A bionanoantibiotic system based on beta-N-acetylglucosaminidase (Ami) and Lysozyme (Lyz) enzymes grafted on the external surface of amino functionalized mesoporous silica nanoparticles, having a radial arrangement of pores (MSNr-NH2), was prepared and fully characterized. Before the enzyme grafting the nanoparticles were also loaded with the antibiotic drug levofloxacin (Levo) to explore the possible synergic effect with the enzymes. MSNr-NH2-Lyz-Levo and MSNr-NH2-Ami-Levo did not show any activity against S. aureus. On the contrary, in the absence of the antibiotic, both Lyz and Ami immobilized on MSNr were able to destroy S. aureus cells, suggesting an inhibiting action of the antibiotic on the enzymes. Although the loading of immobilized Lyz was higher than that of Ami (76 vs. 20 mg/g, respectively), the highest antibacterial efficacy was found for MSNr-NH2-Ami nanoantibiotic. Moreover, MSNr-NH2-Ami was active against S. aureus even at very low concentration (12.5 mu g/ mL) with a bactericidal activity (79%), higher than that determined for MSNr-NH2 loaded with levofloxacin (54%). These results suggest the possibility of using enzyme grafted MSNr as a bionanoantibiotic drug with high efficiency even at low nanoparticles concentration.

Specific ion (Hofmeister) effects in colloid and biological systems represented a scientific challenge for more than 100 years. Recently, possible applications, based on their rationalization, are emerging. Here, Cl-, SO42-, SCN- anions and Na+, K+, Mg2+ cations are added at physiological concentration (similar to 0.15 mol/kg) to Pluronic F127 20 wt% aqueous solutions to suitably tune phase transitions for a smart drug delivery platform. Rheological measurements, along with SAXS and NMR self-diffusion experiments, are used to carefully characterize the prepared F127/salt-based formulations. The critical micellar temperature (cmt), the hard-gel formation temperature (T-hg), liquid crystal structures, and self-diffusion coefficients are determined. The cmt and T-hg values of F127/salt formulations are lower than that of F127 20 wt% sample, following an anionic Hofmeister series: SO42- < Cl- < SCN-. All added salts significantly increase storage modulus and complex viscosity with maximum values occurring at T around 40 degrees C. SAXS data confirm that added salts preserve cubic liquid crystal phases. NMR self-diffusion analysis highlights that the intermolecular interactions and mobility of F127 unimers/aggregates are ion specific at 16 degrees C but not at 40 degrees C. These findings suggest that F127/salt-based formulations may constitute a versatile thermosensitive platform for drug delivery able to assure sustained release in topical or surgery administrations, in the range of temperatures 30-45 degrees C.

The specific effects of salts (strong electrolytes) on biomolecular properties have been investigated for more than a century. By contrast, the specific role of pH buffers (weak electrolytes and their salts) has usually been ignored. Here, specific buffer effects on DNA thermal stability were evaluated by measuring the melting curve of calf thymus DNA through UV-vis spectroscopy. The study was carried out using phosphate, Tris, citrate and cacodylate buffers at fixed pH 7.4 at concentrations varying systematically in the range 1-600 mM. DNA stability increases with buffer concentration and is influenced specifically by buffer type. To interpret empirical data, a theoretical model was applied with parameters quantifying the impact of buffer on the DNA backbone charge. Comparing the buffer effects via buffer ionic strength rather than buffer concentration, we find that the buffers stabilize DNA in the order Tris > cacodylate > phosphate > citrate.(c) 2022 Published by Elsevier Inc.

This work focuses on the preparation of a pH-sensitive antimicrobial drug delivery system based on Mesoporous silica nanoparticles (MSN), functionalized with aminopropyl-triethoxysilane (MSN-NH2), triethylenetetramine (MSN-TETA) and poly-L-lysine (MSN-NH2-PLL, MSN-TETA-PLL), and loaded with the flavonoid quercetin. The systems were fully characterized by means of several techniques. Besides the role of the different functionalization of MSNs, this work aimed to optimize both loading and release processes of quercetin, using two different ethanol-water mixtures as solvent, namely EtOH:H2O mixtures at the ratios 80:20 and 50:50. Whereas loading was higher using the 80:20 solvent mixture, a more efficient release was ascertained using the solvent mixture 50:50 as demonstrated by the release kinetics, and also by the amount of the released drug. It was suggested that in the presence of less ethanol, quercetin solubility decreases, and a physical adsorption of quercetin at the functional groups of MSNs can be favoured with respect to a random distribution over many surface sites with which only weak interactions can occur. This means that in the presence of high amount of ethanol, used very often when dealing with poorly water-soluble drugs, the impregnation process becomes dominant, loading increases significantly, but subsequently burst release of high amounts of drug occurs. In this work, using the specific case of quercetin, we found a more sustained release as the result of a predominant adsorption mechanism due to the careful choice of the solvent mixture composition during the loading step. Moreover, the new drug delivery system allowed for a significant improvement in quercetin stability and the optimal release concentration attainment.

We examine Hofmeister specific ion effects of electrolytes added to protein solution under conditions minimizing electrostatic attraction between cations and positively charged protein. Hemoglobin (Hb) in aqueous solution at the denaturing pH = 2.7 is investigated in the presence of several metal chlorides, along with sodium and potassium bromides, iodides and thiocyanates, using electrospray ionization mass spectrometry (ESI-MS). Salt concentration was varied to maximize peak intensity and bell-shaped profile in the ESI-MS spectrum. The a-chain of myoglobin is identified as the main pattern of the ESI-MS spectra in all Hb-salt systems. Both peak intensity and quality of the bell-shaped profile of the protein spectrum decrease in the cation order: K+ > > Mg2+ > Li+ > > Na+ > Ca2+ approximate to Cs+ > Rb+ for Hb-Metal Chloride systems, and decrease in the anion order: Cl- > Br- > I- > SCN for systems of both Hb-NaX and Hb-KX salts. To quantify salt addition effects two Hofmeister specific electrolyte parameters H-S, and P-S are proposed. H-S is the mean (Hb-salt)/Hb peak intensity ratio, measured for the nine peaks used for ESI-MS spectra deconvolution, taken at the same m/z values of the Hb profile. P-S is the ratio between H-S standard deviation and HS, and provides a specific perturbation parameter measuring the loss of protein structure. These two Hofmeister parameters give clear evidence of the effects induced either by KCl, MgCl2 and LiCl that enhance protein peak intensity, or by NaBr, NaI, NaSCN and KSCN that induce the protein fragmentation, due to electrolyte-mediated dissociation.

This investigation aims to obtain a thermosensitive platform useful for specific nanomedicine applications through the addition of suitable salts. An aqueous mixture consisting of the copolymer Pluronic F127 and sodium carboxymethyl-cellulose, in a ratio of 20/4 by weight, in the presence of different concentrations of Na2SO4, NaCl, and NaSCN, was investigated using the visual inversion tube approach to estimate a phase map, and then characterized through rheological measurements. The formation of a cubic liquid crystalline phase at temper-atures higher than 37 degrees C was suggested in all systems. The complex viscosity, decreases in the presence of salts in the order Na2SO4 > NaCl > NaSCN with more marked effect for lower concentrations. Salt addition allows to tune the crowding effect of NaCMC. For the polymer mixture and for a sample containing NaCl, 1H NMR self -diffusion experiments display a non-mono-exponential decay of the echo signals of Pluronic F127, caused by the polydispersity of commercial Pluronic F127. The rheological properties along with the diffusion behaviour of the liquid crystal micelles suggest that a sample containing NaCl 0.07 mol/kg, with a sol-hard gel transition temperature around 35 degrees C, close to that of the body, may be a suitable and biocompatible thermosensitive platform to administer both hydrophobic and hydrophilic drugs such as antibiotics, anticancer drugs or growing factors.

Mesoporous silica nanoparticles (MSN) were synthesised and functionalised with triethylenetetramine (MSN-TETA). The samples were fully characterised (transmission electron microscopy, small angle X-ray scattering, Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential and nitrogen adsorption/desorption isotherms) and used as carriers for the adsorption of the antimicrobial drug sulphamethizole (SMZ). SMZ loading, quantified by UV–Vis spectroscopy, was higher on MSN-TETA (345.8 mg g−1) compared with bare MSN (215.4 mg g−1) even in the presence of a lower surface area (671 vs. 942 m2 g−1). The kinetics of SMZ adsorption on MSN and MSN-TETA followed a pseudo-second-order model. The adsorption isotherm is described better by a Langmuir model rather than a Temkin or Freundlich model. Release kinetics showed a burst release of SMZ from bare MSN samples (k1 = 136 h−1) in contrast to a slower release found with MSN-TETA (k1 = 3.04 h−1), suggesting attractive intermolecular interactions slow down SMZ release from MSN-TETA. In summary, the MSN surface area did not influence SMZ adsorption and release. On the contrary, the design of an effective drug delivery system must consider the intermolecular interactions between the adsorbent and the adsorbate.

Biofuels could be defined as the fuels of the future, although much work is still required before they will replace fossil fuels. In this review, lignocellulosic biomass based on straw and related crops and wastes is described concerning its lignin contents, structure, and properties, and an overview on the means of current and predictable delignification protocols is presented. The discussion is focused on herbaceous monocot materials and their available pretreatments (physical, chemical, and enzymatic), with special emphasis on fungal ligninolytic enzymes and the most recent findings and developments in their current application, issues, and perspectives.

BSA and lysozyme molecular motion at pH 7.15 is buffer-specific. Adsorption of buffer ions on protein surfaces modulates the protein surface charge and thus protein-protein interactions. Interactions were estimated by means of the interaction parameter kD obtained from plots of diffusion coefficients at different protein concentrations (Dapp = D0[1 + kDCprotein]) via dynamic light scattering and nuclear magnetic resonance. The obtained results agree with recent findings confirming doubts regarding the validity of the Henderson-Hasselbalch equation, which has traditionally provided a basis for understanding pH buffers of primary importance in solution chemistry, electrochemistry, and biochemistry.

This review, devoted to the memory of Kåre Larsson, deals with surfactant and lipid self-assembly. The focus is on the crucial role of NMR techniques in the understanding, at a molecular level, molecular dynamics and microstructure. The strength of NMR self-diffusion in determining size and shape of supramolecular aggregates as well as microstructural features, in terms of water-in-oil, oil-in-water and bicontinuity, is emphasized.

Enzymes have come into use for many new applications outside their natural biological environment, taking advantage of their high efficiency and selectivity as biocatalysts. Such new application often requires encapsulation to preserve the structure and activity of the enzyme, but also to regulate and control the activity. Here, we will discuss two types of encapsulation, soft matrices consisting of polar lipid liquid crystals and hard ordered mesoporous silica matrices. For both types of matrices, the challenge is to control the pore size of the matrices and the interaction with the matrix interface. Here, the polar lipid liquid crystals offer larger flexibility than silica, but on the other hand, it is considerably more sensitive to the environment.

The purpose of this work was the assembly of multicomponent nano-bioconjugates based on mesoporous silica nanoparticles (MSNs), proteins (bovine serum albumin, BSA, or lysozyme, LYZ), and gold nanoparticles (GNPs). These nano-bioconjugates may find applications in nanomedicine as theranostic devices. Indeed, MSNs can act as drug carriers, proteins stabilize MSNs within the bloodstream, or may have therapeutic or targeting functions. Finally, GNPs can either be used as contrast agents for imaging or for photothermal therapy. Here, amino-functionalized MSNs (MSN-NH2) were synthesized and characterized through various techniques (small angle X-rays scattering TEM, N2 adsorption/desorption isotherms, and thermogravimetric analysis (TGA)). BSA or lysozyme were then grafted on the external surface of MSN-NH2 to obtain MSN-BSA and MSN-LYZ bioconjugates, respectively. Protein immobilization on MSNs surface was confirmed by Fourier transform infrared spectroscopy, ζ-potential measurements, and TGA, which also allowed the estimation of protein loading. The MSN-protein samples were then dispersed in a GNP solution to obtain MSN-protein-GNPs nano-bioconjugates. Transmission electron microscopy (TEM) analysis showed the occurrence of GNPs on the MSN-protein surface, whereas almost no GNPs occurred in the protein-free control samples. Fluorescence and Raman spectroscopies suggested that proteins-GNP interactions involve tryptophan residues.

Mesoporous silica particles, based on SBA-15 matrix, were functionalized with triethylenetetramine (TETA), and characterized by transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), and N-2-adsorption/desorption isotherms (surface area and pore size distribution). The functionalization of SBA-15 with TETA to obtain SBA-TETA was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermogravi-metric analysis (TGA). SBA-TETA functional material was used for the adsorption of Cu2+ and Zn2+ metal ions from aqueous solutions at pH 4 and T = 298 K. The adsorption kinetics was faster for Zn2+ with respect to Cu2+ ions, and could be described by the pseudo-second order model indicating the chemisorption of the metal ions as the rate-determining step of the adsorption process. Adsorption isotherms at 298 K were carried out, and the experimental data analyzed with Freundlich, Temkin, and Langmuir models. Among the isotherm models, Langmuir gave the best fitting of the experimental data, allowing to quantify the maximal adsorbable amount of Cu2+ (23.9 mg g(-1)) and Zn2+ (13.6 mg g(-1)) by SBA-TETA. Moreover, the Langmuir constant, K L , was used to calculate the thermodynamic adsorption constant K degrees and the associated Delta G degrees, namely -21.7 kJ mol(-1) and -28.4 kJ mol(-1) for Cu2+ and Zn2+ adsorption processes, respectively. These values are better than those reported in similar works, likely due to the superior performance of TETA chelating agent respect to conventional alkyl-amino ligands once grafted on SBA-15 surface.

Ordered mesoporous silica (OMS) is a very interesting nanostructured material for the design and engineering of new target and controlled drug-delivery systems. Particularly relevant is the interaction between OMS and proteins. Large pores (6–9 nm) micrometric particles can be used for the realization of a drug depot system where therapeutic proteins are adsorbed either inside the mesopores or on the external surface. Small pores (1–2 nm) mesoporous silica nanoparticles (MSNs), can be injected in the blood stream. In the latter case, therapeutic proteins are mainly adsorbed on the MSNs’ external surface. Whenever a protein-OMS conjugate is prepared, a diagnostic method to locate the protein either on the internal or the external silica surface is of utmost importance. To visualize the fine localization of proteins adsorbed in mesoporous silica micro- and nanoparticles, we have employed specific transmission electron microscopy (TEM) analytical strategies based on the use of gold nanoparticles (GNPs) conjugates. GNPs are gaining in popularity, representing a fundamental tool to design future applications of MSNs in nanomedicine by realizing theranostic nanobioconjugates. It may be pointed out that we are at the very beginning of a new age of the nanomaterial science: the “mesoporous golden age„.

A dynamic, rheological, and structural characterization of aqueous gel-like systems containing hydroxypropyl guar gum (HPG), borax and glycerol is presented in this paper. The role of glycerol, which is introduced as a plasticizer in the formulation, is investigated by means of 11B NMR and 1H NMR PGSTE measurements in order to clarify its contribution to the gel network formation and its interaction with borax, with whom it forms a complex. The effect of gels components on the rheological behaviour and on the activation energy related to the relaxation process of the system was assessed by means of rheology. The results obtained suggest that the mechanical properties of these gels can be tuned and controlled by modulating the formulation in a wide range of compositions. Moreover, a structural characterisation has been also carried out by means of Small Angle X-ray Scattering (SAXS) to highlight the role of the various components on the mesh size of the network. The structural and mechanical characteristics of these systems suggest their potential use for applicative purposes. In this regard, one of the gel set up has been successfully tested as cleaning agent on the surface of a XIX stucco fragment coming from the La Fenice theatre (Venice, Italy) for the removal of a dirt layer composed by dust and particulated matter originated during a fire in 1996.

Lipid based formulations, endowed of long term stability as a result of the formation of lamellar liquid crystals, were prepared using the natural lipids lecithin and glycerol trioleate in water, and characterized using optical microscopy, SAXRD and NMR. The formulations, designed as possible carriers for lysozyme and caffeine, were evaluated for structural features and stability after the loading of the guest molecules. Release experiments were performed at 37 C using the PBS medium. No burst release was observed either for lysozyme or caffeine. Although lysozyme released from the lipid formulations does not fully retain its biological activity, the investigated liquid crystal stabilized formulations display a promising potential as drug and cosmetic carriers for topical applications, due to their high biocompatibility. (C) 2018 Elsevier B.V. All rights reserved.

Mesoporous silica nanoparticles (MSNs) were functionalized with amino groups (MSN-NH2 ) and then with hyaluronic acid, a biocompatible biopolymer which can be recognized by CD44 receptors in tumor cells, to obtain a targeting drug delivery system. To this purpose, three hyaluronic acid samples differing for the molecular weight, namely HA(S) (8-15 kDa), HA(M) (30-50 kDa) and HA(L) (90-130 kDa), were used. The MSN-HA(S), MSN-HA(M), and MSN-HA(L) materials were characterized through zeta potential and dynamic light scattering measurements at pH = 7.4 and T=37 degrees C to simulate physiological conditions. While zeta potential showed an increasing negative value with the increase of the HA chain length, an anomalous value of the hydrodynamic diameter was observed for MSN-HA(L), which was smaller than that of MSN-HA(S) and MSN-HA(M) samples. The cellular uptake of MSN-HA samples on HeLa cells at 37 degrees C was studied by optical and electron microscopy. HA chain length affected significantly the cellular uptake that occurred at a higher extent for MSN-NH2 and MSN-HA(S) than for MSN-HA(M) and MSN-HAL samples. Cellular uptake experiments carried out at 4 degrees C showed that the internalization process was inhibited for MSN-HA samples but not for MSN-NH2. This suggests the occurrence of two different mechanisms of internalization. For MSN-NH2 the uptake is mainly driven by the attractive electrostatic interaction with membrane phospholipids, while MSN-HA internalization involves CD44 receptors overexpressed in HeLa cells. (C) 2018 Elsevier B.V. All rights reserved.

The phase behavior in the oleic acid/sodium oleate/normal saline (0.15 M NaCl aqueous solution) system has been determined. For this purpose visual inspection of samples between crossed polarizers, and Small Angle Xray diffraction was used to identify the various phases and their unit cell dimensions. A rich phase behavior was observed for the ternary system, featuring reverse micellar, micellar cubic, hexagonal, and cubic phases, and large regions with lamellar phases. As expected the ratio the 'oleic acid/sodium oleate' determines the pH and as a consequence the phase behavior. The results could be modeled by an extended Henderson-Hasselbalch (HH) equation, which takes into account the electrostatic potential at the aqueous lipid interface. The knowledge obtained is important for understanding the lipolysis of triglycerides, as the phase behavior of the end-product of the reaction regulates how well the insoluble product can be dispersed and consequently the kinetics of the process.

Biomedical application of nanoparticles is largely associated to their fate in biological media which, in turn, is related to their surface properties. Surface functionalization plays a key role in determining biodegradation, cytotoxicity and biodistribution through interactions which may be mediated by the macromolecules occurring in biological media. A typical example is given by several proteins which lead to the formation of coated nanoparticles referred as protein corona. In this work we focus on mesoporous silica nanoparticles which, due to their intrinsic textural features, show potential as carriers for sustained drug release. Mesoporous silica nanoparticles functionalized by different biopolymers such as hyaluronic acid and chitosan were synthesized and characterized through small angle X-rays scattering, thermal analysis, and infrared spectroscopy. Biopolymer-coated mesoporous silica nanoparticles were used to investigate the interaction with bovine serum albumin, and to point out the role of different biopolymer coating. Gold-conjugated-bovine serum albumin was used to gain evidence on the occurrence of surface bound proteins enabling direct observation by transmission electron microscopy. Our findings provide insights on how different biopolymers affect the formation of a protein corona around functionalized mesoporous silica nanoparticles.