A novel effective bio-originated methylene blue adsorbent: the porous biosilica from three marine diatom strains of Nanofrustulum spp. (Bacillariophyta)

In the present paper, for the first time the ability of the porous biosilica originated from three marine diatom strains of 'Nanofrustulum spp.' viz. N. wachnickianum (SZCZCH193), N. shiloi (SZCZM1342), N. cf. shiloi (SZCZP1809), to eliminate MB from aqueous solutions was investigated. The highest biomass was achieved under silicate enrichment for N. wachnickianum and N. shiloi (0.98 g L-1 DW and 0.93 g L-1 DW respectively), and under 15 °C for N. cf. shiloi (2.2 g L-1 DW). The siliceous skeletons of the strains were purified with hydrogen peroxide and characterized by SEM, EDS, the N2 adsorption/desorption, XRD, TGA, and ATR-FTIR. The porous biosilica (20 mg DW) obtained from the strains i.e. SZCZCH193, SZCZM1342, SZCZP1809, showed efficiency in 77.6%, 96.8%, and 98.1% of 14 mg L-1 MB removal under pH 7 for 180 min, and the maximum adsorption capacity was calculated as 8.39, 19.02, and 15.17 mg g-1, respectively. Additionally, it was possible to increase the MB removal efficiency in alkaline (pH = 11) conditions up to 99.08% for SZCZP1809 after 120 min. Modelling revealed that the adsorption of MB follows Pseudo-first order, Bangham's pore diffusion and Sips isotherm models.

Removal of the Basic and Diazo Dyes from Aqueous Solution by the Frustules of Halamphora cf. salinicola (Bacillariophyta)

Industrial wastes with hazardous dyes serve as a major source of water pollution, which is considered to have an enormous impact on public health. In this study, an eco-friendly adsorbent, the porous siliceous frustules extracted from the diatom species Halamphora cf. salinicola, grown under laboratory conditions, has been identified. The porous architecture and negative surface charge under a pH of 7, provided by the various functional groups via Si-O, N-H, and O-H on these surfaces, revealed by SEM, the N₂ adsorption/desorption isotherm, Zeta-potential measurement, and ATR-FTIR, respectively, made the frustules an efficient mean of removal of the diazo and basic dyes from the aqueous solutions, 74.9%, 94.02%, and 99.81% against Congo Red (CR), Crystal Violet (CV), and Malachite Green (MG), respectively. The maximum adsorption capacities were calculated from isotherms, as follows: 13.04 mg g^-1, 41.97 mg g^-1, and 33.19 mg g^-1 against CR, CV, and MG, respectively. Kinetic and isotherm models showed a higher correlation to Pore diffusion and Sips models for CR, and Pseudo-Second Order and Freundlich models for CV and MG. Therefore, the cleaned frustules of the thermal spring-originated diatom strain Halamphora cf. salinicola could be used as a novel adsorbent of a biological origin against anionic and basic dyes.

Functionalization of Alpha-Lactalbumin by Zinc Ions

Alpha-lactalbumin (α-LA) and binding of zinc cations to protein were studied. Molecular characteristics of protein was determined by MALDI-TOF/MS and electrophoresis SDS-PAGE, and also, for complexes, it was determined by spectroscopic techniques (ATR-FT-IR and Raman) and microscopic techniques (SEM along with an EDX detector and also TEM). The pH dependence of zeta potential of α-LA was determined in saline solution. The zinc binding to the protein mechanism was investigated; zinc binding to protein kinetics, the molecular modeling by the DFT method, and electron microscopy (SEM and TEM) for microstructure observation were performed. The experiments performed indicate a quick binding process (equilibrium takes place after 2 min of incubation) which occurs onto the surface of α-LA. Zinc cations change the conformation of the protein and create spherical particles from the morphological point of view. DFT studies indicate the participation of acidic functional groups of the protein (aspartic acid and glutamic acid residues), and these have a decisive influence on the interaction with zinc cations. Application studies of general toxicity and cytotoxicity and bioavailability were conducted.

Synthesis, Physicochemical Characterization, and Antibacterial Performance of Silver—Lactoferrin Complexes

Antibiotic-resistant bacteria pose one of the major threats to human health worldwide. The issue is fundamental in the case of chronic wound treatment. One of the latest trends to overcome the problem is the search for new antibacterial agents based on silver. Thus, the aim of this research was to synthesize the silver-lactoferrin complex as a new generation of substances for the treatment of infected wounds. Moreover, one of the tasks was to investigate the formation mechanisms of the respective complexes and the influence of different synthesis conditions on the features of final product. The batch-sorption study was performed by applying the Langmuir and Freundlich isotherm models for the process description. Characterization of the complexes was carried out by spectroscopy, spectrometry, and separation techniques, as well as with electron microscopy. Additionally, the biological properties of the complex were evaluated, i.e., the antibacterial activity against selected bacteria and the impact on L929 cell-line viability. The results indicate the formation of a heterogeneous silver–lactoferrin complex that comprises silver nanoparticles. The complex has higher antibacterial strength than both native bovine lactoferrin and Ag⁺, while being comparable to silver toxicity.

Synthesis and physicochemical characterization of zinc-lactoferrin complexes

One trend of the modern world is the search for new biologically active substances based on renewable resources. Milk proteins can be a solution for such purposes as they have been known for a long time as compounds that can be used for the manufacturing of multiple food and non-food products. Thus, the goal of the work was to investigate the parameters of Zn-bovine lactoferrin (bLTF) interactions, which enables the synthesis of Zn-rich protein complexes. Zinc-bLTF complexes can be used as food additives or wound-healing agents. Methodology of the study included bLTF characterization by sodium dodecyl sulfate-PAGE, MALDI-TOF, and MALDI-TOF/TOF mass spectrometry as well Zn-bLTF interactions by attenuated total reflection-Fourier-transform infrared, Raman spectroscopy, scanning and transmission microscopy, and zeta potential measurements. The obtained results revealed that the factors that affect Zn-bLTF interactions most significantly were found to be pH and ionic strength of the solution and, in particular, the concentration of Zn²⁺. These findings imply that these factors should be considered when aiming at the synthesis of Zn-bLTF metallocomplexes.

Silver nanoparticles: Synthesis, investigation techniques, and properties

The unique silver properties, especially in the form of nanoparticles (NPs), allow to utilize them in numerous applications. For instance, Ag NPs can be utilized for the production of electronic and solar energy harvesting devices, in advanced analytical techniques (NALDI, SERS), catalysis and photocatalysis. Moreover, the Ag NPs can be useful in medicine for bioimaging, biosensing as well as in antibacterial and anticancer therapies. The Ag NPs utilization requires comprehensive knowledge about their features regarding the synthesis approaches as well as exploitation conditions. Unfortunately, a large number of scientific articles provide only restricted information according to the objects under investigation. Additionally, the results could be affected by artifacts introduced with exploited equipment, the utilized technique or sample preparation stages. However, it is rather difficult to get information about problems, which may occur during the studies. Thus, the review provides information about novel trends in the Ag NPs synthesis, among which the physical, chemical, and biological approaches can be found. Basic information about approaches for the control of critical parameters of NPs, i.e. size and shape, was also revealed. It was shown, that the reducing agent, stabilizer, the synthesis environment, including trace ions, have a direct impact on the Ag NPs properties. Further, the capabilities of modern analytical techniques for Ag NPs and nanocomposites investigations were shown, among other microscopic (optical, TEM, SEM, STEM, AFM), spectroscopic (UV-Vis, IR, Raman, NMR, electron spectroscopy, XRD), spectrometric (MALDI-TOF MS, SIMS, ICP-MS), and separation (CE, FFF, gel electrophoresis) techniques were described. The limitations and possible artifacts of the techniques were mentioned. A large number of presented techniques is a distinguishing feature, which makes the review different from others. Finally, the physicochemical and biological properties of Ag NPs were demonstrated. It was shown, that Ag NPs features are dependent on their basic parameters, such as size, shape, chemical composition, etc. At the end of the review, the modern theories of the Ag NPs toxic mechanism were shown in a way that has never been presented before. The review should be helpful for scientists in their own studies, as it can help to prepare experiments more carefully.

A New Approach for Spontaneous Silver Ions Immobilization onto Casein

The work presents the kinetic and isotherm studies of silver binding on casein, which was carried out using batch sorption technique. Moreover, the influence of light irradiation on the process was shown. In order to investigate the mechanism of metal ions sorption by casein the zero, pseudo-first order kinetics and Weber-Morris intra-particle diffusion as well as Langmuir and Freundlich isotherm models were used. Furthermore, to specify more precisely, the possible binding mechanism, the spectroscopic (FT-IR—Fourier Transform Infrared Spectroscopy, Raman), spectrometric (MALDI-TOF MS—Matrix-Assisted Laser Desorption/Ionization Time Of Flight Mass Spectrometry), microscopic (SEM—Scanning Electron Microscope, TEM/EDX—Transmission Electron Microscopy/Energy Dispersive X-ray detector) and thermal (TGA—Thermogravimetric Analysis, DTG—Derivative Thermogravimetry) analysis were performed. Kinetic study indicates that silver binding onto casein is a heterogeneous process with two main stages: initial rapid stage related to surface adsorption onto casein with immediate creation of silver nanoparticles and slower second stage of intraglobular diffusion with silver binding in chelated form (metalloproteins) or ion-exchange form. Spectroscopic techniques confirmed the binding process and MALDI-TOF MS analysis show the dominant contribution of the α-casein in the process. Moreover, the treatment of silver-casein complex by artificial physiological fluids was performed.