Design of a novel hydrogel-based intelligent system for controlled drug release

Cyclodextrin-based supramolecular deep eutectic solvent (CycloDES): A vehicle for the delivery of poorly soluble drugs

The aim of this work was to develop a new class of deep eutectic solvent (DES) composed of a complexation agent, namely hydroxy-propyl-β-cyclodextrin (HPβCD), to exploit a synergic solubilization-enhancing approach. For this purpose, cyclodextrin-based supramolecular DES (CycloDES) were physical-chemical characterized and loaded with three different BCS class II model drugs, specifically Cannabidiol, Indomethacin, and Dexamethasone, evaluating the influence of different factors on the observed solubility and permeation compared with the only HPβCD/drug complexation. Hence, CycloDESs were presented as a possible vehicle for drugs and represent a novel potential approach for solving BCS class II and IV solubility issues, demonstrating at least a 100-fold improvement in the investigated drug solubilities. Furthermore, CycloDESs demonstrated a significantly improved resistance to dilution preserving a high percentage of drug in solution (i.e. 93% for Indomethacin) when water is added to the DES if compared with a glucose-choline chloride DES, used as a standard. This evidence guarantees the solubility-enhancing effect useful for the delivery of BCS class II and IV drugs converting solid raw material to advantageous liquid vehicles bypassing the rate-determining dissolution step.

Multifunctional GelMA platforms with nanomaterials for advanced tissue therapeutics

Polymeric hydrogels are fascinating platforms as 3D scaffolds for tissue repair and delivery systems of therapeutic molecules and cells. Among others, methacrylated gelatin (GelMA) has become a representative hydrogel formulation, finding various biomedical applications. Recent efforts on GelMA-based hydrogels have been devoted to combining them with bioactive and functional nanomaterials, aiming to provide enhanced physicochemical and biological properties to GelMA. The benefits of this approach are multiple: i) reinforcing mechanical properties, ii) modulating viscoelastic property to allow 3D printability of bio-inks, iii) rendering electrical/magnetic property to produce electro-/magneto-active hydrogels for the repair of specific tissues (e.g., muscle, nerve), iv) providing stimuli-responsiveness to actively deliver therapeutic molecules, and v) endowing therapeutic capacity in tissue repair process (e.g., antioxidant effects). The nanomaterial-combined GelMA systems have shown significantly enhanced and extraordinary behaviors in various tissues (bone, skin, cardiac, and nerve) that are rarely observable with GelMA. Here we systematically review these recent efforts in nanomaterials-combined GelMA hydrogels that are considered as next-generation multifunctional platforms for tissue therapeutics. The approaches used in GelMA can also apply to other existing polymeric hydrogel systems.

d-Mannitol based surfactants for cosmetic and food applications and hydrogels to produce stabilized Ag nanoparticles

A novel synthetic approach for lipid modification of mannitol for hydrogelation, cosmetic and food application.

Formulation strategies to improve the efficacy of intestinal permeation enhancers. Adv Drug Deliv Rev 2021;177:113925. [PMID: 34418495 DOI: 10.1016/j.addr.2021.113925]

The use of chemical permeation enhancers (PEs) is the most widely tested approach to improve oral absorption of low permeability active agents, as represented by peptides. Several hundred PEs increase intestinal permeability in preclinical bioassays, yet few have progressed to clinical testing and, of those, only incremental increases in oral bioavailability (BA) have been observed. Still, average BA values of ~1% were sufficient for two recent FDA approvals of semaglutide and octreotide oral formulations. PEs are typically screened in static in vitro and ex-vivo models where co-presentation of active agent and PE in high concentrations allows the PE to alter barrier integrity with sufficient contact time to promote flux across the intestinal epithelium. The capacity to maintain high concentrations of co-presented agents at the epithelium is not reached by standard oral dosage forms in the upper GI tract in vivo due to dilution, interference from luminal components, fast intestinal transit, and possible absorption of the PE per se. The PE-based formulations that have been assessed in clinical trials in either immediate-release or enteric-coated solid dosage forms produce low and variable oral BA due to these uncontrollable physiological factors. For PEs to appreciably increase intestinal permeability from oral dosage forms in vivo, strategies must facilitate co-presentation of PE and active agent at the epithelium for a sustained period at the required concentrations. Focusing on peptides as examples of a macromolecule class, we review physiological impediments to optimal luminal presentation, discuss the efficacy of current PE-based oral dosage forms, and suggest strategies that might be used to improve them.

Novel amorphous solid dispersion based on natural deep eutectic solvent for enhancing delivery of anti-tumor RA-XII by oral administration in rats

At present, oral chemotherapy showing the advantages of non-invasiveness, convenience, and high patient compliance, is gradually replacing traditional intravenous chemotherapy to treat patients with cancer. RA-XII, a unique natural cyclopeptide, exhibits various biological activities, such as anti-tumor, anti-angiogenic, and anti-metastatic activities. Designing an orally available formulation of RA-XII is of great importance in the development of clinically useful anticancer agents. However, RA-XII shows low oral bioavailability in rats due to its poor solubility and low permeability. To overcome these limitations, in this work, a natural deep eutectic solvent (NADES) was designed to efficiently deliver RA-XII by oral administration. A novel NADES composed of betaine and mandelic acid in the molar ratio of 1:1 (Bet-Man NADES) was successfully prepared based on a binary phase diagram of Bet and Man. Acute toxicity studies indicated that Bet-Man NADES was well tolerated with acceptable toxicity. In Bet-Man NADES solutions, the solubility of RA-XII was increased by up to 17.54-fold, and the diffusion and permeability of RA-XII carried out in a Franz cell was also significantly improved 10.35 times. In terms of biopharmaceutical classification this is translated into a change for RA-XII from class IV to class II systems. More importantly, Bet-Man NADES was transferred into the solid formulation by the inclusion of a polymer, and amorphous solid dispersions based on Bet-Man NADES (PVP K30/NADES/RA-XII, ASDs) were successfully prepared to improve uniformity, apparent solubility, dissolution, and cytotoxicity in vitro. Consequently, the oral bioavailability of RA-XII in NADES solutions and ASDs was enhanced by approximately 11.58 and 7.56 times compared with that of pure RA-XII in 0.5% CMCNa. Thus, it can be seen that a natural deep eutectic solvent and its modified amorphous solid dispersions are appropriate novel strategies for improving dissolution rate and bioavailability of poor soluble natural products such as RA-XII.

Improvement of New Dianionic Ionic Liquids vs Monoanionic in Solubility of Poorly Water-Soluble Drugs

New ionic liquids (ILs) based on dianionic phosphonate anions and ammonium cations were prepared and characterized. They were used as excipients to increase the water solubility of two oral drugs, piroxicam and ibuprofen, that are slightly soluble in water. An increment in solubility of 300-fold was achieved for ibuprofen when compared with pure water, with only 0.25 mol% of IL in water. Interestingly, this was achieved with the less toxic dianionic ionic liquid [N_{4 1 2OH 2OH}]₂ [C₂H₅PO₃], which presents an IC₅₀ of 120 mM (≈0.25 mol%). On the other hand, piroxicam showed an increase of 480-fold for the same dianionic ionic liquid, with the same ionic liquid percentage. In contrast, for monoanionic ionic liquids, the effect was not so pronounced, and only a 10-fold was obtained, in the presence of 0.3 mol% of IL. The lipophilicity (logP) of drugs decreased in the presence of these ILs. Cytotoxicity profile of these ILs was determined and they did not show a significant impact towards healthy fibroblasts. The cytotoxicity of ibuprofen and piroxicam was also determined, and cellular viability almost did not change when ionic liquid was in the presence of 1 mM of oral drug.

Oral Drug Delivery Technologies-A Decade of Developments

Advanced drug delivery technologies, in general, enable drug reformulation and administration routes, together contributing to life-cycle management and allowing the innovator to maintain the product monopoly. Over the years, there has been a steady shift from mere life-cycle management to drug repurposing-applying delivery technologies to tackle solubility and permeability issues in early stages or safety and efficacy issues in the late stages of drug discovery processes. While the drug and the disease in question primarily drive the choice of route of administration, the oral route, for its compliance and safety attributes, is the most preferred route, particularly when it comes to chronic conditions, including pain, which is not considered a disease but a symptom of a primary cause. Therefore, the attempt of this review is to take a stock of the advances in oral delivery technologies that are applicable for injectable to oral transformation, improve risk-benefit profiles of existing orals, and apply them in the early discovery program to minimize the drug attrition rates.

Non-invasive delivery strategies for biologics

Biologics now constitute a significant element of available medical treatments. Owing to their clinical and commercial success, biologics are a rapidly growing class and have become a dominant therapeutic modality. Although most of the successful biologics to date are drugs that bear a peptidic backbone, ranging from small peptides to monoclonal antibodies (~500 residues; 150 kDa), new biologic modalities, such as nucleotide-based therapeutics and viral gene therapies, are rapidly maturing towards widespread clinical use. Given the rise of peptides and proteins in the pharmaceutical landscape, tremendous research and development interest exists in developing less-invasive or non-invasive routes for the systemic delivery of biologics, including subcutaneous, transdermal, oral, inhalation, nasal and buccal routes. This Review summarizes the current status, latest updates and future prospects for such delivery of peptides, proteins and other biologics.

Characterization and evaluation of avermectin solid nanodispersion prepared by microprecipitation and lyophilisation techniques

Poorly water-soluble and photosensitive pesticide compounds are difficult to formulate as solvent-free nanoformulations with high efficacy. A avermectin solid nanodispersion with a mean particle size of 188 nm was developed by microprecipitation and lyophilisation techniques. The suspensibility and wetting time of the solid nanodispersion in water were 99.8% and 13 s, respectively, superior to those of conventional water dispersible granules and wettable powders. The anti-photolysis performance of the nanoformulation was twice that of the technical material, and the biological activity against diamondback moths was more than 1.5 times that of the conventional solid formulations while taking LC 50 as the evaluation index. Moreover, the formulation composition substantially decreased the surfactant content and avoided organic solvents. Microprecipitation combined with lyophilisation is an easy and promising method to construct solid nanoformulations for pesticides with poor water solubility and environmental sensitivity. The application of the highly effective solid nanodispersion in crop production will have a great potential in reducing chemical residues and environmental pollution.

Sodium deoxycholate/TRIS-based hydrogels for multipurpose solute delivery vehicles: Ambient release, drug release, and enantiopreferential release

Herein, we report the investigation of sodium deoxycholate (NaDC)/TRIS-based hydrogels as delivery vehicles for a broad range of applications. Three hydrogel formulations were chosen for unique rheological behaviors that suggest a change in internal hydrogel structure with the application of a shear force. In this work, we compare solute release from sheared and non-sheared hydrogels in order to explore the effect of shear force on structure and release kinetics. It was found that the application of a shear force, in addition to changes in temperature, drug solubility, drug concentration, and hydrogel formulation each affected the amount of solute ultimately released from a hydrogel system. Moreover, the use of the inherent chirality of the hydrogel network for enantio-preferential drug release was also explored. We show significant enantio-preference in the release of model drugs tryptophan and ibuprofen from the hydrogel network. Furthermore, hydrophobic domains within the hydrogel network were exploited to enable ibuprofen loading at ten times the maximum water solubility. Retention of enantio-preference was observed at this higher ibuprofen concentration. Cyclodextrin modification to the hydrogel matrix allowed for enantio-preferential inversion which is an unprecedented observation.

In Vitro and Ex Vivo Permeability Studies of Paclitaxel and Doxorubicin From Drug-Eluting Biodegradable Ureteral Stents

A drug-eluting biodegradable ureteral stent (BUS) has been developed as a new approach for the treatment of urothelial tumors of upper urinary tract cancer. In a previous work, this system has proven to be a good carrier for anticancer drugs as a potential effective and sustainable intravesical drug delivery system. BUS has revealed to reduce in 75% the viability of human urothelial cancer cells (T24) after 72 h of contact and demonstrated minimal cytotoxic effect on human umbilical vein endothelial cells (HUVECs) which were used as a control. In this work, we studied the permeability of the anticancer drugs, such as paclitaxel and doxorubicin, alone or released from the BUS developed. We used 3 different membranes to study the permeability: polyethersulfone (PES) membrane, HUVECs cell monolayer, and an ex vivo porcine ureter. The ureter thickness was measured (864.51 μm) and histological analysis was performed to confirm the integrity of urothelium. Permeability profiles were measured during 8 h for paclitaxel and doxorubicin. The drugs per se have shown to have a different profile and as expected, increasing the complexity of the membrane to be permeated, the permeability decreased, with the PES being more permeable and the ex vivo ureter tissue being less permeable. The molecular weight has also shown to influence the permeability of each drug and a higher percentage for doxorubicin (26%) and lower for paclitaxel (18%) was observed across the ex vivo ureter. The permeability (P), diffusion (D), and partition (K_d) coefficients of paclitaxel and doxorubicin through the permeable membranes were calculated. Finally, we showed that paclitaxel and doxorubicin drugs released from the BUS were able to remain in the ex vivo ureter and only a small amount of the drugs can across the different permeable membranes with a permeability of 3% for paclitaxel and 11% for doxorubicin. The estimated amount of paclitaxel that remains in the ex vivo ureter tissue is shown to be effective to affect the cancer cell and not affect the noncancer cells.

A comparison between pure active pharmaceutical ingredients and therapeutic deep eutectic solvents: Solubility and permeability studies

THEDES, so called therapeutic deep eutectic solvents are here defined as a mixture of two components, which at a particular molar composition become liquid at room temperature and in which one of them is an active pharmaceutical ingredient (API). In this work, THEDES based on menthol complexed with three different APIs, ibuprofen (ibu), BA (BA) and phenylacetic acid (PA), were prepared. The interactions between the components that constitute the THEDES were studied by NMR, confirming that the eutectic system is formed by H-bonds between menthol and the API. The mobility of the THEDES components was studied by PFGSE NMR spectroscopy. It was determined that the self-diffusion of the species followed the same behavior as observed previously for ionic liquids, in which the components migrate via jumping between voids in the suprastructure created by punctual thermal fluctuations. The solubility and permeability of the systems in an isotonic solution was evaluated and a comparison with the pure APIs was established through diffusion and permeability studies carried out in a Franz cell. The solubility of the APIs when in the THEDES system can be improved up to 12 fold, namely for the system containing ibu. Furthermore, for this system the permeability was calculated to be 14×10^-5cm/s representing a 3 fold increase in comparison with the pure API. With the exception of the systems containing PA an increase in the solubility, coupled with an increase in permeability was observed. In this work, we hence demonstrate the efficiency of THEDES as a new formulation for the enhancement of the bioavailability of APIs by changing the physical state of the molecules from a solid dosage to a liquid system.

An Overview of Therapeutic Applications

Over the last few years' great advances have been made on the development drug delivery systems for different purposes for targeting the diseased conditions. Novel drug delivery originates from polymers or associated with some devices is generally related with the emergence of novel characteristics. These changes are what eventually comprise the value of drug delivery system and Novel drug delivery system. Novel properties become existed without making new materials. Novel drug delivery system comparable to traditional system, following Targeted Drug Delivery System (TDDS) is also called targeting drug system. A new drug delivery system makes the drugs densely gather pathological-change structures, and has an improved healing effect and less toxic side effects. The drugs can improve the strength of pharmacological action and reduce the bad effect all over the body, for they release in the target organs.

Preparation and Timed Release Properties of Self-Rupturing Gels

Swelling of polymeric hydrogels is sensitive to their cross-link densities. Here, we exploit this principle to prepare self-rupturing gels which are based on a commonly-used, nontoxic, and inexpensive polyelectrolyte, poly(acrylic acid), and are prepared through a simple and low-cost polymerization-based technique. The self-rupture of these covalently cross-linked gels is achieved by preparing them to have highly nonuniform cross-link densities. This heterogeneity in cross-linking leads to highly nonuniform swelling, which generates stresses that are high enough to induce gel rupture. The time required for this rupture to occur depends on the difference in the cross-link densities between the adjoining gel regions, gel size, order in which the variably cross-linked gel portions are synthesized, and on the ambient pH and ionic strength. Furthermore, when these self-rupturing gels are prepared to have liquid-filled (capsule-like) morphologies, they can act as timed/delayed release devices. The self-rupture of these capsules provides a burst payload release after a preprogrammed delay, which is on the timescale of days and can be easily tuned by varying the rupture time, i.e., by varying either the cross-link nonuniformity or the pH and ionic strength of the release media.

Personalizing Biomaterials for Precision Nanomedicine Considering the Local Tissue Microenvironment

New advances in (nano)biomaterial design coupled with the detailed study of tissue-biomaterial interactions can open a new chapter in personalized medicine, where biomaterials are chosen and designed to match specific tissue types and disease states. The notion of a "one size fits all" biomaterial no longer exists, as growing evidence points to the value of customizing material design to enhance (pre)clinical performance. The complex microenvironment in vivo at different tissue sites exhibits diverse cell types, tissue chemistry, tissue morphology, and mechanical stresses that are further altered by local pathology. This complex and dynamic environment may alter the implanted material's properties and in turn affect its in vivo performance. It is crucial, therefore, to carefully study tissue context and optimize biomaterials considering the implantation conditions. This practice would enable attaining predictable material performance and enhance clinical outcomes.

Micro/nanofabricated platforms for oral drug delivery

The oral route of drug administration is most preferred due to its ease of use, low cost, and high patient compliance. However, the oral uptake of many small molecule drugs and biotherapeutics is limited by various physiological barriers, and, as a result, drugs suffer from issues with low solubility, low permeability, and degradation following oral administration. The flexibility of micro- and nanofabrication techniques has been used to create drug delivery platforms designed to address these barriers to oral drug uptake. Specifically, micro/nanofabricated devices have been designed with planar, asymmetric geometries to promote device adhesion and unidirectional drug release toward epithelial tissue, thereby prolonging drug exposure and increasing drug permeation. Furthermore, surface functionalization, nanotopography, responsive drug release, motion-based responses, and permeation enhancers have been incorporated into such platforms to further enhance drug uptake. This review will outline the application of micro/nanotechnology to specifically address the physiological barriers to oral drug delivery and highlight technologies that may be incorporated into these oral drug delivery systems to further enhance drug uptake.

Planar bioadhesive microdevices: a new technology for oral drug delivery

The oral route is the most convenient and least expensive route of drug administration. Yet, it is accompanied by many physiological barriers to drug uptake including low stomach pH, intestinal enzymes and transporters, mucosal barriers, and high intestinal fluid shear. While many drug delivery systems have been developed for oral drug administration, the physiological components of the gastro intestinal tract remain formidable barriers to drug uptake. Recently, microfabrication techniques have been applied to create micron-scale devices for oral drug delivery with a high degree of control over microdevice size, shape, chemical composition, drug release profile, and targeting ability. With precise control over device properties, microdevices can be fabricated with characteristics that provide increased adhesion for prolonged drug exposure, unidirectional release which serves to avoid luminal drug loss and enhance drug permeation, and protection of a drug payload from the harsh environment of the intestinal tract. Here we review the recent developments in microdevice technology and discuss the potential of these devices to overcome unsolved challenges in oral drug delivery.

CO2-switchable drug release from magneto-polymeric nanohybrids

A CO₂-responsive well-defined magneto-polymeric drug delivery system has been developed. A dosage release of doxorubicin (DOX) in vitro in a time-controllable manner can be easily executed with alternate CO₂/N₂ treatment by these smart nanocarriers.

Tailored freestanding multilayered membranes based on chitosan and alginate

Engineering metabolically demanding tissues requires the supply of nutrients, oxygen, and removal of metabolic byproducts, as well as adequate mechanical properties. In this work, we propose the development of chitosan (CHIT)/alginate (ALG) freestanding membranes fabricated by layer-by-layer (LbL) assembly. CHIT/ALG membranes were cross-linked with genipin at a concentration of 1 mg·mL(-1) or 5 mg·mL(-1). Mass transport properties of glucose and oxygen were evaluated on the freestanding membranes. The diffusion of glucose and oxygen decreases with increasing cross-linking concentration. Mechanical properties were also evaluated in physiological-simulated conditions. Increasing cross-linking density leads to an increase of storage modulus, Young modulus, and ultimate tensile strength, but to a decrease in the maximum hydrostatic pressure. The in vitro biological performance demonstrates that cross-linked films are more favorable for cell adhesion. This work demonstrates the versatility and feasibility of LbL assembly to generate nanostructured constructs with tunable permeability, mechanical, and biological properties.

Therapeutic applications of hydrogels in oral drug delivery

INTRODUCTION

Oral delivery of therapeutics, particularly protein-based pharmaceutics, is of great interest for safe and controlled drug delivery for patients. Hydrogels offer excellent potential as oral therapeutic systems due to inherent biocompatibility, diversity of both natural and synthetic material options and tunable properties. In particular, stimuli-responsive hydrogels exploit physiological changes along the intestinal tract to achieve site-specific, controlled release of protein, peptide and chemotherapeutic molecules for both local and systemic treatment applications.

AREAS COVERED

This review provides a wide perspective on the therapeutic use of hydrogels in oral delivery systems. General features and advantages of hydrogels are addressed, with more considerable focus on stimuli-responsive systems that respond to pH or enzymatic changes in the gastrointestinal environment to achieve controlled drug release. Specific examples of therapeutics are given. Last, in vitro and in vivo methods to evaluate hydrogel performance are discussed.

EXPERT OPINION

Hydrogels are excellent candidates for oral drug delivery, due to the number of adaptable parameters that enable controlled delivery of diverse therapeutic molecules. However, further work is required to more accurately simulate physiological conditions and enhance performance, which is important to achieve improved bioavailability and increase commercial interest.

Biocompatibility, absorption and safety of protein nanoparticle-based delivery of doxorubicin through oral administration in rats

Doxorubicin, a potent anticancer drug associated with cardiotoxicity and low oral bioavailability, was loaded into apotransferrin nanoparticles to improve its pharmacological performance. Here, doxorubicin (doxo)-loaded apotransferrin nanoparticles were termed as Apodoxonano, and they were prepared by sol-oil chemistry. The pH-dependent stability of nanoparticles in simulated fluids was evaluated, and the in vitro release was investigated in phosphate-buffered saline. The pharmacokinetic and toxicity studies were conducted in Wistar rats. Nanoparticles have an average size of 75 nm, with 63% entrapment efficiency, at 10 mg w/w of apotransferrin. The particles displayed good pH-dependent stability in the pH range 1.1-7.4, but sensitive at endosomal pH of 5.5, thus facilitating intracellular drug release in endosomes. Multiplex assay showed high transport ability of nano form across epithelial cells (caco-2) when compared to doxo. Moreover, during oral administration, Apodoxonano localizes significantly in esophagus, stomach and small intestine, suggesting that it was absorbed in GI tract through epithelial lining. The drug localization was shown to be significantly lower in the heart reflecting its decreased cardiotoxic nature. The Apodoxonano with a longer bioavailability and a negligible cardiotoxicity can serve as an effective and safe vehicle of drug delivery.

Free-standing polyelectrolyte membranes made of chitosan and alginate

Free-standing films have increasing applications in the biomedical field as drug delivery systems for wound healing and tissue engineering. Here, we prepared free-standing membranes by the layer-by-layer assembly of chitosan and alginate, two widely used biomaterials. Our aim was to produce a thick membrane and to study the permeation of model drugs and the adhesion of muscle cells. We first defined the optimal growth conditions in terms of pH and alginate concentration. The membranes could be easily detached from polystyrene or polypropylene substrate without any postprocessing step. The dry thickness was varied over a large range from 4 to 35 μm. A 2-fold swelling was observed by confocal microscopy when they were immersed in PBS. In addition, we quantified the permeation of model drugs (fluorescent dextrans) through the free-standing membrane, which depended on the dextran molecular weight. Finally, we showed that myoblast cells exhibited a preferential adhesion on the alginate-ending membrane as compared to the chitosan-ending membrane or to the substrate side.

A novel pulsed drug-delivery system: polyelectrolyte layer-by-layer coating of chitosan-alginate microgels

Purpose

The aim of this report was to introduce a novel “core-membrane” microgel drug-delivery device for spontaneously pulsed release without any external trigger.

Methods

The microgel core was prepared with alginate and chitosan. The semipermeable membrane outside the microgel was made of polyelectrolytes including polycation poly(allylamine hydrochloride) and sodium polystyrene sulfonate. The drug release of this novel system was governed by the swelling pressure of the core and the rupture of the outer membrane.

Results

The size of the core-membrane microgel drug-delivery device was 452.90 ± 2.71 μm. The surface charge depended on the layer-by-layer coating of polyelectrolytes, with zeta potential of 38.6 ± 1.4 mV. The confocal microscope exhibited the layer-by-layer outer membrane and inner core. The in vitro release profile showed that the content release remained low during the first 2.67 hours. After this lag time, the cumulative release increased to 80% in the next 0.95 hours, which suggested a pulsed drug release. The in vivo drug release in mice showed that the outer membrane was ruptured at approximately 3 to 4 hours, as drug was explosively released.

Conclusion

These data suggest that the encapsulated substance in the core-membrane microgel delivery device can achieve a massive drug release after outer membrane rupture. This device was an effective system for pulsed drug delivery.

Pulsatile drug release from PLGA hollow microspheres by controlling the permeability of their walls with a magnetic field

Pulsatile release: When a high-frequency magnetic field is applied, heat will be generated by coupling to the iron oxide nanoparticles encapsulated in the shells of PLGA hollow microspheres. As the temperature approaches the T(g) of PLGA, the polymer chains become more mobile, subsequently increasing the free volume of PLGA matrix and significantly enhancing the diffusion of drug molecules.

Preparation of functional water-soluble low-cytotoxic poly(methacrylate)s with pendant cationic L-lysines for efficient gene delivery

In this work, we present the preparation of water-soluble poly(methacrylate)s with pendant cationic L-lysines PHMLs(6-30 K). Plasmid DNA binding affinity as well as particle sizes and zeta potentials of the polyplexes were examined for these PHML vectors, and their cytotoxicities were assayed with HeLa cells by CCK-8 and lactate dehydrogenase kits. Gene transfection efficacy and intracellular uptake of the polyplexes by the PHML vectors were also studied with HeLa cells. As a result, it was revealed that the low cytotoxic PHMLs tended to exhibit gene transfection efficiencies significantly higher than those of the linear structural PLL (15-30 K) control, in particular the molecular weight of a PHML vector remarkably influenced its pDNA binding affinity, transfection efficacy and intracellular uptake of the polyplexes.