Evaluation of drug delivery characteristics of microspheres of PMMA-PCL-cholesterol obtained by supercritical-CO2 impregnation and by dissolution-evaporation techniques

Preparation of PMMA-Based Temperature/pH Responsive Nanoparticles Encapsulating 5-Fluorouracil and Methotrexate In Situ by One-Pot Dispersion Photopolymerization

In order to achieve long-term and controllable release of anti-tumor drugs at specific sites, temperature/pH responsive nanoparticles encapsulating 5-fluorouracil and methotrexate in situ are prepared through dispersion photopolymerization under green LED irradiation. The physicochemical properties of nanoparticles are characterized by scanning electron microscopy, Fourier transform infrared, dynamic light scattering, thermogravimetric/differential scanning calorimetry, and X-ray diffraction. In vitro drug release at different temperatures and pH values is examined to ascertain the release pattern of two drugs, which can be well described by Korsmeyer-Peppas kinetic model. The cytotoxicity evaluation illustrates that the tumor cells could be more effectively killed by the drug-loaded nanoparticles, and the improved therapeutic effect is attributed to the controllable and sustainable drug release as well as the enhanced cellular uptake. The blood safety and good biocompatibility of nanoparticles are further confirmed by hemolysis assay, indicating the prepared nanoparticles are potential candidates for effective tumor treatment.

Controlled Release of Flurbiprofen from 3D-Printed and Supercritical Carbon Dioxide Processed Methacrylate-Based Polymer

The ability to engineer and predict drug release behavior during treatment is critical to the design and implementation of effective drug delivery systems. In this study, a drug delivery system consisting of a methacrylate-based polymer and flurbiprofen was studied, and its release profile in a controlled phosphate-buffered saline solution was characterized. The polymer, which was 3D printed and processed in supercritical carbon dioxide under different temperature and pressure settings, showed sustained drug release over a prolonged period. A computer algorithm was used to determine the drug release time duration before reaching steady state and the maximum drug release at steady state. Several empirical models were applied to fit the release kinetic data to gain information about the drug release mechanism. The diffusion coefficients for each system were also estimated using Fick's law. Based on the results, the influence of supercritical carbon dioxide processing conditions on the diffusion behavior is interpreted, providing insights into the effective and tunable design of drug delivery systems for targeted treatment specifications.

Supercritical Fluid Technologies for the Incorporation of Synthetic and Natural Active Compounds into Materials for Drug Formulation and Delivery

Various active compounds isolated from natural sources exhibit remarkable benefits, making them attractive for pharmaceutical and biomedical applications, such as antioxidant, antimicrobial, and anti-inflammatory activities, which contribute to the treatment of cardiovascular diseases, neurodegenerative disorders, various types of cancer, diabetes, and obesity. However, their major drawbacks are their reactivity, instability, relatively poor water solubility, and consequently low bioavailability. Synthetic drugs often face similar challenges associated with inadequate solubility or burst release in gastrointestinal media, despite being otherwise a safe and effective option for the treatment of numerous diseases. Therefore, drug-eluting pharmaceutical formulations have been of great importance over the years in efforts to improve the bioavailability of active compounds by increasing their solubility and achieving their controlled release in body media. This review highlights the success of the fabrication of micro- and nanoformulations using environmentally friendly supercritical fluid technologies for the processing and incorporation of active compounds. Several novel approaches, namely micronization to produce micro- and nano-sized particles, supercritical drying to produce aerogels, supercritical foaming, and supercritical solvent impregnation, are described in detail, along with the currently available drug delivery data for these formulations.

Nanoparticle Properties Influence Transendothelial Migration of Monocytes

Nanoparticle-based delivery of therapeutics to the brain has had limited clinical impact due to challenges crossing the blood-brain barrier (BBB). Certain cells, such as monocytes, possess the ability to migrate across the BBB, making them attractive candidates for cell-based brain delivery strategies. In this work, we explore nanoparticle design parameters that impact both monocyte association and monocyte-mediated BBB transport. We use electrohydrodynamic jetting to prepare nanoparticles of varying sizes, compositions, and elasticity to address their impact on uptake by THP-1 monocytes and permeation across the BBB. An in vitro human BBB model is developed using human cerebral microvascular endothelial cells (hCMEC/D3) for the assessment of migration. We compare monocyte uptake of both polymeric and synthetic protein nanoparticles (SPNPs) of various sizes, as well as their effect on cell migration. SPNPs (human serum albumin/HSA or human transferrin/TF) are shown to promote increased monocyte-mediated transport across the BBB over polymeric nanoparticles. TF SPNPs (200 nm) associate readily, with an average uptake of 138 particles/cell. Nanoparticle loading is shown to influence the migration of THP-1 monocytes. The migration of monocytes loaded with 200 nm TF and 200 nm HSA SPNPs was 2.3-fold and 2.1-fold higher than that of an untreated control. RNA-seq analysis after TF SPNP treatment suggests that the upregulation of several migration genes may be implicated in increased monocyte migration (ex. integrin subunits α M and α L). Integrin β 2 chain combines with either integrin subunit α M chain or integrin subunit α L chain to form macrophage antigen 1 and lymphocyte function-associated antigen 1 integrins. Both products play a pivotal role in the transendothelial migration cascade. Our findings highlight the potential of SPNPs as drug and/or gene delivery platforms for monocyte-mediated BBB transport, especially where conventional polymer nanoparticles are ineffective or otherwise not desirable.

Smart pH-Responsive Polyaniline-Coated Hollow Polymethylmethacrylate Microspheres: A Potential pH Neutralizer for Water Purification Systems

Smart materials with potential pH controllability are gaining widespread concern due to their versatile applicability in water purification systems. A study presented here demonstrates a successful synthesis of smart pH-responsive polyaniline (PANI)-coated hollow polymethylmethacrylate microspheres (PHPMs) using a combination of solvent evaporation and in situ coating techniques. The material was characterized by using conventional techniques. Images recorded by an optical microscope displayed clear evidence in support of the coating, which was further supported by the SEM images. Surface roughness due to the coating was distinct in the SEM images. The PANI coating has enabled the microsphere to effectively neutralize the pH of water in water purification systems, which is very important in tackling the excessive acidic or basic problem of water resources. This study introduces a simple, facile, and cost-effective synthetic route to develop polyaniline-coated hollow polymethylmethacrylate microspheres with high performance as a pH-responsive material for water purification. The low density of the material and relatively large surface area compared to conventionally used chemicals further enhance the application prospect of the material.

New Insight into the Mechanism of Drug Release from Poly(d,l-lactide) Film by Electron Paramagnetic Resonance

A novel approach based on convolution of the electron paramagnetic resonance (EPR) spectra was used for quantitative study of the release kinetics of paramagnetic dopants from poly(d,l-lactide) films. A non-monotonic dependence of the release rate on time was reliably recorded. The release regularities were compared with the dynamics of polymer structure changes determined by EPR, SEM, and optic microscopy. The data obtained allow for the conclusion that the main factor governing dopant release is the formation of pores connected with the surface. In contrast, the contribution of the dopant diffusion through the polymer matrix is negligible. The dopant release can be divided into two phases: release through surface pores, which are partially closed with time, and release through pores initially formed inside the polymer matrix due to autocatalytic hydrolysis of the polymer and gradually connected to the surface of the sample. For some time, these processes co-occur. The mathematical model of the release kinetics based on pore formation is presented, describing the kinetics of release of various dopants from the polymer films of different thicknesses.

Using Supercritical Fluid Technology as a Green Alternative During the Preparation of Drug Delivery Systems

Micro- and nano-carrier formulations have been developed as drug delivery systems for active pharmaceutical ingredients (APIs) that suffer from poor physico-chemical, pharmacokinetic, and pharmacodynamic properties. Encapsulating the APIs in such systems can help improve their stability by protecting them from harsh conditions such as light, oxygen, temperature, pH, enzymes, and others. Consequently, the API's dissolution rate and bioavailability are tremendously improved. Conventional techniques used in the production of these drug carrier formulations have several drawbacks, including thermal and chemical stability of the APIs, excessive use of organic solvents, high residual solvent levels, difficult particle size control and distributions, drug loading-related challenges, and time and energy consumption. This review illustrates how supercritical fluid (SCF) technologies can be superior in controlling the morphology of API particles and in the production of drug carriers due to SCF's non-toxic, inert, economical, and environmentally friendly properties. The SCF's advantages, benefits, and various preparation methods are discussed. Drug carrier formulations discussed in this review include microparticles, nanoparticles, polymeric membranes, aerogels, microporous foams, solid lipid nanoparticles, and liposomes.

Targeted delivery of poly (methyl methacrylate) particles in colon cancer cells selectively attenuates cancer cell proliferation

Poly (methyl methacrylate) (PMMA) is basically biocompatible polyester with high resistance to chemical hydrolysis, and high drug permeability and the most important characteristics of PMMA is that it does not produce any toxicity. There is not much information about PMMA action on the colon cancer cells. In the present study, we have synthesized PMMA nanoparticles. The distribution pattern of PMMA particles was analysed by Zeta sizer and the size of the particles was calculated by using quasi elastic light scattering (QELS). The surface structure and the morphology of PMMA were characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM), respectively. We have also analysed their effects on cancerous cells (human colorectal carcinoma cells, HCT-116) and normal, healthy cells (human embryonic kidney cells, HEK-293) by using morphometric, MTT, DAPI and wound healing methods. We report that PMMA particles inhibited the cancer cell viability in a dose-dependent manner. The lower dose (1.0 μg/ml) showed a moderate decrease in cancer cell viability, whereas higher dosages (2.5 μg/ml, 5.0 μg/mL and 7.5 μg/mL) showed steadily decrease in the cancer cell viability. We also report that PMMA is highly selective to cancerous cells (HCT-116), as we did not find any action on the normal healthy cells (HEK-293). In conclusion, our results suggest PMMA particles are potential biomaterials to be used in the treatment of colon cancer.

Curcuminoid-loaded poly(methyl methacrylate) nanoparticles for cancer therapy

Curcuminoids (Curs), oleoresins from Curcuma longa L., have known anticarcinogenic and anti-inflammatory properties, but high toxicity, poor aqueous solubility and susceptibility to degradation in body fluids are deterrents to their clinical administration. Poly(methyl methacrylate) nanoparticles (PMMA-NPs) are biocompatible and resilient and can entrap hydrophobic drugs. The present investigation is related to solubilizing Curs by incorporating them in these nanoparticles (NPs) and is related to a study comparing the anticarcinogenic effect of drug-loaded NPs with free Cur using lung cancer (A549) cell line. Freshly extracted oleoresins were post loaded in PMMA-NPs prepared using emulsion polymerization. The presence of the three components of oleoresins was confirmed by thin-layer chromatography. The size and morphology of void and loaded NPs were determined by dynamic light scattering, scanning electron microscopy and transmission electron microscopy. The NPs were spherical with diameters of 192.66±5 nm (void) and 199.16±5 nm (loaded). Drug loading and encapsulation efficiency were 6% and 93%, respectively. From the Fourier transform infrared spectroscopy spectra, the characteristic absorption vibration of poly(methyl methacrylate) and the bands at 1,383, 1,233 and 962 cm^-1 for Cur moiety were observed. Drug release up to 10 days was estimated in buffer, saline and serum. The highest release of ~55% in ~3 days was noted in buffer that exhibited the highest bioavailability. The in vitro anticancer activity of loaded drug was evaluated up to 72 hours by MTT assay using A549 cell line. Cellular uptake of dye-loaded NPs was visualized within 30 minutes of incubation. The results revealed that the dose- and time-dependent cell death in case of loaded PMMA-NPs was comparable to that of free Cur. According to the study, the drug-loaded PMMA-NPs appear to be highly suitable for effective, localized and safe chemotherapy.

Environmental Scanning Electron Microscope Imaging of Vesicle Systems

The structural characteristics of liposomes have been widely investigated and there is certainly a strong understanding of their morphological characteristics. Imaging of these systems, using techniques such as freeze-fracturing methods, transmission electron microscopy, and cryo-electron imaging, has allowed us to appreciate their bilayer structures and factors which can influence this. However, there are few methods which all us to study these systems in their natural hydrated state; commonly the liposomes are visualized after drying, staining, and/or fixation of the vesicles. Environmental Scanning Electron Microscopy (ESEM) offers the ability to image a liposome in its hydrated state without the need for prior sample preparation. Within our studies we were the first to use ESEM to study liposomes and niosomes and we have been able to dynamically follow the hydration of lipid films and changes in liposome suspensions as water condenses on to, or evaporates from, the sample in real time. This provides insight into the resistance of liposomes to coalescence during dehydration, thereby providing an alternative assay of liposome formulation and stability.

Supercritical Fluid Technology: An Emphasis on Drug Delivery and Related Biomedical Applications

During the past few decades, supercritical fluid (SCF) has emerged as an effective alternative for many traditional pharmaceutical manufacturing processes. Operating active pharmaceutical ingredients (APIs) alone or in combination with various biodegradable polymeric carriers in high-pressure conditions provides enhanced features with respect to their physical properties such as bioavailability enhancement, is of relevance to the application of SCF in the pharmaceutical industry. Herein, recent advances in drug delivery systems manufactured using the SCF technology are reviewed. We provide a brief description of the history, principle, and various preparation methods involved in the SCF technology. Next, we aim to give a brief overview, which provides an emphasis and discussion of recent reports using supercritical carbon dioxide (SC-CO2 ) for fabrication of polymeric carriers, for applications in areas related to drug delivery, tissue engineering, bio-imaging, and other biomedical applications. We finally summarize with perspectives.

Chitosan impregnation with biologically active tryaryl imidazoles in supercritical carbon dioxide

The presented paper is focused on impregnation of chitosan and its derivatives with a biologically active triaryl imidazole model compound ((2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole) in the supercritical carbon dioxide medium. Since initial chitosan represents a polycation-exchange resin and does not swell in supercritical carbon dioxide, the impregnation was carried out in the presence of water (0.15-3.0 vol%). The maximum 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole concentration in a chitosan film was achieved at the ~5 × 10(-3) g/cm(3) water content in the reactor. We also used hydroxy carboxylic acid derivatives of chitosan and its copolymer with polylactide as matrices for introduction of hydrophobic 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole. We have shown that unmodified chitosan contains the greatest amount of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole, as compared with its hydrophobic derivatives. The kinetics of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole diffusion from a chitosan matrix was studied in acidified water with pH 1.6. We found that the complete release of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole into the aqueous phase from unmodified chitosan films occurred in 48 h, while its complete release from chitosan modified with hydroxy carboxylic acids occurred in 5 min or less.

Drug-eluting biodegradable ureteral stent: New approach for urothelial tumors of upper urinary tract cancer

Upper urinary tract urothelial carcinoma (UTUC) accounts for 5-10% of urothelial carcinomas and is a disease that has not been widely studied as carcinoma of the bladder. To avoid the problems of conventional therapies, such as the need for frequent drug instillation due to poor drug retention, we developed a biodegradable ureteral stent (BUS) impregnated by supercritical fluid CO₂ (scCO₂) with the most commonly used anti-cancer drugs, namely paclitaxel, epirubicin, doxorubicin, and gemcitabine. The release kinetics of anti-cancer therapeutics from drug-eluting stents was measured in artificial urine solution (AUS). The in vitro release showed a faster release in the first 72h for the four anti-cancer drugs, after this time a plateau was achieved and finally the stent degraded after 9days. Regarding the amount of impregnated drugs by scCO₂, gemcitabine showed the highest amount of loading (19.57μg _drug/mg _polymer: 2% loaded), while the lowest amount was obtained for paclitaxel (0.067μg _drug/mg _polymer: 0.01% loaded). A cancer cell line (T24) was exposed to graded concentrations (0.01-2000ng/ml) of each drugs for 4 and 72h to determine the sensitivities of the cells to each drug (IC₅₀). The direct and indirect contact study of the anti-cancer biodegradable ureteral stents with the T24 and HUVEC cell lines confirmed the anti-tumoral effect of the BUS impregnated with the four anti-cancer drugs tested, reducing around 75% of the viability of the T24 cell line after 72h and demonstrating minimal cytotoxic effect on HUVECs.

Swelling of Poly(n-butyl methacrylate) Films Exposed to Supercritical Carbon Dioxide: A Comparative Study with Polystyrene

We report here the swelling and relaxation properties of confined poly(n-butyl methacrylate) (PBMA) films having thicknesses of less than 70 nm under supercritical carbon dioxide (scCO2) using the X-ray reflectivity technique. Swellability is found to be dominant in thinner films compared to thicker ones as a consequence of the confinement-induced densification of the former. Swellability is proportionately increased with the density of the film. PBMA films exhibit a more significant swelling than do PS films, and their differences become more prominent with the increase in film thickness. A comparison between the results obtained for polystyrene (PS) and PBMA ultrathin films reveals that the swellability is dependent upon the specific intermolecular interaction between CO2 and the chemical groups available in the polymers. Owing to strong Lewis acid-base interactions with scCO2 and the lower glass-transition temperature (bulk Tg ≈ 29 °C), PBMA films exhibit a greater amount of swelling than do PS films (bulk Tg ≈ 100 °C). Though they reach to the different swollen state upon exposition, identical relaxation behavior as a function of aging time is evidenced. This unprecedented behavior can be ascribed to the strong bonding between trapped CO2 and PBMA that probably impedes the release of CO2 molecules from the swollen PBMA films manifested in suppressed relaxation.

A green approach to crosslinked polymer microspheres with undoped methacrylate monomers and their potential application as dental restorative materials

Pure polymer microspheres with undoped methacrylate monomers were prepared and firstly applied as organic fillers for dental restorative materials.

Surface modified PMMA nanoparticles with tunable drug release and cellular uptake

Differentialin vitrocellular uptake efficiency of fluorophore-loaded PMMA nanoparticles, with (a) different size, and (b) different surface coating.

In vitro and in vivo evaluation of electrospun PCL/PMMA fibrous scaffolds for bone regeneration

Scaffolds were fabricated by electrospinning using polycaprolactone (PCL) blended with poly(methyl methacrylate) (PMMA) in ratios of 10/0, 7/3, 5/5 and 3/7. The PCL/PMMA ratio affected the fiber diameter, contact angle, tensile strength and biological in vitro and in vivo properties of the scaffolds, and the 7/3 ratio resulted in a higher mechanical strength than 5/5 and 3/7. In vitro cytotoxicity and proliferation of MG-63 osteoblast cells on these blended scaffolds were examined by MTT assay, and it was found that PCL/PMMA blends are suitable for osteoblast cell proliferation. Confocal images and expression of proliferating cell nuclear antigen confirmed the good proliferation and expression of cells on the 7/3 PCL/PMMA fibrous scaffolds. In vivo bone formation was examined using rat models, and bone formation was observed on the 7/3 PCL/PMMA scaffold within 2 months. In vitro and in vivo results suggest that 7/3 PCL/PMMA scaffolds can be used for bone tissue regeneration.

Polymeric nanoparticles loaded with the 3,5,3'-triiodothyroacetic acid (Triac), a thyroid hormone: factorial design, characterization, and release kinetics

This present investigation deals with the development and optimization of polymeric nanoparticle systems loaded with 3,5,3'-triiodothyroacetic acid (Triac). A 2(11-6) fractional factorial design and another 2(2) factorial design were used to study the contrasts on particle size distribution, morphology, surface charge, drug content, entrapment efficiency, and in vitro drug release profiles. The independent variables were the concentration of Triac, type and quantity of both polymer and oil, quantity of Span™ 60 and Tween® 80, volume of solvent and water, and velocity of both magnetic stirring and the transfer of the organic phase into the aqueous solution. The results of optimized formulations showed a narrow size distribution with a polydispersity index lower than 0.200. The particle sizes were on average 159.6 nm and 285.6 nm for nanospheres and nanocapsules, respectively. The zeta potential was higher than 20 mV (in module) and the entrapment efficiency was nearly 100%. A high-performance liquid chromatography method was developed, validated, and efficiently applied to Triac quantification in colloidal suspension. The main independent variables were the type and quantity of the polymer and oil. In vitro drug release profile depicted several features to sustain Triac release. Different formulations showed various release rates indicating an interaction between Triac and other formulation compounds such as polymer and/or oil quantity. Two different models were identified (biexponential and monoexponential) that allowed the control of both the release rate and Triac concentration. Thus, the prepared nanoparticles described here may be of clinical importance in delivering Triac for thyroid treatment.

Poly(methyl methacrylate) particulate carriers in drug delivery

Poly(methyl methacrylate) (PMMA) is one of the most widely explored biomedical materials because of its biocompatibility, and recent publications have shown an increasing interest in its applications as a drug carrier. PMMA-based particulate carriers (PMMA(P)) can be prepared either by polymerization methods or from pre-formed polymer-based techniques. Potential biomedical application of these particles includes their use as adjuvant for vaccines and carrier of many drugs as antibiotics and antioxidants via different routes of administration. Release of drugs from PMMA(P) occurs typically in a biphasic way with an incomplete drug release. To improve release profiles, recent strategies are focusing on increasing polymer hydrophilicity by synthesizing functionalized PMMA microspheres or by formulating PMMA composites with hydrophilic polymers. This review examines the current status of preparation techniques, drug release kinetics, biomedical applications and toxicity of these nano/micro PMMA-based particulate carriers.

Supercritical fluid-mediated methods to encapsulate drugs: recent advances and new opportunities

With the advent of the development of novel pharmaceutical products and therapies, there is a need for effective delivery of these products to patients. Dependent on whether they are small-molecular weight drugs or biologics, many new compounds may suffer from poor solubility, poor stability or require frequent administration and therefore require optimized delivery. For example, the utilization of polymorphism and the enhanced solubility in the amorphous state is being exploited to improve the dissolution of small-molecular weight poorly soluble drugs. This can be achieved by the formation of solid dispersions in water-soluble matrices. In addition, encapsulation in biodegradable polymeric materials is one potential route to reduce the frequency of administration through the formation of sustained-release formulations. This is desirable for biologics, for example, which generally require administration once or twice daily. Supercritical fluid processing can achieve both of these outcomes, and this review focuses on the use of supercritical CO2 to encapsulate active pharmaceutical ingredients to enhance solubility or achieve sustained release. Using supercritical CO2-mediated processes provides a clean and potentially solvent-free route to prepare novel drug products and is therefore an attractive alternative to conventional manufacturing technologies.

Functionalized bridged silsesquioxane-based nanostructured microspheres: ultrasound-assisted synthesis and in vitro cytotoxicity characterization

Different kinds of polymers have been employed in medicine as biomaterials for different purposes. In recent years, considerable attention has been focused on the development of new drug-delivery systems in order to increase bio-availability, sustain, localize and target drug action in the human body. The versatility of the sol-gel processing to synthesize nanostructured materials and the possibility of incorporating organic molecules into the matrix of the final hybrid material, represent a novel and attractive path to the synthesis of new functionalized hybrid biomaterials with advanced properties. In this work, acetylsalicylic acid (ASA)-functionalized hybrid microspheres based on bridged silsesquioxanes synthesized via ultrasound-assisted sol-gel processing, were characterized. An investigation concerning the cytotoxic response of these new microspheres on CHO-K1 cells was accomplished based on ISO 10993-5 standard (Biological Evaluation of Medical Devices). Microspheres incorporating ASA showed a cytotoxic effect when pure extracts of the microspheres were analyzed, however, they strongly diminished their cytotoxicity as the extracts were diluted. When a 10% concentration extract was employed, hybrid microspheres were shown to be non cytotoxic. These results are promising for considering these novel functionalized organic-inorganic microspheres as potential drug-carriers to be employed in drug delivery-related applications.

Design of submicron and nanoparticle delivery systems using supercritical carbon dioxide-mediated processes: an overview

Supercritical carbon dioxide technology is an environmentally benign technique that allows precise control of particle morphology, while minimizing organic solvent use for a wide variety of biomedical and pharmaceutical applications. Supercritical carbon dioxide processes have benefits over the conventional particle formation methods in terms of improved control, flexibility and operational ease. This article gives an insight into a variety of supercritical fluid techniques relevant to drug formulation, recent advances and novel applications in the field of controlled delivery. These new methods have been designed to alleviate the scaling-up of the traditional methods for nanoparticle formulation either in the form of polymeric scaffolds, impregnation or nanoencapsules using a simple one-step process to produce micron-size particles.