A gellan gum derivative as in-situ gelling cationic polymer for nasal drug delivery

Recent advances in gellan gum production and modification for enhanced applicability in food printing and bioactive delivery applications

The importance of Gellan gum has been increasing gradually and its unique characteristics are suitable for various advanced food technologies. This review outlines recent developments in gellan gum production, modification, and newer applications focusing on food printing and bioactive delivery applications, in the last three years. The yield and production condition of gellan gum is a major factor that affects the cost and its applications. Moreover, modified Gellan gum has been shown to have superior characteristics and functionality as compared to native one. The viscosifying, thermosensitive, gelling etc. characteristics of gellan gum makes it an crucial ingredient in case of preparation of 3D printing ink. Further, gellan gum is also found to be important wall material in case of bioactive delivery application through encapsulation. Optimized methods of production, sustainable feedstock, and stress conditions are critical for the desired functionality and yield of the Gellan gum.

Mixed-Micelle in Situ Gel as a Candidate for Oral Inflammatory Ulcerative Diseases

The current treatment for oral inflammatory ulcerative diseases has limitations. In situ forming hydrogels have shown great potential to deliver therapeutic substances for drug delivery to the buccal cavity. This study aimed to prepare and characterize lipid- and surfactant-based mixed micelle in situ gel (MIG) and evaluate whether it can offer more favorable properties than the in situ gel for effective treatment of the disease. Dexamethasone was incorporated into the MIGs particles, based on Poloxamer 407 and chitosan. The lower gelation time at 37 ℃ was considered a criterion to select superior formulations among the different lipid- and surfactant-based candidates. Further characterization was performed to evaluate the opted formulations regarding morphology, physical stability, rheology, texture, and release profile. All formulations were thermoresponsive and had a shorter gelation time as the temperature increased. Dexamethasone was released in a highly controlled manner, and morphological evaluation revealed that the mixed micelle in situ gels had spherical nanoparticles. Thixotropic behavior was observed in all MIGs, indicating a prolonged retention time of the formulation after oral administration. This study has shown that among different MIGs, the one with oleic acid is a more promising candidate than the in situ gel and other MIGs for drug delivery to the buccal cavity.

Recent advances on biomedical applications of gellan gum: A review

Gellan gum (GG) has attracted considerable attention as a versatile biopolymer with numerous potential biological applications, especially in the fields of tissue engineering, wound healing, and cargo delivery. Due to its distinctive characteristics like biocompatibility, biodegradability, nontoxicity, and gel-forming ability, GG is well-suited for these applications. This review focuses on recent research on GG-based hydrogels and biocomposites and their biomedical applications. It discusses the incorporation of GG into hydrogels for controlled drug release, its role in promoting wound healing processes, and its potential in tissue engineering for various tissues including bone, retina, cartilage, vascular, adipose, and cardiac tissue. It provides an in-depth analysis of the latest findings and advancements in these areas, making it a valuable resource for researchers and professionals in these fields.

Nanocrystalline cellulose as a reinforcing agent for poly (vinyl alcohol)/ gellan-gum-based composite film for moxifloxacin ocular delivery

Nanocrystalline cellulose (NCC) is a star material in drug delivery applications due to its good biocompatibility, large specific surface area, high tensile strength (TS), and high hydrophilicity. Poly(Vinyl Alcohol)/Gellan-gum-based innovative composite film has been prepared using nanocrystalline cellulose (PVA/GG/NCC) as a strengthening agent for ocular delivery of moxifloxacin (MOX) via solvent casting method. Impedance analysis was studied using the capacitive sensing technique for examining new capacitance nature of the nanocomposite MOX film. Antimicrobial properties of films were evaluated using Pseudomonas aeruginosa and Staphylococcus aureus as gram-negative and gram-positive bacteria respectively by disc diffusion technique. XRD revealed the characteristic peak of NCC and the amorphous form of the drug. Sustained in vitro release and enhanced corneal permeation of drug were noticed in the presence of NCC. Polymer matrix enhanced the mechanical properties (tensile strength 22.05 to 28.41 MPa) and impedance behavior (resistance 59.23 to 213.23 Ω) in the film due to the presence of NCC rather than its absence (16.78 MPa and 39.03 Ω respectively). Occurrence of NCC brought about good antimicrobial behavior (both gram-positive and gram-negative) of the film. NCC incorporated poly(vinyl alcohol)/gellan-gum-based composite film exhibited increased mechanical properties and impedance behavior for improved ocular delivery of moxifloxacin.

Exploring gellan gum-based hydrogels for regenerating human embryonic stem cells in age-related macular degeneration therapy: A literature review

Age-related macular degeneration (AMD) is a progressive ocular disease marked by the deterioration of retinal photoreceptor cells, leading to central vision decline, predominantly affecting the elderly population worldwide. Current treatment modalities, such as anti-VEGF agents, laser therapy, and photodynamic therapy, aim to manage the condition, with emerging strategies like stem cell replacement therapy showing promise. However, challenges like immune rejection and cell survival hinder the efficacy of stem cell interventions. Regenerative medicine faces obstacles in maximizing stem cell potential due to limitations in mimicking the dynamic cues of the extracellular matrix (ECM) crucial for guiding stem cell behaviour. Innovative biomaterials like gellan gum hydrogels offer tailored microenvironments conducive to enhancing stem cell culture efficacy and tissue regeneration. Gellan gum-based hydrogels, renowned for biocompatibility and customizable mechanical properties, provide crucial support for cell viability, differentiation, and controlled release of therapeutic factors, making them an ideal platform for culturing human embryonic stem cells (hESCs). These hydrogels mimic native tissue mechanics, promoting optimal hESC differentiation while minimizing immune responses and facilitating localized delivery. This review explores the potential of Gellan Gum-Based Hydrogels in regenerative AMD therapy, emphasizing their role in enhancing hESC regeneration and addressing current status, treatment limitations, and future directions.

Transient, Image-Guided Gel-Dissection for Percutaneous Thermal Ablation

Image-guided tumor ablative therapies are mainstay cancer treatment options but often require intra-procedural protective tissue displacement to reduce the risk of collateral damage to neighboring organs. Standard of care strategies, such as hydrodissection (fluidic injection), are limited by rapid diffusion of fluid and poor retention time, risking injury to adjacent organs, increasing cancer recurrence rates from incomplete tumor ablations, and limiting patient qualification. Herein, a "gel-dissection" technique is developed, leveraging injectable hydrogels for longer-lasting, shapeable, and transient tissue separation to empower clinicans with improved ablation operation windows and greater control. A rheological model is designed to understand and tune gel-dissection parameters. In swine models, gel-dissection achieves 24 times longer-lasting tissue separation dynamics compared to saline, with 40% less injected volume. Gel-dissection achieves anti-dependent dissection between free-floating organs in the peritoneal cavity and clinically significant thermal protection, with the potential to expand minimally invasive therapeutic techniques, especially across locoregional therapies including radiation, cryoablation, endoscopy, and surgery.

Essential considerations towards development of effective nasal antibiotic formulation: features, strategies, and future directions

INTRODUCTION

Intranasal antibiotic products are gaining popularity as a promising method of administering antibiotics, which provide numerous benefits, e.g. enhancing drug bioavailability, reducing adverse effects, and potentially minimizing resistance threats. However, some issues related to the antibiotic substances and nasal route challenges must be addressed to prepare effective formulations.

AREAS COVERED

This review focuses on the valuable points of nasal delivery as an alternative route for administering antibiotics, coupled with the challenges in the nasal cavity that might affect the formulations. Moreover, this review also highlights the application of nasal delivery to introduce antibiotics for local therapy, brain targeting, and systemic effects that have been conducted. In addition, this viewpoint provides strategies to maintain antibiotic stability and several crucial aspects to be considered for enabling effective nasal formulation.

EXPERT OPINION

In-depth knowledge and understanding regarding various key considerations with respect to the antibiotic substances and nasal route delivery requirement in preparing effective nasal antibiotic formulation would greatly improve the development of nasally administered antibiotic products, enabling better therapeutic outcomes of antibiotic treatment and establishing appropriate use of antibiotics, which in turn might reduce the chance of antibiotic resistance and enhance patient comfort.

Preliminary Assessment of Polysaccharide-Based Emulgels Containing Delta-Aminolevulinic Acid for Oral Lichen planus Treatment

Photodynamic therapy using delta-aminolevulinic acid is considered a promising option in the treatment of oral lichen planus. In the present work, three emulgel compositions prepared from natural polysaccharide gums, tragacanth, xanthan and gellan, were preliminarily tested for oromucosal delivery of delta-aminolevulinic acid. Apart from cytotoxicity studies in two gingival cell lines, the precise goal was to investigate whether the presence of the drug altered the rheological and mucoadhesive behavior of applied gelling agents and to examine how dilution with saliva fluid influenced the retention of the designed emulgels by oromucosal tissue. Ex vivo mucoadhesive studies revealed that a combination of xanthan and gellan gum enhanced carrier retention by buccal tissue even upon dilution with the saliva. In turn, the incorporation of delta-aminolevulinic acid favored interactions with mucosal tissue, particularly formulations comprised of tragacanth. The designed preparations had no significant impact on the cell viability after a 24 h incubation in the tested concentration range. Cytotoxicity studies demonstrated that tragacanth-based and gellan/xanthan-based emulgels might exert a protective effect on the metabolic activity of human gingival fibroblasts and keratinocytes. Overall, the presented data show the potential of designed emulgels as oromucosal platforms for delta-aminolevulinic acid delivery.

Evaluation of Oromucosal Natural Gum-Based Emulgels as Novel Strategy for Photodynamic Therapy of Oral Premalignant Lesions

Photodynamic therapy (PDT) recently has been shown as a promising option in the treatment of premalignant lesions of the soft oral tissues. Effective delivery of photosensitizer is challenging due to poor drug adherence to the oromucosal epithelium. In the present work, emulgels composed of natural polysaccharide gums (tragacanth, xanthan and gellan) were evaluated as novel oromucosal platforms of delta-aminolevulinic acid (ALA) for PDT. Apart from mucoadhesive and textural analysis, the specific steps involved studies on drug penetration behavior and safety profile using a three-dimensional human oral epithelium model (HOE). All designed emulgels presented greater mucoadhesiveness when compared to commercial oromucosal gel. Incorporation of ALA affected textural properties of emulgels, and tragacanth/xanthan formulation with greater hardness and cohesiveness exhibited a protective function against the mechanical tongue stress. Permeability studies revealed that ALA is capable of penetrating across oromucosal epithelium by passive transport and all formulations promoted its absorption rate when compared to a commercial topical product with ALA. Importantly, the combination of tragacanth and xanthan profoundly enhanced photosensitizer retention in the buccal epithelium. Tested samples performed negligible reduction in cell viability and moderately low IL-1β release, confirming their non-irritancy and compatibility with HOE. Overall, the presented findings indicate that tragacanth/xanthan emulgel holds promise as an oromucosal ALA-carrier for PDT strategy.

Quality by design-based optimization of in situ ionic-sensitive gels of amoxicillin-loaded bovine serum albumin nanoparticles for enhanced local nasal delivery

A recommended first-line acute bacterial rhinosinusitis (ABR) treatment regimen includes a high dose of orally administered amoxicillin, despite its frequent systemic adverse reactions coupled with poor oral bioavailability. Therefore, to overcome these issues, nasal administration of amoxicillin might become a potential approach for treating ABR locally. The present study aimed to develop a suitable carrier system for improved local nasal delivery of amoxicillin employing the combination of albumin nanoparticles and gellan gum, an ionic-sensitive polymer, under the Quality by Design methodology framework. The application of albumin nanocarrier for local nasal antibiotic therapy means a novel approach by hindering the nasal absorption of the drug through embedding into an in situ gelling matrix, further prolonging the drug release in the nasal cavity. The developed formulations were characterized, including mucoadhesive properties, in vitro drug release and antibacterial activities. Based on the results, 0.3 % w/v gellan gum concentration was selected as the optimal in situ gelling matrix. Essentially, each formulation adequately inhibited the growth of five common nasal pathogens in ABR. In conclusion, the preparation of albumin-based nanoparticles integrated with in situ ionic-sensitive polymer provides promising ability as nanocarrier systems for delivering amoxicillin intranasally for local antibiotic therapy.

Piperine-Loaded In Situ Gel: Formulation, In Vitro Characterization, and Clinical Evaluation against Periodontitis

Periodontitis is an inflammatory disorder associated with dysbiosis and characterized by microbiologically related, host-mediated inflammation that leads to the damage of periodontal tissues including gingiva, connective tissues, and alveolar bone. The aim of this study was to develop an in situ gel consisting of piperine. Eight in situ gel formulations were designed by varying the concentration of deacylated gellan gum cross-linked with sodium tripolyphosphate, and poloxamer-407. The prepared gels were evaluated for gelation temperature, gelation time, viscosity, piperine-loading efficiency, and piperine release. Finally, the optimized formula was evaluated for anti-inflammatory effectiveness among human patients during a 14-day follow-up. The optimized in situ gel formulation exhibited a gelation temperature of 35 ± 1 °C, gelling of 36 ± 1 s, excellent syringeability, and piperine loading of 95.3 ± 2.3%. This formulation efficiently sustained in vitro drug release for up to 72 h. In vivo studies revealed an efficient sol-to-gel transformation of optimized in situ gel formulation at physiological conditions, permitting an efficient residence time of the formulation within a periodontitis pocket. Most importantly, a clinical study revealed that treatment with the optimized formulation elicited a significant reduction in the mean plaque score (p = 0.001), gingival index (p = 0.003), and pocket depth (p = 0.002), and exerted a potent anti-inflammatory potential, compared to the control group. Collectively, piperine-loaded in situ gel might represent a viable therapeutic approach for the management of gingival and periodontal diseases.

Hydroxyethyl cellulose functionalised with maleimide groups as a new excipient with enhanced mucoadhesive properties

Hydroxyethylcellulose (HEC) is a non-ionic water-soluble polymer with poor mucoadhesive properties. The mucoadhesive properties of hydroxyethylcellulose can be improved by modifying it through conjugation with molecules containing maleimide groups. Maleimide groups interact with the thiol groups present in cysteine domains in the mucin via Michael addition reaction under physiological conditions to form a strong mucoadhesive bond. This will prolong the residence time of a dosage form containing this modified polymer and drug on mucosal surfaces. In this study HEC was modified by reaction with 4-bromophenyl maleimide in varying molar ratios and the successful synthesis was confirmed using ¹H NMR and FTIR spectroscopies. The safety of the newly synthesised polymer derivatives was assessed with in vivo planaria assays and in vitro MTT assay utilising Caco-2 cell line. The synthesized maleimide-functionalised HEC solutions were sprayed onto blank tablets to develop a model dosage form. The physical properties and mucoadhesive behavior of these tablets were evaluated using a tensile test with sheep buccal mucosa. The maleimide-functionalised HEC exhibited superior mucoadhesive properties compared to unmodified HEC.

Modification of chicha gum: Antibacterial activity, ex vivo mucoadhesion, antioxidant activity and cellular viability

The aim of the present work was to modify the exuded gum of Sterculia striata tree by an amination reaction. The viscosity and zero potential of the chicha gum varied as a function of pH. The modification was confirmed by X-ray diffraction (XRD), infrared spectroscopy (FTIR), size exclusion chromatography (SEC), zeta potential, thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). Furthermore, the chemical modification changed the molar mass and surface charge of the chicha gum. In addition, the gums were used in tests for ex vivo mucoadhesion strength, antibacterial activity against the standard strain of Staphylococcus aureus (ATCC 25923), inhibitory activity of α-glucosidase, antioxidant capacity, and viability of Caco-2 cells. Through these tests, it was found that amination caused an increase in the mucoadhesive and inhibitory activity of chicha gum against the bacterium Staphylococcus aureus. In addition, the gums (pure and modified) showed antioxidant capacity and an inhibitory effect against the α-glucosidase enzyme and did not show cytotoxic potential.

Biomaterials-Enhanced Intranasal Delivery of Drugs as a Direct Route for Brain Targeting

Intranasal (IN) drug delivery is a non-invasive and effective route for the administration of drugs to the brain at pharmacologically relevant concentrations, bypassing the blood-brain barrier (BBB) and minimizing adverse side effects. IN drug delivery can be particularly promising for the treatment of neurodegenerative diseases. The drug delivery mechanism involves the initial drug penetration through the nasal epithelial barrier, followed by drug diffusion in the perivascular or perineural spaces along the olfactory or trigeminal nerves, and final extracellular diffusion throughout the brain. A part of the drug may be lost by drainage through the lymphatic system, while a part may even enter the systemic circulation and reach the brain by crossing the BBB. Alternatively, drugs can be directly transported to the brain by axons of the olfactory nerve. To improve the effectiveness of drug delivery to the brain by the IN route, various types of nanocarriers and hydrogels and their combinations have been proposed. This review paper analyzes the main biomaterials-based strategies to enhance IN drug delivery to the brain, outlining unsolved challenges and proposing ways to address them.

Preparation and evaluation of niosomal chitosan-based in situ gel formulation for direct nose-to-brain methotrexate delivery

Achieving effective treatments for various brain disorders due to the blood-brain barrier existence and the brain's complex structure has become a challenging goal. To overcome these challenges, one of the non-invasive strategies aimed at direct brain drug delivery is the use of the intranasal route. Novel drug delivery systems can be used to overcome the limitations in this administration route. This study suggested niosomal methotrexate (MTX) in situ gel formulation, which could be a suitable candidate for drug delivery to the brain. Here, niosomal MTX was prepared by a modified reverse-phase evaporation method, optimized with the aid of the design expert® software, and characterized. Optimum niosomal MTX with particle size, zeta potential, and entrapment efficiency (EE%), equal to 130.5 nm, -38.5 mV, and 91.39 %, respectively, were added into the temperature-sensitive in situ gel formulation composed of chitosan and Poloxamer 407. This study demonstrates that the simultaneous use of niosome and in situ gel formulations causes long-term persistence in the nasal cavity and helps us to have a more controlled drug release system with higher brain concentration, lower plasma concentration, higher Kp, and lower side effects compared to the free drug (MTX solution), MTX-gel (MTX-loaded in situ gel), and niosomal MTX formulations.

Heat- and shear-reversible networks in food: A review

While nature behaves like an irreversible network with respect to entropy and time, certain systems in nature exist that are, to some extent, reversible. The property of reversibility imparts unique benefits to systems that possess them, making them suitable for designing self-healing, stimuli-responsive, and smart materials that can be used in widely divergent fields. Reversible networks are currently being exploited for applications in tissue engineering, drug delivery, and soft robotics. They are also being utilized as low-calorie fat mimetics with melt-in-your-mouth textures, as well as being explored as potential scaffolds for three-dimensional (3D) printable food, among other applications. This review aims to gather representative examples of heat- and shear-reversible networks in the food science literature from the last 30 or so years, in other words, reversible food gels made either from linear biopolymers or from colloidal, particulate dispersions, including those that have been modified specifically to induce reversibility. An overview of the network mechanisms involved that impart reversibility, including a discussion of the strength and range of forces involved, will be highlighted. A model that explains why certain networks are thermoreversible while others are shear-reversible, and why others are both, will also be proposed. A fundamental understanding of these mechanisms will prove invaluable when designing reversible networks in the future, making possible the precise control of their properties, thus fostering innovative applications within the food industry and beyond.

The gelling behavior of gellan in the presence of different sodium salts

It is well known that metal ions have great effects on gelling behaviors of gellan aqueous systems, however, the effects of their co-ions - anions have rarely been studied. Herein, we investigated the effects of four kinds of sodium salts with different anions (NaCl, CH₃COONa, Na₂C₂O₄ and Na₃C₆H₅O₇) on gelling behaviors of gellan aqueous systems in terms of gelling temperature and gel hardness. It was found that, when [Na⁺] was low (20 mM), the salt with Cl^- or CH₃COO^- favored the gelling of gellan aqueous systems, while the salt with C₂O₄^2- or C₆H₅O₇^3- took adverse effects probably because C₂O₄^2- or C₆H₅O₇^3- could react with divalent cations (Ca²⁺ and Mg²⁺) in gellan to form precipitates or chelates and break their interactions with gellan (salt bridges). When [Na⁺] was high (50 or 80 mM), all the four kinds of salts facilitated gelling due to the shielding effects of high concentrations of Na⁺ on the negative charges along the gellan chains, and followed the order of: Cl^- > CH₃COO^- > C₂O₄^2- > C₆H₅O₇^3-. This study demonstrates the effects of anion kind of salts on gelling behaviors of gellan aqueous systems and provides references for the application of gellan.

Stimuli-Responsive Polymers for Transdermal, Transmucosal and Ocular Drug Delivery

Despite their conventional and widespread use, oral and intravenous routes of drug administration face several limitations. In particular, orally administered drugs undergo enzymatic degradation in the gastrointestinal tract and first-pass metabolism in the liver, which tend to decrease their bioavailability. Intravenous infusions of medications are invasive, painful and stressful for patients and carry the risk of infections, tissue damage and other adverse reactions. In order to account for these disadvantages, alternative routes of drug delivery, such as transdermal, nasal, oromucosal, ocular and others, have been considered. Moreover, drug formulations have been modified in order to improve their storage stability, solubility, absorption and safety. Recently, stimuli-responsive polymers have been shown to achieve controlled release and enhance the bioavailability of multiple drugs. In this review, we discuss the most up-to-date use of stimuli-responsive materials in order to optimize the delivery of medications that are unstable to pH or undergo primary metabolism via transdermal, nasal, oromucosal and ocular routes. Release kinetics, diffusion parameters and permeation rate of the drug via the mucosa or skin are discussed as well.

Development of mucoadhesive modified kappa-carrageenan/pectin patches for controlled delivery of drug in the buccal cavity

In this study, modified kappa-carrageenan/pectin hydrogel patches were fabricated for treatment of buccal fungal infections. For this purpose, kappa-carrageenan-g-acrylic acid was modified with different thiolated agents (L-cysteine and 3-mercaptopropionic acid), and the thiol content of the resulting modified kappa-carrageenan was confirmed by elemental analyzer. Then, the hydrogel patches were fabricated, and characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, ex vivo mucoadhesion test, and swelling behavior. Triamcinolone acetonide was added either directly or by encapsulating within the poly(lactic-co-glycolic acid) nanoparticles. The release amount of the drug from the directly loaded patch was 7.81 mg/g polymer, while it was 3.28 mg/g polymer for the encapsulated patch with the same content at 7 hr. The hydrogel patches had no cytotoxicity by cell culture studies. Finally, the drug loaded hydrogel patches were demonstrated antifungal activity against Aspergillus fumigatus and Aspergillus flavus. These results provide that the novel modified kappa-carrageenan and pectin based buccal delivery system has promising antifungal property, and could have advantages compared to conventional buccal delivery systems.

Nose-to-brain delivery of amisulpride-loaded lipid-based poloxamer-gellan gum nanoemulgel: In vitro and in vivo pharmacological studies

Unfavorable side effects of available antipsychotics limit the use of conventional delivery systems, where limited exposure of the drugs to the systemic circulation could reduce the associated risks. The potential of intranasal delivery is gaining interest to treat brain disorders by delivering the drugs directly to the brain circumventing the tight junctions of the blood-brain barrier with limited systemic exposure of the entrapped therapeutic. Therefore, the present research was aimed to fabricate, optimize and investigate the therapeutic efficacy of amisulpride (AMS)-loaded intranasal in situ nanoemulgel (AMS-NG) in the treatment of schizophrenia. In this context, AMS nanoemulsion (AMS-NE) was prepared by employing aqueous-titration method and optimized using Box-Behnken statistical design. The optimized nanoemulsion was subjected to evaluation of globule size, transmittance, zeta potential, and mucoadhesive strength, which were found to be 92.15 nm, 99.57%, -18.22 mV, and 8.90 g, respectively. The AMS-NE was converted to AMS-NG using poloxamer 407 and gellan gum. Following pharmacokinetic evaluation in Wistar rats, the brain C_max for intranasal AMS-NG was found to be 1.48-folds and 3.39-folds higher when compared to intranasal AMS-NE and intravenous AMS-NE, respectively. Moreover, behavioral investigations of developed formulations were devoid of any extrapyramidal side effects in the experimental model. Finally, outcomes of the in vivo hematological study confirmed that intranasal administration of formulation for 28 days did not alter leukocytes and agranulocytes count. In conclusion, the promising results of the developed and optimized intranasal AMS-NG could provide a novel platform for the effective and safe delivery of AMS in schizophrenic patients.

Biomaterials for Drugs Nose-Brain Transport: A New Therapeutic Approach for Neurological Diseases

In the last years, neurological diseases have resulted in a global health issue, representing the first cause of disability worldwide. Current therapeutic approaches against neurological disorders include oral, topical, or intravenous administration of drugs and more invasive techniques such as surgery and brain implants. Unfortunately, at present, there are no fully effective treatments against neurodegenerative diseases, because they are not associated with a regeneration of the neural tissue but rather act on slowing the neurodegenerative process. The main limitation of central nervous system therapeutics is related to their delivery to the nervous system in therapeutic quantities due to the presence of the blood-brain barrier. In this regard, recently, the intranasal route has emerged as a promising administration site for central nervous system therapeutics since it provides a direct connection to the central nervous system, avoiding the passage through the blood-brain barrier, consequently increasing drug cerebral bioavailability. This review provides an overview of the nose-to-brain route: first, we summarize the anatomy of this route, focusing on the neural mechanisms responsible for the delivery of central nervous system therapeutics to the brain, and then we discuss the recent advances made on the design of intranasal drug delivery systems of central nervous system therapeutics to the brain, focusing in particular on stimuli-responsive hydrogels.

Immobilized anticancer agents and metal nanoparticles in a matrix of gellan: achievements and prospects

A review is devoted to recent achievements in development of anticancer drugs based on natural polysaccharide – gellan that possesses coil-helix conformational transition, sol-gel phase transition, thermo- and salt sensitivity. The characteristics of high- and low-acyl gellan are briefly given and the influence of mono- and multivalent metal ions on the gelation efficiency is described. The mucoadhesive properties of gellan and its modified derivatives are briefly considered in the context of application in pharmacy as oral, buccal, nasal, ophthalmologic, vaginal forms. The main attention is paid to anticancer drugs, gold and silver nanoparticles immobilized within gellan matrix by chemical bonds, physical adsorption and chemosorption. The state-of-the art and perspectives of development of plasmonic photothermal therapy of cancer cells that is one of the promising direction of nanomedicine in diagnosis and treatment of oncological diseases are highlighted. It is outlined that the further strategy of development and application of plasmonic photothermal therapy into clinical practice is due to selection of metal nanoparticles with optimal sizes, high concentration, low cytotoxicity and suitable optical characteristics.

Nose-to-brain delivery of drug nanocrystals by using Ca2+ responsive deacetylated gellan gum based in situ-nanogel

The objective of this study is to use a carbohydrate polymer deacetylated gellan gum (DGG) as matrix to design nanocrystals based intranasal in situ gel (IG) for nose-to -brain delivery of drug. The harmine nanocrystals (HAR-NC) as model drug were prepared by coupling homogenization and spray-drying technology. The HAR-NC was redispersed in the (DGG) solutions and formed the ionic-triggered harmine nanocrystals based in situ gel (HAR-NC-IG). The crystal state of HAR remained unchanged during the homogenization and spray-drying. And the HAR-NC-IG with 0.5% DGG exhibited excellent in situ-gelation ability, water retention property and in vitro release behavior. The bioavailability in brain of intranasal HAR-NC-IG were 25-fold higher than that of oral HAR-NC, which could be attributed to nanosizing effect of HAR-NC and bioadhesive property of DGG triggered by nasal fluid. And the HAR-NC-IG could significantly inhibit the expression of acetylcholinesterase (AchE) and increase the content of acetylcholin (ACh) in brain compared with those of reference formulations (p < 0.01). The DGG based nanocrystals-in situ gel was a promising carrier for nose-to-brain delivery of poorly soluble drug, which could prolong the residence time and improve the bioavailability of poorly soluble drugs in brain.