Drug delivery systems for wound healing treatment of upper airway injury.

INTRODUCTION: Endotracheal intubation is a common procedure to maintain an open airway with risks for traumatic injury. Pathological changes resulting from intubation can cause upper airway complications, including vocal fold scarring, laryngotracheal stenosis, and granulomas and present with symptoms such as dysphonia, dysphagia, and dyspnea. Current intubation-related laryngotracheal injury treatment approaches lack standardized guidelines, relying on individual clinician experience, and surgical and medical interventions have limitations and carry risks. AREAS COVERED: The clinical and preclinical therapeutics for wound healing in the upper airway are described. This review discusses the current developments on local drug delivery systems in the upper airway utilizing particle-based delivery systems, including nanoparticles and microparticles, and bulk-based delivery systems, encompassing hydrogels and polymer-based approaches. EXPERT OPINION: Complex laryngotracheal diseases pose challenges for effective treatment, struggling due to the intricate anatomy, limited access, and recurrence. Symptomatic management often requires invasive surgical procedures or medications that are unable to achieve lasting effects. Recent advances in nanotechnology and biocompatible materials provide potential solutions, enabling precise drug delivery, personalization, and extended treatment efficacy. Combining these technologies could lead to groundbreaking treatments for upper airways diseases, significantly improving patients' quality of life. Research and innovation in this field are crucial for further advancements.

The Effects of ROCK Inhibitor on Prevention of Dexamethasone-Induced Glaucoma Phenotype in Human Trabecular Meshwork Cells.

Purpose: This study investigated the effects of dexamethasone (Dex) on human trabecular meshwork (TM) cells, a model of glucocorticoid-induced glaucoma, and evaluated the impact of ripasudil (Rip) as a co-delivery or sequential dosing strategy. Methods: In vitro experiments were conducted to assess the effects of Dex and Rip on TM cells. Confocal microscopy was used to evaluate the impact of Dex and Rip on F-actin staining signals. Contractility of the TM cells upon Dex and Rip treatment mimicking co-delivery and sequential delivery was quantified using collagen gel contraction assay. Transepithelial electrical resistance (TEER) values and fluorescein isothiocyanate (FITC)-dextran permeability were also measured to assess the impact of Dex and Rip on TM cells. Results: Dex and Rip did not exhibit cytotoxicity at the maximum tested concentration (20 µM). Dex-treated TM cells exhibited higher F-actin staining signals compared to controls, which were reduced when co-treated with Rip. Rip inhibited Dex-induced collagen gel contraction activity in both co-delivery and sequential treatments. Dex resulted in increased TEER values as the dose increased, whereas TEER values were maintained when co-treated with Rip. Conclusions: Co-delivery of Rip has the potential to prevent glaucoma symptoms when patients are treated with Dex. This study highlights the importance of identifying strategies to reduce the side effects of prolonged use of glucocorticoids, such as Dex, in the treatment of various diseases. Translational Relevance: This study demonstrates the potential of co-delivering ripasudil with dexamethasone to mitigate glucocorticoid-induced ocular hypertension and a secondary glaucoma that resembles primary open-angle glaucoma, providing insights for the development of novel preventive strategies in clinical care.

Long-Term Antibody Release Polycaprolactone Capsule and the Release Kinetics in Natural and Accelerated Degradation.

Although therapy using monoclonal antibodies (mAbs) has been steadily successful over the last 20 years, the means of delivery of mAbs has not been optimized, especially for long-term delivery. Frequent injections or infusions have been the current standard of care. In this study, we have developed a long-term antibody biodegradable implant using a porous polycaprolactone (PCL) capsule. It released bevacizumab (Bev) slowly for 8 months to date. The Bev release kinetics fit a drug release model with experimental data of the diffusion coefficient and partition coefficient through the polymer capsule. Since screening drug release profiles for the long term (>6 months) is time consuming, an accelerated degradation method was used after validating the characteristics of the PCL capsule in natural and accelerated degradation conditions. The correlation of the time period between natural and accelerated degradation was determined. Overall, the study suggests that mAbs can be released from a porous PCL capsule without an effect of the polymer degradation over a long period (∼6 months) and the long-term release kinetics can be determined by the accelerated degradation within 14 days.

Repetitive drug delivery using Light-Activated liposomes for potential antimicrobial therapies.

Overuse or misuse of antibiotics and their residues in the environment results in the emergence and prevalence of drug-resistant bacteria and leads to serious health problems. Notable progress in liposome research has been made in drug delivery and several liposomal drugs have been approved for clinical use owing to its biocompatibility and improved efficacy. Recently, liposomes have been engineered further to release encapsulated drugs on the target of interest in a dose-controlled fashion in response to external stimuli such as light, pH, and heat. Among those, light-activated liposomal drug delivery gained a lot of attention because drug release at the targeted sites can be precisely controlled by varying laser/light duration, energy and beam area. We envision potential applications of the light-activated liposomal delivery systems for effective drug-resistant antimicrobial therapies. The use of light-activated liposomes will be widely spread in antimicrobial therapies if the amount of drug is precisely controlled for a prolonged time at a target location. In this review, we discussed the breadth and depth of various light-activated liposomal drug delivery technology. Emphasis was given to repetitive release mechanism and applications of light-activated liposomes because the repeatability provides stability and precise control of the drug delivery system to prevent overdose of antimicrobials and treat with minimal doses. We described limitations on translation from pre-clinical to clinical settings and strategies to overcome the limitations. Careful consideration of light-responsive materials, lipid composition, laser parameters and laser safety is important when selecting and designing the drug delivery system for successful applications.

Effect of Cholesterol on Nano-Structural Alteration of Light-Activatable Liposomes via Laser Irradiation: Small Angle Neutron Scattering Study.

Although the light-activated liposomes have been extensively studied for drug delivery applications, the fundamental mechanism of the drug release based on lipid compositions has not been fully understood. Especially, despite the extensive use of cholesterol in the lipid composition, the role of cholesterol in the light-activated drug release has not been studied. In this study, the influence of cholesterol on drug release from light-responsive drug-encapsulated liposomes after activated by near infrared (NIR) laser was investigated. We prepared methotrexate (MTX)-encapsulated DSPC liposomes consisting of 0 mol% (-Chol) or 35 mol% cholesterol (+Chol), with (+Au) or without gold nanorods (-Au) on the lipid bilayer to compare drug release, morphological changes, and nanostructures after laser irradiations. Transmission electron microscopy (TEM) and small angel neutron scattering (SANS) data revealed that only +Chol +Au liposomes showed partial aggregation of the liposomes after laser irradiation. Similar trends on the drug release and structural change were observed when the liposomes were heated to above chain-transition temperature. Overall, we have found that (1) inclusion of 35 mol% cholesterol enhanced the permeability of lipid bilayers above Tc; (2) the mechanism of laser-activated liposomal drug delivery is disrupting lipid bilayer membranes by the photothermal effect in the presence of plasmonic materials. By understanding the fundamentals of the technology, precise controlled drug release at a targeted site with great stability and repeatability is anticipated.

Repetitive drug releases from light-activatable micron-sized liposomes.

In this work, a novel light activatable micron-sized liposomal drug carrier that has a unique capability to release drug repetitively in proportion to the cycle number of short irradiation (5 s) of near-infrared (NIR) pulsed laser is reported. We synthesized methotrexate (MTX)-loaded liposomes based on a modified reverse-phase evaporation method. Gold nanorods (AuNR) were attached to the liposomal surfaces, enabling the liposomes to release drug under short NIR irradiation via the photothermal effect. The concentrations of methotrexate (MTX) released from the liposomes were 10.6, 29.8, 43.7 and 65.9 µg/mL after one, two, three or four NIR laser cycles (1.1 W at 1064 nm, 5 s per cycle), respectively. The current finding will provide possible solution to the previously reported inconsistency in drug release from light activatable liposomal drug carriers at each activation cycle. The repeatability of drug release described in this work is believed to be due to reversible nature of the liposomes. The liposomes release drug via lipid bilayer melting when irradiated by laser due to gold nanorods' plasmonic heat on the lipid bilayer surface and quickly regain their original structure once the laser source is removed. We provided evidence of the reversible liposomal structures by monitoring the change of number densities of liposomes using a microelectrode sensor with different laser irradiation durations and powers. We also assessed the micron-sized liposome with respect to long-term stability, drug encapsulation efficiency, and drug-releasing efficiency, demonstrating the possibility of utilizing these liposomes as long-term drug delivery vehicles for various drugs.

Laser-Activated Drug Implant for Controlled Release to the Posterior Segment of the Eye.

To treat chronic posterior eye diseases, frequent intravitreal injections or sustained-release drug implants are the current standard of care. Sustained-release drug implants often involve burst release of the drugs and the dosage from the implants cannot be controlled after implantation, which may lead to local side effects. The present study attempts to develop a dosage-controllable drug delivery implant that consists of a nanoporous biodegradable PLGA capsule and light-activated liposomes. Controllable drug release from the implant was achieved using a pulsed near-infrared (NIR) laser both in vitro and in vivo. The in vitro drug release kinetics from two different initial dose implants, 1000 and 500 µg, was analyzed by fitting zero-order and first-order kinetics, as well as the Korsmeyer-Peppas and Higuchi models. The 1000 and 500 µg implants fit the first-order and zero-order kinetics model, respectively, the best. The multiple drug releases in the vitreous were determined by an in vivo fluorimeter, which was consistent with the in vitro data. The dose released was also clinically relevant. Histology and optical and ultrasound imaging data showed no abnormality in the eyes received implant treatment, suggesting that the drug delivery system was safe to the retina. This on-demand dose-controllable drug delivery system could be potentially used for long-term posterior eye disease treatment to avoid frequent invasive injections.

Effect of Laser Irradiation on Reversibility and Drug Release of Light-Activatable Drug-Encapsulated Liposomes.

Although several studies have demonstrated repetitive drug release using light-activatable liposomes, inconsistent drug release at each activation limits widespread usage. Here, we report reversible plasmonic material-coated encapsulated liposomes for proportional controlled delivery of methotrexate (MTX), which is a common drug for cancer and autoimmune diseases, using repetitive laser irradiation. Our results suggest a proportional increase in total drug release after repetitive laser irradiation. We hypothesize that the drug is released via "melted" lipid bilayers when the plasmonic materials on the liposome surface are heated by laser irradiation followed by reversible formation of the liposome. To evaluate our hypothesis, the number density of liposomes after laser irradiation was measured using single-particle (liposome) collision experiments at an ultramicroelectrode. Collisional frequency data suggest that the number density of liposomes remains unaltered even after 60 s of laser irradiation at 1.1 and 1.8 W, indicating that the liposome structure is reversible. The results were further compared with gold nanorod-coated nanodroplets where drug is released via irreversible phase transition. In contrast to what was observed with the liposome particles, the number density of the nanodroplets decreased with increasing laser irradiation duration. The structure reversibility of our liposome particles may be responsible for repetitive drug release with laser heating. We also studied the temperature rise in the lipid bilayer by incorporating polymerized 10,12-pentacosadiynoic acid (PCDA) in the lipid composition. The red shift in the UV-vis spectrum due to the structural change in PCDA lipids after laser irradiation indicates a rise in temperature above 75 °C, which is also above the chain-melting temperature of the main lipid used in the liposomes. All these results indicate that drug is released from the light-activatable liposomes due to reversible nanostructural alteration in the lipid bilayer by plasmonic resonance heating. The liposomes have potential to be a drug carrier for dose-controlled repetitive drug delivery.

Effect of Surfactant-Keratin Hydrolysate Interactions on the Hydration Properties of a Stratum Corneum Substitute.

A novel stratum corneum substitute (SCS) has been developed, and the fundamental mechanism of the dehydration process has been studied using the SCS. After washing with cleansers which contain surfactants, our skin "feels" dehydrated (or hydrated). Although many studies have focused on the effect of surfactants on the regulation of the water loss by the lipid bilayers in the stratum corneum (SC) for a long timescale or at equilibrium, only few studies have focused on the acute effect of the surfactant interaction on dehydration. In addition, the interaction between the surfactant and keratin has been often underappreciated compared to lipid bilayers although keratin is the major nonaqueous component of the SC. Here, we have developed novel SCS models, nonkeratinized (lipid only) and keratinized, to study the effect of keratin hydrolysates on the dehydration rate. We have confirmed that the lipid organizational structure of the SCS was similar to that of the human SC using X-ray scattering. We have revealed that keratin hydrolysates play a significant role in the dehydration rate, accelerating the rate for the short term. We have also demonstrated that the effect of surfactants on dehydration is more pronounced for keratinized samples than that for the nonkeratinized sample. However, the dehydration rate for the nonkeratinized SCS with the surfactant became faster than the that for the keratinized SCS after the 20 min evaporation process, suggesting that the water binding sites of keratin hydrolysates slowed down evaporation, while the surfactant interacting with the lipids accelerated the water loss. Lastly, the study demonstrated that the SCS model can be a great platform to test macroscopic properties and analyze the underlying mechanism at the molecular level for various chemicals.

Size-Exclusive Nanoporous Biodegradable PLGA Capsules for Drug Delivery Implants and In Vivo Stability in the Posterior Segment.

The current standard of care for posterior segment eye diseases, such as neovascular age-related macular degeneration, diabetic macular edema, is frequent intravitreal injections or sustained-release drug implants. Intravitreal injections have a low incidence of serious complications such as retinal detachment, endophthalmitis, iatrogenic traumatic cataract, or iridocyclitis and injection-site reactions. However, there is a significant burden to the patient, the patient's family, and the health system because current intravitreal therapies require between every 4 and 12 week administration over many years. Drug implants have side effects due to the burst release of the drugs, and their release cannot be easily controlled after implantation. We have developed a size-exclusive nanoporous biodegradable PLGA capsule for dosage-controllable drug delivery implants. We have optimized the nanoporous structure by tuning the ratio between porogen and high molecular weight PLGA and tested the stability against passive leakage of the liposomal drug (1-2 µm) and the safety in vivo rabbit eyes for 6 months. Our results suggest that PLGA implants made of the nanoporous PLGA sheet can selectively release drug molecules, keeping the liposomal drug inside. In addition, the implant was biocompatible, causing no inflammation and foreign body response when implanted for 6 months. Overall, the implant shows great potential for on-demand dose-controllable drug release applications.

Light-activated doxorubicin-encapsulated perfluorocarbon nanodroplets for on-demand drug delivery in an in vitro angiogenesis model: Comparison between perfluoropentane and perfluorohexane.

Phase-transition perfluorocarbon (PFC) nanodroplets have been developed for on-demand drug delivery carriers with external triggers such as ultrasound or laser irradiation techniques. Although various perfluorocarbons, including perfluoropentane (C5F12) and perfluorohexane (C6F14), have been investigated for their theranostic use, comparison of the phase-transition efficiency, the drug delivery efficacy by light activation, and physical properties of the PFC nanodroplets have not been reported. We have synthesized gold nanorod-coated doxorubicin-encapsulated perfluorocarbon nanodroplets using perfluoropentane and perfluorohexane as light-activated on-demand drug delivery carriers, called PF5 and PF6, respectively. When gold nanorods on the perfluorocarbon nanodroplets resonate with a laser wavelength, plasmonic heat generated on the gold nanorods vaporizes the nanodroplets to gas bubbles (phase-transition), and releases the encapsulated drug from the nanodroplet core. Overall, the nanodroplet size, drug encapsulation efficiency, number density, and cytotoxicity were similar between PF5 and PF6. However, the long-term stability against passive phase-transition or coalescence in physiological conditions and the phase-transition efficiency were different from each other. PF6 was better in long-term stability but showed lower phase-transition than PF5. The lower phase-transition of PF6 might have led to lower drug delivery efficiency compared to PF5. This is probably because PF6 has higher temperature thresholds required for phase-transition due to its higher boiling point. The study demonstrated feasibility of the light-activated nanodroplets for on-demand targeted nanotherapy, which suppresses the development of angiogenesis.

Phase-Transition Temperature of Gold-Nanorod-Coated Nanodroplets to Microbubbles by Pulsed Laser.

Previously, gold-nanorod-coated perfluorocarbon nanodroplets have been developed as light-activated on-demand drug delivery carriers. When gold nanorods on the perfluorocarbon nanodroplets resonate with a laser wavelength, plasmonic heat is generated and vaporizes the nanodroplets to gas bubbles. Optimal laser parameters such as pulse duration, pulse repetition frequency, and average power are critical to effectively trigger the phase transition of nanodroplets and allow for drug release. This study focused on determining the temperature of a gold-nanorod-coated perfluorocarbon nanodroplet during phase transition to a gas bubble using a femtosecond laser. Two integrated experimental and theoretical methods were explored. First, the theoretical temperature was determined by the Arrhenius equation and the time it took for the phase transition to occur, assuming the phase-transition process followed a first-order kinetic model. The activation energy and Arrhenius constant of the phase-transition process were obtained via light transmittance through a nanodroplet suspension at different temperatures. The time required for phase transition by a femtosecond laser was measured using an optical microscope. The second approach used a classical heat diffusion model. When the pulse peak energy was considered in the model, the temperature predicted matched the experimental observation of phase-transition temperature threshold, while the total energy value failed to predict the temperature threshold. The results suggest that the phase-transition mechanism is triggered by the vaporization of the nanodroplets via photothermal heating, which is influenced by the peak energy of the laser. It also indicates that optimal laser parameters can be determined by a simple calculation using the classical heat diffusion model and peak energy to control phase transition.

Light-Activatable Theranostic Agents for Image-Monitored Controlled Drug Delivery.

A novel drug delivery vehicle using nanodroplets activated by light irradiation for drug release in a controlled manner has been developed. The drug encapsulated in the nanodroplets was released upon phase transition from a liquid droplet to microbubbles (vaporization) by plasmonic photothermal heat from gold nanorods adsorbed on the surface of the nanodroplets. The nanodroplets were stable against aggregation and dissolution at 4 °C over 3 months to date. The phase transition was quantitatively analyzed by ultrasound imaging to examine the amount of drug release noninvasively. In vitro studies showed that cell death occurred only when light irradiation was performed on the drug-encapsulated nanodroplets. Ex vivo studies demonstrated a potential application of the nanodroplets for treating posterior eye diseases. Thus, it has been demonstrated that our gold-nanorod-coated light-activatable nanodroplets can be a candidate for a controlled release and a dosage-monitored drug delivery system.

Microvessels-on-a-Chip to Assess Targeted Ultrasound-Assisted Drug Delivery.

Microbubbles have been used in ultrasound-assisted drug delivery to help target solid tumors via blood vessels in vivo; however, studies to understand the phenomena at the cellular level and to optimize parameters for ultrasound or microbubbles in vivo are challenging and expensive to perform. Here, we utilize microfluidic microvessels-on-a-chip that enable visualization of microbubble/ultrasound-dependent drug delivery to microvasculature. When exposed to pulsed ultrasound, microbubbles perfused through microvessels-on-a-chip were observed to stably oscillate. Minimal cellular damage was observed for both microbubbles and untargeted doxorubicin-encapsulating liposomes (DOX-liposomes) perfused through chip microvessels. In contrast, passive and ultrasound-assisted perfusion of integrin-targeted DOX-liposomes induced cytotoxicity, which was only significantly enhanced for ultrasound-assisted perfusion when microbubbles were coperfused. These results suggest that stably oscillating microbubbles enhance targeted DOX-liposome internalization/cytotoxicity largely by stimulating integrin receptor endocytosis. Furthermore, our study demonstrates the utility of our microvessels-on-a-chip as a screening platform for optimizing drug dosage, targeting ligands and drugs.

Effect of PEG molecular weight on stability, T2 contrast, cytotoxicity, and cellular uptake of superparamagnetic iron oxide nanoparticles (SPIONs).

Superparamagnetic iron oxide nanoparticles (SPIONs) are currently unavailable as MRI contrast agents for detecting atherosclerosis in the clinical setting because of either low signal enhancement or safety concerns. Therefore, a new generation of SPIONs with increased circulation time, enhanced image contrast, and less cytotoxicity is essential. In this study, monodisperse SPIONs were synthesized and coated with polyethylene glycol (PEG) of varying molecular weights. The resulting PEGylated SPIONs were characterized, and their interactions with vascular smooth muscle cells (VSMCs) were examined. SPIONs were tested at different concentrations (100 and 500 ppm Fe) for stability, T2 contrast, cytotoxicity, and cellular uptake to determine an optimal formulation for in vivo use. We found that at 100 ppm Fe, the PEG 2K SPIONs showed adequate stability and magnetic contrast, and exhibited the least cytotoxicity and nonspecific cellular uptake. An increase in cell viability was observed when the SPION-treated cells were washed with PBS after 1h incubation compared to 5 and 24h incubation without washing. Our investigation provides insight into the potential safe application of SPIONs in the clinic.

Adsorption of superparamagnetic iron oxide nanoparticles on silica and calcium carbonate sand.

Superparamagnetic iron oxide (SPIO) nanoparticles have the potential to be used in the characterization of porous rock formations in oil fields as a contrast agent for NMR logging because they are small enough to traverse through nanopores and enhance contrast by shortening NMR T2 relaxation time. However, successful development and application require detailed knowledge of particle stability and mobility in reservoir rocks. Because nanoparticle adsorption to sand (SiO2) and rock (often CaCO3) affects their mobility, we investigated the thermodynamic equilibrium adsorption behavior of citric acid-coated SPIO nanoparticles (CA SPIO NPs) and poly(ethylene glycol)-grafted SPIO nanoparticles (PEG SPIO NPs) on SiO2 (silica) and CaCO3 (calcium carbonate). Adsorption behavior was determined at various pH and salt conditions via chemical analysis and NMR, and the results were compared with molecular theory predictions. Most of the NPs were recovered from silica, whereas far fewer NPs were recovered from calcium carbonate because of differences in the mineral surface properties. NP adsorption increased with increasing salt concentration: this trend was qualitatively explained by molecular theory, as was the role of the PEG grafting in preventing NPs adsorption. Quantitative disagreement between the theoretical predictions and the data was due to NP aggregation, especially at high salt concentration and in the presence of calcium carbonate. Upon aggregation, NP concentrations as determined by NMR T2 were initially overestimated and subsequently corrected using the relaxation rate 1/T2, which is a function of aggregate size and fractal dimension of the aggregate. Our experimental validation of the theoretical predictions of NP adsorption to minerals in the absence of aggregation at various pH and salt conditions demonstrates that molecular theory can be used to determine interactions between NPs and relevant reservoir surfaces. Importantly, this integrated experimental and theoretical approach can be used to gain insight into NP mobility in the reservoir.