Loading of cancer drug resveratrol to pH-Sensitive, smart, alginate-chitosan hydrogels and investigation of controlled release kinetics

The stomach, small intestine, and colon-specific gastrointestinal tract delivery systems for bioactive nutrients

Oral administration is a convenient way to deliver bioactive nutrients. However, the complex and dynamic environment of the gastrointestinal (GI) tract poses distinct challenges. These include the acidic environment of the stomach, limited transport across the GI mucosa, and the risk of enzymatic degradation, all of which can compromise the nutritional effectiveness of orally delivered nutrients. In response to these challenges, various GI tract delivery systems have been developed to target specific regions, such as the stomach, small intestine, or colon, to precisely control the release of bioactive nutrients and enhance their health-promoting benefits. This review critically examines the principles underlying stomach-, small intestine-, and colon-targeted delivery systems, highlighting the selection of appropriate wall materials and the interactions between delivery systems and the mucosal epithelial barrier. Moreover, we describe relevant biological models and quantitative analyses to measure these interactions. In particular, we emphasize the significant advantages offered by colon-targeted delivery systems in maintaining a healthy colonic microenvironment. This review aims to inspire novel concepts and stimulate further research into GI tract delivery systems, offering promising avenues for maximizing the therapeutic effects of bioactive nutrients in practical applications.

Next-generation biopolymer gels: innovations in drug delivery and theranostics

Biopolymers or natural polymers like chitosan, cellulose, alginate, collagen, etc. have gained significant interest recently due to their remarkable tunable properties that make them appropriate for a variety of applications & play a crucial role in everyday life. The features of biopolymers which include biodegradability, biocompatibility, sustainability, affordability, & availability are vital for creating products for use in biomedical fields. Apart from these characteristics, smart or stimuli-responsive biopolymers also show a distinctive property of being susceptible to various factors like pH, temperature, light intensity, & electrical or magnetic fields. The current review would present a brief idea about smart biopolymer gels along with their biomedical applications. The use of smart biopolymers gels as theranostic agents are also discussed in the present review. This review also focuses on the application of biopolymers in the fields of drug delivery, cancer treatment, tissue engineering & wound healing. These areas demonstrate the development and utilization of different types of biopolymers in current biomedical applications.

Resveratrol: Challenges and prospects in extraction and hybridization with nanoparticles, polymers, and bio-ceramics

Resveratrol (RSV), a bioactive natural phenolic compound found in plants, fruits, and vegetables, has garnered significant attention in pharmaceutical, food, and cosmetic industries due to its remarkable biological and pharmacological activities. Despite its potential in treating various diseases, its poor pharmacokinetic properties, such as low solubility, stability, bioavailability, and susceptibility to rapid oxidation, limit its biomedical applications. Recent advancements focus on incorporating resveratrol into innovative materials like nanoparticles, polymers, and bio-ceramics to enhance its properties and bioavailability. In this review, an exhaustive literature search was conducted from PubMed, Google Scholar, Science Direct, Scopus, and Web of Science databases to explore these advancements, to compares conventional and innovative extraction methods, and to highlights resveratrol's therapeutic potential, including its anti-inflammatory, anti-oxidative, anti-cancerogenic, antidiabetic, neuroprotective, and cardio-protective properties. Additionally, we discuss the challenges and prospects of hybrid materials combining resveratrol with nanoparticles, polymers, and bio-ceramics for therapeutic applications. Rigorous studies are still needed to confirm their clinical efficacy.

Recent advances in nanodelivery systems of resveratrol and their biomedical and food applications: a review

Resveratrol is a non-flavonoid polyphenolic compound with numerous functional properties, such as anticancer, anti-inflammation, anti-oxidation, anti-obesity and more. However, resveratrol's poor solubility within aqueous media and low stability usually lead to compromised bioavailability, ultimately limiting its uptake and applications. Nanodelivery technologies have been studied intensively due to their potential in effectively improving resveratrol properties, thereby providing promising solutions for enhancing the bioavailability of resveratrol. Thus, this article aimed to review the recent advances of resveratrol nanodelivery systems, specifically on the types of nanodelivery systems, the corresponding preparation principles, advantages, as well as potential limitations associated. Meanwhile, studies have also found that coupled with nanodelivery systems, the functional properties of resveratrol could trigger apoptosis in cancer cells and inflammatory cells through various signaling pathways. Therefore, this article will also lead into discussions on the application aspects of resveratrol nanodelivery systems, emphasizing toward the fields of biomedical and food sciences. Potential pitfalls of resveratrol nanodelivery systems, such as issues with toxicity and target release, as well as outlooks regarding resveratrol nanodelivery systems are included in the Conclusion section, in the hope to provide insights for relevant future research.

New approaches for modulation of alginate-chitosan delivery properties

Alginate is a biopolymer widely used on delivery systems when bioactive protection at acidic pH is required, while chitosan can enhance mucoadhesion and controlled release at alkaline pHs. In this work, alginate ionotropic gelation and electrostatic complexation to chitosan were evaluated concomitantly or in a two-step approach to improve the delivery properties of systems in different pHs. The effect of pH on alginate gelation and chitosan interactions were also evaluated. Alginate microspheres were prepared by ionotropic gelation in CaCl2 at different pH values (2.5 and 6.0) by extrusion. Complexation with chitosan was carried out during alginate ionotropic gelation (one-step approach) or after alginate gel formation (two-step approach). Alginate microparticles without chitosan showed larger pores and lower mechanical strength. Extruded microspheres at pH 6.0 were more stable to pH and showed smaller pores than the formed at pH 2.5. One-step production retained a large amount of bioactive at pH 7.0 and resulted in lower release at the pH of intestinal digestion. The two-step approach retained less amount of bioactive but confer more protection to the pH of the stomach phase and higher release in pH of the intestinal phase than one-step samples. These results indicate that the formation of alginate gels by ionotropic gelation followed by the complexation with chitosan (in two-step) is promising for the transport and delivery of bioactives into intestinal conditions, whereas the ionotropic gelation concomitantly to electrostatic complexation (one-step approach) is indicated to the delivery of bioactives into lower pH environments.

Use of Double Gelled Microspheres to Improve Release Control of Cinnamon-Loaded Nanoemulsions

The use of nanoemulsions as encapsulation systems for active ingredients, such as cinnamon oil, has been studied. A surfactant based on polyoxyethylene glycerol esters from coconut/palm kernel oil has been used. The nanoemulsions were obtained by the two most commonly low-energy emulsification methods, the composition inversion phase (PIC) and the temperature inversion phase (PIT) methods. Nanoemulsions were successfully obtained by both methods, with very small droplet sizes (5-14 nm) in both cases, but a greater stability was observed when the PIT method was used. Nanoemulsions were encapsulated by external gelation using two different polysaccharides, alginate or chitosan, dissolved in the continuous phase of the nanoemulsion. Then, the nanoemulsion was dropped into a bath with a gelling agent. To improve the release control of cinnamon oil and avoid the burst effect, beads prepared with one of the polysaccharides were coated with the second polysaccharide and then gelled again. Double gelled beads were successfully obtained, the core with chitosan and the outer layer (shell) with alginate. SEM images showed the morphology of the single beads presenting high porosity. When the beads were coated, the porosity decreased because the second polysaccharide molecules covered the pre-existing pores. The smoother surface was obtained when this second layer was, in turn, gelled. The release patterns at pH = 2 and pH = 7 were studied. It was observed that the double gelled bead provided a more gradual release, but maintained approximately the same amount of final released oil. The release patterns were fitted to the Korsmeyer-Peppas model. The fitting parameters reflected the effect of the different coating layers, correlating with different diffusion mechanisms according to the bead core and shell materials.

Chitosan-Based Particulate Carriers: Structure, Production and Corresponding Controlled Release

The state of the art in the use of chitosan (CS) for preparing particulate carriers for drug delivery applications is reviewed. After evidencing the scientific and commercial potentials of CS, the links between targeted controlled activity, the preparation process and the kinetics of release are detailed, focusing on two types of particulate carriers: matrix particles and capsules. More precisely, the relationship between the size/structure of CS-based particles as multifunctional delivery systems and drug release kinetics (models) is emphasized. The preparation method and conditions greatly influence particle structure and size, which affect release properties. Various techniques available for characterizing particle structural properties and size distribution are reviewed. CS particulate carriers with different structures can achieve various release patterns, including zero-order, multi-pulsed, and pulse-triggered. Mathematical models have an unavoidable role in understanding release mechanisms and their interrelationships. Moreover, models help identify the key structural characteristics, thus saving experimental time. Furthermore, by investigating the close relation between preparation process parameters and particulate structural characteristics as well as their effect on release properties, a novel "on-demand" strategy for the design of drug delivery devices may be developed. This reverse strategy involves designing the production process and the related particles' structure based on the targeted release pattern.

Encapsulation of Carvacrol-Loaded Nanoemulsion Obtained Using Phase Inversion Composition Method in Alginate Beads and Polysaccharide-Coated Alginate Beads

Nanoemulsions have been widely studied as lipophilic compound loading systems. A low-energy emulsification method, phase inversion composition (PIC), was used to prepare oil-in-water nanoemulsions in a carvacrol-coconut oil/Tween 80^®-(linoleic acid-potassium linoleate)/water system. The phase behaviour of several emulsification paths was studied and related to the composition range in which small-sized stable nanoemulsions could be obtained. An experimental design was carried out to determine the best formulation in terms of size and stability. Nanoemulsions with a very small mean droplet diameter (16-20 nm) were obtained and successfully encapsulated to add carvacrol to foods as a natural antimicrobial and antioxidant agent. They were encapsulated into alginate beads by external gelation. In order to improve the carvacrol kinetics release, the beads were coated with two different biopolymers: chitosan and pullulan. All formulations were analysed with scanning electron microscopy to investigate the surface morphology. The release patterns at different pHs were evaluated. Different kinetics release models were fitted in order to study the release mechanisms affecting each formulation. Chitosan-coated beads avoided the initial release burst effect, improving the beads' structure and producing a Fickian release. At basic pH, the chitosan-coated beads collapsed and the pullulan-coated beads moderately improved the release pattern of the alginate beads. For acid and neutral pHs, the chitosan-coated beads presented more sustained release patterns.

Strategically designed SPEEK nanofibrous scaffold with tailored delivery ofresveratrolfor skin wound regeneration

Electro-spinnable polymeric materials can easily form two-dimensional (2D) nanofibrous scaffolds improving biochemical functionalities specially in the area of skin wound healing and nanomedicine, but it has been hard to achieve this on a highly mechanically stable biopolymer, Poly ether ether ketone (PEEK), due to its intrinsic hydrophobicity and chemical inertness. Herein, we demonstrated a novel nanomedicine healing system consisting of sulphonated poly ether ether ketone combined withresveratrol(SPEEK+RSV), which could act as an effective 2D nano bio-materialin vitroandin vivo, without observable cytotoxicity. The fabricated nanocomposites exhibited enriched skin cell proliferation and adhesion as confirmed from the results of MTT, cell adhesion and live-dead assay. Results of SEM analysis showed a uniform nano-sized distribution with adequate pore size and porosity % facilitating a desired breathable environment at the wound site. The results of FT-IR, tensile studies and TGA analyses confirmed the presence of appropriate bonds and improved mechanical stability of theRSVincorporated nanofibrous scaffold. Results of anti-microbial analysis portrayed good potentiality of the fabricated nanofibers in treating wounds colonized with bacterial infections. Controlled drug release of resveratrol established the bio-compatibility of the nanofibers in skin wound regeneration.In vivoanalysis assessed in female Wistar rats enabled complete wound closure with 100 % wound contraction within 16 days. Results of histopathology analysis through H-E and MT staining presented the re-surfing of the wound environment with regeneration of epithelium, granulation tissue and collagen. Thus, the fabricated 2D nanofibrous scaffold incorporated with pharmaceutical RSV bio-medicine perceptively mimicked skin ECM convincingly aiding the progression of skin wound regeneration mechanism.

Resveratrol Triggered the Quick Self-Assembly of Gallic Acid into Therapeutic Hydrogels for Healing of Bacterially Infected Wounds

Programing self-assembly of naturally bioactive molecules has been a wide topic of great significance for biomedical uses. Despite the fact that plant-derived polyphenols with catechol or pyrogallol moieties have been widely studied to construct nanocomplexes or nanocoatings via self-polymerization, there is no report on the self-assembly of these polyphenols into therapeutic hydrogels for potential applications. Here, we reported that adding a very small amount of resveratrol (Res) into the gallic acid (GA) aqueous solution could trigger the quick self-assembly of GA to form a fibrous hydrogel within 5 min through hydrogen bonds and π-π interactions. The length of GA/Res (GR) fibrils in gels varied from 100 to 1000 microns, with a diameter of around 1 μm. Notably, these GR hydrogels showed excellent colloid stability, providing better slow release and outstanding biocompatibility. Also, in vivo experiments indicated the hydrogels had high antibacterial effects and excellent wound healing capabilities in a total skin defect model via regulating the expression of inflammatory factors (IL-6, IL-1β, and TNF-α) due to the release of therapeutic agents (GA and Res) into the matrix. Overall, our results provide a new strategy to accelerate self-assembly of GA by adding Res to form hydrogels, which is further proved as a promising therapeutic carrier for wound healing.

Hybrid Nanobeads for Oral Indomethacin Delivery

The oral administration of the anti-inflammatory indomethacin (INDO) causes severe gastrointestinal side effects, which are intensified in chronic inflammatory conditions when a continuous treatment is mandatory. The development of hybrid delivery systems associates the benefits of different (nano) carriers in a single system, designed to improve the efficacy and/or minimize the toxicity of drugs. This work describes the preparation of hybrid nanobeads composed of nanostructured lipid carriers (NLC) loading INDO (2%; w/v) and chitosan, coated by xanthan. NLC formulations were monitored in a long-term stability study (25 °C). After one year, they showed suitable physicochemical properties (size < 250 nm, polydispersity < 0.2, zeta potential of −30 mV and spherical morphology) and an INDO encapsulation efficiency of 99%. The hybrid (lipid-biopolymers) nanobeads exhibited excellent compatibility between the biomaterials, as revealed by structural and thermodynamic properties, monodisperse size distribution, desirable in vitro water uptake and prolonged in vitro INDO release (26 h). The in vivo safety of hybrid nanobeads was confirmed by the chicken embryo (CE) toxicity test, considering the embryos viability, weights of CE and annexes and changes in the biochemical markers. The results point out a safe gastro-resistant pharmaceutical form for further efficacy assays.

Cytocompatible drug delivery hydrogels based on carboxymethylagarose/chitosan pH-responsive polyelectrolyte complexes

Several drugs are chemically unstable in the gastric environment and have low bioavailability restricted by intestinal absorption, which motivates the development of alternative routes for drug release, such as transdermal drug carriers for drug delivery to specific areas of the skin. Herein, novel polyelectrolyte complexes (PEC) consisting of carboxymethylagarose (CMA) and chitosan (CS) were prepared. pH-responsive CMA/CS hydrogels were obtained by mixing CMA and CS at various weight ratios. Swelling ratio was modulated by varying the CMA and CS weight ratio, and the highest swelling values were achieved for 2:1 wt% hydrogels at 25 °C and pH 6.0. PEC films were characterized by ATR-FTIR spectroscopy, TGA, DSC, and SEM. Results indicated that CMA and CS were successfully crosslinked by ionic complexation. As a model drug, diclofenac sodium (DS) was loaded in CMA/CS PECs. Association efficiency and loading capacity were ca. 69% and 79%, respectively, exhibiting 67% cumulative release after 72 h at 37 °C and pH 6.0 through Fickian diffusion mechanism. Viability assay of immortalized human keratinocyte (HaCat) cells showed ca. 100% survival in the presence of hydrogels and DS. Therefore, this work suggests that CMA/CS PECs can be applied as pH-responsive carriers for dermal drug delivery.

Synthesis and characterization of levan hydrogels and their use for resveratrol release

Considering the need for systematic studies on levan based hydrogels to widen their use in drug delivery systems and biomedical applications, this study is mainly focused on the synthesis and comprehensive characterization as well as drug release properties of hydrogels based on Halomonas levan (HL) and its chemical derivatives. For this, hydrolyzed and phosphonated HL derivatives were chemically synthesized and then cross-linked with 1,4-Butanediol diglycidyl ether (BDDE) and the obtained hydrogels were characterized in terms of their swelling, adhesivity, and rheological properties. Both native and phosphonated HL hydrogels retained their rigid gel like structure with increasing shear stress levels and tack test analysis showed superior adhesive properties of the phosphonated HL hydrogels. Moreover, hydrogels were loaded with resveratrol and entrapment and release studies as well as cell culture studies with human keratinocytes were performed. Biocompatible and adhesive features of the hydrogels confirmed their suitability for tissue engineering and drug delivery applications.

Synthesis of chitosan-grafted poly-acrylic acid (CTS-g-PAA) hydrogel and its potential application in biosensors for signal enhancing and bioanalysis

Nowadays, hydrogels have been attracted a lot of interest due to their immense potential in different fields such as biomedicine and biotechnology. Biodegradable and biocompatible pH-sensitive chitosan-grafted polyacrylic acid (CTS-g-PAA) hydrogel was synthesized by grafting an acrylic acid monomer onto chitosan at the presence of methylene bisacrylamide as a cross-linking agent and ammonium persulphate as an initiator. FT-IR spectroscopy and scanning electron microscopy (SEM) were used to analyze the properties of the obtained hydrogel. The synthesized hydrogel is suitable for the delivery of many hydrophilic drugs or species. Using a multi-walled carbon nanotube modified-glassy carbon electrode (CNT-GCE), the loading and release conditions of Nile Blue (NB) as an electroactive compound were evaluated utilizing the differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The effect of various parameters on the electrochemical signal of NB was investigated, and the optimal conditions for the efficient performance of hydrogel to delivery of NB were obtained. The electrocatalytic current values show linear dependence to NB concentration in the range of 0.098 - 0.971 μM while the detection limit of this electrochemical platform was 12.3 nM. The unique proposed hydrogel with the electroactive NB has a broad range of possible applications in biosensors for signal enhancement and bioanalysis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10854-021-06939-7.

Deciphering the Molecular Mechanism of Water Interaction with Gelatin Methacryloyl Hydrogels: Role of Ionic Strength, pH, Drug Loading and Hydrogel Network Characteristics

Water plays a primary role in the functionality of biomedical polymers such as hydrogels. The state of water, defined as bound, intermediate, or free, and its molecular organization within hydrogels is an important factor governing biocompatibility and hemocompatibility. Here, we present a systematic study of water states in gelatin methacryloyl (GelMA) hydrogels designed for drug delivery and tissue engineering applications. We demonstrate that increasing ionic strength of the swelling media correlated with the proportion of non-freezable bound water. We attribute this to the capability of ions to create ion–dipole bonds with both the polymer and water, thereby reinforcing the first layer of polymer hydration. Both pH and ionic strength impacted the mesh size, having potential implications for drug delivery applications. The mechanical properties of GelMA hydrogels were largely unaffected by variations in ionic strength or pH. Loading of cefazolin, a small polar antibiotic molecule, led to a dose-dependent increase of non-freezable bound water, attributed to the drug’s capacity to form hydrogen bonds with water, which helped recruit water molecules in the hydrogels’ first hydration layer. This work enables a deeper understanding of water states and molecular arrangement at the hydrogel–polymer interface and how environmental cues influence them.

Polyphenols against infectious diseases: Controlled release nano-formulations

The emergence of multi-drug resistant (MDR) pathogens has become a global threat and a cause of significant morbidity and mortality around the world. Natural products have been used as a promising approach to counter the infectious diseases associated with these pathogens. The application of natural products and their derivatives especially polyphenolic compounds as antibacterial agents is an active area of research, and prior studies have successfully treated a variety of bacterial infections using these polyphenolic compounds. However, delivery of polyphenolic compounds has been challenging due to their physicochemical properties and often poor aqueous solubility. In this regard, nanotechnology-based novel drug delivery systems offer many advantages, including improving bioavailability and the controlled release of polyphenolic compounds. This review summarizes the pharmacological mechanism and use of nano-formulations in developing controlled release delivery systems of naturally occurring polyphenols in infectious diseases.

Hydrogels as Drug Delivery Systems: A Review of Current Characterization and Evaluation Techniques

Owing to their tunable properties, controllable degradation, and ability to protect labile drugs, hydrogels are increasingly investigated as local drug delivery systems. However, a lack of standardized methodologies used to characterize and evaluate drug release poses significant difficulties when comparing findings from different investigations, preventing an accurate assessment of systems. Here, we review the commonly used analytical techniques for drug detection and quantification from hydrogel delivery systems. The experimental conditions of drug release in saline solutions and their impact are discussed, along with the main mathematical and statistical approaches to characterize drug release profiles. We also review methods to determine drug diffusion coefficients and in vitro and in vivo models used to assess drug release and efficacy with the goal to provide guidelines and harmonized practices when investigating novel hydrogel drug delivery systems.

DNA biodots based targeted theranostic nanomedicine for the imaging and treatment of non-small cell lung cancer

The light absorption and emission characteristics of DNA biodots (DNA-BD), along with biocompatibility, give them a high potential for use in various medical applications, particularly in diagnostic purpose. DNA, under high pressure and temperature, condenses to form luminescent biodots. The objective of this research is to develop DNA-biodots (BD) loaded and cetuximab conjugated targeted theranostic liposomes of etoposide for lung cancer imaging and therapy. Theranostic liposomes were prepared by using the solvent injection method and characterized for their particle size, polydispersity, zeta potential, encapsulation efficiency, and pH-dependent in-vitro release, SEM, TEM AFM, EDX, and XRD. The t₅₀% (time at which 50% of the drug releases from the preparation) of the formulations was pH-dependent, with a significant increase in the release at lower pH (5.5). To kill A549 adenocarcinoma cells, the etoposide (control) required significantly (p < 0.05) higher drug concentrations in comparison to non-targeted and; the non-targeted formulation required more concentrations in comparison to targeted liposomes. The in-vivo results demonstrated that CTX-TPGS decorated theranostic liposomes could be a promising carrier for lung theranostics due to their nano-size and selectivity towards EGFR overexpressed cells which provided an improved NSCLC targeted delivery of ETP in comparison to the non-targeted and control formulations.

Hydrogels as Potential Nano-, Micro- and Macro-Scale Systems for Controlled Drug Delivery

This review is an extensive evaluation and essential analysis of the design and formation of hydrogels (HGs) for drug delivery. We review the fundamental principles of HGs (their chemical structures, physicochemical properties, synthesis routes, different types, etc.) that influence their biological properties and medical and pharmaceutical applications. Strategies for fabricating HGs with different diameters (macro, micro, and nano) are also presented. The size of biocompatible HG materials determines their potential uses in medicine as drug carriers. Additionally, novel drug delivery methods for enhancing treatment are discussed. A critical review is performed based on the latest literature reports.