Lysozyme-dextran core-shell nanogels prepared via a green process

Biogenic Synthesis of Antibacterial, Hemocompatible, and Antiplatelets Lysozyme Functionalized Silver Nanoparticles through the One-Step Process for Therapeutic Applications

To evaluate silver nanoparticles’ (AgNPs) therapeutic and clinical potentials, antibacterial action, blood compatibility, and antiplatelet activities are the main concerns for toxicity profiling. Heat-denatured lysozyme-mediated formulation stabilized the AgNPs, thereby providing more bactericidal activity and blood compatibility. The study of the synthesis of AgNPs suggests the rapid and cost-effective formulation of AgNPs by one-step reaction using a 10:1 ratio of silver nitrate and lysozyme by incubating at 60 °C for two hours. Characterization of AgNPs was analyzed by UV–Visible spectroscopy, DLS, TEM, EDX, XRD, AFM, and FTIR, followed by antibacterial, hemocompatibility, and platelet aggregation testing. The average size of synthesized AgNPs was found to be 94.10 nm with 0.45 mV zeta potential and 0.293 polydispersity index by DLS. The TEM and EXD results indicated homogeneously 28.08 nm spherical-shaped pure formations of AgNPs. The XRD peaks showed the synthesis of small AgNPs with a crystallite size of 22.88 nm, while the AFM confirmed the homogeneity and smoothness of the monodispersed AgNPs. The FTIR spectra specified the coating of the lysozyme-derived amide group on the AgNPs surface, which provides stability and functionality of nanoparticles. The antibacterial activity of AgNPs was remarkable against six pathogenic bacteria and three multidrug resistance (MDR) strains (i.e., Escherichia coli, Klebsiella aerogenes, and Pseudomonas aeruginosa), which exhibited inhibition zones with diameters ranging between 13.5 ±  0.2 mm to 19.0 ±  0.3 mm. The non-hemolytic nature of the AgNPs was calculated by percentage hemolysis with four concentrations. The negative result of platelet aggregation using platelet-rich plasma suggests the antiplatelet effect of AgNPs. Only minor hemolysis of 6.17% in human erythrocytes and mild platelet aggregation of 1.98% were induced, respectively, by the use of 1000 µL of 1 mM AgNPs, which contains approximately 107.8 μg silver. The results indicated that the antiplatelet potency and non-hemolytic nature with the antibacterial action of the lysozyme functionalized AgNPs have a good chance to be used to solve in-stent restenosis and thrombosis issues of the coronary stent and may also have a possibility to use in vaccination to resolve the blood clotting problem. So, the optimized biogenic formulation of AgNPs offers promising opportunities to be used as a therapeutic agent.

Supramolecular arrangement of protein in nanoparticle structures predicts nanoparticle tropism for neutrophils in acute lung inflammation

This study shows that the supramolecular arrangement of proteins in nanoparticle structures predicts nanoparticle accumulation in neutrophils in acute lung inflammation (ALI). We observed homing to inflamed lungs for a variety of nanoparticles with agglutinated protein (NAPs), defined by arrangement of protein in or on the nanoparticles via hydrophobic interactions, crosslinking and electrostatic interactions. Nanoparticles with symmetric protein arrangement (for example, viral capsids) had no selectivity for inflamed lungs. Flow cytometry and immunohistochemistry showed NAPs have tropism for pulmonary neutrophils. Protein-conjugated liposomes were engineered to recapitulate NAP tropism for pulmonary neutrophils. NAP uptake in neutrophils was shown to depend on complement opsonization. We demonstrate diagnostic imaging of ALI with NAPs; show NAP tropism for inflamed human donor lungs; and show that NAPs can remediate pulmonary oedema in ALI. This work demonstrates that structure-dependent tropism for neutrophils drives NAPs to inflamed lungs and shows NAPs can detect and treat ALI.

Construction and evaluation of ovalbumin-pullulan nanogels as a potential delivery carrier for curcumin

Preparation of protein/polysaccharide nanocomplexes for delivering environment-sensitive bioactive compounds is significant in the fields of functional foods and pharmaceuticals. In this work, ovalbumin-pullulan (OVA-Pul) nanogels were fabricated through Maillard reaction combined with heat treatment. The results of SDS-PAGE, circular dichroism and conjugation yield (84.96%) confirmed the covalent crosslinking of ovalbumin to pullulan. Dynamic light scattering measurements indicated that nanogels and curcumin-loaded nanogels exhibited small particle diameter at around 190 nm and 160 nm, and excellent polydispersity index at 0.227 and 0.146, respectively. OVA-Pul nanogels showed good encapsulation efficiency (88.38%) and loading capacity (8.78%) for curcumin. Transmission electron microscope observations and in vitro gastrointestinal digestion suggested that OVA-Pul nanogels facilitated the controlled release of curcumin and the spherical structure of curcumin-loaded nanogels was damaged during digestion. Notably, both nanogels and curcumin-loaded nanogels showed desirable storage stability during 30 d. Hence, OVA-Pul nanogels have the potential for effectively delivering nutrients and drugs.

Glycation of soy proteins leads to a range of fractions with various supramolecular assemblies and surface activities

Dry and subsequent wet heating were used to glycate soy proteins with dextran or glucose, followed by fractionation based on size and solubility. Dry heating led to protein glycation (formation of furosine, Nε-(carboxymethyl)-l-lysine, Nε-(carboxyethyl)-l-lysine, and protein-bound carbonyls) and aggregation (increased particle size); while subsequent wet heating induced partial unfolding and de-aggregation. The measurable free amino group content of soy proteins changed from 0.77 to 0.14, then to 0.62 mmol/g upon dry and subsequent wet heating; this non-monotonic evolution is probably due to protein structural changes, and shows that this content should be interpreted with caution as a glycation marker. After both heating steps, the smaller-sized water-soluble fractions showed higher surface activity than the larger insoluble ones, and dextran conjugates exhibited a higher surface activity than their glucose counterparts. We thereby achieved a comprehensive understanding of the properties of various fractions in plant protein fractions, which is essential when targeting applications.

Different Strategies for the Preparation of Galactose-Functionalized Thermo-Responsive Nanogels with Potential as Smart Drug Delivery Systems

Different synthetic strategies were tested for the incorporation of galactose molecules on thermoresponsive nanogels owing to their affinity for receptors expressed in cancer cells. Three families of galactose-functionalized poly(N-vinylcaprolactam) nanogels were prepared with the aim to control the introduction of galactose-moieties into the core, the core-shell interface and the shell. First and second of the above mentioned, were prepared via surfactant free emulsion polymerization (SFEP) by a free-radical mechanism and the third one, via SFEP/reversible addition-fragmentation chain transfer (RAFT) polymerization. Synthetic recipes for the SFEP/free radical method included besides N-vinylcaprolactam (NVCL), a shell forming poly(ethylene glycol) methyl ether methacrylate (PEGMA), while the galactose (GAL) moiety was introduced via 6-O-acryloyl-1,2,:3,4-bis-O-(1-methyl-ethylidene)-α-D-galactopiranose (6-ABG, protected GAL-monomer): nanogels I, or 2-lactobionamidoethyl methacrylate (LAMA, GAL-monomer): nanogels II. For the SFEP/RAFT methodology poly(2-lactobionamidoethyl methacrylate) as GAL macro-chain transfer agent (PLAMA macro-CTA) was first prepared and on a following stage, the macro-CTA was copolymerized with PEGMA and NVCL, nanogels III. The crosslinker ethylene glycol dimethacrylate (EGDMA) was added in both methodologies for the polymer network construction. Nanogel's sizes obtained resulted between 90 and 370 nm. With higher content of PLAMA macro-CTA or GAL monomer in nanogels, a higher the phase-transition temperature (TVPT) was observed with values ranging from 28 to 46 °C. The ρ-parameter, calculated by the ratio of gyration and hydrodynamic radii from static (SLS) and dynamic (DLS) light scattering measurements, and transmission electron microscopy (TEM) micrographs suggest that core-shell nanogels of flexible chains were obtained; in either spherical (nanogels II and III) or hyperbranched (nanogels I) form.

Cross-linker-Modulated Nanogel Flexibility Correlates with Tunable Targeting to a Sterically Impeded Endothelial Marker

Deformability of injectable nanocarriers impacts rheological behavior, drug loading, and affinity target adhesion. Here, we present atomic force microscopy (AFM) and spectroscopy measurements of nanocarrier Young's moduli, tune the moduli of deformable nanocarriers with cross-linkers, and demonstrate vascular targeting behavior that correlates with Young's modulus. Homobifunctional cross-linkers were introduced into lysozyme-dextran nanogels (NGs). Single particle-scale AFM measurements determined NG moduli varying from ∼50-150 kPa for unmodified NGs or NGs with a short hydrophilic cross-linker (2,2'-(ethylenedioxy)bis(ethylamine), EOD) to ∼350 kPa for NGs modified with a longer hydrophilic cross-linker (4,9-dioxa-1,12-dodecanediamine, DODD) to ∼10 MPa for NGs modified with a longer hydrophobic cross-linker (1,12-diaminododecane, DAD). Cross-linked NGs were conjugated to antibodies for plasmalemma vesicle associated protein (PLVAP), a caveolar endothelial marker that cannot be accessed by rigid particles larger than ∼100 nm. In previous work, 150 nm NGs effectively targeted PLVAP, where rigid particles of similar diameter did not. EOD-modified NGs targeted PLVAP less effectively than unmodified NGs, but more effectively than DODD or DAD modified NGs, which both yielded low levels of targeting, resembling results previously obtained with polystyrene particles. Cross-linked NGs were also conjugated to antibodies against intracellular adhesion molecule-1 (ICAM-1), an endothelial marker accessible to large rigid particles. Cross-linked NGs and unmodified NGs targeted uniformly to ICAM-1. We thus demonstrate cross-linker modification of NGs, AFM determination of NG mechanical properties varying with cross-linker, and tuning of specific sterically constrained vascular targeting behavior in correlation with cross-linker-modified NG mechanical properties.

Stimulus-responsive polymeric nanogels as smart drug delivery systems

Nanogels are three-dimensional nanoscale networks formed by physically or chemically cross-linking polymers. Nanogels have been explored as drug delivery systems due to their advantageous properties, such as biocompatibility, high stability, tunable particle size, drug loading capacity, and possible modification of the surface for active targeting by attaching ligands that recognize cognate receptors on the target cells or tissues. Nanogels can be designed to be stimulus responsive, and react to internal or external stimuli such as pH, temperature, light and redox, thus resulting in the controlled release of loaded drugs. This "smart" targeting ability prevents drug accumulation in non-target tissues and minimizes the side effects of the drug. This review aims to provide an introduction to nanogels, their preparation methods, and to discuss the design of various stimulus-responsive nanogels that are able to provide controlled drug release in response to particular stimuli. STATEMENT OF SIGNIFICANCE: Smart and stimulus-responsive drug delivery is a rapidly growing area of biomaterial research. The explosive rise in nanotechnology and nanomedicine, has provided a host of nanoparticles and nanovehicles which may bewilder the uninitiated reader. This review will lay out the evidence that polymeric nanogels have an important role to play in the design of innovative drug delivery vehicles that respond to internal and external stimuli such as temperature, pH, redox, and light.

Curcumin-loaded galactosylated BSA nanoparticles as targeted drug delivery carriers inhibit hepatocellular carcinoma cell proliferation and migration

Background

The main objective of this study was to develop novel BSA nanoparticles (BSA NPs) for improving the bioavailability of curcumin as an anticancer drug, and those BSA NPs were galactosylated for forming the curcumin-loaded galactosylated BSA nanoparticles (Gal-BSA-Cur NPs), thus enhancing their ability to target asialoglycoprotein receptor (ASGPR) overexpressed on hepatocellular carcinoma (HCC) cells.

Materials and methods

Gal-BSA-Cur NPs were prepared by the desolvation method and showed a spherical shape and well distribution with the average particle size of 116.24 nm.

Results

In vitro drug release assay exhibited that Gal-BSA-Cur NPs had higher release rates and improved the curcumin solubility. Cell uptake studies confirmed that Gal-BSA-Cur NPs could selectively recognize receptors on the surface of HCC (HepG2) cells and improve internalization ability of drug compared with BSA NPs-loaded curcumin (BSA-Cur NPs), which might be due to high affinity to galactose. Further, the effects of Gal-BSA-Cur NPs were evaluated by cytotoxicity assay, crystal violet assay, cell apoptosis assay, and wound healing assay, respectively, which revealed that Gal-BSA-Cur NPs could inhibit HepG2 cells proliferation, induce cell apoptosis, and inhibit cell migration.

Conclusion

Immunofluorescence staining has proved that the effects of Gal-BSA-Cur NPs related to the suppression of the nuclear factor κB-p65 (NF-κB-p65) expression in HepG2 cell nucleus. Therefore, these results indicate that novel Gal-BSA-Cur NPs are potential candidates for targeted curcumin delivery to HCC cells.

Protein-polysaccharide nanohybrids: Hybridization techniques and drug delivery applications

Complex nanosystems fabricated by hybridization of different types of materials such as lipids, proteins, or polysaccharides are usually superior to simple ones in terms of features and applications. Proteins and polysaccharides hold great potential for development of nanocarriers for drug delivery purposes based on their unique biocompatibility, biodegradability, ease of functionalization, improved biodistribution and minimal toxicity profiles. Protein-polysaccharide nanohybrids have gained a lot of attention in the past few years particularly for drug delivery applications. In this review, different hybridization techniques utilized in the fabrication of such nanohybrids including electrostatic complexation, Maillard conjugation, chemical coupling and electrospinning were thoroughly reviewed. Moreover, various formulation factors affecting the characteristics of the formed nanohybrids were discussed. We also reviewed in depth the outcomes of such hybridization ranging from stability enhancement, to toxicity reduction, improved biocompatibility, and drug release modulation. We also gave an insight on their limitations and what hinders their clinical translation and market introduction.

Bioengineering of Functional Nanosilver Nanogels for Smart Healthcare Systems

Functional designing of nanogels has become an attractive domain of biomedical engineering to develop bioactive materials with innovative features for the human healthcare system. Nanosilver has attracted enormous attention due to its wide antimicrobial spectrum and ability to kill almost all types of bacteria in its vicinity. However, the most crucial challenge for bioscientists is the lack of binding ability of nanosilver with the material surfaces that allow nanosilver to leach out to the surrounding tissue and exert toxicity while the biomaterial is in contact with the living system. Designing nanosilver within a nanogel confinement offers enormous possibilities to develop functional bioactive nanoparticles that may be bonded to any biomaterial surface via the nanogel functionality. This approach requires the proper combination of material science with nanotechnology and biotechnology to innovate interesting domain of functional nanogels with unique features. This work aims at providing a critical review on the current progress, approaches, and vision in designing nanosilver-entrapped nanogel particles with diverse functionality, and their bioactivity against microorganisms for human healthcare devices.

Nanoparticle Properties Modulate Their Attachment and Effect on Carrier Red Blood Cells

Attachment of nanoparticles (NPs) to the surface of carrier red blood cells (RBCs) profoundly alters their interactions with the host organism, decelerating NP clearance from the bloodstream while enabling NP transfer from the RBC surface to the vascular cells. These changes in pharmacokinetics of NPs imposed by carrier RBCs are favorable for many drug delivery purposes. On the other hand, understanding effects of NPs on the carrier RBCs is vital for successful translation of this novel drug delivery paradigm. Here, using two types of distinct nanoparticles (polystyrene (PSNP) and lysozyme-dextran nanogels (LDNG)) we assessed potential adverse and sensitizing effects of surface adsorption of NPs on mouse and human RBCs. At similar NP loadings (approx. 50 particles per RBC), adsorption of PSNPs, but not LDNGs, induces RBCs agglutination and sensitizes RBCs to damage by osmotic, mechanical and oxidative stress. PSNPs, but not LDNGs, increase RBC stiffening and surface exposure of phosphatidylserine, both known to accelerate RBC clearance in vivo. Therefore, NP properties and loading amounts have a profound impact on RBCs. Furthermore, LDNGs appear conducive to nanoparticle drug delivery using carrier RBCs.

Fabrication of supramolecular hyperbranched polyamidoamine–dextran conjugates and their self-assembly in the presence of EGCG

A supramolecular hyperbranched conjugate, HPAM–Dex, was prepared and it could self-assemble into size-controllable micelles in the presence of EGCG.

Fluorescence Microscopy Imaging Calibration for Quantifying Nanocarrier Binding to Cells During Shear Flow Exposure

Targeted drug delivery is a fast growing industry in healthcare and technologies are being developed for applications utilizing nanocarriers as vehicles for drug transport. As the size scale of these particles becomes further reduced, advanced fluorescence microscopy and image analysis techniques become increasingly important for facilitating our understanding of nanocarrier binding and avidity, thereby establishing the basis for nanocarrier design optimization. While there is a significant body of published work using nanocarriers in vitro and in vivo, the advent of smaller particles that have typically been studied (~500 nm) limits the ability to attain quantitative measurements of nanocarrier binding dynamics since image acquisition and analysis methods are restricted by microscopy pixel size. This work demonstrates the use of a novel calibration technique based on radioisotope counting and fluorescence imaging for enabling quantitative determination of nanocarrier binding dynamics. The technique is then applied to assess the temporal profile of endothelial cell binding of two antibody targeted nanocarrier types in the presence of fluid shear stress. Results are provided for binding of nanoparticles smaller than a microscopy image pixel.

Folate-functionalized assembly of low density lipoprotein/sodium carboxymethyl cellulose nanoparticles for targeted delivery

In this study, well-defined folate (FA)-functionalized low density lipoproteins (LDL)/sodium carboxymethyl cellulose (CMC) nanoparticles (NP) were first formulated, utilized in tumor targeting and pH-triggered drug release. CMC was modified with FA before the preparation of NP. A model anti-tumor drug, doxorubicin (DOX), was effectively loaded into the LDL/CMC-FA NP by ionic bonding and hydrophobic interactions. To enhance non-covalent encapsulation stability, self-assembly of DOX-loaded LDL/CMC-FA NP (NP-DOX) was cross-linked by multivalent cations such as Ca²⁺ (Ca²⁺-NP-DOX). The active targeting efficiency of NP-DOX and Ca²⁺-NP-DOX was tested against KB cells (FA-receptor over-expressing cells, FR+) and A549 cells (FA-receptor negative-expressing cells, FR-), using FA non-modified DOX-loaded LDL/CMC NP (NG-DOX) as control. The competition assay proved that free FA molecules prevented the cellular uptake of the NP by competitive binding to the FA receptors on the surface of KB cells. This new pH-responsive and FA-targeted nanocarrier may be a promising efficient drug delivery system for potential cancer therapy.

Nanogels fabricated from bovine serum albumin and chitosan via self-assembly for delivery of anticancer drug

In this study, bovine serum albumin (BSA) and chitosan (CS) were used to prepare BSA-CS nanogels by a simple green self-assembly technique. Then the nanogels were successfully used to entrap doxorubicin hydrochloride (DOX) with an entrapment ratio of 46.3%, aiming to realize the slow-release effect and lower the cytotoxicity of DOX. The IC50 values of DOX-loaded BSA-CS (DOX-BSA-CS) and free DOX obtained by MTT assay in SGC7901 cells were 0.22 and 0.05μg/mL, respectively. The cytotoxicity of DOX significantly decreased within 24h after encapsulation by the nanogels, indicating that the loaded drug could slowly release within 24h and the BSA-CS was a good slow release system. The cellular uptake experiments indicated DOX-BSA-CS diffused faster into the cancer cell than the bare drug. The flow cytometry and TUNEL assay proved DOX-BSA-CS could induce a larger apoptosis proportion of gastric cancer cells 7901 than the bare drug and it is promising to be used for curing gastric cancer.

Strain-rate Dependence of Elastic Modulus Reveals Silver Nanoparticle Induced Cytotoxicity

Force-displacement measurements are taken at different rates with an atomic force microscope to assess the correlation between cell health and cell viscoelasticity in THP-1 cells that have been treated with a novel drug carrier. A variable indentation-rate viscoelastic analysis, VIVA, is employed to identify the relaxation time of the cells that are known to exhibit a frequency dependent stiffness. The VIVA agrees with a fluorescent viability assay. This indicates that dextran-lysozyme drug carriers are biocompatible and deliver concentrated toxic material (rhodamine or silver nanoparticles) to the cytoplasm of THP-1 cells. By modelling the frequency dependence of the elastic modulus, the VIVA provides three metrics of cytoplasmic viscoelasticity: a low frequency modulus, a high frequency modulus and viscosity. The signature of cytotoxicity by rhodamine or silver exposure is a frequency independent twofold increase in the elastic modulus and cytoplasmic viscosity, while the cytoskeletal relaxation time remains unchanged. This is consistent with the known toxic mechanism of silver nanoparticles, where metabolic stress causes an increase in the rigidity of the cytoplasm. A variable indentation-rate viscoelastic analysis is presented as a straightforward method to promote the self-consistent comparison between cells. This is paramount to the development of early diagnosis and treatment of disease.

Fabrication and Characterization of Stable Soy β-Conglycinin-Dextran Core-Shell Nanogels Prepared via a Self-Assembly Approach at the Isoelectric Point

The preparation of soy β-conglycinin-dextran nanogels (∼90 nm) went through two stages, which are safe, facile, and green. First, amphiphilic graft copolymers were formed by dextran covalently attaching to β-conglycinin via Maillard dry-heating reaction. Second, the synthesized conjugates were heated above the denaturation temperature at the isoelectric point (pH4.8) so as to assemble nanogels. The effects of pH, concentration, heating temperature, and time on the fabrication of nanogels were examined. The morphology study displayed that the nanogels exhibited spherical shape with core-shell structures, which was reconfirmed by zeta-potential investigation. Both circular dichroism spectra and surface hydrophobicity analyses indicated that the conformations of β-conglycinin in the core of nanogels were changed, and the latter experiment further revealed that the hydrophobic groups of β-conglycinin were exposed to the surface of protein. The nanogels were stable against various conditions and might be useful to deliver hydrophobic bioactive compounds.

Stable nanoparticles prepared by heating electrostatic complexes of whey protein isolate-dextran conjugate and chondroitin sulfate

A simple and green method was developed for preparing the stable biopolymer nanoparticles with pH and salt resistance. The method involved the macromolecular crowding Maillard process and heat-induced gelation process. The conjugates of whey protein isolate (WPI) and dextran were produced by Maillard reaction. The nanoparticles were fabricated by heating electrostatic complexes of WPI-dextran conjugate and chondroitin sulfate (ChS) above the denaturation temperature and near the isoelectric point of WPI. Then, the nanoparticles were characterized by spectrophotometry, dynamic laser scattering, zeta potential, transmission electron microscopy, atomic force microscopy, and scanning electron microscopy. Results showed that the nanoparticles were stable in the pH range from 1.0 to 8.0 and in the presence of high salt concentration of 200 mM NaCl. WPI-dextran conjugate, WPI, and ChS were assembled into the nanoparticles with dextran conjugated to WPI/ChS shell and WPI/ChS core. The repulsive steric interactions, from both dextran covalently conjugated to WPI and ChS electrostatically interacted with WPI, were the major formation mechanism of the stable nanoparticles. As a nutrient model, lutein could be effectively encapsulated into the nanoparticles. Additionally, the nanoparticles exhibited a spherical shape and homogeneous size distribution regardless of lutein loading. The results suggested that the stable nanoparticles from proteins and strong polyelectrolyte polysaccharides would be used as a promising target delivery system for hydrophobic nutrients and drugs at physiological pH and salt conditions.

Self-assembled lysozyme/carboxymethylcellulose nanogels for delivery of methotrexate

Nanogels (NGs) were fabricated with lysozyme and carboxymethylcellulose via a green self-assembly method. The prepared NGs were characterized by dynamic light scattering (DLS), zeta potential, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Pyrene and isothiocyanate were introduced as fluorescent probes to research the hydrophobic area of the NGs and cells endocytosis, respectively. Methotrexate (MTX) was used to investigate the drug encapsulation property of the NGs. It turned out to be that the drug loaded NGs were regular spherical shape with a hydrodynamic diameter of about 123 nm. The drug loading efficiency was about 14.2%. The NGs can slowly release the drug and increase the bioavailability of the loaded drug. The NGs are promising carriers for the delivery of drugs and other bioactive molecules.

Nanogel Carrier Design for Targeted Drug Delivery

Polymer-based nanogel formulations offer features attractive for drug delivery, including ease of synthesis, controllable swelling and viscoelasticity as well as drug loading and release characteristics, passive and active targeting, and the ability to formulate nanogel carriers that can respond to biological stimuli. These unique features and low toxicity make the nanogels a favorable option for vascular drug targeting. In this review, we address key chemical and biological aspects of nanogel drug carrier design. In particular, we highlight published studies of nanogel design, descriptions of nanogel functional characteristics and their behavior in biological models. These studies form a compendium of information that supports the scientific and clinical rationale for development of this carrier for targeted therapeutic interventions.

Icam-1 targeted nanogels loaded with dexamethasone alleviate pulmonary inflammation

Lysozyme dextran nanogels (NG) have great potential in vitro as a drug delivery platform, combining simple chemistry with rapid uptake and cargo release in target cells with “stealth” properties and low toxicity. In this work, we study for the first time the potential of targeted NG as a drug delivery platform in vivo to alleviate acute pulmonary inflammation in animal model of LPS-induced lung injury. NG are targeted to the endothelium via conjugation with an antibody (Ab) directed to Intercellular Adhesion Molecule-1(ICAM-NG), whereas IgG conjugated NG (IgG-NG) are used for control formulations. The amount of Ab conjugated to the NG and distribution in the body after intravenous (IV) injection have been quantitatively analyzed using a tracer isotope-labeled [¹²⁵I]IgG. As a proof of concept, Ab-NG are loaded with dexamethasone, an anti-inflammatory therapeutic, and the drug uptake and release kinetics are measured by HPLC. In vivo studies in mice showed that: i) ICAM-NG accumulates in mouse lungs (∼120% ID/g vs ∼15% ID/g of IgG-NG); and, ii) DEX encapsulated in ICAM-NG, but not in IgG-NG practically blocks LPS-induced overexpression of pro-inflammatory cell adhesion molecules including ICAM-1 in the pulmonary inflammation.

Modified lysozymes as novel broad spectrum natural antimicrobial agents in foods

In recent years much attention and interest have been directed toward application of natural antimicrobial agents in foods. Some naturally occurring proteins such as lactoperoxidase, lactoferrin, and lysozyme have received considerable attention and are being considered as potential antimicrobial agents in foods. Lysozyme kills bacteria by hydrolyzing the peptidoglycan layer of the cell wall of certain bacterial species, hence its application as a natural antimicrobial agent has been suggested. However, limitations in the action of lysozyme against only Gram-positive bacteria have prompted scientists to extend the antimicrobial effects of lysozyme by several types of chemical modifications. During the last 2 decades extensive research has been directed toward modification of lysozyme in order to improve its antimicrobial properties. This review will report on the latest information available on lysozyme modifications and examine the applicability of the modified lysozymes in controlling growth of Gram-positive and Gram-negative bacteria in foods. The results of modifications of lysozyme using its conjugation with different small molecule, polysaccharides, as well as modifications using proteolytic enzymes will be reviewed. These types of modifications have not only increased the functional properties of lysozyme (such as solubility and heat stability) but also extended the antimicrobial activity of lysozyme. Many examples will be given to show that modification can decrease the count of Gram-negative bacteria in bacterial culture and in foods by as much as 5 log CFU/mL and in some cases essentially eliminated Escherichia coli. In conclusion this review demonstrates that modified lysozymes are excellent natural food preservatives, which can be used in food industry.

PRACTICAL APPLICATION

The subject described in this review article can lead to the development of methods to produce new broad-spectrum natural antimicrobial agents, based on modification of chicken egg white lysozyme, which might potentially replace the currently used synthetic food preservatives.

Designing nanogel carriers for antibacterial applications

We have developed a novel and simple synthesis route to create nanosized (∼5nm) silver nanoparticles (Ag NPs) embedded in a biocompatible nanogel (NG) comprising degradable, natural polymers, namely dextran and lysozyme. In this study, we prepared hybrid nanogels with varying lysozyme content, evaluated their potential to reduce Ag NPs in situ (using ultraviolet-visible spectroscopy, cryo-transmission electronic microscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy) and determined their antibacterial properties against Escherichia coli and Staphylococcus aureus. Lysozyme was found to enhance nucleation and stabilization of Ag NPs while limiting their growth. As lysozyme concentration increased, larger nanogels with greater loading of smaller Ag NPs were obtained. The antibacterial properties of hybrid NGs were found to depend upon nanogel type and bacterial conditions. Hybrid nanogels with the largest Ag NPs showed the lowest minimum inhibition concentration. However, the greatest bacterial killing efficiency (up to 100%) occurred within 1h if the bacteria were exposed to hybrid nanogels with smaller Ag NPs while agitating the medium. These results suggest that nanogel properties as well as antibacterial activity can be tuned by varying the lysozyme content. By targeting drug delivery (e.g. ligand grafted surface), these nanogels can be used to prevent biofilm formation and control infection without the complications (i.e. overexposure) associated with classical antibiotic delivery platforms.

Cellular Uptake and Intracellular Cargo Release From Dextran Based Nanogel Drug Carriers

Nanogels (NG) hold great promise as a drug delivery platform. In this work, we examine the potential of lysozyme-dextran nanogels (LDNG) as drug carriers in vitro using two cell lines: a model target tissue, human umbilical cord vein endothelial cells (HUVEC) and a model of the mononuclear phagocyte system (phorbol 12-myristate 13-acetate (PMA)-stimulated THP-1 cells). The LDNG (∼100 nm) were prepared with rhodamine-label dextran (LRDNG) via Maillard reaction followed by heat-gelation reaction and were loaded with a fluorescent probe, 5-hexadecanoylaminofluorescein (HAF), as a mock drug. Epifluorescence microscopy confirmed rapid uptake of LRDNG by HUVEC. Although LysoTracker Green staining indicated a lysosomal fate for LRDNG, the mock drug cargo (HAF) diffused extensively inside the cell within 15 min. Flow cytometry and confocal microscopy indicated slow uptake of LRDNG in PMA-stimulated THP-1 cells, with only 41% of cells containing LRDNG after 24 h exposure. Finally, 24 h exposure to LRDNG did not affect the viability of either cell type at the dose studied (20 μg/ml). At a higher dose (200 μg/ml), LRDNG resulted in a marked loss of viability of HUVEC and THP-1, measuring 30% and 38%, respectively. Collectively, our results demonstrate the great potential of LRDNG as a drug delivery platform, combining simple production, rapid uptake and cargo release in target cells with "stealth" properties and low cytotoxicity.

Soy protein/soy polysaccharide complex nanogels: folic acid loading, protection, and controlled delivery

In this study, we developed a facile approach to produce nanogels via self-assembly of folic acid, soy protein, and soy polysaccharide. High-pressure homogenization was introduced to break down the original aggregates of soy protein, which benefits the binding of soy protein with soy polysaccharide and folic acid at pH 4.0. After a heat treatment that causes the soy protein denaturation and gelation, folic acid-loaded soy protein/soy polysaccharide complex nanogels were fabricated. The nanogels have a polysaccharide surface that makes the nanogels dispersible in acidic conditions where folic acid is insoluble and soy protein forms precipitates after heating. More importantly, the protein and polysaccharide can inhibit the reactions between dissolved oxygen and folic acid during UV irradiation. After the preparation and storage of the nanogels in the presence of heat, oxygen, and light in acidic conditions, most of the folic acid molecules in the nanogels remain in their natural structure and can be released rapidly at neutral pH, that is, in the intestine. Because most food and beverages are acidic, the nanogels are a suitable delivery system of folic acid in food and beverages.

In situ preparation of gold nanoparticle-loaded lysozyme-dextran nanogels and applications for cell imaging and drug delivery

An effective, green, and facile approach to synthesize gold nanoparticle-loaded protein-polysaccharide nanogels was developed in this study. Biocompatible gold nanoparticle-loaded lysozyme-dextran (Au@Lys-Dex) nanogels were produced using lysozyme-dextran nanogels as reducing and stabilizing agents. Lysozyme-dextran nanogels have a size of about 200 nm and a structure of lysozyme core and dextran shell. At pH around 4, AuCl4(-) ions are attracted and locally enriched by lysozyme due to the electrostatic and coordination interactions. When the solution is under UV irradiation, the AuCl4(-) ions are reduced to gold nanoparticles in situ by solvated electrons and reactive radicals produced from aromatic amino acid residues in the lysozyme. The produced gold nanoparticles with a size of about 8 nm are trapped inside the nanogels and the Au@Lys-Dex nanogels are well dispersible by virtue of the dextran shell. Antitumor drug, doxorubicin, can be loaded effectively inside Au@Lys-Dex nanogels via diffusion. In vitro study demonstrates the doxorubicin loaded Au@Lys-Dex nanogels have the same antitumor activity as free doxorubicin. The nanogels can be used as a contrasting agent in optical cell imaging, in which direct visual images of the subcellular distributions of the gold nanoparticles and the released doxorubicin are presented synchronously. The dual functional drug loaded Au@Lys-Dex nanogels are a promising system for simultaneous drug delivery and biomedical imaging.

A facile route to synthesize nanogels doped with silver nanoparticles

In this work, we describe a simple method to prepare hybrid nanogels consisting of a biocompatible core-shell polymer host containing silver nanoparticles. First, the nanogels (NG, ~160 nm) containing a lysozyme rich core and a dextran rich shell, are prepared via Maillard and heat-gelation reactions. Second, silver nanoparticles (Ag NPs, ~5nm) are synthesized in situ in the NG solution without requiring additional reducing agents. This approach leads to stable Ag NPs located in the NG. Furthermore, we demonstrate that the amount of Ag NPs in the NG can be tuned by varying silver precursor concentration. Hybrid nanogels with silver nanoparticles have potential in antimicrobial, optical and therapeutic applications.