Maleimide-functionalised PLGA-PEG nanoparticles as mucoadhesive carriers for intravesical drug delivery

Mucoadhesive Thiolated Hyaluronic Acid/Pluronic F127 Nanogel Formation via Thiol-Maleimide Click Reaction for Intravesical Drug Delivery

The development of nanocarriers to prolong the residence time and enhance the permeability of chemotherapeutic drugs on bladder mucosa is important in the postsurgery treatment of superficial bladder cancers (BCs). Here, the mucoadhesive HA-SH/PF127 nanogels composed of a temperature-sensitive Pluronic F127 (PF127) core and thiolated hyaluronic acid (HA-SH) shell were prepared by the emulsification/solvent evaporation method. The nanogels were constructed through the thiol-maleimide click reaction in the HA-SH aqueous side of the oil-water interface and self-oxidized cross-linking thiols between HA-SH. The HA-SH/PF127 nanogels prepared at different thiol-to-maleimide group molar ratios, water-to-oil volume ratios, and cross-linking reaction times were characterized regarding hydrodynamic diameter (Dh) and zeta potential (ζ), and the optimal formulation was obtained. The excellent mucoadhesive properties of the HA-SH/PF127 nanogels were evaluated by using the mucin particle method. Doxorubicin (DOX) was encapsulated in the PF127 core of DOX@HA-SH/PF127 nanogels with a high loading efficiency (87.5%) and sustained release from the nanogels in artificial urine. Ex vivo studies on porcine bladder mucosa showed that the DOX@HA-SH/PF127 nanogels enhanced the penetration of the DOX into the bladder mucosa without disrupting the mucus structure or the bladder tissue. A significant dose-dependent cytotoxic effect of DOX@HA-SH/PF127 nanogels on both T24 and MB49 cells was observed. The present study demonstrates that the mucoadhesive HA-SH/PF127 nanogels are a promising intravesical drug delivery system for superficial BC therapy.

Enhancing Mucoadhesive Properties of Gelatin through Chemical Modification with Unsaturated Anhydrides

Gelatin is a water-soluble natural polyampholyte with poor mucoadhesive properties. It has traditionally been used as a major ingredient in many pharmaceuticals, including soft and hard capsules, suppositories, tissue engineering, and regenerative medicine. The mucoadhesive properties of gelatin can be improved by modifying it through conjugation with specific adhesive unsaturated groups. In this study, gelatin was modified by reacting with crotonic, itaconic, and methacrylic anhydrides in varying molar ratios to yield crotonoylated-, itaconoylated-, and methacryloylated gelatins (abbreviated as Gel-CA, Gel-IA, and Gel-MA, respectively). The successful synthesis was confirmed using 1H NMR, FTIR spectroscopies, and colorimetric TNBSA assay. The effect of chemical modification on the isoelectric point was studied through viscosity and electrophoretic mobility measurements. The evolution of the storage (G') and loss (G'') moduli was employed to determine thermoreversible gelation points of modified and unmodified gelatins. The safety of modified gelatin derivatives was assessed with an in vivo slug mucosal irritation test (SMIT) and an in vitro MTT assay utilizing human pulmonary fibroblasts cell line. Two different model dosage forms, such as physical gels and spray-dried microparticles, were prepared and their mucoadhesive properties were evaluated using a flow-through technique with fluorescent detection and a tensile test with ex vivo porcine vaginal tissues and sheep nasal mucosa. Gelatins modified with unsaturated groups exhibited superior mucoadhesive properties compared to native gelatin. The enhanced ability of gelatin modified with these unsaturated functional groups is due to the formation of covalent bonds with cysteine-rich subdomains present in the mucin via thiol-ene click Michael-type addition reactions occurring under physiologically relevant conditions.

Immunomodulatory Nanoparticles for Modulating Arthritis Flares

Disease-modifying drugs have improved the treatment for autoimmune joint disorders, such as rheumatoid arthritis, but inflammatory flares are a common experience. This work reports the development and application of flare-modulating poly(lactic-co-glycolic acid)-poly(ethylene glycol)-maleimide (PLGA-PEG-MAL)-based nanoparticles conjugated with joint-relevant peptide antigens, aggrecan70-84 and type 2 bovine collagen256-270. Peptide-conjugated PLGA-PEG-MAL nanoparticles encapsulated calcitriol, which acted as an immunoregulatory agent, and were termed calcitriol-loaded nanoparticles (CLNP). CLNP had a ∼200 nm hydrodynamic diameter with a low polydispersity index. In vitro, CLNP induced phenotypic changes in bone marrow derived dendritic cells (DC), reducing the expression of costimulatory and major histocompatibility complex class II molecules, and proinflammatory cytokines. Bulk RNA sequencing of DC showed that CLNP enhanced expression of Ctla4, a gene associated with downregulation of immune responses. In vivo, CLNP accumulated in the proximal lymph nodes after intramuscular injection. Administration of CLNP was not associated with changes in peripheral blood cell numbers or cytokine levels. In the collagen-induced arthritis and SKG mouse models of autoimmune joint disorders, CLNP reduced clinical scores, prevented bone erosion, and preserved cartilage proteoglycan, as assessed by high-resolution microcomputed tomography and histomorphometry analysis. The disease protective effects were associated with increased CTLA-4 expression in joint-localized DC and CD4+ T cells but without generalized suppression of T cell-dependent immune response. The results support the potential of CLNP as modulators of disease flares in autoimmune arthropathies.

Local Drug Delivery in Bladder Cancer: Advances of Nano/Micro/Macro-Scale Drug Delivery Systems

Treatment of bladder cancer remains a critical unmet need and requires advanced approaches, particularly the development of local drug delivery systems. The physiology of the urinary bladder causes the main difficulties in the local treatment of bladder cancer: regular voiding prevents the maintenance of optimal concentration of the instilled drugs, while poor permeability of the urothelium limits the penetration of the drugs into the bladder wall. Therefore, great research efforts have been spent to overcome these hurdles, thereby improving the efficacy of available therapies. The explosive development of nanotechnology, polymer science, and related fields has contributed to the emergence of a number of nanostructured vehicles (nano- and micro-scale) applicable for intravesical drug delivery. Moreover, the engineering approach has facilitated the design of several macro-sized depot systems (centimeter scale) capable of remaining in the bladder for weeks and months. In this article, the main rationales and strategies for improved intravesical delivery are reviewed. Here, we focused on analysis of colloidal nano- and micro-sized drug carriers and indwelling macro-scale devices, which were evaluated for applicability in local therapy for bladder cancer in vivo.

Polymer-based nanosystems and their applications in bone anticancer therapy

The mortality rate of bone cancer has witnessed a substantial reduction in recent years, all thanks to the advent of advanced cancer treatment modalities such as surgical intervention, radiation, and chemotherapy. Nevertheless, these popular modalities come with a set of clinical challenges, including non-specificity, side effects, and drug intolerance. In recent years, polymer-based nanosystems have emerged as a promising solution in bone anti-cancer therapy by virtue of their unique physical and chemical properties. These nanosystems can be tailored for use in different drug release mechanisms for therapeutic implementations. This review delves into the efficacy of these therapy applications in bone cancer (with a focus on one of the most common types of cancers, Osteosarcoma) treatment and their correlation with the properties of polymer-based nanosystems, in addition to their interaction with the tumor microenvironment and the biological milieu.

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.

Mucoadhesive gellan gum-based and carboxymethyl cellulose -based hydrogels containing gemcitabine and papain for bladder cancer treatment

Local treatment of bladder cancer faces several limitations such as short residence time or low permeation through urothelium tissue. The aim of this work was to develop patient-friendly mucoadhesive gel formulations combining gemcitabine and the enzyme papain for improved intravesical chemotherapy delivery. Hydrogels based on two different polysaccharides, gellan gum and sodium carboxymethylcellulose (CMC), were prepared with either native papain or papain nanoparticles (nanopapain) to explore for the first time their use as permeability enhancers through bladder tissue. Gel formulations were characterized regarding enzyme stability, rheological behavior, retention on bladder tissue and bioadhesion, drug release properties, permeation capacity, and biocompatibility. After 90 days of storage, the enzyme loaded in the CMC gels retained up to 83.5 ± 4.9 % of its activity in the absence of the drug, and up to 78.1 ± 5.3 with gemcitabine. The gels were mucoadhesive and the enzyme papain showed mucolytic action, which resulted in resistance against washing off from the urothelium and enhanced permeability of gemcitabine in the ex vivo tissue diffusion tests. Native papain shortened lag-time tissue penetration to 0.6 h and enhanced 2-fold drug permeability All formulations demonstrated pseudoplastic behavior and no irritability. Overall, the developed formulations have potential as an upgraded alternative to intravesical therapy for bladder cancer treatment.

Hydrogels for Mucosal Drug Delivery

Mucosal tissues are often a desirable site of drug action to treat disease and engage the immune system. However, systemically administered drugs suffer from limited bioavailability in mucosal tissues where technologies to enable direct, local delivery to these sites would prove useful. In this Spotlight on Applications article, we discuss hydrogels as an attractive means for local delivery of therapeutics to address a range of conditions affecting the eye, nose, oral cavity, gastrointestinal, urinary bladder, and vaginal tracts. Considering the barriers to effective mucosal delivery, we provide an overview of the key parameters in the use of hydrogels for these applications. Finally, we highlight recent work demonstrating their use for inflammatory and infectious diseases affecting these tissues.

Recent advances of polymer based nanosystems in cancer management

Cancer is still one of the leading causes of death worldwide. Nanotechnology, particularly nanoparticle-based platforms, is at the leading edge of current cancer management research. Polymer-based nanosystems have piqued the interest of researchers owing to their many benefits over other conventional drug delivery systems. Polymers derived from both natural and synthetic sources have various biomedical applications due to unique qualities like porosity, mechanical strength, biocompatibility, and biodegradability. Polymers such as poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL), and polyethylene glycol (PEG) have been approved by the USFDA and are being researched for drug delivery applications. They have been reported to be potential carriers for drug loading and are used in theranostic applications. In this review, we have primarily focused on the aforementioned polymers and their conjugates. In addition, the therapeutic and diagnostic implications of polymer-based nanosystems have been briefly reviewed. Furthermore, the safety of the developed polymeric formulations is crucial, and we have discussed their biocompatibility in detail. This article also discusses recent developments in block co-polymer-based nanosystems for cancer treatment. The review ends with the challenges of clinical translation of polymer-based nanosystems in drug delivery for cancer therapy.

Maleimide-Decorated PEGylated Mucoadhesive Liposomes for Ocular Drug Delivery

Liposomes are promising spherical vesicles for topical drug delivery to the eye. Several types of vesicles were formulated in this study, including conventional, PEGylated, and maleimide-decorated PEGylated liposomes. The physicochemical characteristics of these liposomes, including their size, zeta potential, ciprofloxacin encapsulation efficiency, loading capacity, and release, were evaluated. The structure of these liposomes was examined using dynamic light scattering, transmission electron microscopy, and small angle neutron scattering. The ex vivo corneal and conjunctival retention of these liposomes were examined using the fluorescence flow-through method. Maleimide-decorated liposomes exhibited the best retention performance on bovine conjunctiva compared to other types of liposomes studied. Poor retention of all liposomal formulations was observed on bovine cornea.

Assessment of Efficacy and Safety Using PPAR-γ Agonist-Loaded Nanocarriers for Inflammatory Eye Diseases

Drug-loaded nanocarriers (NCs) are new systems that can greatly improve the delivery and targeting of drugs to specific tissues and organs. In our work, a PPAR-γ agonist loaded into polymeric NCs was prepared, stabilized by spray-drying, and tested in vitro, ex vivo, and in vivo (animal models) to provide a safe formulation for optical anti-inflammatory treatments. The NCs were shown to be well tolerated, and no signs of irritancy or alterations of the eye properties were detected by the in vitro HET-CAM test and in vivo Draize test. Furthermore, no signs of cytotoxicity were found in the NC formulations on retinoblastoma cells (Y-79) analyzed using the alamarBlue assay, and the transmittance experiments evidenced good corneal transparency with the formulations tested. The ocular anti-inflammatory study confirmed the significant prevention efficacy using the NCs, and these systems did not affect the corneal tissue structure. Moreover, the animal corneal structure treated with the NCs was analyzed using X-ray diffraction using synchrotron light. Small-angle X-ray scattering (SAXS) analysis did not show a significant difference in corneal collagen interfibrillar spacing after the treatment with freshly prepared NCs or NCs after the drying process compared to the corresponding negative control when inflammation was induced. Considering these results, the PPAR-γ agonist NCs could be a safe and effective alternative for the treatment of inflammatory ocular processes.

Aldehyde-functional thermoresponsive diblock copolymer worm gels exhibit strong mucoadhesion

A series of thermoresponsive diblock copolymer worm gels is prepared via reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization of 2-hydroxypropyl methacrylate using a water-soluble methacrylic precursor bearing pendent cis-diol groups. Selective oxidation using an aqueous solution of sodium periodate affords the corresponding aldehyde-functional worm gels. The aldehyde groups are located within the steric stabilizer chains and the aldehyde content can be adjusted by varying the periodate/cis-diol molar ratio. These aldehyde-functional worm gels are evaluated in terms of their mucoadhesion performance with the aid of a fluorescence microscopy-based assay. Using porcine urinary bladder mucosa as a model substrate, we demonstrate that these worm gels offer a comparable degree of mucoadhesion to that afforded by chitosan, which is widely regarded to be a ‘gold standard’ positive control in this context. The optimum degree of aldehyde functionality is approximately 30%: lower degrees of functionalization lead to weaker mucoadhesion, whereas higher values compromise the desirable thermoresponsive behavior of these worm gels.

Optimizing the aldehyde content of thermoresponsive diblock copolymer worm gels via periodate oxidation leads to mucoadhesion performance comparable to that of chitosan (a gold standard positive control) in a fluorescence assay using porcine mucosa.

Surface Modification of Lipid-Based Nanoparticles

There is a growing interest in the development of lipid-based nanocarriers for multiple purposes, including the recent increase of these nanocarriers as vaccine components during the COVID-19 pandemic. The number of studies that involve the surface modification of nanocarriers to improve their performance (increase the delivery of a therapeutic to its target site with less off-site accumulation) is enormous. The present review aims to provide an overview of various methods associated with lipid nanoparticle grafting, including techniques used to separate grafted nanoparticles from unbound ligands or to characterize grafted nanoparticles. We also provide a critical perspective on the usefulness and true impact of these modifications on overcoming different biological barriers, with our prediction on what to expect in the near future in this field.

Polyaphron Formulations Stabilised with Different Water-Soluble Polymers for Ocular Drug Delivery

As drug delivery to the eye has evolved over the last decades, researchers have explored more effective treatments for ocular diseases. Despite this, delivering drugs to the cornea remains one of the most problematic issues in ophthalmology due to the poor permeability of the cornea and tear clearance mechanisms. In this study, four different types of polyaphron formulations are prepared with 10% poloxamer 188 (P188), 10% poly(2-ethyl-2-oxazoline), 1% polyquaternium 10, and 3% sodium carboxymethylcellulose solutions mixed with 1% Brij® L4 in a caprylic/capric triglycerides solution. Their physicochemical characteristics, rheological properties, and stability are assessed. Additionally, a polyaphron with 3% polyquaternium 10 was prepared for the assessment of ex vivo corneal retention along with four other polyaphrons. The best retention on the ex vivo cornea was displayed by the 3% polyquaternium 10-based formulation. The 10% poloxamer 188 along with 1% polyquaternium 10-based polyaphrons appeared to be the most stable among the four prepared formulations. A toxicological evaluation of these formulations was performed using a slug mucosal irritation test and bovine corneal opacity and permeability assay, with all four polyaphrons proving good biocompatibility with ocular tissues. The developed drug delivery systems demonstrated an excellent potential for ocular drug delivery.

Study on the Mechanism of Action of Paclitaxel-Loaded Polylactic-co-glycolic Acid Nanoparticles in Non-Small-Cell Lung Carcinoma Cells

Objective. To study effective carriers that can enhance the antitumor effect of paclitaxel (PTX). Methods. PTX-loaded polylactic-co-glycolic acid (PLGA) nanoparticles (NPs) (PTX-PLGA NPs), constructed using the emulsification solvent evaporation method, were characterized by scanning electron microscopy and dynamic light scattering. Non-small-cell lung carcinoma (NSCLC) cells were divided into the dimethyl sulfoxide (DMSO) group, PLGA NPs group, PTX group, and PTX-PLGA NPs group. Cell viability was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), cell apoptosis was determined by flow cytometry, and cell migration and invasion were assessed using Transwell assay. Results. PTX-PLGA NPs were smooth in the surface and spherical in shape, with a particle size of $268\pm 1.3$  nm. Both PTX and PTX-PLGA NPs could effectively inhibit the activity of A549 and H1650 cells. At 12 and 24 h, PTX-PLGA NPs presented weaker inhibition on the activity of NSCLC cells than PTX, but at 48 and 72 h, PTX-PLGA NPs presented stronger inhibition. Compared with PTX, PTX-PLGA NPs were more effective in enhancing apoptosis and inhibiting migration and invasion of NSCLC cells. Conclusion. With good sustained release and the ability to promote cellular uptake, PTX-PLGA NPs can strongly inhibit the malignant activities of NSCLC cells, which can be used as a promising drug carrier.

Recent Advances in Nanoplatforms for the Treatment of Osteosarcoma

Osteosarcoma (OS) is the most common primary bone tumor in children and young people. Traditional surgical excision combined with chemotherapy presents many limitations, such as resistance and systemic side effects of chemotherapy drugs, postoperative recurrence, and bone defects. Given these limitations, novel therapeutic modalities for OS treatment using nanometer-sized platform-based chemotherapeutic delivery have emerged as a promising alternative therapy. This form of therapy offers multiple advantages, such as accurate delivery of the drug to the tumor site and repair of limited bone defects after tumor resection. In this review, we briefly summarize nanoplatforms, including liposomes, polymeric nanoparticles, inorganic nanoparticles, nanomicelles, dendrimers, nanocapsules, and exosomes. The essential shortcomings involved in these nanoplatforms, such as poor stability, immunogenicity, insufficient circulation, and drug leakage are also discussed, and related solutions are briefly proposed. Finally, the application prospects of nanoplatforms in the treatment of OS are discussed.

Activity of Povidone in Recent Biomedical Applications with Emphasis on Micro- and Nano Drug Delivery Systems

Due to the unwanted toxic properties of some drugs, new efficient methods of protection of the organisms against that toxicity are required. New materials are synthesized to effectively disseminate the active substance without affecting the healthy cells. Thus far, a number of polymers have been applied to build novel drug delivery systems. One of interesting polymers for this purpose is povidone, pVP. Contrary to other polymeric materials, the synthesis of povidone nanoparticles can take place under various condition, due to good solubility of this polymer in several organic and inorganic solvents. Moreover, povidone is known as nontoxic, non-carcinogenic, and temperature-insensitive substance. Its flexible design and the presence of various functional groups allow connection with the hydrophobic and hydrophilic drugs. It is worth noting, that pVP is regarded as an ecofriendly substance. Despite wide application of pVP in medicine, it was not often selected for the production of drug carriers. This review article is focused on recent reports on the role povidone can play in micro- and nano drug delivery systems. Advantages and possible threats resulting from the use of povidone are indicated. Moreover, popular biomedical aspects are discussed.

Reversible multilayered vesicle-like structures with fluid hydrophobic and interpolyelectrolyte layers

Hydrophobic blocks of amphiphilic block copolymers often form glassy micellar cores at room temperature with a rigid structure that limits their applications as nanocapsules for targeted delivery. Nevertheless, we prepared and analyzed core/shell micelles with a soft core, formed by a self-assembled block copolymer consisting of a hydrophobic block and a polycation block, poly(lauryl acrylate)-block-poly(trimethyl-aminoethyl acrylate) (PLA-QPDMAEA), in aqueous solution. By light and small-angle neutron scattering, by transmission electron microscopy and by fluorescence spectroscopy, we showed that these core/shell micelles are spherical and cylindrical with a fluid-like PLA core and a positively charged outer shell and that they can encapsulate and release hydrophobic solutes. Moreover, after mixing these PLA-QPDMAEA core/shell micelles with another diblock copolymer, consisting of a hydrophilic block and a polyanion block, namely poly(ethylene oxide)-block-poly(methacrylic acid) (PEO-PMAA), we observed the formation of novel vesicle-like multicompartment structures containing both soft hydrophobic and interpolyelectrolyte (IPEC) layers. By combining small-angle neutron scattering with self-consistent field modeling, we confirmed the formation of these complex vesicle-like structures with a swollen PEO core, an IPEC inner layer, a PLA soft layer, an IPEC outer layer and a loose PEO corona. Thus, these multicompartment micelles with fluid and IPEC layers and a hydrophilic corona may be used as nanocapsules with several tunable properties, including the ability to control the thickness of each layer, the charge of the IPEC layers and the stability of the micelles, to deliver both hydrophobic and multivalent solutes.

Optimization of artificial urine formula for in vitro cellular study compared with native urine

Several artificial urine (AU) formulas have been developed to mimic the normal urine. Most of them are protein-free, particularly when secreted proteins (secretome) is to be analyzed. However, the normal urine actually contains a tiny amount of proteins. We hypothesized that urinary proteins at physiologic level play a role in preservation of renal cell biology and function. This study evaluated the effects from supplementation of 0-10% fetal bovine serum (FBS) into the well-established AU-Siriraj protocol on MDCK renal tubular cells. Time to deformation (T_D) was reduced by both native urine and AU-Siriraj without/with FBS compared with complete culture medium (control). Among the native urine and AU-Siriraj without/with FBS, the cells in AU-Siriraj+2.5% FBS had the longest T_D. Supplementation of FBS increased cell death in a dose-dependent manner (but still <10%). Transepithelial electrical resistance (TER) of the polarized cells in the native urine was comparable to the control, whereas that of the cells in AU-Siriraj+2.5% FBS had the highest TER. These data indicate that supplementation of 2.5% FBS into AU-Siriraj can prolong time to deformation and enhance polarization of renal tubular cells. Therefore, AU-Siriraj+2.5% FBS is highly recommended for in vitro study of cell biology and function (when secretome is not subjected to analysis).

Engineering the drug carrier biointerface to overcome biological barriers to drug delivery

Micro and nanoscale drug carriers must navigate through a plethora of dynamic biological systems prior to reaching their tissue or disease targets. The biological obstacles to drug delivery come in many forms and include tissue barriers, mucus and bacterial biofilm hydrogels, the immune system, and cellular uptake and intracellular trafficking. The biointerface of drug carriers influences how these carriers navigate and overcome biological barriers for successful drug delivery. In this review, we examine how key material design parameters lead to dynamic biointerfaces and improved drug delivery across biological barriers. We provide a brief overview of approaches used to engineer key physicochemical properties of drug carriers, such as morphology, surface chemistry, and topography, as well as the development of dynamic responsive materials for barrier navigation. We then discuss essential biological barriers and how biointerface engineering can enable drug carriers to better navigate and overcome these barriers to drug delivery.

Drug Delivery Systems of Natural Products in Oncology

In recent decades, increasing interest in the use of natural products in anticancer therapy field has been observed, mainly due to unsolved drug-resistance problems. The antitumoral effect of natural compounds involving different signaling pathways and cellular mechanisms has been largely demonstrated in in vitro and in vivo studies. The encapsulation of natural products into different delivery systems may lead to a significant enhancement of their anticancer efficacy by increasing in vivo stability and bioavailability, reducing side adverse effects and improving target-specific activity. This review will focus on research studies related to nanostructured systems containing natural compounds for new drug delivery tools in anticancer therapies.

Planarian toxicity fluorescent assay: A rapid and cheap pre-screening tool for potential skin irritants

Here we report a new planarian (Dugesia lugubris) fluorescent assay as a rapid and cheap pre-screening tool to predict strong skin irritants. Our aim was to provide a simple and cost-effective in vivo method that avoided use of higher vertebrates. Adapting previously reported methods for planaria mobility alongside an acute toxicity assay, different irritants at five concentrations (0.1%, 0.05%, 0.025%, 0.01% and 0.005% w/v) were tested but both methods failed to discriminate the irritation potential of the test compounds. Therefore, a new alternative fluorescence assay was developed, hypothesising that increasing damage from the irritant to the planarian outer protective membrane will increase accumulation of sodium fluorescein in the flatworm. Fourteen test chemicals were selected representing strong, moderate, mild and non-irritants. In general, results showed increasing sodium fluorescein accumulation within planaria following acute exposure to increasingly strong skin irritants; on exposure to the strong irritants, benzalkonium chloride, citronellal, methyl palmitate, 1-bromohexane and carvacrol, fluorescence within the planaria was significantly greater (P < 0.05) than the negative controls and the common non-irritants PEG-400, dipropylene glycol and isopropyl alcohol; fluorescence values of planaria tested with negative controls and non-irritants were not significantly different. For all test compounds, Fluorescence Intensity of the planaria was compared with literature Primary Irritation Index data and generated a statistically significant (P < 0.005) Pearson correlation (r) of 0.87. Thus, the planarian fluorescent assay is a promising tool for rapid early testing of potential strong skin irritants, and non-irritants, and avoids use of higher vertebrate models.

Multifunctional carriers for controlled drug delivery

In the review we describe a method for concentration of anionic liposomes with encapsulated water-soluble substances within a small volume via electrostatic liposome adsorption on the surface of polymer particles with grafted cationic chains (spherical polycationic brushes), or cationic microgel particles. Dozens of intact liposomes can be bound to each polymer particle, the resulting polymer/liposome complex does not dissociate into the original components in a physiological solution. This allows fabrication of multi-liposomal complexes (MLCs) with a required ratio of encapsulated substances. Two approaches are discussed for the synthesis of stimuli-sensitive MLCs. The first is to incorporate the conformation switch, morpholinocyclohexanol-based lipid, into the liposomal membrane thus forming pH-sensitive liposomes capable of releasing their cargo when acidifying the surrounding solution. These liposomes complexed with the brushes release encapsulated substances much faster than the uncomplexed liposomes. The second is to adsorb liposomes on cationic thermo-responsive microgels. The resulting MLCs contracts upon heating over a volume phase transition temperature from the swollen to the collapsed state of microgel, thus causing the adsorbed liposomes to change drastically their morphology and release an encapsulated substance. Complexation of anionic liposomes with chitosan microgels and polylactide micelles gives MLCs which degrade in the presence of enzymes down to small particles, 10–15 nm in diameter. A novel promising approach suggests that immobilized liposomes can act as a capacious depot for biologically active compounds and ensure their controllable leakage to surrounding solution.

S-protected thiolated hyaluronic acid: In-situ crosslinking hydrogels for 3D cell culture scaffold

The purpose of this study was to synthesize S-protected thiolated hyaluronic acid (HA) and to evaluate its potential for 3D cell culture scaffold. S-protected thiolated HA was synthesized by the covalent attachment of N-acetyl-S-((3-((2,5-dioxopyrrolidin-1-yl)oxy)-3-oxopropyl)thio)cysteine hydrazide ligand to the HA. Hydrogels were characterized for texture, swelling behavior and rheological properties. Furthermore, the potential of S-protected thiolated HA hydrogels as a scaffold for tissue engineering was evaluated by cell proliferation studies with Caco-2 and NIH 3T3 cells. It showed enhanced cohesion upon addition of N-acetyl cysteine (NAC). Dynamic viscosity of S-protected thiolated HA hydrogel was increased up to 19.5-fold by addition of NAC and 10.1-fold after mixing with mucus. Furthermore, Caco-2 and NIH 3T3 cells encapsulated into hydrogels proliferated in-vitro. As this novel S-protected thiolated HA is stable towards oxidation and forms highly cohesive gels when getting into contact with endogenous thiols due to disulfide-crosslinking, it is a promising tool for 3D cell culture scaffold.

Recent Advancements in Using Polymers for Intestinal Mucoadhesion and Mucopenetration

Oral administration of actives is the most desired form of delivery, but the formulations need to overcome a variety of barriers including the intestinal mucus. This feature article summarizes the developments from the past 2-3 years in this context focusing on polymer-based formulations. The progress in assembling mucopenetrating nanoparticles is outlined considering coatings using noninteracting polymers as well as virus-like particles and charge-shifting particles. Next, polymers and their modification to enhance mucoadhesion are discussed, followed by providing examples of double-encapsulation systems that aim to combine mucopenetration with mucoadhesion in the same formulation. Finally, a short outlook is provided highlighting a few of the most pressing challenges to address.