High Molecular Weight Drugs Research Articles

Cryomilled electrospun nanofiber mats containing d-mannitol exhibit suitable for aerosol delivery of proteins

Dry powder inhalers (DPIs) are the first choice for inhalation drug development. However, some conventional DPI formulation processes require heating, which may damage high molecular weight drugs such as proteins and nucleic acids. In this study, we propose a novel DPI preparation process that avoids the use of heat. Dry powders were prepared by cryomilling nanofiber mats composed of polyvinyl alcohol, D(−)-mannitol (Man), and α-chymotrypsin (α-Chy) as the model drug using the electrospinning method. The addition of Man conferred high dispersibility and excellent in vitro aerosol performance to the nanofiber mat powder in a very short milling time (less than 0.5 min) as assessed using the Andersen cascade impactor. Powders were classified according to the degree of friability, and among these, nanofiber mats containing 15 % Man and milled for 0.25 min exhibited the highest aerosol performance. Nanofiber mats containing Man milled for less than 0.5 min also exhibited greater α-Chy enzymatic activity than a nebulized α-Chy solution. Furthermore, single inhalation induced no significant lung tissue damage as evidenced by lactate dehydrogenase activity assays of mouse bronchoalveolar lavage fluid. This novel DPI formulation process may facilitate the safe and efficient inhalational delivery of therapeutic proteins.

Abstract 3097: CETSA HT: Employing rapid high-throughput target engagement technology in primary screening of P53

Abstract The confirmation of target engagement for candidate drugs is a fundamental requisite in drug discovery. A significant portion of projects fail to reach the clinic due to lack of efficacy or failure to show lead candidates interacting with the intended target in a more complex environment. The utility of using the CETSA® (CEllular Thermal Shift Assay) technology to measure target engagement in intact cells is increasingly exploited in high throughput screening, where examples demonstrate low false positive rates in screens of up to 500K compounds. The p53 tumor suppressor protein, a crucial guardian against cancer, functions as a transcription factor that mediates cancer suppression by regulating genes involved in a wide range of cellular processes such as DNA repair, cell cycle and apoptosis. Unfortunately, frequent mutations in the TP53 gene hinder p53's tumor suppressor role in human cancers, thus designating it as a promising target for anticancer therapy. However, attempts to restore p53 function for therapeutic purposes have not yet advanced to clinical approval, highlighting the complexities in leveraging p53 for cancer treatment. Its undruggable nature, attributed to the absence of accessible deep pockets, lack of enzymatic activity, and its intracellular location, further complicates targeted interventions with both low and high molecular weight drugs. Here, we demonstrate the analysis of a high-throughput plate based CETSA® HT screen on the challenging target p53, performed using AlphaLISA® SureFire® Ultra™ technology and our newly developed high-throughput screening platform. Hits identified from this screen are privileged from the onset by binding to the target in a physiologically relevant cellular matrix and in a binding-mode agnostic way. This is in contrast to traditional screening methods targeting activity or in vitro interaction where cellular activity is addressed in later stages. This assay cascade highlights a rapid target-to-hit lead generation strategy placing the emphasis on finding chemical matter that interacts with endogenous target in living cells first, followed by analysis of hit material activity. The ‘shortcut’ to chemical matter active in living cells represents significant potential cost savings in comparison to assay development time on recombinantly produced proteins and/or modified cell lines for traditional HTS screening approaches that still rely on target engagement assessment downstream. Citation Format: Merve Kacal, Tomas Friman, Laurence Arnold, Victoria Brehmer, Daniel Martinez Molina, Stina Lundgren. CETSA HT: Employing rapid high-throughput target engagement technology in primary screening of P53 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3097.

Evaluation of a compounding phospholipid base for the percutaneous absorption of high molecular weight drugs using the Franz finite dose model.

Permeation-enhancing compounding bases are aimed to facilitate the penetration of the active pharmaceutical ingredients (APIs) across the skin barrier. The purpose of this study was to evaluate the percutaneous absorption of radiolabeled human insulin (14 C-isototpe) when incorporated in a proprietary phospholipid base designed to deliver APIs with high molecular weights (HMW). The aim was not to claim the transdermal delivery of insulin with potential therapeutic applications in diabetes but, instead, to evaluate the ability of the compounding phospholipid base to deliver HMW drugs. The percutaneous absorption of 14 C-insulin was determined using human torso skin and the Franz skin finite dose model. Two topical test formulations were prepared for in vitro evaluation: insulin 1% in phospholipid base (standard) and insulin 1% in phospholipid base HMW. The rate of percutaneous absorption (mean flux) and the distribution of 14 C-insulin through the skin were evaluated for both topical test formulations. A two-way ANOVA was used to determine statistical differences. The 14 C-insulin was distributed into the stratum corneum, epidermis and dermis. Mean flux values showed a rapid penetration upon application and the maximum flux was achieved at 30 min, followed by a slow decline. Subsequently, a slower decline was observed for the topical test formulation including the phospholipid base HMW. The phospholipid base HMW facilitates the percutaneous absorption of HMW drugs across human cadaver skin and, therefore, it may potentially be a useful option for compounding pharmacists and practitioners when considering the skin for the percutaneous delivery of large drugs.

Ionic liquid-mediated ethosome for transdermal delivery of insulin.

Herein, we report ethosome (ET) formulations composed of a safe amount of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC)-based ionic liquid with various concentrations of ethanol as a carrier for the transdermal delivery of a high molecular weight drug, insulin. The Insulin-loaded ET vesicles exhibited long-term stability compared to conventional DMPC ETs, showing significantly higher drug encapsulation efficiency and increased skin permeation ability.

New Applications of Gas Chromatography and Gas Chromatography-Mass Spectrometry for Novel Sample Matrices in the Forensic Sciences: A Literature Review

The investigation of novel sample matrices in the forensic sciences offers several possible advantages, such as allowing for results to be obtained in cases where common sample types are absent. This review focuses on the application of gas chromatography and gas chromatography–mass spectrometry (GC-MS) for the determination of drugs in alternative sample matrices, including hair, sweat, meconium, breast milk, and vitreous humour. Less common sample types are also reported including air, cerumen, insects, and their larvae and pupae. The application of pyrolysis GC-MS (Py GC-MS) is also reviewed, showing the possibility of determining high molecular weight drugs which would commonly be unattainable by GC-MS. The application of Py GC-MS for the simulation and investigation of the underlying chemistry and the products formed in the smoking of drugs is also reported.

Evaluation of Function and Features of Human Induced Pluripotent Stem Cell-Derived Small Intestinal Epithelial Cells for Analyzing Peptide Drug Intestinal Absorption Profiles

Caco-2 cell monolayers are widely employed as an in vitro model of the intestinal barrier, capable of accurately predicting the absorption of conventional small-molecule drugs. However, this model may not be applicable to all drugs, and the accuracy of absorption prediction is typically poor for high molecular weight drugs. Recently, human induced pluripotent stem (iPS) cell-derived small intestinal epithelial cells (hiPSC-SIECs), exhibiting properties similar to those of the small intestine when compared with Caco-2 cells, have been developed and are considered a novel candidate model for in vitro evaluation of intestinal drug permeability. Therefore, we evaluated the utility of human hiPSC-SIECs as a new in vitro model to predict the intestinal absorption of middle-molecular weight drugs and peptide drugs. Firstly, we showed that the hiPSC-SIEC monolayer allowed faster transport of peptide drugs (insulin and glucagon-like peptide-1) than the Caco- 2 cell monolayer. Second, we revealed that hiPSC-SIECs require divalent cations (Mg2+ and Ca2+) to maintain barrier integrity. Third, we demonstrated that experimental conditions established for Caco-2 cells are not persistently applicable to hiPSC-SICEs when analyzing absorption enhancers. Comprehensively clarifying the features of hiPSC-SICEs is essential to establish a new in vitro evaluation model.

Targeted Therapy for Glomerulonephritis Using Arterial Delivery of Encapsulated Etanercept.

Complex immunosuppressive therapy is prescribed in medical practice to patients with glomerulonephritis to help them overcome symptoms and prevent chronic renal failure. Such an approach requires long-term systemic administration of strong medications, which causes severe side effects. This work shows the efficiency of polymer capsule accumulation (2.8 ± 0.4 µm) containing labeled etanercept (100 μg per dose) in the kidneys of mice. The comparison of injection into the renal artery and tail vein shows the significant superiority of the intra-arterial administration strategy. The etanercept retention rate of 18% and 8% ID in kidneys was found 1 min and 1 h after injection, respectively. The capsules were predominantly localized in the glomeruli after injection in mice using a model of acute glomerulonephritis. Histological analysis confirmed a significant therapeutic effect only in animals with intra-arterial administration of microcapsules with etanercept. The proposed strategy combines endovascular surgery and the use of polymer microcapsules containing a high molecular weight drug that can be successfully applied to treat a wide range of kidney diseases associated with glomerular pathology.

High Molecular Weight Fucoidan Loading Into and Release from Hyaluronate‐Based Prefabricated Hydrogel and its Nanogel Particles Controlled by Variable Pitch and Differential Extensional Shear Technology of Advanced Twin Screw‐Based System

AbstractEfficient incorporation of high molecular weight drug into prefabricated hydrogel and its delivery are big challenges in its applications to drug delivery and tissue regeneration using a 3D bioprinting system. In this work, a new method of loading a model high molecular weight drug (fucoidan with 200 kDa) into prefabricated hyaluronate‐based terpolymeric gel is developed by using an advanced screw‐based extrusion printing system. This system effectively incorporates the fucoidan biomolecules into the prefabricated crosslinked gel within 60 s at significantly higher percentages without much change in gel properties. Less damage in gel network is achieved through variable pitch and differential extensional shear mechanism by optimization of bioprinting conditions. Importantly, fucoidan‐loaded nanoparticles (NPs) are developed using the advanced extrusion system at high screw rpm and with increased residence time using recirculation. The encapsulation efficiency, sustained release of fucoidan, and in vitro cell culture studies confirm the nontoxic nature of the drug‐loaded gels and nanogels at lower doses, exhibiting the biomedical application potentials of this advanced screw‐based extrusion printing system and drug‐loaded NPs formation in pharmaceuticals, 3D bioprinting, tissue engineering as well as maximal drug loading into and sustained release from prefabricated gels.

Development and In Vitro/Ex Vivo Evaluation of Lecithin-Based Deformable Transfersomes and Transfersome-Based Gels for Combined Dermal Delivery of Meloxicam and Dexamethasone.

Transfersomes (TFS) are the promising carriers for transdermal delivery of various low and high molecular weight drugs, owing to their self-regulating and self-optimizing nature. Herein, we report synthesis and characterization of TFS loaded with meloxicam (MLX), an NSAID, and dexamethasone (DEX), a steroid, for simultaneous transdermal delivery. The different formulations of TFS containing varying amounts of lecithin, Span 80, and Tween 80 (TFS-1 to TFS-6) were successfully prepared by thin-film hydration method. The size of ranged between 248 and 273 nm, zeta potential values covering from -62.6 to -69.5 mV, polydispersity index (PDI) values in between 0.329 and 0.526, and entrapment efficiency of MLX and DEX ranged between 63-96% and 48-81%, respectively. Release experiments at pH 7.4 demonstrated higher cumulative drug release attained with Tween 80 compared to Span 80-based TFS. The scanning electron microscopy (SEM) of selected formulations -1 and TFS-3 revealed spherical shape of vesicles. Furthermore, three optimized transfersomal formulations (based on entrapment efficiency, TFS-1, TFS-3, and TFS-5) were incorporated into carbopol-940 gels coded as TF-G1, TF-G3, and TF-G5. These transfersomal gels were subjected to pH, spreadability, viscosity, homogeneity, skin irritation, in vitro drug release, and ex vivo skin permeation studies, and the results were compared with plain (nontransfersomal) gel having MLX and DEX. TFS released 71.72% to 81.87% MLX in 12 h; whereas, DEX release was quantified as 74.72% to 83.72% in same time. Nevertheless, TF-based gels showed slower drug release; 51.54% to 59.60% for MLX and 48.98% to 61.23% for DEX. The TF-G systems showed 85.87% permeation of MLX (TF-G1), 68.15% (TF-G3), and 68.94% (TF-G5); whereas, 78.59%, 70.54%, and 75.97% of DEX was permeated by TF-G1, TF-G3, and TF-G5, respectively. Kinetic modeling of release and permeation data indicated to follow Korsmeyer-Peppas model showing diffusion diffusion-based drug moment. Conversely, plain gel influx was found mere 26.18% and 22.94% for MLX and DEX, respectively. These results suggest that TF-G loaded with MLX and DEX can be proposed as an alternate drug carriers for improved transdermal flux that will certainly increase therapeutic outcomes.

Mechanistic Modelling of Targeted Pulmonary Delivery of Dactinomycin Iron Oxide Loaded Nanoparticles for Lung Cancer Therapy

With the increase in respiratory conditions including lung cancer post covid-19 pandemic, drug-loaded nanoparticulate dry powder inhalers (DPIs) can facilitate targeted lung delivery as a patient-friendly, non-invasive method. The aim of this work was to synthesise and optimise iron oxide nanoparticles (IONPs) containing dactinomycin as a model drug, using Quality by Design (QbD) principles. Chitosan and sodium alginate were investigated as polymeric coatings. The mass median aerodynamic diameter (MMAD), fine particle fraction (FPF), burst-effect (BE), entrapment-efficiency (EE) and the emitted-dose (ED) were investigated in initial screening studies and outcomes used to set up a Design of Experiments (DoE). Results revealed that chitosan IONPs were superior to that of sodium alginate in delivering DPI with optimal properties [ED (89.9%), FPF (59.7%), MMAD (1.59 µm) and BE (12.7%)]. Design space for targeted IONPs included formulations containing 2.1-2.5% dactinomycin and 0.5–0.9% chitosan. Differential scanning calorimetry and X-ray diffraction and SEM-EDS analysis revealed effective formation of IONPs, and TEM images revealed the production of spherical IONPs with particle size of 4.4 ± 0.77 nm. This work overcame the light sensitivity of dactinomycin to potentially target the high molecular weight drugs to the lungs, with controlled delivery based on a reduced burst effect.

Transferrin-modified chitosan nanoparticles for targeted nose-to-brain delivery of proteins

Nose-to-brain delivery presents a promising alternative route compared to classical blood–brain barrier passage, especially for the delivery of high molecular weight drugs. In general, macromolecules are rapidly degraded in physiological environment. Therefore, nanoparticulate systems can be used to protect biomolecules from premature degradation. Furthermore, targeting ligands on the surface of nanoparticles are able to improve bioavailability by enhancing cellular uptake due to specific binding and longer residence time. In this work, transferrin-decorated chitosan nanoparticles are used to evaluate the passage of a model protein through the nasal epithelial barrier in vitro. It was demonstrated that strain-promoted azide–alkyne cycloaddition reaction can be utilized to attach a functional group to both transferrin and chitosan enabling a rapid covalent surface-conjugation under mild reaction conditions after chitosan nanoparticle preparation. The intactness of transferrin and its binding efficiency were confirmed via SDS-PAGE and SPR measurements. Resulting transferrin-decorated nanoparticles exhibited a size of about 110–150 nm with a positive surface potential. Nanoparticles with the highest amount of surface bound targeting ligand also displayed the highest cellular uptake into a human nasal epithelial cell line (RPMI 2650). In an air–liquid interface co-culture model with glioblastoma cells (U87), transferrin-decorated nanoparticles showed a faster passage through the epithelial cell layer as well as increased cellular uptake into glioblastoma cells. These findings demonstrate the beneficial characteristics of a specific targeting ligand. With this chemical and technological formulation concept, a variety of targeting ligands can be attached to the surface after nanoparticle formation while maintaining cargo integrity.Graphical abstract

Autonomous Untethered Microinjectors for Gastrointestinal Delivery of Insulin.

The delivery of macromolecular drugs via the gastrointestinal (GI) tract is challenging as these drugs display low stability as well as poor absorption across the intestinal epithelium. While permeation-enhancing drug delivery methods can increase the bioavailability of low molecular weight drugs, the effective delivery of high molecular weight drugs across the tight epithelial cell junctions remains a formidable challenge. Here, we describe autonomous microinjectors that are deployed in the GI tract, then efficiently penetrate the GI mucosa to deliver a macromolecular drug, insulin, to the systemic circulation. We performed in vitro studies to characterize insulin release and assess the penetration capability of microinjectors and we measured the in vivo release of insulin in live rats. We found that the microinjectors administered within the luminal GI tract could deliver insulin transmucosally to the systemic circulation at levels similar to those with intravenously administered insulin. Due to their small size, tunability in sizing and dosing, wafer-scale fabrication, and parallel, autonomous operation, we anticipate that these microinjectors will significantly advance drug delivery across the GI tract mucosa to the systemic circulation in a safe manner.

Intestinal Absorption Study: Challenges and Absorption Enhancement Strategies in Improving Oral Drug Delivery.

The oral route is the most common and practical means of drug administration, particularly from a patient’s perspective. However, the pharmacokinetic profile of oral drugs depends on the rate of drug absorption through the intestinal wall before entering the systemic circulation. However, the enteric epithelium represents one of the major limiting steps for drug absorption, due to the presence of efflux transporters on the intestinal membrane, mucous layer, enzymatic degradation, and the existence of tight junctions along the intestinal linings. These challenges are more noticeable for hydrophilic drugs, high molecular weight drugs, and drugs that are substrates of the efflux transporters. Another challenge faced by oral drug delivery is the presence of first-pass hepatic metabolism that can result in reduced drug bioavailability. Over the years, a wide range of compounds have been investigated for their permeation-enhancing effect in order to circumvent these challenges. There is also a growing interest in developing nanocarrier-based formulation strategies to enhance the drug absorption. Therefore, this review aims to provide an overview of the challenges faced by oral drug delivery and selected strategies to enhance the oral drug absorption, including the application of absorption enhancers and nanocarrier-based formulations based on in vitro, in vivo, and in situ studies.

35 years of discussions with Prof. Maeda on the EPR effect and future directions

In May 2021, 35 years after first announcing the enhanced permeability and retention (EPR) effect, Dr. Maeda passed away. As a theoretical pillar of high molecular weight drug delivery systems (DDS) with high biocompatibility, the EPR effect has been proven worldwide in experimental mouse models. However, in clinical solid tumors, awareness of the EPR effect is insufficient, and more importantly, DDS has not become the mainstream cancer treatment. Both Dr. Maeda and I were acutely aware of this, and for 35 years, we discussed what to do about it and strived to make up for the inadequacies of the EPR effect by employing different strategies. Dr. Maeda came up with ways to use tumor vascular permeability more effectively and to apply oxidative stress to tumor cells. I proposed cancer stromal targeting (CAST) therapy using the anti-insoluble fibrin antibody conjugated with an anticancer agent in order to overcome the insufficiency of the EPR effect in clinical solid cancers, which possess abundant stromal tissue. Clinical cancers are surrounded by an abundant stroma and survive even under hypoxia and malnutrition due to this stromal barrier. Cancer cells become resistant to any external attack, including with anticancer drugs and radiation. While it goes without saying that EPR effects are important in clinical solid cancer strategies, DDSs that offer both accumulation and even distribution in solid cancers are also required.

Transfersomes: An Innovative Vesicular Carrier for Boosted Transdermal Delivery System

One may find difficulties with oral and parenteral drug delivery systems in a routine of clinical practice because they do not have sufficient compliance and bioavailability for patients. So, nowadays transdermal route is a greater area of interest of pharmaceutical research for delivering drug. But skin is the most challenging area to cross in transdermal delivery of drug as the stratum corneum & the outer layer of the skin have tight intracellular junctions. Researchers have developed various approaches like micro needle, sonophoresis, electrophoresis, and iontophoresis etc to overcome those complications for the transdermal delivery of drugs. Chemical permeation enhancers are needed in vesicular drug delivery system such as niosomes, liposomes, elastic liposomes (transfersomes and ethosomes) to improve their penetration property. Transferosomes can be prepared by a number of methods like vortexing, sonication method, freeze–thaw method, ethanol injection method, Reverse-phase evaporation method, etc. Transfersomes can carry wide ranges of drugs having a wide range of solubility within it as they are constructed of hydrophobic as well as hydrophilic moieties. The main property of transferosome is deformability. This flexible nature of the vesicle membrane helps transfersome to go across the narrow pores with a maximum amount of drugs present within it. They have high deformable capacity which exhibits advanced penetration capability of intact vesicles. Both high and low molecular weight drugs like albumin, insulin, corticosteroids, sex hormones, anesthetic, anticancer, analgesic can be fused within transfersome.

Factors influencing the swelling behaviour of polymethyl vinyl ether-co-maleic acid hydrogels crosslinked by polyethylene glycol

In past decades, polyethylene glycol (PEG) crosslinked polymethyl vinyl ether-co-maleic acid (PMVE/MA) hydrogel systems have been studied for various biomedical applications, mainly in the field of drug delivery. Nevertheless, successful delivery of clinically relevant dosage, especially high molecular weight drugs is still a major hindrance for this hydrogel system which delays its progress into clinical trials. Since the swelling property of this hydrogel plays a crucial role in its effectiveness as a drug delivery vehicle, we have investigated the influence of environmental factors such as pH, crosslinking temperature and swelling medium on their swelling pattern. Besides, we have also performed a comparison study on the effect of widely used foaming agents (NaHCO3 and Na2CO3) in the swelling kinetics and network properties of PEG crosslinked PMVE/MA hydrogels. The % swelling at 24 h for hydrogels with Na2CO3 was 3463%, significantly higher than hydrogels with NaHCO3 (1212%), suggesting the former as a better alternative for the delivery of macromolecular drugs. Besides, a slight increase in formulation pH and a decrease in the crosslinking temperature by 10 °C resulted in a significantly higher Seq% for the hydrogels. We also reported that the hydrogel exhibit significantly enhanced swelling characteristics in neutral and alkaline conditions compared to the acidic medium. These findings suggest that environmental factors such as pH and temperature and chemical factors such as the type of foaming agents strongly affect the swelling and network characteristics of PEG crosslinked PMVE/MA hydrogels. Therefore, these factors can be customised accordingly to regulate the release of therapeutics from PMVE/MA hydrogels as well as widen its application in biomedicine.

Mimicking the Gastrointestinal Mucus Barrier: Laboratory-Based Approaches to Facilitate an Enhanced Understanding of Mucus Permeation.

The gastrointestinal mucus layer plays a significant role in maintaining gut homeostasis and health, offering protective capacities against the absorption of harmful pathogens as well as commensal gut bacteria and buffering stomach acid to protect the underlying epithelium. Despite this, the mucus barrier is often overlooked during preclinical pharmaceutical development and may pose a significant absorption barrier to high molecular weight or lipophilic drug species. The complex chemical and physical nature of the dynamic mucus layer has proven problematic to reliably replicate in a laboratory setting, leading to the development of multiple mucus models with varying complexity and predictive capacity. This, coupled with the wide range of analysis methods available, has led to a plethora of possible approaches to quantifying mucus permeation; however, the field remains significantly under-represented in biomedical research. For this reason, the development of a concise collation of the available approaches to mucus permeation is essential. In this review, we explore widely utilized mucus mimics ranging in complexity from simple mucin solutions to native mucus preparations for their predictive capacity in mucus permeation analysis. Furthermore, we highlight the diverse range of laboratory-based models available for the analysis of mucus interaction and permeability with a specific focus on in vitro, ex vivo, and in situ models. Finally, we highlight the predictive capacity of these models in correlation with in vivo pharmacokinetic data. This review provides a comprehensive and critical overview of the available technologies to analyze mucus permeation, facilitating the efficient selection of appropriate tools for further advancement in oral drug delivery.

Dissolving Microneedles Developed in Association with Nanosystems: A Scoping Review on the Quality Parameters of These Emerging Systems for Drug or Protein Transdermal Delivery.

The largest organ of the body provides the main challenge for the transdermal delivery of lipophilic or high molecular weight drugs. To cross the main barrier of the skin, the stratum corneum, many techniques have been developed and improved. In the last 20 years, the association of microneedles with nanostructured systems has gained prominence for its versatility and for enabling targeted drug delivery. Currently, the combination of these mechanisms is pointed to as an emerging technology; however, some gaps need to be answered to transcend the development of these devices from the laboratory scale to the pharmaceutical market. It is known that the lack of regulatory guidelines for quality control is a hindrance to market conquest. In this context, this study undertakes a scoping review of original papers concerning methods applied to evaluate both the quality and drug/protein delivery of dissolving and hydrogel-forming microneedles developed in association with nanostructured systems.

Injectable and In Situ Gelling Dextran Derivatives Containing Hydrolyzable Groups for the Delivery of Large Molecules.

Recently, we reported the synthesis and characterization of a new dextran derivative obtained by grafting polyethylene glycol methacrylate to a polysaccharide backbone through a carbonate bond. This moiety was introduced because it allows for the fabrication, through a photo-induced crosslinking reaction, of biodegradable hydrogels particularly suitable for the release of high molecular weight molecules. Here, we investigate the influence of the oxyethylene chain length and the molecular weight of the starting dextran on the main properties of the polymeric solutions as well as those of the corresponding hydrogels. All synthesized polymeric derivatives were characterized by FTIR, NMR, and rheological analyses. The photo-crosslinking reaction of the polymers allowed us to obtain biodegradable networks tested for their mechanical properties, swelling, and degradation behavior. The results showed that both the oxyethylene chain length as well as the molecular weight of the starting dextran influenced swelling and degradation of the hydrogel network. As a consequence, the different behaviors in terms of swelling and degradability were able to affect the release of a large model molecule over time, making these matrices suitable candidates for the delivery of high molecular weight drug substances.

Chitosan-Based Glycolipid Conjugated siRNA Delivery System for Improving Radiosensitivity of Laryngocarcinoma.

Glucose Transporter-1 (GLUT-1) is considered to be a possible intrinsic marker of hypoxia in malignant tumors, which is an important factor in radioresistance of laryngocarcinoma. We speculated that the inhibition of GLUT-1 expression might improve the radiosensitivity of laryngocarcinoma. GLUT-1 siRNA was designed to inhibit the GLUT-1 expression, but the high molecular weight and difficult drug delivery limited the application. Herein, we constructed a glycolipid polymer chitosan oligosaccharide grafted stearic acid (CSSA) to conjugate siRNA via electrostatic interaction. The characteristics of CSSA and CSSA/siRNA were studied, as well as the radiosensitization effect of siRNA on human laryngocarcinoma epithelial (Hep-2) cells. Compared with the traditional commercial vector LipofectamineTM2000 (Lipo), CSSA exhibited lower cytotoxicity, more efficiently cellular uptake. Incubating with CSSA/siRNA, the survival rates of Hep-2 cells were significantly decreased comparing with either the group before transfection or Lipo/siRNA. CSSA is a promising carrier for efficient siRNA delivery and radiosensitization of laryngocarcinoma.