Highly efficient immobilization of beta-lactoglobulin in functionalized mesoporous nanoparticles: A simple and useful approach for enhancement of protein stability

Adsorption of β-Lactoglobulin on Thiol-Functionalized Mesoporous Silica

SBA-15 mesoporous materials were synthesized with different pore sizes (5 and 10 nm) and thiol-functionalized groups and then characterized to describe their ability to differentially adsorb β-lactoglobulin (BLG), a globular protein with an ellipsoid shape measuring 6.9 nm in length and 3.6 nm in width. All adsorption experiments showed that the adsorption capacities of mesoporous materials for BLG were dependent on the duration of contact between the two materials (mesoporous material and BLG) and the initial BLG concentration. It was also shown that the pore sizes and thiol groups of SBA-15-based adsorbents are important factors for the BLG adsorption capacities. Among the tested adsorbents, thiol-functionalized SBA-15 with a 10 nm pore size (SBA-15-SH-10) showed the highest adsorption capacity (0.560 g·g-1) under optimal experimental conditions. Kinetics studies demonstrated that the adsorption occurs predominantly inside the pores, with interactions occurring on heterogeneous surfaces. In addition, the thermodynamic parameters indicate a spontaneous and exothermic behavior of the BLG adsorption process onto the thiol-functionalized SBA-15 mesoporous adsorbent. Finally, the characterization of the SBA-15-SH-10 adsorbent at 308 K showed the occurrence of an oxidation reaction of the thiol groups to sulfonate groups during the adsorption process as confirmed by Raman spectroscopy. The spectra recorded after adsorption of the protein showed that this adsorption did not affect the secondary structure of the protein.

Design and synthesis of Fe3O4@SiO2@KIT-6@DTZ-Pd0 as a new and efficient mesoporous magnetic catalyst in carbon-carbon cross-coupling reactions

In this paper, a new type of mesoporous material based on KIT-6 has been introduced. In this aim, magnetic Fe3O4 nanoparticles and mesoporous silica KIT-6 have been combined to obtain mesoporous MNPs. The prepared magnetic mesoporous catalyst has been applied in different carbon-carbon cross-coupling reactions including Mizoroki-Heck, Suzuki-Miyaura, and Stille reactions. This magnetic mesoporous compound is characterized by various techniques including FT-IR, BET, VSM, SEM, XRD, and TGA.

Perspectives on new opportunities for nano-enabled strategies for gene delivery to plants using nanoporous materials

Engineered nanocarriers have great potential to deliver different genetic cargos to plant cells and increase the efficiency of plant genetic engineering. Genetic engineering has improved the quality and quantity of crops by introducing desired DNA sequences into the plant genome. Traditional transformation strategies face constraints such as low transformation efficiency, damage to plant tissues, and genotype dependency. Smart nanovehicle-based delivery is a newly emerged method for direct DNA delivery to plant genomes. The basis of this new approach of plant genetic transformation, nanomaterial-mediated gene delivery, is the appropriate protection of transferred DNA from the nucleases present in the cell cytoplasm through the nanocarriers. The conjugation of desired nucleic acids with engineered nanocarriers can solve the problem of genetic manipulation in some valuable recalcitrant plant genotypes. Combining nano-enabled genetic transformation with the new and powerful technique of targeted genome editing, CRISPR (clustered regularly interspaced short palindromic repeats), can create new protocols for efficient improvement of desired plants. Silica-based nanoporous materials, especially mesoporous silica nanoparticles (MSNs), are currently regarded as exciting nanoscale platforms for genetic engineering as they possess several useful properties including ordered and porous structure, biocompatibility, biodegradability, and surface chemistry. These specific features have made MSNs promising candidates for the design of smart, controlled, and targeted delivery systems in agricultural sciences. In the present review, we discuss the usability, challenges, and opportunities for possible application of nano-enabled biomolecule transformation as part of innovative approaches for target delivery of genes of interest into plants.

Probing gold nanoparticles for the desensitization to β-lactoglobulin from binding mechanism, structure and IgE binding changes

Because of the adsorption of proteins, gold nanoparticles (AuNPs) create potential biological risks in biomedicine, leading to the formation of the protein corona. This adsorption is mainly due to the formation of gold-sulfur (AuS) covalent bonds between the AuNPs and the -SH groups, causing bioactivity denaturation and biological problems; however, it could also lead to some biological benefits. We explored AuNPs as a potential material for desensitization to allergens, such as β-lactoglobulin (βLG). To address the desensitization of AuNPs, we investigated the binding mechanism and the specific relationship of the time evolution of AuS bond, secondary structure, and allergy changes. The formation of AuS bond takes approximately 9 h, consistent with the complete changes time in secondary structure and immunoglobulin E (IgE) combining capacity of the βLG, decreasing allergic reactions. These results indicate that AuNPs have the potential to minimize allergic reactions in the future.

Novel folic acid-conjugated doxorubicin loaded β-lactoglobulin nanoparticles induce apoptosis in breast cancer cells

Chemotherapy constitutes the main strategy in management of breast cancer (BC). Lack of specificity and high burden of adverse effects of chemotherapeutic agents remain the most important impediments to successful treatment of BC patients. Folate receptor α (FRα) could be very promising for therapeutic targeting in this type of cancer. In this study, ß-lactoglobulin nanoparticles (BNPs) conjugated with folic acid and loaded with doxorubicin (FDBNPs) were prepared. Various characterization techniques were applied to determine the size, polydispersity and doxorubicin loading of prepared FDBNPs in comparison with doxorubicin-loaded BNPs (DBNPs). The results showed that FDBNPs are 109.77 ± 2.80 nm in diameter with well dispersed and spherical shapes. The biodegradation of FDBNPs in the presence of trypsin enzyme and in PBS at different pH (4 and 7) was spectrophotometrically monitored and the results showed that the FDBNPs with encapsulation efficiency of 68.82%±1.76% could deliver doxorubicin at clinically relevant doses. Effects of DBNPs and FDBNPs against MCF-7 and MDA-MB-231, BC and triple negative BC (TNBC) cell lines, respectively, showed significant inhibition of cell proliferation as well as induction of apoptosis. Based on these findings, FDBNPs with facilitated drug release and targeted doxorubicin delivery capacities could have high therapeutic potential for BC and TNBC.

Combined Spectroscopic and Calorimetric Studies to Reveal Absorption Mechanisms and Conformational Changes of Protein on Nanoporous Biomaterials

In this study the effect of surface modification of mesoporous silica nanoparticles (MSNs) on its adsorption capacities and protein stability after immobilization of beta-lactoglobulin B (BLG-B) was investigated. For this purpose, non-functionalized (KIT-6) and aminopropyl-functionalized cubic Ia3d mesoporous silica ([n-PrNH₂-KIT-6]) nanoparticles were used as nanoporous supports. Aminopropyl-functionalized mesoporous nanoparticles exhibited more potential candidates for BLG-B adsorption and minimum BLG leaching than non-functionalized nanoparticles. It was observed that the amount of adsorbed BLG is dependent on the initial BLG concentration for both KIT-6 and [n-PrNH₂-KIT-6] mesoporous nanoparticles. Also larger amounts of BLG-B on KIT-6 was immobilized upon raising the temperature of the medium from 4 to 55 °C while such increase was undetectable in the case of immobilization of BLG-B on the [n-PrNH₂-KIT-6]. At temperatures above 55 °C the amounts of adsorbed BLG on both studied nanomaterials decreased significantly. By Differential scanning calorimetry or DSC analysis the heterogeneity of the protein solution and increase in Tm may indicate that immobilization of BLG-B onto the modified KIT-6 results in higher thermal stability compared to unmodified one. The obtained results provide several crucial factors in determining the mechanism(s) of protein adsorption and stability on the nanostructured solid supports and the development of engineered nano-biomaterials for controlled drug-delivery systems and biomimetic interfaces for the immobilization of living cells.

Probing of the interaction between β-lactoglobulin and the anticancer drug oxaliplatin

The potential carrier role of β-lactoglobulin (β-LG) and its interactions with oxaliplatin were studied using various spectroscopic techniques (fluorescence, UV-visible, and circular dichroism (CD)) in an aqueous medium at two temperatures of 25 and 37 °C in combination with a molecular docking study. Fluorescence measurements have shown that the observed quenching is a combination of static and dynamic quenching with a predominant contribution of static mode. The presence of a single binding site located in the internal cavity of the β-barrel of β-LG was confirmed by molecular docking calculations. Thermodynamic data as well as molecular docking indicated that the hydrophobic interactions dominate in the binding site. Results of fluorescence resonance energy transfer (FRET) measurements in combination with docking results imply that resonance energy transfer occurs between β-LG and its ligand oxaliplatin. Additionally, CD results revealed that oxaliplatin binding has no influence on the β-LG structure. The molecular docking results indicate that docking may be an appropriate method for the prediction and confirmation of experimental results. Complementary molecular docking results may be useful for the determination of the binding mechanism of proteins such as β-LG in pharmaceutical and biophysical studies providing new insight in the novel pharmacology and new solutions in the formulation of advanced oral drug delivery systems.

Enzymes immobilized in mesoporous silica: a physical-chemical perspective

Mesoporous materials as support for immobilized enzymes have been explored extensively during the last two decades, primarily not only for biocatalysis applications, but also for biosensing, biofuels and enzyme-controlled drug delivery. The activity of the immobilized enzymes inside the pores is often different compared to that of the free enzymes, and an important challenge is to understand how the immobilization affects the enzymes in order to design immobilization conditions that lead to optimal enzyme activity. This review summarizes methods that can be used to understand how material properties can be linked to changes in enzyme activity. Real-time monitoring of the immobilization process and techniques that demonstrate that the enzymes are located inside the pores is discussed by contrasting them to the common practice of indirectly measuring the depletion of the protein concentration or enzyme activity in the surrounding bulk phase. We propose that pore filling (pore volume fraction occupied by proteins) is the best standard for comparing the amount of immobilized enzymes at the molecular level, and present equations to calculate pore filling from the more commonly reported immobilized mass. Methods to detect changes in enzyme structure upon immobilization and to study the microenvironment inside the pores are discussed in detail. Combining the knowledge generated from these methodologies should aid in rationally designing biocatalyst based on enzymes immobilized in mesoporous materials.

Spectroscopic and theoretical investigation of oxali-palladium interactions with β-lactoglobulin

The possibility of using a small cheap dairy protein, β-lactoglobulin (β-LG), as a carrier for oxali-palladium for drug delivery was studied. Their binding in an aqueous solution at two temperatures of 25 and 37°C was investigated using spectroscopic techniques in combination with a molecular docking study. Fluorescence intensity changes showed combined static and dynamic quenching during β-LG oxali-palladium binding, with the static mode being predominant in the quenching mechanism. The binding and thermodynamic parameters were determined by analyzing the results of quenching and those of the van't Hoff equation. According to obtained results the binding constants at two temperatures of 25 and 37°C are 3.3×10(9) M(-1) and 18.4×10(6) M(-1) respectively. Fluorescence resonance energy transfer (FRET) showed that the experimental results and the molecular docking results were coherent. An absence change of β-LG secondary structure was confirmed by the CD results. Molecular docking results agreed fully with the experimental results since the fluorescence studies also revealed the presence of two binding sites with a negative value for the Gibbs free energy of binding of oxali-palladium to β-LG. Furthermore, molecular docking and experimental results suggest that the hydrophobic effect plays a critical role in the formation of the oxali-palladium complex with β-LG. This agreement between molecular docking and experimental results implies that docking studies may be a suitable method for predicting and confirming experimental results, as shown in this study. Hence, the combination of molecular docking and spectroscopy methods is an effective innovative approach for binding studies, particularly for pharmacophores.