Preparation and characterisation of gelatin–gum arabic aldehyde nanogels via inverse miniemulsion technique

Polysaccharides gums in drug delivery systems: A review

For the drug delivery system, drug carriers' selection is critical to the drug's success in reaching the desired target. Drug carriers from natural biopolymers are preferred over synthetic materials due to their biocompatibility. The use of polysaccharide gums in the drug delivery system has received considerable attention in recent years. Polysaccharide gums are renewable resources and abundantly found in nature. They could be isolated from marine algae, microorganisms, and higher plants. In terms of carbohydrates, the gums are water-soluble, non-starch polysaccharides with high commercial value. Polysaccharide gums are widely used for controlled-release products, capsules, medicinal binders, wound healing agents, capsules, and tablet excipients. One of the essential applications of polysaccharide gum is drug delivery systems. The various kinds of polysaccharide gums obtained from different plants, marine algae, and microorganisms for the drug delivery system application are discussed comprehensively in this review paper.

Formation of substituted dioxanes in the oxidation of gum arabic with periodate

Renewable polysaccharide feedstocks are of interest in bio-based food packaging, coatings and hydrogels. Their physical properties often need to be tuned by chemical modification, e.g. by oxidation using periodate, to introduce carboxylic acid, ketone or aldehyde functional groups. The reproducibility required for application on an industrial scale, however, is challenged by uncertainty about the composition of product mixtures obtained and of the precise structural changes that the reaction with periodate induces. Here, we show that despite the structural diversity of gum arabic, primarily rhamnose and arabinose subunits undergo oxidation, whereas (in-chain) galacturonic acids are unreactive towards periodate. Using model sugars, we show that periodate preferentially oxidises the anti 1,2-diols in the rhamnopyranoside monosaccharides present as terminal groups in the biopolymer. While formally oxidation of vicinal diols results in the formation of two aldehyde groups, only traces of aldehydes are observed in solution, with the main final products obtained being substituted dioxanes, both in solution and in the solid state. The substituted dioxanes form most likely by the intramolecular reaction of one aldehyde with a nearby hydroxyl group, followed by hydration of the remaining aldehyde to form a geminal diol. The absence of significant amounts of aldehyde functional groups in the modified polymer impacts crosslinking strategies currently attempted in the preparation of renewable polysaccharide-based materials.

Gelatin as a bioactive nanodelivery system for functional food applications

Gelatin has long been used as an encapsulant agent in the pharmaceutical and biomedical industries because of its low cost, wide availability, biocompatibility, and degradability. However, the exploitation of gelatin for nanodelivery application is not fully achieved in the functional food filed. In this review article, we highlight the latest work being performed for gelatin-based nanocarriers, including polyelectrolyte complexes, nanoemulsions, nanoliposomes, nanogels, and nanofibers. Specifically, we discuss the applications and challenges of these nanocarriers for stabilization and controlled release of bioactive compounds. To achieve better efficacy, gelatin is frequently used in combination with other biomaterials such as polysaccharides. The fabrication and synergistic effects of the newly developed gelatin composite nanocarriers are also present.

Natural Gums in Drug-Loaded Micro- and Nanogels

Gums are polysaccharide compounds obtained from natural sources, such as plants, algae and bacteria. Because of their excellent biocompatibility and biodegradability, as well as their ability to swell and their sensitivity to degradation by the colon microbiome, they are regarded as interesting potential drug carriers. In order to obtain properties differing from the original compounds, blends with other polymers and chemical modifications are usually applied. Gums and gum-derived compounds can be applied in the form of macroscopic hydrogels or can be formulated into particulate systems that can deliver the drugs via different administration routes. In this review, we present and summarize the most recent studies regarding micro- and nanoparticles obtained with the use of gums extensively investigated in pharmaceutical technology, their derivatives and blends with other polymers. This review focuses on the most important aspects of micro- and nanoparticulate systems formulation and their application as drug carriers, as well as the challenges related to these formulations.

High-Axial-Aspect Tannic Acid Microparticles Facilitate Gelation and Injectability of Collagen-Based Hydrogels

Injectable collagen-based hydrogels offer great promise for tissue engineering and regeneration, but their use is limited by poor mechanical strength. Herein, we incorporate tannic acid (TA) to tailor the rheology of the corresponding hydrogels while simultaneously adding the therapeutic benefits inherent to this polyphenolic component. TA in the solution form and needle-shaped TA microparticles are combined with collagen and the respective systems studied for their time-dependent sol-gel transitions (from storage to body temperatures, 4-37 °C) as a function of TA concentration. Compared to systems incorporating TA microparticles, those with dissolved TA, applied at a similar concentration, generate a less significant enhancement of the elastic modulus. Premature gelation at a low temperature and associated colloidal arrest of the system are proposed as a main factor explaining this limited performance. A higher yield stress (elastic stress method) is determined for systems loaded with TA microparticles compared to the system with dissolved TA. These results are interpreted in terms of the underlying interactions of TA with collagen, as probed by spectroscopy and isothermal titration calorimetry. Importantly, hydrogels containing TA microparticles show high cell viability (human dermal fibroblasts) and comparative cellular activity relative to the collagen-only hydrogel. Overall, composite hydrogels incorporating TA microparticles demonstrate a new, simple, and better-performance alternative to cell culturing and difficult implantation scenarios.

Folic acid-modified photoluminescent dialdehyde carboxymethyl cellulose crosslinked bionanogels for pH-controlled and tumor-targeted co-drug delivery

This work aimed to fabricate a new photoluminescent bionanogel with both targeted anticancer drug delivery and bioimaging potentials. Briefly, at first photoluminescent carbon dots (CDs) were synthesized from the low-cost and more available black pepper with traditional medicinal properties. The as-synthesized dialdehyde carboxymethyl cellulose (DCMC) was used as a safe crosslinker for gelatin crosslinking in the presence of CDs (CDs/DCMC-Gel). Eventually, the residual amine functional groups of gelatin were used for the conjugation of CDs/DCMC-Gel with folic acid (FA) ((CDs/DCMC-Gel)-FA bionanogels). All employed physicochemical characterization methods approved the (CDs/DCMC-Gel)-FA bionanogels fabrication route. SEM analysis specified the spherical morphology with a diameter of ~70-90 nm for it. Curcumin (CUR) and doxorubicin (DOX) respectively were loaded with drug entrapment efficiency of about 44.0% and 41.4%. The release rate for both drugs in acidic conditions was higher than in physiological conditions. In vitro antitumor experiments; MTT, DAPI staining, cellular uptake, and cell cycle tests showed the superior anticancer effect of the CUR@DOX@(CDs/DCMC-Gel)-FA in comparison with free CUR@DOX. Moreover, the (CDs/DCMC-Gel)-FA acted as a hopeful bio-imaging tool. Taken together, the designed (CDs/DCMC-Gel)-FA could be proposed as a promising nanosystem for efficient chemotherapy.

Synthesis and physicochemical characterization of methacrylic acid modified Arabic gum microgel as potential drug carrier

Carbohydrate polymers microgels are non-toxic and biocompatible which can be readily used in applications such as drug delivery, medicine, and pharmacy. This work synthesized Arabic gum (AG) microgel and methacrylic acid modified Arabic gum microgel (AGMAA) via water in oil emulsion polymerization technique using Tween 20 as surfactant and hexane as the solvent. The microgels were characterized using various physicochemical analysis such as Fourier Transform Infrared spectroscopy, thermal stability using Differential Scanning Calorimetry, diffraction pattern analysis using X-Ray Diffraction, morphology observation using Field Emission Scanning Electron Microscope and zetasizer was used to analyze the size and zeta potential. The rate of deformation was higher in AG microgel compared to the AGMAA microgel. The particle size and zeta potential of AGMAA microgel were found larger and more negative than AG microgel, respectively. The microgels particle size and zeta potentials were found dependent on the amount of methacrylic acid as the modifying agents. The microgels were encapsulated with doxorubicin through the swelling method and the in-vitro release was studied in medium with pH 4.2 and 7.4. The results suggest the potentials of these microgels for drugs delivery.

Nanogels: A novel approach in antimicrobial delivery systems and antimicrobial coatings

The implementation of nanotechnology to develop efficient antimicrobial systems has a significant impact on the prospects of the biomedical field. Nanogels are soft polymeric particles with an internally cross-linked structure, which behave as hydrogels and can be reversibly hydrated/dehydrated (swollen/shrunken) by the dispersing solvent and external stimuli. Their excellent properties, such as biocompatibility, colloidal stability, high water content, desirable mechanical properties, tunable chemical functionalities, and interior gel-like network for the incorporation of biomolecules, make them fascinating in the field of biological/biomedical applications. In this review, various approaches will be discussed and compared to the newly developed nanogel technology in terms of efficiency and applicability for determining their potential role in combating infections in the biomedical area including implant-associated infections.

Protein-Based Nanohydrogels for Bioactive Delivery

Hydrogels possess a unique three-dimensional, cross-linked network of polymers capable of absorbing large amounts of water and biological fluids without dissolving. Nanohydrogels (NGs) or nanogels are composed of diverse types of polymers of synthetic or natural origin. Their combination is bound by a chemical covalent bond or is physically cross-linked with non-covalent bonds like electrostatic interactions, hydrophobic interactions, and hydrogen bonding. Its remarkable ability to absorb water or other fluids is mainly attributed to hydrophilic groups like hydroxyl, amide, and sulphate, etc. Natural biomolecules such as protein- or peptide-based nanohydrogels are an important category of hydrogels which possess high biocompatibility and metabolic degradability. The preparation of protein nanohydrogels and the subsequent encapsulation process generally involve use of environment friendly solvents and can be fabricated using different proteins, such as fibroins, albumin, collagen, elastin, gelatin, and lipoprotein, etc. involving emulsion, electrospray, and desolvation methods to name a few. Nanohydrogels are excellent biomaterials with broad applications in the areas of regenerative medicine, tissue engineering, and drug delivery due to certain advantages like biodegradability, biocompatibility, tunable mechanical strength, molecular binding abilities, and customizable responses to certain stimuli like ionic concentration, pH, and temperature. The present review aims to provide an insightful analysis of protein/peptide nanohydrogels including their preparation, biophysiochemical aspects, and applications in diverse disciplines like in drug delivery, immunotherapy, intracellular delivery, nutraceutical delivery, cell adhesion, and wound dressing. Naturally occurring structural proteins that are being explored in protein nanohydrogels, along with their unique properties, are also discussed briefly. Further, the review also covers the advantages, limitations, overview of clinical potential, toxicity aspects, stability issues, and future perspectives of protein nanohydrogels.

Glycans in scaffold design in tissue reconstruction

Development of an artificial tissue by tissue engineering is witnessed to be one of the long lasting clarified solutions for the damaged tissue function restoration. To accomplish this, a scaffold is designed as a cell carrier in which the extracellular matrix (ECM) performs a prominent task of controlling the inoculated cell’s destiny. ECM composition, topography and mechanical properties lead to different types of interactions between cells and ECM components that trigger an assortment of cellular reactions via diverse sensing mechanisms and downstream signaling pathways. The polysaccharides in the form of proteoglycans and glycoproteins yield better outcomes when included in the designed matrices. Glycosaminoglycan (GAG) chains present on proteoglycans show a wide range of operations such as sequestering of critical effector morphogens which encourage proficient nutrient contribution toward the growing stem cells for their development and endurance. In this review we discuss how the glycosylation aspects are of considerable importance in everyday housekeeping functions of a cell especially when placed in a controlled environment under ideal growth conditions. Hydrogels made from these GAG chains have been used extensively as a resorbable material that mimics the natural ECM functions for an efficient control over cell attachment, permeability, viability, proliferation, and differentiation processes. Also the incorporation of non-mammalian polysaccharides can elicit specific receptor responses which authorize the creation of numerous vigorous frameworks while prolonging the low cost and immunogenicity of the substance.

Tissue engineering of collagen scaffolds crosslinked with plant based polysaccharides

Ideally, a bioscaffold should mimic the characteristics of an extracellular matrix of a living organ of interest. The present study deals with the formation of composite scaffolds of collagen with gum arabic. Collagen was cross-linked with oxidized gum arabic having aldehyde groups to form a porous block. By changing the oxidation level of gum arabic, incorporation of the polysaccharides into the scaffold could be varied resulting in scaffolds with variable polysaccharide to protein content. A series of scaffolds were made by altering collagen concentration and oxidation level of gum arabic. The scaffolds were tested for their physical properties, stability, biocompatibility and ability to support the cell growth. Results implied that variable polysaccharide incorporation into the scaffolds was possible depending on the oxidation level of gum arabic which could influence the swelling behavior. The scaffolds showed non-toxic behavior towards the mesenchymal stem cells and nucleus pulposa cells using viability assay in culture conditions up to 30 days; the growth of cells was seen at all combinations of gels. Nucleus pulposa cells were able to maintain their phenotype in the GACO gels. The studies show that these scaffolds are potential candidates in applications, such as tissue engineering, and can be designed to match the requirement of different cell/tissues as per their ECM.

Synthesis and characterization of Schiff base containing bovine serum albumin-gum arabic aldehyde hybrid nanogels via inverse miniemulsion for delivery of anticancer drug

The periodate modified gum arabic was used as a natural-based, non-toxic cross-linker to synthesize hybrid bovine serum albumin-gum arabic aldehyde (BSA-GAA) nanogels by Schiff base reaction through the inverse miniemulsion method for the first time. The synthesis process was performed in the absence of toxic organic solvents using fractionated coconut oil as the continuous phase. The particle size of the nanogels was managed by tweaking the concentration of the surfactants (Span 80/Tween 80) and the total volume of the aqueous phase. Based on the bicinchoninic acid method, the cross-linking efficiency of BSA and GAA was estimated at 98%. 5-fluorouracil (5-FU) was selected as the sample drug. The 5-FU-loaded hybrid nanogels showed a spherical morphology with an average diameter of 231.33 ±12.74 nm and a zeta potential of -31.6 mV. The encapsulation and loading efficiency of the nanogels were calculated at 42 ± 4.52% and 2.37 ± 0.59%, respectively. The properties of the hybrid nanogels were analyzed by dynamic light scattering (DLS), Fourier transform infrared microscopy (FTIR) analysis, field emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA). The pH sensitivity of the hybrid nanogels was confirmed by the in vitro release profiles of 5-FU in different buffers. Hemolysis assay revealed the in vitro hemocompatibility of the hybrid nanogels which inhibited the growth of MCF-7 cells with an IC50 value of 16.21 μM. The present study suggested that these biobased hybrid nanogels could have a great potential in drug delivery and other biomedical applications.

Fabrication of Chlorophyll-Incorporated Nanogels for Potential Applications in Photothermal Cancer Therapy

Nanogels have been widely used in biomedical applications, such as carriers for hyperthermia cancer treatment, drug delivery, and imaging. Owing to the enhanced permeability and retention effect, nanogels have shown a great potential in cancer therapy. In this study, sodium copper chlorophyllin (SCC), a low cytotoxicity and biodegradable photothermal agent, was copolymerized with a nanogel of N-[3-(dimethylamino)propyl]methacrylamide. The nanogels could produce heat under exposure to a green laser with a 532 nm wavelength. The positively charged nature of the nanogels enhanced the endocytosis of the nanogels. The cell mortality was greatly enhanced with the treatment of the SCC-containing nanogels and green light illumination. Our results suggest the potential of SCC-containing nanogels in photothermal cancer therapy.

Nanogels as potential drug nanocarriers for CNS drug delivery

Hydrogel-based drug delivery systems (DDSs) have versatile applications such, as tissue engineering, scaffolds, drug delivery, and regenerative medicines. The drawback of higher size and poor stability in such DDSs are being addressed by developing nano-sized hydrogel particles, known as nanogels, to achieve the desired biocompatibility and encapsulation efficiency for better efficacy than conventional bulk hydrogels. In this review, we describe advances in the development of nanogels and their promotion as nanocarriers to deliver therapeutic agents to the central nervous system (CNS). We also discuss the challenges, possible solutions, and future prospects for the use of nanogel-based DDSs for CNS therapies.

Radiation Engineering of Multifunctional Nanogels

Nanogels combine the favourable properties of hydrogels with those of colloids. They can be soft and conformable, stimuli-responsive and highly permeable, and can expose a large surface with functional groups for conjugation to small and large molecules, and even macromolecules. They are among the very few systems that can be generated and used as aqueous dispersions. Nanogels are emerging materials for targeted drug delivery and bio-imaging, but they have also shown potential for water purification and in catalysis. The possibility of manufacturing nanogels with a simple process and at relatively low cost is a key criterion for their continued development and successful application. This paper highlights the most important structural features of nanogels related to their distinctive properties, and briefly presents the most common manufacturing strategies. It then focuses on synthetic approaches that are based on the irradiation of dilute aqueous polymer solutions using high-energy photons or electron beams. The reactions constituting the basis for nanogel formation and the approaches for controlling particle size and functionality are discussed in the context of a qualitative analysis of the kinetics of the various reactions.

Curcumin loaded gum arabic aldehyde-gelatin nanogels for breast cancer therapy

Curcumin, a widely studied hydrophobic polyphenol with anticancer potential is loaded in gum arabic aldehyde-gelatin (GA Ald-Gel) nanogels to improve its bioavailability and therapeutic efficacy towards cancer cells. Physicochemical properties of the curcumin loaded GA Ald-Gel nanogels are investigated by different techniques including dynamic light scattering (DLS), NMR spectroscopy and scanning electron microscopy (SEM). These nanogels exhibit hydrodynamic diameter of 452±8nm with a zeta potential of -27mV. The nanogels possess an encapsulation efficiency of 65±3%. Potential of the nanogels for controlled release of curcumin is illustrated by in vitro drug release studies. Hemocompatibility and cytocompatibility of the drug loaded nanogels are evaluated. In vitro cytotoxicity of the bare and curcumin loaded nanogels are analyzed by MTT assay towards MCF-7 cells. The results manifest that curcumin loaded nanogels induce toxicity in MCF-7 cells. Confocal laser scanning microscopy (CLSM) studies indicate in vitro cellular uptake of the nanogels in MCF-7 cells. All these results prove the suitability of the curcumin loaded GA Ald-Gel nanogels for cancer therapy.