pH-Sensitive Starch-Based Hydrogels: Synthesis and Effect of Molecular Components on Drug Release Behavior

The drug release behavior of pH-sensitive starch-based hydrogels was systematically studied. Hydrogels were synthesized by copolymerization of acrylic acid (AA) and other acrylate comonomers onto the starch backbone. The hydrophilic agents 2-hydroxy ethyl methacrylate (HEMA), and acrylamide (AAm), as well as the hydrophobic butyl-methacrylate (BMA), were utilized as comonomers. Methylene-bisacrylamide (MBA) was employed as a crosslinking agent. The synthesized hydrogels were loaded with caffeine as a model drug. The effects of the hydrophobic/hydrophilic character of the comonomers and chemical crosslinking on the swelling capacity and the release rate of caffeine were investigated. The use of the crosslinking agent and hydrophobic monomers decreased the swelling capacity of the hydrogels. The release rate of caffeine increased with the presence of a hydrophobic monomer. The fastest release was obtained with the AA/BMA/AAm formulation, and the slowest release was observed with the AA/HEMA/AAm formulation. The transport mechanism was controlled by Fickian diffusion in formulations containing AAm, and controlled by the polymer-relaxation mechanism in formulations containing MBA. Overall, our results showed that the swelling and drug delivery behavior can be tuned by varying the chemical composition of the copolymer formulations. These starch-based hydrogels can be useful as drug delivery devices in many biomedical applications.

Gold embedded chitosan nanoparticles with cell membrane mimetic polymer coating for pH-sensitive controlled drug release and cellular fluorescence imaging

In this work, gold embedded chitosan nanoparticles (Au@CS NPs) were fabricated by a one-pot method. The benzaldehyde-terminated poly[(2-methacryloyloxy) ethyl phosphorylcholine] (PMPC) was applied to modification of the gold doped chitosan nanoparticles. The obtained Au@CS-PMPC NPs had the diameter of 135 nm with a narrow distribution. The size of the Au@CS-PMPC NPs, as well as the size of the embedded gold NPs, might be well-controlled by adjusting the feeding ratio between chitosan and HAuCl₄. Furthermore, the Au@CS-PMPC NPs showed increased colloidal stability, high drug loading content, pH-responsive drug release, excellent biocompatibility and bright fluorescence emission. The results demonstrated that Au@CS-PMPC NPs showed a great potential for tumor therapy via the combination advantages of pH-sensitive controlled drug release and cellular fluorescence imaging.

Controlled Drug Release and Cytotoxicity Studies of Beta-Lapachone and Doxorubicin Loaded into Cyclodextrins Attached to a Polyethyleneimine Matrix

This work presents a new look at the application of cyclodextrins (CD) as a drug nanocarrier. Two different cyclodextrins (αCD, βCD) were covalently conjugated to branched polyethylenimine (PEI), which was additionally functionalized with folic acid (PEI-βCD-αCD-FA). Here, we demonstrated that the combination of αCD and βCD enabled to load and control release of two anticancer drugs: doxorubicin (DOX) and beta-lapachone (beta-LP) (DOX in β-CD and beta-LP into α-CD) via host-guest inclusion. The PEI-βCD(DOX)-αCD-FA nanoconjugate was used to transport anticancer drugs into A549 lung cancer cells for estimation the cytotoxic and antitumor effect of this nanoconjugate. The presence of FA molecules should facilitate the penetration of studied nanoconjugate into the cell. Whereas, the non-cellular experiments proved that the drugs are released from the carrier mainly in the pH 4.0. The release mechanism is found to be anomalous in all studied cases.

Controlled Growth Factor Release in 3D-Printed Hydrogels

Growth factors (GFs) are critical components in governing cell fate during tissue regeneration. Their controlled delivery is challenging due to rapid turnover rates in vivo. Functionalized hydrogels, such as heparin-based hydrogels, have demonstrated great potential in regulating GF release. While the retention effects of various concentrations and molecular weights of heparin have been investigated, the role of geometry is unknown. In this work, 3D printing is used to fabricate GF-embedded heparin-based hydrogels with arbitrarily complex geometry (i.e., teabag, flower shapes). Simplified cylindrical core-shell structures with varied shell thickness are printed, and the rates of GF release are measured over the course of 28 days. Increasing the shell layers' thickness decreases the rate of GF release. Additionally, a mathematical model is developed, which is found capable of accurately predicting GF release kinetics in hydrogels with shell layers greater than 0.5 mm thick (R2 > 0.96). Finally, the sequential release is demonstrated by printing two GFs in alternating radial layers. By switching the spatial order, the delivery sequence of the GFs can be modulated. This study demonstrates how 3D printing can be utilized to fabricate user-defined structures with unique geometry in order to control the rate of GF release in hydrogels.

Silicon Nanofluidic Membrane for Electrostatic Control of Drugs and Analytes Elution

Individualized long-term management of chronic pathologies remains an elusive goal despite recent progress in drug formulation and implantable devices. The lack of advanced systems for therapeutic administration that can be controlled and tailored based on patient needs precludes optimal management of pathologies, such as diabetes, hypertension, rheumatoid arthritis. Several triggered systems for drug delivery have been demonstrated. However, they mostly rely on continuous external stimuli, which hinder their application for long-term treatments. In this work, we investigated a silicon nanofluidic technology that incorporates a gate electrode and examined its ability to achieve reproducible control of drug release. Silicon carbide (SiC) was used to coat the membrane surface, including nanochannels, ensuring biocompatibility and chemical inertness for long-term stability for in vivo deployment. With the application of a small voltage (≤ 3 V DC) to the buried polysilicon electrode, we showed in vitro repeatable modulation of membrane permeability of two model analytes-methotrexate and quantum dots. Methotrexate is a first-line therapeutic approach for rheumatoid arthritis; quantum dots represent multi-functional nanoparticles with broad applicability from bio-labeling to targeted drug delivery. Importantly, SiC coating demonstrated optimal properties as a gate dielectric, which rendered our membrane relevant for multiple applications beyond drug delivery, such as lab on a chip and micro total analysis systems (µTAS).

Controlling the Release of Neurotrophin-3 and Chondroitinase ABC Enhances the Efficacy of Nerve Guidance Conduits

Nerve guidance conduits (NGCs) have the potential to replace autografts in repairing peripheral nerve injuries, but their efficacy still needs to be improved. The efficacy of NGCs is augmented by neurotrophic factors that promote axon growth and by enzymes capable of degrading molecules that inhibit axon growth. In the current study, two types of NGCs loaded with factors (both neurotrophin-3 and chondroitinase ABC) are constructed and their abilities to repair an 8 mm gap in the rat sciatic nerve are examined. The factors are encapsulated in microparticles made of a phase-change material (PCM) or collagen and then sandwiched between two layers of electrospun fibers. The use of PCM allows to achieve pulsed release of the factors upon irradiation with a near-infrared laser. The use of collagen enables slow, continuous release via diffusion. The efficacy is evaluated by measuring compound muscle action potentials (CMAP) in the gastrocnemius muscle and analyzing the nerve histology. Continuous release of the factors from collagen results in enhanced CMAP amplitude and increased axon counts in the distal nerve relative to the plain conduit. In contrast, pulsed release of the same factors from PCM shows a markedly adverse impact on the efficacy, possibly by inhibiting axon growth.

Fabrication of 3D-Printed Fish-Gelatin-Based Polymer Hydrogel Patches for Local Delivery of PEGylated Liposomal Doxorubicin

3D printing technology has been applied to various fields and its medical applications are expanding. Here, we fabricated implantable 3D bio-printed hydrogel patches containing a nanomedicine as a future tailored cancer treatment. The patches were prepared using a semi-solid extrusion-type 3D bioprinter, a hydrogel-based printer ink, and UV-LED exposure. We focused on the composition of the printer ink and semi-synthesized fish gelatin methacryloyl (F-GelMA), derived from cold fish gelatin, as the main component. The low viscosity of F-GelMA due to its low melting point was remarkably improved by the addition of carboxymethyl cellulose sodium (CMC), a pharmaceutical excipient. PEGylated liposomal doxorubicin (DOX), as a model nanomedicine, was incorporated into the hydrogel and liposome stability after photo-polymerization was evaluated. The addition of CMC inhibited particle size increase. Three types of 3D-designed patches (cylinder, torus, gridlines) were produced using a 3D bioprinter. Drug release was dependent on the shape of the 3D-printed patches and UV-LED exposure time. The current study provides useful information for the preparation of 3D printed nanomedicine-based objects.

Superparamagnetic Iron Oxide Nanoparticles Modified with Silica Layers as Potential Agents for Lung Cancer Treatment

Superparamagnetic iron oxide nanoparticles (SPIONs) are promising drug delivery carriers and hyperthermia agents for the treatment of cancer. However, to ensure their safety in vivo, SPIONs must be modified in order to prevent unwanted iron release. Thus, SPIONs were coated with silica layers of different morphologies: non-porous (@SiO₂), mesoporous (@mSiO₂) or with a combination of non-porous and mesoporous layers (@SiO₂@mSiO₂) deposited via a sol-gel method. The presence of SiO₂ drastically changed the surface properties of the nanoparticles. The zeta potential changed from 19.6 ± 0.8 mV for SPIONs to -26.1 ± 0.1 mV for SPION@mSiO₂. The Brunauer-Emmett-Teller (BET) surface area increased from 7.54 ± 0.02 m²/g for SPIONs to 101.3 ± 2.8 m²/g for SPION@mSiO₂. All types of coatings significantly decreased iron release (at least 10 fold as compared to unmodified SPIONs). SPIONs and SPION@mSiO₂ were tested in vitro in contact with human lung epithelial cells (A549 and BEAS-2B). Both nanoparticle types were cytocompatible, although some delay in proliferation was observed for BEAS-2B cells as compared to A549 cells, which was correlated with increased cell velocity and nanoparticles uptake.

Robustness of Controlled Release Tablets Based on a Cross-linked Pregelatinized Potato Starch Matrix

The aim of this study was to evaluate the potential of a cross-linked pregelatinized potato starch (PREGEFLO® PI10) as matrix former for controlled release tablets. Different types of tablets loaded with diprophylline, diltiazem HCl or theophylline were prepared by direct compression of binary drug/polymer blends. The drug content was varied from 20 to 50%. Two hydroxypropyl methylcellulose grades (HPMC K100LV and K100M) were studied as alternative matrix formers. Drug release was measured in a variety of release media using different types of experimental set-ups. This includes 0.1 N HCl, phosphate buffer pH 6.8 and water, optionally containing different amounts of NaCl, sucrose, ethanol or pancreatin, fasted state simulated gastric fluid, fed state simulated gastric fluid, fasted state simulated intestinal fluid, fed state simulated intestinal fluid as well as media simulating the conditions in the colon of healthy subjects and patients suffering from Crohn's disease. The USP apparatuses I/II/III were used under a range of operating conditions and optionally coupled with the simulation of additional mechanical stress. Importantly, the drug release kinetics was not substantially affected by the investigated environmental conditions from tablets based on the cross-linked pregelatinized potato starch, similar to HPMC tablets. However, in contrast to the latter, the starch-based tablets roughly kept their shape upon exposure to the release media (they "only" increased in size) during the observation period, and the water penetration into the systems was much less pronounced. Thus, the investigated cross-linked pregelatinized potato starch offers an interesting potential as matrix former in controlled release tablets.

Locally Controlled Release of Methotrexate and Alendronate by Thermo-Sensitive Hydrogels for Synergistic Inhibition of Osteosarcoma Progression

Osteosarcoma (OS) is a serious primary bone malignant tumor that can easily affect children and adolescents. Chemotherapy is one of the important and feasible clinical treatment strategies for the treatment of OS at present, which is severely limited due to insufficient retention time, poor penetration ability, and serious side effects of current anti-tumor drug preparations. In this work, a novel injectable thermo-sensitive hydrogel (mPEG₄₅-PLV₁₉) loaded with methotrexate and alendronate, and the sustained release at the tumor site synergistically inhibited the progression of OS. The mPEG₄₅-PLV₁₉ shows excellent physical and chemical properties. Compared with other treatment groups, the in vivo treatment of gel+ methotrexate + alendronate effectively inhibited the growth of tumor. More importantly, it significantly reduced bone destruction and lung metastasis caused by OS. Therefore, this injectable thermo-sensitive hydrogel drug delivery system has broad prospects for OS chemotherapy.

Pulsatile Drug Delivery System Triggered by Acoustic Radiation Force

Since biological systems exhibit a circadian rhythm (24-hour cycle), they are susceptible to the timing of drug administration. Indeed, several disorders require a therapy that synchronizes with the onset of symptoms. A targeted therapy with spatially and temporally precise controlled drug release can guarantee a considerable gain in terms of efficacy and safety of the treatment compared to traditional pharmacological methods, especially for chronotherapeutic disorders. This paper presents a proof of concept of an innovative pulsatile drug delivery system remotely triggered by the acoustic radiation force of ultrasound. The device consists of a case, in which a drug-loaded gel can be embedded, and a sliding top that can be moved on demand by the application of an acoustic stimulus, thus enabling drug release. Results demonstrate for the first time that ultrasound acoustic radiation force (up to 0.1 N) can be used for an efficient pulsatile drug delivery (up to 20 μg of drug released for each shot).

Triple Functional AB2 Unit-Modulated Facile Preparation of Bioreducible Hyperbranched Copolymers

Facile preparation of hyperbranched polymers (HPs) has been advanced tremendously by the use of either various multifunctional agent-mediated controlled living radical polymerizations or a highly reactive AB_x unit-modulated self-stepwise polymerizations. However, it remains, to our knowledge, a significant challenge to prepare HPs with simultaneously precisely controlled degree of branching (DB) and biorelevant signal-triggered degradation property for controlled release applications due to the respective limitations of the aforementioned two strategies. For this purpose, a triple functional AB₂ unit, A-SS-B₂ chain transfer agent (AB₂ CTA), that integrates the merits of both multifunctional agents and highly reactive AB_x units was designed and synthesized successfully to include a disulfide bond for reduction-triggered polymer degradation toward promoted intracellular release of encapsulated cargoes, a trithiocarbonate group for a universal reversible addition-fragmentation chain transfer (RAFT) polymerization of any vinyl-based monomer, and three terminal groups consisting of one azide and two alkyne functions for the generation of hyperbranched topology via a self-click coupling-based polymerization. A subsequent self-click polymerization of the resulting AB₂ CTA by click coupling in the presence of CuSO₄·5H₂O and sodium ascorbate (NaVc) generated a hyperbranched polymer template (HPT) with precisely modulated DB and a plurality of CTA units for a universal reversible addition-fragmentation chain transfer (RAFT) polymerization of any vinyl-containing monomer. The HPT was next used as a multimacro-CTA for RAFT polymerization of a typical hydrophilic monomer, oligo(ethylene glycol) monomethyl ether methacrylate (OEGMA), to demonstrate the potential of this HPT for a robust and facile production of bioreducible hyperbranched polymers for controlled release applications. The synthesized HPT-4-POEGMA can form unimolecular micelles with enhanced stability due to the hyperbranched structure, and the size of micelles varied in the range from 82.4 to 140.3 nm by a modulation of the molar feed ratio of monomer to HPT and polymerization time. More importantly, HPT-POEGMA micelles incubated with 10 mM glutathione (GSH) showed reduction-triggered cleavage of the disulfide links and polymer degradation for promoted intracellular doxorubicin (DOX) release and enhanced therapeutic efficiency. Taken together, this triple functional AB₂ CTA provided a powerful means for the facile preparation of bioreducible hyperbranched polymers with precisely controlled DB for controlled release applications.

Influence of the Surface Functionalization on the Fate and Performance of Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles have been broadly applied as drug delivery systems owing to their exquisite features, such as excellent textural properties or biocompatibility. However, there are various biological barriers that prevent their proper translation into the clinic, including: (1) lack of selectivity toward tumor tissues, (2) lack of selectivity for tumoral cells and (3) endosomal sequestration of the particles upon internalization. In addition, their open porous structure may lead to premature drug release, consequently affecting healthy tissues and decreasing the efficacy of the treatment. First, this review will provide a comprehensive and systematic overview of the different approximations that have been implemented into mesoporous silica nanoparticles to overcome each of such biological barriers. Afterward, the potential premature and non-specific drug release from these mesoporous nanocarriers will be addressed by introducing the concept of stimuli-responsive gatekeepers, which endow the particles with on-demand and localized drug delivery.

Polymer nanoparticle-assisted chemotherapy of pancreatic cancer

Pancreatic cancer is a lethal disease characterized by highly dense stroma fibrosis. Only 15-20% of patients with pancreatic cancer have resectable tumors, and only around 20% of them survive to 5 years. Traditional cancer treatments have little effect on their prognosis, and successful surgical resection combined with effective perioperative therapy is the main method for maximizing long-term survival. For this reason, chemotherapy is an adjunct treatment for resectable cancer and is the main therapy for incurable pancreatic cancer, including metastatic pancreatic adenocarcinoma. However, there are various side effects of chemotherapeutic medicine and low drug penetration because the complex tumor microenvironment limits the application of chemotherapy. As a novel strategy, polymer nanoparticles make it possible to target the tumor microenvironment, release cytotoxic agents through various responsive reactions, and thus overcome the treatment barrier. As drug carriers, polymer nanoparticles show marked advantages, such as increased drug delivery and efficiency, controlled drug release, decreased side effects, prolonged half-life, and evasion of immunogenic blockade. In this review, we discuss the factors that cause chemotherapy obstacles in pancreatic cancer, and introduce the application of polymer nanoparticles to treat pancreatic cancer.

Nanotechnology and Microtechnology in Drug Delivery Systems

A special issue of the journal Dose-Response entitled “Nanotechnology and Microtechnology in Drug Delivery Systems” is proposed. In pharmaceutical studies, new and existing drugs continue to be investigated for their poor specificity, solubility, therapeutic index, and immunogenicity. In order to solve these problems, drug delivery systems are essential for controlled drug release. It has been shown that the size and shape (nano- or micro-) of drug carriers can affect a drug’s circulation time, distribution, and cellular uptake. Hence, it is not surprising that nanotechnology and microtechnology have been explored as powerful tools for drug delivery in past decades. The main topics will be related to the technologies including microtechnology for the sustained release of drug, nanotechnology for the targeting delivery of drugs, new polymer materials nanotechnology, nanotechnology in drugs combination application, and so on.

Retinal Cell Protection in Ocular Excitotoxicity Diseases. Possible Alternatives Offered by Microparticulate Drug Delivery Systems and Future Prospects

Excitotoxicity seems to play a critical role in ocular neurodegeneration. Excess-glutamate-mediated retinal ganglion cells death is the principal cause of cell loss. Uncontrolled glutamate in the synapsis has significant implications in the pathogenesis of neurodegenerative disorders. The exploitation of various approaches of controlled release systems enhances the pharmacokinetic and pharmacodynamic activity of drugs. In particular, microparticles are secure, can maintain therapeutic drug concentrations in the eye for prolonged periods, and make intimate contact by improving drug bioavailability. According to the promising results reported, possible new investigations will focus intense attention on microparticulate formulations and can be expected to open the field to new alternatives for doctors, as currently required by patients.

Bioresponsive microspheres for on-demand delivery of anti-inflammatory cytokines for articular cartilage repair

Despite innovations in surgical interventions, treatment of cartilage injury in osteoarthritic joints remains a challenge due to concomitant inflammation. Obstructing a single dominant inflammatory cytokine has shown remarkable clinical benefits in rheumatoid arthritis, and similar strategies are being suggested to target inflammatory pathways in osteoarthritis (OA). Here, we describe the utility of gelatin microspheres that are responsive to proteolytic enzymes typically expressed in arthritic flares, resulting in on-demand and spatiotemporally controlled release of anti-inflammatory cytokines for cartilage preservation and repair. These microspheres were designed with a net negative charge to sequester cationic anti-inflammatory cytokines, and the magnitude of the negative charge potential increased with an increase in crosslinking density. Collagenase-mediated degradation of the microspheres was dependent on the concentration of the enzyme. Release of anti-inflammatory cytokines from the loaded microspheres directly correlated with the degradation of the gelatin matrix. Exposure of the IL-4 and IL-13 loaded microspheres reduced the inflammation of chondrocytes up to 80%. Hence, the delivery of these microspheres in an OA joint can attenuate the stimulation of chondrocytes and the resulting secretion of catabolic factors such as proteinases and nitric oxide. The microsphere format also allows for minimally invasive delivery and is less susceptible to mechanically induced drug release. Consequently, bioresponsive microspheres can be an effective tool for cartilage preservation and arthritis treatment.

Multifunctional Nanorobot System for Active Therapeutic Delivery and Synergistic Chemo-photothermal Therapy

Nanorobots are safe and exhibit powerful functionalities, including delivery, therapy, and diagnosis. Therefore, they are in high demand for the development of new cancer therapies. Although many studies have contributed to the progressive development of the nanorobot system for anticancer drug delivery, these systems still face some critical limitations, such as potentially toxic materials in the nanorobots, unreasonable sizes for passive targeting, and the lack of several essential functions of the nanorobot for anticancer drug delivery including sensing, active targeting, controlling drug release, and sufficient drug loading capacity. Here, we developed a multifunctional nanorobot system capable of precise magnetic control, sufficient drug loading for chemotherapy, light-triggered controlled drug release, light absorption for photothermal therapy, enhanced magnetic resonance imaging, and tumor sensing. The developed nanorobot system exhibits an in vitro synergetic antitumor effect of photothermal therapy and chemotherapy and outstanding tumor-targeting efficiency in both in vitro and in vivo environments. The results of this study encourage further explorations of an efficient active drug delivery system for cancer treatment and the development of nanorobot systems for other biomedical applications.

Double-Emulsion Copolyester Microcapsules for Sustained Intraperitoneal Release of Carboplatin

Despite on-going medical advances, ovarian cancer survival rates have stagnated. In order to improve IP delivery of platinum-based antineoplastics, we aimed to develop a sustained drug delivery system for carboplatin (CPt). Toward this aim, we pursued a double emulsion process for obtaining CPt-loaded microcapsules composed of poly(ethylene terephthalate-ethylene dilinoleate) (PET-DLA) copolymer. We were able to obtain PET-DLA microspheres in the targeted size range of 10–25 µm (median: 18.5 µm), to reduce intraperitoneal clearance by phagocytosis and lymphoid transit. Empty microspheres showed the lack of toxicity in vitro. The double emulsion process yielded 2.5% w/w CPt loading and obtained microcapsules exhibited sustained (>20 day) zero-order release. The encapsulated CPt was confirmed to be bioavailable, as the microcapsules demonstrated efficacy against human ovarian adenocarcinoma (SK-OV-3) cells in vitro. Following intraperitoneal injection in mice, we did not observe adhesions, only mild, clinically-insignificant, local inflammatory response. Tissue platinum levels, monitored over 14 days using atomic absorption spectroscopy, revealed low burst and reduced systemic uptake (plasma, kidney), as compared to neat carboplatin injection. Overall, the results demonstrate the potential of the developed microencapsulation system for long-term intraperitoneal sustained release of carboplatin for the treatment of ovarian cancer.

PH-Sensitive, Polymer Functionalized, Nonporous Silica Nanoparticles for Quercetin Controlled Release

Some pH-sensitive, poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) grafted silica nanoparticles (SNPs) (SNPs-g-PDEAEMA) were designed and synthesized via surface initiated, metal-free, photoinduced atom transfer radical polymerization (ATRP). The structures of the polymers formed in solution were determined by 1H NMR. The modified nanoparticles were characterized by FT-IR spectroscopy, XPS, GPC, TEM and TGA. The analytical results show that α-bromoisobutyryl bromide (BIBB) (ATRP initiator) had been successfully anchored onto SNPs' surfaces, and was followed by surface-initiated, metal-free ATRP of 2-(diethylamino)ethyl methacrylate (DEAEMA). The resultant SNPs-g-PDEAEMA were uniform spherical nanoparticles with the particles size of about 22-25 nm, and the graft density of PDEAEMA on SNPs' surfaces obtained by TGA was 19.98 μmol/m2. Owing to the covalent grafting of pH-sensitive PDEAEMA, SNPs-g-PDEAEMA can dispersed well in acidic aqueous solution, but poorly in neutral and alkaline aqueous solutions, which is conducive to being employed as drug carriers to construct a pH-sensitive controlled drug delivery system. In vitro cytotoxicity evaluation results showed that the cytotoxicity of SNPs-g-PDEAEMA to the L929 cells had completely disappeared on the 3rd day. The loading of quercetin on SNPs-g-PDEAEMA was performed using adsorption process from ethanol solutions, and the dialysis release rate increased sharply when the pH value of phosphate-buffered saline (PBS) decreased from 7.4 to 5.5. All these results indicated that the pH-responsive microcapsules could serve as potential anti-cancer drug carriers.

Release of Antibiotics Out of a Moldable Collagen-β-Tricalciumphosphate-Composite Compared to Two Calcium Phosphate Granules

Bacterial bone infections after revision surgeries and diseases, like osteomyelitis, are still a challenge with regard to surgical treatments. Local bone infections were treated with antibiotics directly or by controlled drug-releasing scaffolds, like polymethylmethacrylate (PMMA) spheres, which have to be removed at a later stage, but there is a risk of a bacterial contamination during the removement. Therefore, biomaterials loaded with antibiotics for controlled release could be the method of choice: The biomaterials degrade during the drug release, therefore, there is no need for a second surgery to remove the drug eluting agent. Even non-resorbable bone materials are available (e.g., hydroxyapatite (HA)) or resorbable bone graft materials (e.g., beta-tricalcium phosphate (β-TCP)) that will be replaced by newly formed bone. Composite materials with organic additives (e.g., collagen) supports the handling during surgery and enhances the drug loading capacity, as well as the drug releasing time. The purpose of this study was to investigate the loading capacity and the release rate of Vancomycin and Gentamicin on TCP and HA granules in the shape of a degradable scaffold compared to composite materials from TCP mixed with porcine collagen. Its antibacterial efficacy to a more elementary drug with eluting in aqueous solution was examined. The loading capacity of the biomaterials was measured and compared according to the Minimum Inhibition Concentration (MIC) and the Minimum Biofilm Eradication Concentration (MBEC) of a bacterial biofilm after 24 h aging. Antibiotic elution and concentration of gentamycin and vancomycin, as well as inhibition zones, were measured by using the Quantitative Microparticle Systems (QMS) immunoassays. The antibiotic concentration was determined by the automated Beckman Coulter (BC) chemistry device. For examination of the antibacterial activity, inhibition zone diameters were measured. Generally, the antibiotic release is more pronounced during the first couple of days than later. Both TCP granules and HA granules experienced a significantly decline of antibiotics release during the first three days. After the fourth day and beyond, the antibiotic release was below the detection threshold. The antibiotic release of the composite material TCP and porcine collagen declined less drastically and was still in the frame of the specification during the first nine days. There was no significant evidence of interaction effect between antibiotic and material, i.e., the fitted lines for Gentamycin and Vancomycin are almost parallel. During this first in vitro study, β-TCP-Collagen composites shows a significantly higher loading capacity and a steadily release of the antibiotics Gentamycin and Vancomycin, compared to the also used TCP and HA Granules.

Nanocarriers Used Most in Drug Delivery and Drug Release: Nanohydrogel, Chitosan, Graphene, and Solid Lipid

Over the past few years, nanocarriers have become an ideal solution for safe and efficient drug delivery and release. This is mainly due to the extraordinary characteristics that nanomaterials exhibit when compared with their larger scaled forms. A variety of these carriers are more popular due to their high biocompatibility, ensuring greater efficacy especially in cancer treatments. Nanocrystal, liposomal, and micelle designs of these materials as nanocarriers for drug delivery and release have been extensively researched throughout the past 50 years. Successful applications have not only ensured a greater focus on therapeutic development but also created a new solution available in the pharmaceutical market. Herein, a brief review of research studies focused on nanocarrier materials and designs to achieve superior benefits of drugs for disease treatments is presented. Nanohydrogels, chitosan, graphene oxide, and solid lipid nanoparticle nanocarrier designs and applications are selectively given due to the great attention they have gained from being highly biocompatible and easy-to-manipulate nanocarrier options from organic and inorganic nanocarrier materials. Each summary exhibits the progress that has been achieved to date. With greater understanding of the current state in the development process of these nanomaterials, there is a rising chance to provide better treatment to patients, which is a desperate need in pharmaceutical technologies.

Traumatic Brain Injuries: Pathophysiology and Potential Therapeutic Targets

Traumatic brain injury (TBI) remains one of the leading causes of morbidity and mortality amongst civilians and military personnel globally. Despite advances in our knowledge of the complex pathophysiology of TBI, the underlying mechanisms are yet to be fully elucidated. While initial brain insult involves acute and irreversible primary damage to the parenchyma, the ensuing secondary brain injuries often progress slowly over months to years, hence providing a window for therapeutic interventions. To date, hallmark events during delayed secondary CNS damage include Wallerian degeneration of axons, mitochondrial dysfunction, excitotoxicity, oxidative stress and apoptotic cell death of neurons and glia. Extensive research has been directed to the identification of druggable targets associated with these processes. Furthermore, tremendous effort has been put forth to improve the bioavailability of therapeutics to CNS by devising strategies for efficient, specific and controlled delivery of bioactive agents to cellular targets. Here, we give an overview of the pathophysiology of TBI and the underlying molecular mechanisms, followed by an update on novel therapeutic targets and agents. Recent development of various approaches of drug delivery to the CNS is also discussed.

Nanoparticles And Human Saliva: A Step Towards Drug Delivery Systems For Dental And Craniofacial Biomaterials

Aim

The aims of this study were to investigate new nano-formulations based on ZnO and Ag nanoparticle (NP) compounds when used against clinical strains of oral gram-positive and gram-negative bacteria, and to examine the stability and behaviour of nano-formulation mixtures in saliva based on different compositions of Ag NPs, ZnO NPs and ZnO+x·Ag NPs. Methods: ZnO NPs with and without nanosilver were obtained by microwave solvothermal synthesis. Then, antibacterial activity was evaluated against bacteria isolated from human saliva. Behavior and nanoparticle solutions were evaluated in human saliva and control (artificial saliva and deionized water). Results were statistically compared.

Results

The NP mixtures had an average size of 30±3 nm, while the commercial Ag NPs had an average size of 55±5 nm. The suspensions displayed differing antibacterial activities and kinetics of destabilisation processes, depending on NPs composition and fluid types.

Conclusion

The present study showed that all NPs suspensions displayed significant destabilisation and high destabilisation over the 24 h of the analyses. The agglomeration processes of NPs in human saliva can be reversible.

A Direct Compression Matrix Made from Xanthan Gum and Low Molecular Weight Chitosan Designed to Improve Compressibility in Controlled Release Tablets

The subject of our research is the optimization of direct compression (DC), controlled release drug matrices comprising chitosan/xanthan gum. The foregoing is considered from two main perspectives; the use of low molecular weight chitosan (LCS) with xanthan gum (XG) and the determination of important attributes for direct compression of the mixtures of the two polymers. Powder flow, deformation behaviour, and work of compression parameters were used to characterize powder and tableting properties. Compression pressure and LCS content within the matrix were investigated for their influence on the crushing strength of the tablets produced. Response surface methodology (RSM) was applied to determine the optimum parameters required for DC of the matrices investigated. Results confirm the positive contribution of LCS in enhancing powder compressibility and crushing strength of the resultant compacts. Compactibility of the XG/LCS mixtures was found to be more sensitive to applied compression pressure than LCS content. LCS can be added at concentrations as low as 15% w/w to achieve hard compacts, as indicated by the RSM results. The introduction of the plasticity factor, using LCS, to the fragmenting material XG was the main reason for the high volume reduction and reduced porosity of the polymer mixture. Combinations of XG with other commonly utilized polymers in controlled release studies such as glucosamine, hydroxypropyl methylcellulose (HPMC), Na alginate (ALG), guar gum, lactose and high molecular weight (HMW) chitosan were also used; all the foregoing polymers failed to reduce the matrix porosity beyond a certain compression pressure. Application of the LCS/XG mixture, at its optimum composition, for the controlled release of two model drugs (metoprolol succinate and dyphylline) was examined. The XG/LCS matrix at 15% w/w LCS content was found to control the release of metoprolol succinate and dyphylline. The former preparation confirmed the strong influence of compression pressure on changing the drug release profile. The latter preparation showed the ability of XG/LCS to extend the drug release at a fixed rate for 12 h of dissolution time after which the release became slightly slower.

Ultrasound controlled paclitaxel releasing system-A novel method for improving the availability of coronary artery drug coated balloon

OBJECTIVES

The aim of this study is to improve local-drug delivery efficiency and tissue absorption using the ultrasound (US)-responsible drug coating based on a newly developed US-controlled paclitaxel release balloon.

BACKGROUND

Low availability of the drug coating remains a major concern of the current drug coated balloon (DCB). The goal of this study is to develop a method to use an US-responsible paclitaxel-loaded microcapsules (PM) as the main content of balloon drug coating to enhance bioavailability of DCB.

METHODS

An US-controlled paclitaxel release balloon is designed and fabricated based on the US-responsible paclitaxel-loaded poly (lactic-co-glycolic acid) (PLGA) microcapsules. Rapid exchange percutaneous transluminal coronary angioplasty (PTCA) balloon catheters were coated with the PM. The deployment processes of the paclitaxel-loaded microcapsules coated balloons (PMCB) under US, PMCB without US and a homogenous matrix of paclitaxel and iopromide coated balloon (PICB) were then placed in healthy and stent implanted porcine coronary arteries.

RESULTS

In vitro release assay demonstrated an ability of US (1 MHz, 1.22 W/cm² , 1 minute) to affect the release kinetics of paclitaxel from PM by inducing a 76 ± 5.4% increase in the rate of release. The paclitaxel content in target vessels are 203 ± 37 μg/g for PMCB under US, 85 ± 23 μg/g for PMCB without US, and 107 ± 31 μg/g for PICB 1-hr post-surgery. The availability of the drug for the PMCB reaches 27% under US.

CONCLUSIONS

The US-controlled paclitaxel release balloon significantly improved the drug content of the target vessels in the porcine model.

Bubble-Manipulated Local Drug Release from a Smart Thermosensitive Cerasome for Dual-Mode Imaging Guided Tumor Chemo-Photothermal Therapy

Thermosensitive liposomes have demonstrated great potential for tumor-specific chemotherapy. Near infrared (NIR) dyes loaded liposomes have also shown improved photothermal effect in cancer theranostics. However, the instability of liposomes often causes premature release of drugs or dyes, impeding their antitumor efficacy. Herein, we fabricated a highly stable thermo-responsive bubble-generating liposomal nanohybrid cerasome with a silicate framework, combined with a NIR dye to achieve NIR light stimulated, tumor-specific, chemo-photothermal synergistic therapy. Methods: In this system, NIR dye of 1,1'-Dioctadecyl-3,3,3',3'- Tetramethylindotricarbocyanine iodide (DiR) with long carbon chains was self-assembled with a cerasome-forming lipid (CFL) to encapsulate ammonium bicarbonate (ABC), which was further used for actively loading doxorubicin (DOX), affording a thermosensitive and photosensitive DOX-DiR@cerasome (ABC). Results: The resulting cerasome could disperse well in different media. Upon NIR light mediated thermal effect, ABC was decomposed to generate CO2 bubbles, resulting in a permeable channel in the cerasome bilayer that significantly enhanced DOX release. After intravenous injection into tumor-bearing mice, DOX-DiR@cerasome (ABC) could be efficiently accumulated at the tumor tissue, as monitored by DiR fluorescence, lasting for more than 5 days. NIR light irradiation was then performed at 36h to locally heat the tumors, resulting in immediate CO2 bubble generation, which could be clearly detected by ultrasound imaging, facilitating the monitoring process of controlled release of the drug. Significant antitumor efficacy could be obtained for the DOX-DiR@cerasome (ABC) + laser group, which was further confirmed by tumor tissue histological analysis.

Design of Zein Conjugation and Surface Modification for Targeting Drug Delivery

Various strategies for the use of zein for controlled drug release have been investigated and reported in the literature, especially engineering strategies for using zein conjugates to enhance oral bioavailability and targeted delivery, which has attracted interest in recent research. Although still limited, the ability to fabricate self-assembling nanoparticles loaded with molecules of interest offering functional groups for potential conjugation could yield zein-based conjugates with promise as materials for drug delivery. In the current review, recent studies on zein-based conjugates with outstanding features are discussed based on the various types of conjugation. The key physicochemical characterization methods for the chemical conjugation and identification of zein are also summarized. Further opportunities to develop zein-based materials through conjugation will provide promising alternative formulations for a number of drug candidates.

Host-Guest Polypyrrole Nanocomplex for Three-Stimuli-Responsive Drug Delivery and Imaging-Guided Chemo-Photothermal Synergetic Therapy of Refractory Thyroid Cancer

Despite the good prognosis of the low-risk thyroid cancer, there are no truly effective treatments for radioactive iodine-refractory thyroid cancer. Herein, a novel theranostic nanoplatform, as well as a smart doxorubucin (DOX) delivery system is fabricated. Gelatin-stabilized polypyrrole nanoparticles are reported for the first time. The combination of gelatin-stabilized polypyrrole and cyclodextrin-DOX complexes enabling three-stimuli-controlled drug delivery, including the enzyme-sensitive, pH-sensitive and photothermal-sensitive drug release, exhibiting a new way to equip photothermal agents with precisely controlled drug delivery. Anti-galectin-3 antibodies are utilized as the targeting molecules of nanoparticles in the first time, which surprisingly increase intracellular DOX uptake by enhanced clathrin-mediated endocytosis, showing galectin-3 can be employed as a highly efficient target of drug delivery systems. The nanoparticles achieve excellent photoacoustic imaging effect, enabled chemo-photothermal combined therapy with pinpointed drug delivery. Compared to free DOX, these multifunctional nanoparticles decrease the heart damage, but greatly increase the tumor/heart ratio of DOX concentration by 12.9-fold. The tumors are completely eradicated without any recurrence after the in vivo combined therapy. To the best of the authors' knowledge, this is also the first report to apply photoacoustic imaging-guided chemo-photothermal therapy for thyroid cancer, showing great potential to solve the dilemma in thyroid cancer therapy.

X-ray-Controlled Bilayer Permeability of Bionic Nanocapsules Stabilized by Nucleobase Pairing Interactions for Pulsatile Drug Delivery

The targeted and sustained drug release from stimuli-responsive nanodelivery systems is limited by the irreversible and uncontrolled disruption of the currently used nanostructures. Bionic nanocapsules are designed by cross-linking polythymine and photoisomerized polyazobenzene (PETAzo) with adenine-modified ZnS (ZnS-A) nanoparticles (NPs) via nucleobase pairing. The ZnS-A NPs convert X-rays into UV radiation that isomerizes the azobenzene groups, which allows controlled diffusion of the active payloads across the bilayer membranes. In addition, the nucleobase pairing interactions between PETAzo and ZnS-A prevent drug leakage during their in vivo circulation, which not only enhances tumor accumulation but also maintains stability. These nanocapsules with tunable permeability show prolonged retention, remotely controlled drug release, enhanced targeted accumulation, and effective antitumor effects, indicating their potential as an anticancer drug delivery system.

Self-Assembly of DNA-Minocycline Complexes by Metal Ions with Controlled Drug Release

Here we reported a study of metal ions-assisted assembly of DNA-minocycline (MC) complexes and their potential application for controlling MC release. In the presence of divalent cations of magnesium or calcium ions (M²⁺), MC, a zwitterionic tetracycline analogue, was found to bind to phosphate groups of nucleic acids via an electrostatic bridge of phosphate (DNA)-M²⁺-MC. We investigated multiple parameters for affecting the formation of DNA-Mg²⁺-MC complex, including metal ion concentrations, base composition, DNA length, and single- versus double-stranded DNA. For different nitrogen bases, single-stranded poly(A)₂₀ and poly(T)₂₀ showed a higher MC entrapment efficiency of DNA-Mg²⁺-MC complex than poly(C)₂₀ and poly(G)₂₀. Single-stranded DNA was also found to form a more stable DNA-Mg²⁺-MC complex than double-stranded DNA. Between different divalent metal ions, we observed that the formation of DNA-Ca²⁺-MC complex was more stable and efficient than the formation of DNA-Mg²⁺-MC complex. Toward drug release, we used agarose gel to encapsulate DNA-Mg²⁺-MC complexes and monitored MC release. Some DNA-Mg²⁺-MC complexes could prolong MC release from agarose gel to more than 10 days as compared with the quick release of free MC from agarose gel in less than 1 day. The released MC from DNA-Mg²⁺-MC complexes retained the anti-inflammatory bioactivity to inhibit nitric oxide production from pro-inflammatory macrophages. The reported study of metal ion-assisted DNA-MC assembly not only increased our understanding of biochemical interactions between tetracycline molecules and nucleic acids but also contributed to the development of a highly tunable drug delivery system to mediate MC release for clinical applications.

Gel network comprising UV crosslinked PLGA-b-PEG-MA nanoparticles for ibuprofen topical delivery

Ibuprofen is a non-steroidal anti-inflammatory drug for the treatment of Rheumatoid Arthritis and osteoarthritis. In this study, we prepared topical gel network for enhancement of ibuprofen penetration, maintenance of controlled release and increased patient compliance. Nanoparticles containing ibuprofen were prepared by means of emulsion formation/solvent diffusion method using synthesized copolymer. Nanoparticles were then conjugated with aminoethylmethacrylate, resulting in ibuprofen-loaded nanoparticles in PLGA-b-PEG-MA structure. Ibuprofen-loaded gel networks were developed by crosslinking nanoparticles via UV exposure. Suitability for topical application has been assessed through characterization of particle size, zeta potential, morphology, encapsulation efficiency, in vitro release, cytotoxicity and enhancement of in vitro wound healing. The mean diameter of nanoparticles was measured as 230 ± 20 nm. Gel network formulations with higher particle size (2800 ± 350 nm) and zeta potential (39.8 ± 9.2 mV), depending on conjugation of methacrylate within copolymeric structure, and having encapsulation efficacy of 73.6 ± 2.8% were prepared. The in vitro release of ibuprofen was sustained for more than 7 hours. Gel network improved collagen synthesis, type I collagen mRNA expression and fibrosis in dose dependent manner. Based on this, we can conclude that PLGA-b-PEG gel network might be a promising systems for the local delivery of ibuprofen in RA patients.

Emerging frontiers in drug release control by core-shell nanofibers: a review

In recent years, core-shell (CS) nanofiber has widely been used as a carrier for controlled drug release. This outstanding attention toward CS nanofiber is mainly due to its tremendous significance in controllable drug release in specific locations. The major advantage of CS nanofibers is forming a highly porous mesh, boosting its performance for many applications, due to its large surface-to-volume ratio. This inherently high ratio has prompted electrospun fibers to be considered one of the best drug-delivery-systems available, with the capacity to enhance properties such as cell attachment, drug loading, and mass transfer. Using electrospun fibers as CS nanofibers to incorporate different cargos such as antibiotics, anticancer agents, proteins, DNA, RNA, living cells, and diverse growth factors would considerably satisfy the need for a universal carrier in the field of nanotechnology. In addition to their high surface area, other benefit included in these nanofibers is the ability to trap drugs, easily controlled morphology, and their biomimetic characteristics. In this review, by taking the best advantages of the preparation and uses of CS nanofibers, a novel work in the domain of the controlled drug delivery by nanofiber-based scaffolds is presented.

Targeted acetylcholinesterase-responsive drug carriers with long duration of drug action and reduced hepatotoxicity

PURPOSE

Acetylcholinesterase (AChE) plays a critical role in the transmission of nerve impulse at the cholinergic synapses. Design and synthesis of AChE inhibitors that increase the cholinergic transmission by blocking the degradation of acetylcholine can serve as a strategy for the treatment of AChE-associated disease. Herein, an operational targeted drug delivery platform based on AChE-responsive system has been presented by combining the unique properties of enzyme-controlled mesoporous silica nanoparticles (MSN) with clinical-used AChE inhibitor.

METHODS

Functionalized MSNs were synthesized by liquid phase method and characterized by using different analytical methods. The biocompatibility and cytotoxicity of MSNs were determined by hemolysis experiment and MTT assay, respectively. Comparison of AChE activity between drug-loading system and inhibitor was developed with kits and by ELISA method. The efficacy of drug-loaded nanocarriers was investigated in a mouse model.

RESULTS

Compared with AChE inhibitor itself, the inhibition efficiency of this drug delivery system was strongly dependent on the concentration of AChE. Only AChE with high concentration could cause the opening of pores in the MSN, leading to the controlled release of AChE inhibitor in disease condition. Critically, the drug delivery system can not only exhibit long duration of drug action on AChE inhibition but also reduce the hepatotoxicity in vivo.

CONCLUSION

In summary, AChE-responsive drug release systems have been far less explored. Our results would shed lights on the design of enzyme controlled-release multifunctional system for enzyme-associated disease treatment.

Vitamin E-Loaded PLA- and PLGA-Based Core-Shell Nanoparticles: Synthesis, Structure Optimization and Controlled Drug Release

The (±)-α-Tocopherol (TP) with vitamin E activity has been encapsulated into biocompatible poly(lactic acid) (PLA) and poly(lactide-co-glycolide) (PLGA) carriers, which results in the formation of well-defined nanosized (d ~200–220 nm) core-shell structured particles (NPs) with 15–19% of drug loading (DL%). The optimal ratios of the polymer carriers, the TP active drug as well as the applied Pluronic F127 (PLUR) non-ionic stabilizing surfactant, have been determined to obtain NPs with a TP core and a polymer shell with high encapsulation efficiency (EE%) (69%). The size and the structure of the prepared core-shell NPs as well as the interaction of the carriers and the PLUR with the TP molecules have been determined by transmission electron microscopy (TEM), dynamic light scattering (DLS), infrared spectroscopy (FT-IR) and turbidity studies, respectively. Moreover, the dissolution of the TP from the polymer NPs has been investigated by spectrophotometric measurements. It was clearly confirmed that increase in the EE% from ca. 70% (PLA/TP) to ca. 88% (PLGA65/TP) results in the controlled release of the hydrophobic TP molecules (7 h, PLA/TP: 34%; PLGA75/TP: 25%; PLGA65/TP: 18%). By replacing the PLA carrier to PLGA, ca. 15% more active substance can be encapsulated in the core (PLA/TP: 65%; PLGA65/TP: 80%).

Synthesis of Saponite Based Nanocomposites to Improve the Controlled Oral Drug Release of Model Drug Quinine Hydrochloride Dihydrate

In the present research study, a 2:1 type of smectite clay minerals, namely natural saponite (NSAP) and synthetic saponite (SSAP), was demonstrated for the first time to be controlled drug release host materials for the model drug quinine hydrochloride dihydrate (QU). The popular sol-gel hydrothermal technique was followed for the synthesis of saponite. The QU was ion exchanged and intercalated into an interlayered gallery of synthetic as well as natural saponite matrices. The developed QU-loaded hybrid composite materials along with the pristine materials were characterized by powder X-ray diffraction (PXRD), Fourier transformed infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), the Brunauer-Emmett-Teller method (BET) for surface area (SA), and scanning electron microscopy (SEM). The characterization of material results using DSC, FTIR and PXRD confirmed the presence of saponite clay mineral phases in the original and the synthesized saponite samples. Similarly, the drug-loaded composites confirmed the successful intercalation of QU drug on the natural and synthesized saponite matrices. The oral drug release performance of both nanocomposites along with pure quinine drug was monitored in sequential buffer environments at 37 ± 0.5 °C. These composite hybrid materials showed the superior controlled release of QU in gastric fluid (pH = 1.2) and intestinal fluid (pH = 7.4). QU release was best fitted in the Korsmeyer-Peppas kinetic model and demonstrated a diffusion-controlled release from nanocomposite layered materials. The observed controlled drug release results suggest that the applied natural/synthetic saponite matrices have the potential to provide critical design parameters for the development of bioengineered materials for controlled drug release.

A facile method to fabricate thermo- and pH-sensitive hydrogels with good mechanical performance based on poly(ethylene glycol) methyl ether methacrylate and acrylic acid as a potential drug carriers

A thermo- and pH-sensitive hydrogel was prepared by a facile free aqueous radical copolymerization of PEGMA and AAc without any crosslinkers for controlled drug delivery. The successful fabrication of hydrogels was confirmed by Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA) measurements. The morphological, mechanical and swelling properties of the obtained hydrogels were studied systematically. The results showed that the morphological and mechanical behaviors of the resultant hydrogels were strongly affected by the content of AAc. Moreover, the obtained hydrogels showed an excellent thermo-, pH- and salinity sensitivities. Release profiles of 5-Fu were studied at different pH (gastric pH 1.2 and intestinal pH 7.4) and temperatures (25 °C and 37 °C). The results showed that the release is very low at pH 1.2/37 °C and high at pH 7.4/25 °C. The cytotoxicity of hydrogels to cells was determined by an MTT assay. The result demonstrated that the blank hydrogels had negligible toxicity to cells, whereas the 5-Fu-loaded hydrogels remained high in cytotoxicity for LO2 and HepG-2 cells. Results of the present investigation exemplify the potential of this novel thermo- and pH-sensitive hydrogel for the controlled and targeted delivery of the anti cancer drug 5-Fu.

Synthesis of Thermosensitive Conjugated Triblock Copolymers by Sequential Click Couplings for Drug Delivery and Cell Imaging

The elegant integration of an excellent light-emitting segment and a biorelevant signal-responsive moiety could generate advanced polymeric delivery systems with simultaneously favorable diagnostic and therapeutic functions with respect to cancer theranostics. Although polymeric delivery systems based on fluorescent polyfluorene (PF) or thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) have been extensively developed, the preparation of a ternary polymer formulation composed of a PF block, a PNIPAAm sequence, and a hydrophilic moiety remains rarely explored likely because of the difficulty in integrating different synthesis strategies for polymer synthesis. To this end, herein we reported the design and controlled synthesis of a PF- and PNIPAAm-based amphiphilic triblock copolymer, PF₁₁-b-PNIPAAm₁₂₀-b-poly(oligo(ethylene glycol) monomethyl ether methacrylate)₁₇ (PF₁₁-b-PNIPAAm₁₂₀-b-POEGMA₁₇), with a well-defined structure by a strategy of sequential click couplings between Suzuki-coupling-generated PF and atom-transfer radical polymerization (ATRP)-produced PNIPAAm and POEGMA. The as-prepared triblock copolymers can self-assemble into micelles with a core-shell-corona (CSC) structure that is composed of an inner hydrophobic core of the PF moiety for fluorescent tracking and drug encapsulation, a thermosensitive middle shell of PNIPAAm block for thermomodulated drug loading and release, and a hydrophilic outer corona of the POEGMA segment for micelle stabilization. Interestingly, the doxorubicin (DOX)-loaded micelles prepared at 25 °C had a greater drug loading capacity than the analogues fabricated at 37 °C due to the better stability of the former formulation, leading to its higher in vitro cytotoxicity in HeLa cells. Together with the integration of a localized hyperthermia-triggered drug release profile and efficiently intracellular trafficking of the nanocarriers by monitoring the fluorescence of the PF moiety, this formulation demonstrates a great potential for cancer theranostics.

Sustained Local Delivery of Diclofenac from Three-Dimensional Ultrafine Fibrous Protein Scaffolds with Ultrahigh Drug Loading Capacity

The three-dimensional (3D) ultrafine fibrous scaffolds loaded with functional components can not only provide support to 3D tissue repair, but also deliver the components in-situ with small dosage and low fusion frequency. However, the conventional loading methods possess drawbacks such as low loading capacity or high burst release. In this research, an ultralow concentration phase separation (ULCPS) technique was developed to form 3D ultrafine gelatin fibers and, meanwhile, load an anti-inflammatory drug, diclofenac, with high capacities for the long-term delivery. The developed scaffolds could achieve a maximum drug loading capacity of 12 wt.% and a highest drug loading efficiency of 84% while maintaining their 3D ultrafine fibrous structure with high specific pore volumes from 227.9 to 237.19 cm3/mg. The initial release at the first hour could be reduced from 34.7% to 42.2%, and a sustained linear release profile was observed with a rate of about 1% per day in the following 30 days. The diclofenac loaded in and released from the ULCPS scaffolds could keep its therapeutic molecular structure. The cell viability has not been affected by the release of drug when the loading was less than 12 wt.%. The results proved the possibility to develop various 3D ultrafine fibrous scaffolds, which can supply functional components in-situ with a long-term.

Controlled Release Film Forming Systems in Drug Delivery: The Potential for Efficient Drug Delivery

Despite many available approaches for transdermal drug delivery, patient compliance and drug targeting at the desired concentration are still concerns for effective therapies. Precise and efficient film-forming systems provide great potential for controlling drug delivery through the skin with the combined advantages of films and hydrogels. The associated disadvantages of both systems (films and hydrogels) will be overcome in film-forming systems. Different strategies have been designed to control drug release through the skin, including changes to film-forming polymers, plasticizers, additives or even model drugs in formulations. In the current review, we aim to discuss the recent advances in film-forming systems to provide the principles and review the methods of these systems as applied to controlled drug release. Advances in the design of film-forming systems open a new generation of these systems.

Injectable calcium phosphate foams for the delivery of Pitavastatin as osteogenic and angiogenic agent

Apatitic bone cements have been used as a clinical bone substitutes and drug delivery vehicles for therapeutic agents in orthopedic applications. This has led to their combination with different drugs with known ability to foster bone formation. Recent studies have evaluated Simvastatin for its role in enhanced bone regeneration, but its lipophilicity hampers incorporation and release to and from the bone graft. In this study, injectable calcium phosphate foams (i-CPF) based on α-tricalcium phosphate were loaded for the first time with Pitavastatin. The stability of the drug in different conditions relevant to this study, the effect of the drug on the i-CPFs properties, the release profile, and the in vitro biological performance with regard to mineralization and vascularization were investigated. Pitavastatin did not cause any changes in neither the micro nor the macro structure of the i-CPFs, which retained their biomimetic features. PITA-loaded i-CPFs showed a dose-dependent drug release, with early stage release kinetics clearly affected by the evolving microstructure due to the setting of cement. in vitro studies showed dose-dependent enhancement of mineralization and vascularization. Our findings contribute towards the design of controlled release with low drug dosing bone grafts: i-CPFs loaded with PITA as osteogenic and angiogenic agent.

Nonviolent Self-Catabolic DNAzyme Nanosponges for Smart Anticancer Drug Delivery

The development of self-assembled DNA nanomedicine requires a facile and accurate DNA degradation strategy for precisely programmable drug release. Conventional DNA catabolic strategies are restrained with the fragile and unclear enzymatic reactions that might lead to inefficient and uncontrollable digestion of DNA scaffolds and thus might bring undesirable side effects to the sophisticated biosystems. Herein we reported a versatile self-sufficient DNAzyme-driven drug delivery system consisting of the rolling circle polymerized DNAzyme-substrate scaffolds and the encapsulated pH-responsive ZnO nanoparticles (NPs). The full DNAzyme nanosponges (NSs) were also encoded with multivalent tandem aptamer sequences to facilitate their efficient delivery into cancer cells, where the acidic endo/lysosomal microenvironment stimulates the dissolution of ZnO into Zn²⁺ ions as DNAzyme cofactors and therapeutic reactive oxygen species generators. The supplement Zn²⁺ cofactors mediated the nonviolent DNAzyme-catalyzed cleavage of DNA scaffolds for precise and efficient drug administrations with synergistically enhanced therapeutic performance. The facile design of DNAzyme, together with their cost-effective and intrinsic robust features, is anticipated to provide extensive insights for the development of DNA-based therapeutic platforms by activating the specific intracellular biocatalytic reactions. As an intelligent and nonviolent self-driven drug delivery platform, the present DNAzyme NS system could be engineered with more therapeutic sequences and agents and was anticipated to show exceptional promise and versatility for applications in biomedicine and bioengineering.

A Catalase-Like Metal-Organic Framework Nanohybrid for O2 -Evolving Synergistic Chemoradiotherapy

Tumor hypoxia, the "Achilles' heel" of current cancer therapies, is indispensable to drug resistance and poor therapeutic outcomes especially for radiotherapy. Here we propose an in situ catalytic oxygenation strategy in tumor using porphyrinic metal-organic framework (MOF)-gold nanoparticles (AuNPs) nanohybrid as a therapeutic platform to achieve O₂ -evolving chemoradiotherapy. The AuNPs decorated on the surface of MOF effectively stabilize the nanocomposite and serve as radiosensitizers, whereas the MOF scaffold acts as a container to encapsulate chemotherapeutic drug doxorubicin. In vitro and in vivo studies verify that the catalase-like nanohybrid significantly enhances the radiotherapy effect, alleviating tumor hypoxia and achieving synergistic anticancer efficacy. This hybrid nanomaterial remarkably suppresses the tumor growth with minimized systemic toxicity, opening new horizons for the next generation of theranostic nanomedicines.

Investigation of the Size Distribution for Diffusion-Controlled Drug Release From Drug Delivery Systems of Various Geometries

Various drug delivery systems (DDSs) are often used in modern medicine to achieve controlled and targeted drug release. Diffusional release of drugs from DDSs is often the main mechanism, especially at early times. Generally, average dimensions of DDS are used to model the drug release, but our recent work on drug release from fibers demonstrated that taking into account diameter distribution is essential. This work systematically investigated the effect of size distribution on diffusional drug release from DDSs of various geometric forms such as membranes, fibers, and spherical particles. The investigation clearly demonstrated that the size distribution has the largest effect on the drug release profiles from spherical particles compared to other geometric forms. Published experimental data for drug release from polymer microparticles and nanoparticles were fitted, and the diffusion coefficients were determined assuming reported radius distributions. Assuming the average radius when fitting the data leads to up to 5 times underestimation of the diffusion coefficient of drug in the polymer.

Multimodality imaging-guided local injection of eccentric magnetic microcapsules with electromagnetically controlled drug release

BACKGROUND

In the past decade, trackable smart drug delivery systems have played important roles in the treatment of many diseases such as cancer because the drug carriers can be visualized through their distinct physical properties. However, it is still difficult to achieve precise drug delivery because such systems usually rely on a single imaging system.

AIM

This study aimed to present a novel type of multimodality imaging-guided strategy to visualize the drug carriers of eccentric magnetic microcapsule (EMM) designed for potential treatment of hepatocellular carcinoma (HCC).

METHOD AND RESULTS

The EMMs were prepared by using a three-phase microfluidic device. The as-prepared EMMs embedded with Fe₃O₄ nanoparticles are magnetic, with high density and acoustic impedance, allowing for visualization by magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound (US) imaging during local injection. The release of drug from these EMMs can be further controlled by an external electromagnetic field (EMF). As a proof of concept, we demonstrated the process of multimodality imaging to guide local injection and the controlled release of doxorubicin (DOX) from the EMMs in a phantom. We showed that the release rate of DOX was directly correlated to the strength of the EMF. In addition, we cocultured green fluorescent protein (GFP)-transfected HeLa cancer cells with the DOX-loaded EMMs and documented their apoptosis by DOX following the release triggered by EMF.

CONCLUSION

The results suggest that these EMMs serve both as contrast agents that can be visualized by multimodality imaging techniques and as smart drug delivery systems, with great potential for precision medicine.

Design of diffusion-controlled drug delivery devices for controlled release of Paclitaxel

Controlled drug delivery devices were predicted in a reverse engineering framework for the controlled release of Paclitaxel, an anti-cancer drug, widely used in the treatment of solid tumors. Using quantitative structure-property relationship models for mutual diffusion coefficients of the drug in biocompatible and biodegradable polymers and partition coefficients of the drug between polymers and blood, a framework was developed to predict optimal drug delivery devices for desired dosage regimens. The validation of the predicted mutual diffusion and partition coefficients using experimental data was reported in previous studies. Optimal design parameters along with selection of most appropriate polymers suitable for different dosage regimens, selected based on current clinical practice, were predicted for maximum bioavailability of the drug while maintaining the released drug concentration in blood within the therapeutic range. Reservoir and monolithic type of diffusion-controlled drug delivery devices of different shapes and sizes were predicted with different initial drug loadings and bioavailability for different dosage regimens. The effects of the released Paclitaxel from these devices on the tumor growth were also modeled using a previously reported mathematical pharmacokinetic-pharmacodynamic model. The proposed approach can easily be used to design other diffusion-controlled drug delivery devices.

Conductomeric Evaluation of the Release Kinetics of Active Substances from Pharmaceutical Preparations Containing Iron Ions

The aim of this study was to verify the effect of the formulation on the release kinetics of active substances from preparations containing iron ions using in-line conductivity measurements. A simple, fast method was developed and may be applied for detailed evaluation of some kinetics factors obtained from the release data. Four different equations were used: zero-order equation, first-order equation, models: Korsmeyer–Peppas and Hixson–Crowell. Values of the determined half-time release for zero and first-order kinetic models ranged from 11.56 to 89.97 min. In the case of analysis according to these typical models, the values of the square root of the correlation coefficients were included between 0.9916 and 0.9995. The results transformed for the Hixson–Crowell model as constant release Ks, ranged between 0.0160 and 0.0437. The values of the respective calculated squares of the correlation coefficient ranged from 0.9933 to 0.9959. The determined release rate constants according to the Korsmeyer–Peppas model were between 0.0023 and 0.1630. The coefficients ‘n’ of the Korsmeyer–Peppas equation did not exceed 1.2 with the corresponding r² values 0.9408–0.9960. Obtained results confirmed that the method is applicable for evaluation of selected drug compositions containing iron ions.

Redox and pH responsive polymeric vesicles constructed from a water-soluble pillar[5]arene and a paraquat-containing block copolymer for rate-tunable controlled release

Herein, for rate-tunable controlled release, pH and redox dual responsive polymeric vesicles were constructed based on host-guest interaction between a water soluble pillar[5]arene (WP5) and a paraquat-containing block copolymer (BCP) in water. The yielding polymeric vesicles can be further applied in the controlled release of a hydrophilic model drug, doxorubicin hydrochloride (DOX). The drug release rate is regulated depending on the type of single stimulus or the combination of two stimuli. Meanwhile, DOX-loaded polymeric vesicles present anticancer activity in vitro comparable to free DOX under the studied conditions, which may be important for applications in the therapy of cancers as a controlled-release drug carrier.

Dual controlled release nanomicelle-in-nanofiber system for long-term antibacterial medical dressings

Long-term antibacterial medical dressings can prevent infection as skin wounds heal. In this study, we used the hydrophobic antibacterial drug amoxicillin as a model to prepare drug-loaded nanomicelles using a film dispersion-hydration method, and drug-loaded nanomicelles were coaxially electrospun into nanofiber to create a novel nanomicelle-in-nanofiber (NM-in-NF) drug delivery system. Scanning electron microscopy and transmission electron microscopy were used to characterize the morphology of nanomicelles and nanofibers. Thermal property of as-prepared samples was tested using differential scanning calorimetry. The drug release behavior, cytotoxicity, and antibacterial properties of NM-in-NFs were examined in vitro to evaluate the system's potential to be used in the treatment of skin wounds. Experimental results indicated that the novel NM-in-NF system had dual controlled release effect, which greatly reduced burst release and prolonged effective drug duration. Moreover, NM-in-NFs was also found to be safe and non-toxic, with a broad-spectrum antibacterial activity. It thus could potentially be used in long-term antibacterial medical dressings to treat skin wounds.

Systematic Evaluation of a Diclofenac-Loaded Carboxymethyl Cellulose-Based Wound Dressing and Its Release Performance with Changing pH and Temperature

Development of drug-loaded wound dressings is often performed without systematic consideration of the changing wound environment that can influence such materials' performance. Among the crucial changes are the wound pH and temperature, which have an immense effect on the drug release. Detailed release studies based on the consideration of these changing properties provide an important aspect of the in vitro performance testing of novel wound dressing materials. A sodium carboxymethyl cellulose-based wound dressing, with the incorporated non-steroidal anti-inflammatory drug diclofenac, was developed and characterised in regard to its physico-chemical, structural and morphological properties. Further, the influence of pH and temperature were studied on the drug release. Finally, the biocompatibility of the wound dressing towards human skin cells was tested. Incorporation of diclofenac did not alter important properties (water retention value, air permeability) of the host material. Changes in the pH and temperature were shown to influence the release performance and have to be accounted for in the evaluation of such dressings. Furthermore, the knowledge about the potential changes of these parameters in the wound bed could be used potentially to predict, and potentially even to control the drug release from the developed wound dressing. The prepared wound dressing was also proven biocompatible towards human skin cells, making it interesting for potential future use in the clinics.