scavenging activity (RSA), tyrosinase inhibitory activity (TIA), and collagenase inhibitory activity (CIA), was identified as an extraction time of 12.0 min, an extraction temperature of 65.2 °C, and ethanol of 53.5%. Under these conditions, the RSA, TIA, and CIA of S. thunbergii extract were 86.5%, 88.3%, and 91.4%, respectively. We also confirmed S. thunbergii extract had inhibitory effects on the mRNA expression of tyrosinase-related protein-1, matrix metalloproteinase-1, and matrix metalloproteinase-9, which are the main genes of melanin synthesis and collagen hydrolysis. Liquid chromatography-tandem mass spectrometry was used to identify the main phenolic compounds in S. thunbergii extract, and caffeic acid was identified as a major peak, demonstrating that high value-added ingredients with skin-whitening and anti-wrinkling effects can be produced from S. thunbergii and used for developing cosmetic materials.

Caffeic Acid and Its Derivatives: Antimicrobial Drugs toward Microbial Pathogens

Caffeic acid is a plant-derived compound that is classified as hydroxycinnamic acid which contains both phenolic and acrylic functional groups. Caffeic acid has been greatly employed as an alternative strategy to combat microbial pathogenesis and chronic infection induced by microbes such as bacteria, fungi, and viruses. Similarly, several derivatives of caffeic acid such as sugar esters, organic esters, glycosides, and amides have been chemically synthesized or naturally isolated as potential antimicrobial agents. To overcome the issue of water insolubility and poor stability, caffeic acid and its derivative have been utilized either in conjugation with other bioactive molecules or in nanoformulation. Besides, caffeic acid and its derivatives have also been applied in combination with antibiotics or photoirradiation to achieve a synergistic mode of action. The present review describes the antimicrobial roles of caffeic acid and its derivatives exploited either in free form or in combination or in nanoformulation to kill a diverse range of microbial pathogens along with their mode of action. The chemistry employed for the synthesis of the caffeic acid derivatives has been discussed in detail as well.

Porous Silica-Based Organic-Inorganic Hybrid Catalysts: A Review

Hybrid organic-inorganic catalysts have been extensively investigated by several research groups in the last decades, as they allow combining the structural robust-ness of inorganic solids with the versatility of organic chemistry. Within the field of hybrid catalysts, synthetic strategies based on silica are among the most exploitable, due to the convenience of sol-gel chemistry, to the array of silyl-derivative precursors that can be synthesized and to the number of post-synthetic functionalization strategies available, amongst others. This review proposes to highlight these advantages, firstly describing the most common synthetic tools and the chemistry behind sol-gel syntheses of hybrid catalysts, then presenting exemplificative studies involving mono- and multi-functional silica-based hybrid catalysts featuring different types of active sites (acid, base, redox). Materials obtained through different approaches are described and their properties, as well as their catalytic performances, are compared. The general scope of this review is to gather useful information for those approaching the synthesis of organic-inorganic hybrid materials, while providing an overview on the state-of-the art in the synthesis of such materials and highlighting their capacities.

Low-Cost Deposition of Antibacterial Ion-Substituted Hydroxyapatite Coatings onto 316L Stainless Steel for Biomedical and Dental Applications

Substitutions of ions into an apatitic lattice may result in antibacterial properties. In this study, magnesium (Mg)-, zinc (Zn)-, and silicon (Si)-substituted hydroxyapatite (HA) were synthesized using a microwave irradiation technique. Polyvinyl alcohol (PVA) was added during the synthesis of the substituted HA as a binding agent. The synthesized Mg-, Zn-, and Si-substituted HAs were then coated onto a 316L-grade stainless-steel substrate using low-cost electrophoretic deposition (EPD), thereby avoiding exposure to high temperatures. The deposited layer thickness was measured and the structural, phase and morphological analysis were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The bacterial adhesion of Staphylococcus aureus was characterized at 30 min, 2 h and 6 h. The results showed homogeneous, uniform thickness (50–70 µm) of the substrate. FTIR and XRD showed the characteristic spectral peaks of HA, where the presence of Mg, Zn and Si changed the spectral peak intensities. The Mg–HA coating showed the least bacterial adhesion at 30 min and 2 h. In contrast, the Si–HA coating showed the least adhesion at 6 h. EPD showed an effective way to get a uniform coating on bio-grade metal implants, where ionic-substituted HA appeared as alternative coating material compared to conventional HA and showed the least bacterial adhesion.

Biopolymer-Based Hybrids as Effective Admixtures for Cement Composites

In the framework of this publication, silica-lignin hybrid materials were designed, obtained, characterized and then used as admixtures for cement composites. High-energy mechanical grinding of individual components was used to produce the systems that allowed ensuring adequate homogeneity of the final products. As a result of the analysis of Fourier transform infrared spectroscopy, it has been confirmed that weak physical interactions occur between the components. This allowed classifying the resulting systems as I class hybrid materials. In addition, the efficiency of obtaining final products was also inferred on the basis of obtained porous structure parameters and colorimetric data. The achieved bio-admixture with different weight ratios of silica and lignin was added to cement pastes in the amount ranging from 0.5 to 1 wt.%. The study showed that increasing the ratio of lignin in the admixture from 0.15 to 1 wt.% had a positive effect on the rheological properties of the pastes, while the mechanical properties of the composite were deteriorated. In turn, a higher amount of silica in the admixture acted in reverse. The most favorable results were obtained for a silica-lignin bio-admixture with a weight ratio of components equal to 5:1 wt./wt. A significant increase in compressive strength was gained at satisfactory plasticity of the paste.

Wear Resistant Nanocomposites Based on Biomedical Grade UHMWPE Paraffin Oil and Carbon Nano-Filler: Preliminary Biocompatibility and Antibacterial Activity Investigation

In the present paper, we investigate the effectiveness of nanocomposites (composed of ultra-high molecular weight polyethylene (UHMWPE) mixed with carbon nano-filler (CNF) and medical grade paraffin oil (PO), from the biological point of view. Wear measurements were carried out without (air) and with lubricant (distilled water, natural, and artificial lubricant), and antibacterial activity and cytotoxicity were evaluated. The results highlighted that the presence of CNF is important in the nanocomposite formulation because it reduces the wear rate and prevents oxidative degradation during its processing. An amount of 1.0 wt % of CNF is best because it reaches the optimal distribution within the polymeric matrix, resulting in the best wear resistant, bio-active, and anti-bacterial nanocomposite among all investigated samples.