Poly(Lactic Acid)-Based Microparticles for Drug Delivery Applications: An Overview of Recent Advances

Tectorigenin: A Review of Its Sources, Pharmacology, Toxicity, and Pharmacokinetics

Tectorigenin is a well-known natural flavonoid aglycone and an active component that exists in numerous plants. Growing evidence suggests that tectorigenin has multiple pharmacological effects, such as anticancer, antidiabetic, hepatoprotective, anti-inflammatory, antioxidative, antimicrobial, cardioprotective, and neuroprotective. These pharmacological properties provide the basis for the treatment of many kinds of illnesses, including several types of cancer, diabetes, hepatic fibrosis, osteoarthritis, Alzheimer's disease, etc. The purpose of this paper is to provide a comprehensive summary and review of the sources, extraction and synthesis, pharmacological effects, toxicity, pharmacokinetics, and delivery strategy aspects of tectorigenin. Tectorigenin may exert certain cytotoxicity, which is related to the administration time and concentration. Pharmacokinetic studies have demonstrated that the main metabolic pathways in rats for tectorigenin are glucuronidation, sulfation, demethylation and methoxylation, but that it exhibits poor bioavailability. From our perspective, further research on tectorigenin should cover: exploring the pharmacological targets and mechanisms of action; finding an appropriate concentration to balance pharmacological effects and toxicity; attempting diversified delivery strategies to improve the bioavailability; and structural modification to obtain tectorigenin derivatives with higher pharmacological activity.

Oral Nanotherapeutics of Andrographolide/Carbon Monoxide Donor for Synergistically Anti-inflammatory and Pro-resolving Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology affecting the colon and rectum. Current therapeutics are focused on suppressing inflammation but are ineffective. Combining anti-inflammatory therapeutic approaches with pro-resolution might be a superior strategy for UC treatment. Andrographolide (AG), an active compound from the plant Andrographis paniculata, presented anti-inflammatory effects in various inflammatory diseases. Gaseous mediators, such as carbon monoxide (CO), have a role in inflammatory resolution. Herein, we developed a dextran-functionalized PLGA nanocarrier for efficient delivery of AG and a carbon monoxide donor (CORM-2) for synergistically anti-inflammatory/pro-resolving treatment of UC (AG/CORM-2@NP-Dex) based on PLGA with good biocompatibility, slow drug release, efficient targeting, and biodegradability. The resulting nanocarrier had a nano-scaled diameter of ∼200 nm and a spherical shape. After being coated with dextran (Dex), the resulting AG/CORM-2@NP-Dex could be efficiently internalized by Colon-26 and Raw 264.7 cells in vitro and preferentially localized to the inflamed colon with chitosan/alginate hydrogel protection by gavage. AG/CORM-2@NP-Dex performed anti-inflammatory effects by eliminating the over-production of pro-inflammatory mediator, nitric oxide (NO), and down-regulating the expression of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6), while it showed pro-resolving function by accelerating M1 to M2 macrophage conversion and up-regulating resolution-related genes (IL-10, TGF-β, and HO-1). In the colitis model, oral administration of AG/CORM-2@NP-Dex in a chitosan/alginate hydrogel also showed synergistically anti-inflammatory/pro-resolving effects, therefore relieving UC effectively. Without appreciable systemic toxicity, this bifunctional nanocarrier represents a novel therapeutic approach for UC and is expected to achieve long-term inflammatory remission.

Electrospun core-sheath PCL nanofibers loaded with nHA and simvastatin and their potential bone regeneration applications

Introduction: Drugs and biocompatible nanoparticles have raised significant potential in advancing the bone regeneration. Electrospinning technology enables the full realization of the value of drugs and nanoparticles. Methods: In this study, we have successfully fabricated core-sheath nanofibers solely composed of polycaprolactone (PCL) polymer. Simvastatin (SIM) was confined to the core of the nanofibers while nanohydroxyapatite (nHA) was loaded on the nanofiber surface. Results: All the prepared nanofibers exhibited a cylindrical micromorphology, and the core-sheath structure was exploited using a Transmission Electron Microscope. X-ray pattern results indicated that SIM was in an amorphous state within nanofibers, while Fourier Transform InfraRed spectroscopy showed excellent chemical compatibility among SIM, nHA, and PCL. The actual loading of nHA within the nanofiber was determined by a thermogravimetric test due to the high melting point of nHA. Core-sheath nanofibers could release SIM for 672 h, which was attributed to the core-sheath structure. Furthermore, nanofibers loaded with SIM or nHA had a positive impact on cell proliferation, with the core-sheath nanofibers displaying the most favorable cell proliferation behavior. Discussion: Such a synergistic facilitation strategy based on materials and nanostructure may encourage researchers to exploit new biomedical materials in future.

Thiol-Michael Addition Microparticles: Their Synthesis, Characterization, and Uptake by Macrophages

Polymeric microparticles are promising biomaterial platforms for targeting macrophages in the treatment of disease. This study investigates microparticles formed by a thiol-Michael addition step-growth polymerization reaction with tunable physiochemical properties and their uptake by macrophages. The hexafunctional thiol monomer dipentaerythritol hexa-3-mercaptopropionate (DPHMP) and tetrafunctional acrylate monomer di(trimethylolpropane) tetraacrylate (DTPTA) were reacted in a stepwise dispersion polymerization, achieving tunable monodisperse particles over a size range (1-10 μm) relevant for targeting macrophages. An off-stoichiometry thiol-acrylate reaction afforded facile secondary chemical functionalization to create particles with different chemical moieties. Uptake of the microparticles by RAW 264.7 macrophages was highly dependent on treatment time, particle size, and particle chemistry with amide, carboxyl, and thiol terminal chemistries. The amide-terminated particles were non-inflammatory, while the carboxyl- and thiol-terminated particles induced pro-inflammatory cytokine production in conjunction with particle phagocytosis. Finally, a lung-specific application was explored through time-dependent uptake of amide-terminated particles by human alveolar macrophages in vitro and mouse lungs in vivo without inducing inflammation. The findings demonstrate a promising microparticulate delivery vehicle that is cyto-compatible, is non-inflammatory, and exhibits high rates of uptake by macrophages.

The recent insight in the release of anticancer drug loaded into PLGA microspheres

Cancer is a series of diseases leading to a high rate of death worldwide. Microspheres display specific characteristics that make them appropriate for a variety of biomedical purposes such as cancer therapy. Newly, microspheres have the potentials to be used as controlled drug release carriers. Recently, PLGA-based microspheres have attracted exceptional attention relating to effective drug delivery systems (DDS) because of their distinctive properties for a simple preparation, biodegradability, and high capability of drug loading which might be increased drug delivery. In this line, the mechanisms of controlled drug release and parameters that influence the release features of loaded agents from PLGA-based microspheres should be mentioned. The current review is focused on the new development of the release features of anticancer drugs, which are loaded into PLGA-based microspheres. Consequently, future perspective and challenges of anticancer drug release from PLGA-based microspheres are mentioned concisely.

Biomedical applications of PLGA nanoparticles in nanomedicine: advances in drug delivery systems and cancer therapy

INTRODUCTION

During the last decades, the ever-increasing proportion of patients with cancer has been led to serious concerns worldwide. Therefore, the development and use of novel pharmaceuticals, like nanoparticles (NPs)-based drug delivery systems (DDSs), can be potentially effective in cancer therapy.

AREA COVERED

Poly lactic-co-glycolic acid (PLGA) NPs, as a kind of bioavailable, biocompatible, and biodegradable polymers, have approved by the Food and Drug Administration (FDA) for some biomedical and pharmaceutical applications. PLGA is comprised of lactic acid (LA) and glycolic acid (GA) and their ratio could be controlled during various syntheses and preparation approaches. LA/GA ratio determines the stability and degradation time of PLGA; lower content of GA results in fast degradation. There are several approaches for preparing PLGA NPs that can affect their various aspects, such as size, solubility, stability, drug loading, pharmacokinetics, and pharmacodynamics, and so on.

EXPERT OPINION

These NPs have indicated the controlled and sustained drug release in the cancer site and can use in passive and active (via surface modification) DDSs. This review aims to provide an overview of PLGA NPs, their preparation approach and physicochemical aspects, drug release mechanism and the cellular fate, DDSs for efficient cancer therapy, and status in the pharmaceutical industry and nanomedicine.

A New Self-Healing Degradable Copolymer Based on Polylactide and Poly(p-dioxanone)

In this paper, the copolymerization of poly (p-dioxanone) (PPDO) and polylactide (PLA) was carried out via a Diels-Alder reaction to obtain a new biodegradable copolymer with self-healing abilities. By altering the molecular weights of PPDO and PLA precursors, a series of copolymers (DA2300, DA3200, DA4700 and DA5500) with various chain segment lengths were created. After verifying the structure and molecular weight by 1H NMR, FT-IR and GPC, the crystallization behavior, self-healing properties and degradation properties of the copolymers were evaluated by DSC, POM, XRD, rheological measurements and enzymatic degradation. The results show that copolymerization based on the DA reaction effectively avoids the phase separation of PPDO and PLA. Among the products, DA4700 showed a better crystallization performance than PLA, and the half-crystallization time was 2.8 min. Compared to PPDO, the heat resistance of the DA copolymers was improved and the Tm increased from 93 °C to 103 °C. Significantly, the rheological data also confirmed that the copolymer was self-healing and showed obvious self-repairing properties after simple tempering. In addition, an enzyme degradation experiment showed that the DA copolymer can be degraded by a certain amount, with the degradation rate lying between those of PPDO and PLA.

Injectable sustained-release poly(lactic-co-glycolic acid) (PLGA) microspheres of exenatide prepared by supercritical fluid extraction of emulsion process based on a design of experiment approach

This study aimed to develop an improved sustained-release (SR) PLGA microsphere of exenatide using supercritical fluid extraction of emulsions (SFEE). As a translational research, we investigated the effect of various process parameters on the fabrication of exenatide-loaded PLGA microspheres by SFEE (ELPM_SFEE) using the Box-Behnken design (BBD), a design of experiment approach. Further, ELPM obtained under optimized conditions and satisfying all the response criteria were compared with PLGA microspheres prepared using the conventional solvent evaporation (ELPM_SE) method through various solid-state characterizations and in vitro and in vivo evaluations. The four process parameters selected as independent variables were pressure (X 1), temperature (X 2), stirring rate (X 3), and flow ratio (X 4). The effects of these independent variables on five responses, namely the particle size, its distribution (SPAN value), encapsulation efficiency (EE), initial drug burst release (IBR), and residual organic solvent, were evaluated using BBD. Based on the experimental results, a desirable range of combinations of various variables in the SFEE process was determined by graphical optimization. Solid-state characterization and in vitro evaluation revealed that ELPM_SFEE improved properties, including a smaller particle size and SPAN value, higher EE, lower IBR, and lower residual solvent. Furthermore, the pharmacokinetic and pharmacodynamic study results indicated better in vivo efficacy with desirable SR properties, including a reduction in blood glucose levels, weight gain, and food intake, for ELPM_SFEE than those generated using SE. Therefore, the potential drawback of conventional technologies such as the SE for the preparation of injectable SR PLGA microspheres could be improved by optimizing the SFEE process.

Recent advances in modified poly (lactic acid) as tissue engineering materials

As an emerging science, tissue engineering and regenerative medicine focus on developing materials to replace, restore or improve organs or tissues and enhancing the cellular capacity to proliferate, migrate and differentiate into different cell types and specific tissues. Renewable resources have been used to develop new materials, resulting in attempts to produce various environmentally friendly biomaterials. Poly (lactic acid) (PLA) is a biopolymer known to be biodegradable and it is produced from the fermentation of carbohydrates. PLA can be combined with other polymers to produce new biomaterials with suitable physicochemical properties for tissue engineering applications. Here, the advances in modified PLA as tissue engineering materials are discussed in light of its drawbacks, such as biological inertness, low cell adhesion, and low degradation rate, and the efforts conducted to address these challenges toward the design of new enhanced alternative biomaterials.

Modular microfluidics for life sciences

The advancement of microfluidics has enabled numerous discoveries and technologies in life sciences. However, due to the lack of industry standards and configurability, the design and fabrication of microfluidic devices require highly skilled technicians. The diversity of microfluidic devices discourages biologists and chemists from applying this technique in their laboratories. Modular microfluidics, which integrates the standardized microfluidic modules into a whole, complex platform, brings the capability of configurability to conventional microfluidics. The exciting features, including portability, on-site deployability, and high customization motivate us to review the state-of-the-art modular microfluidics and discuss future perspectives. In this review, we first introduce the working mechanisms of the basic microfluidic modules and evaluate their feasibility as modular microfluidic components. Next, we explain the connection approaches among these microfluidic modules, and summarize the advantages of modular microfluidics over integrated microfluidics in biological applications. Finally, we discuss the challenge and future perspectives of modular microfluidics.

H2O2-PLA-(Alg)2Ca Hydrogel Enriched in Matrigel® Promotes Diabetic Wound Healing

Hydrogel-based dressings exhibit suitable features for successful wound healing, including flexibility, high water-vapor permeability and moisture retention, and exudate absorption capacity. Moreover, enriching the hydrogel matrix with additional therapeutic components has the potential to generate synergistic results. Thus, the present study centered on diabetic wound healing using a Matrigel-enriched alginate hydrogel embedded with polylactic acid (PLA) microspheres containing hydrogen peroxide (H2O2). The synthesis and physicochemical characterization of the samples, performed to evidence their compositional and microstructural features, swelling, and oxygen-entrapping capacity, were reported. For investigating the three-fold goal of the designed dressings (i.e., releasing oxygen at the wound site and maintaining a moist environment for faster healing, ensuring the absorption of a significant amount of exudate, and providing biocompatibility), in vivo biological tests on wounds of diabetic mice were approached. Evaluating multiple aspects during the healing process, the obtained composite material proved its efficiency for wound dressing applications by accelerating wound healing and promoting angiogenesis in diabetic skin injuries.

Evaluation of the Effects of Gamma Radiation Sterilization on Rhein-Loaded Biodegradable Microparticles for the Treatment of Osteoarthritis

In previous work, we reported on the design of biodegradable rhein-loaded PLGA microparticles for the treatment of osteoarthritis. Considering that a formulation designed for intra-articular administration must meet sterility requirements to guarantee its safety, in this study the effect of gamma radiation sterilization on these microparticles was evaluated. The size, morphology, and surface characteristics of the microparticles and the encapsulation efficiency of rhein were not affected by the sterilization process. Although DSC and PXRD analyses suggested otherwise, rhein release profiles were not altered by gamma radiation. The release of rhein from the microparticles was fitted to a Gompertz model. In conclusion, the results of this study suggest that gamma radiation is a suitable method for the sterilization of rhein-loaded PLGA microparticles to enable their intra-articular administration in order to provide a therapeutic solution to patients suffering from chronic joint diseases.

Recent Advances in the Investigation of Poly(lactic acid) (PLA) Nanocomposites: Incorporation of Various Nanofillers and their Properties and Applications

Poly(lactic acid) (PLA) is considered the most promising biobased substitute for fossil-derived polymers due to its compostability, biocompatibility, renewability, and good thermomechanical properties. However, PLA suffers from several shortcomings, such as low heat distortion temperature, thermal resistance, and rate of crystallization, whereas some other specific properties, i.e., flame retardancy, anti-UV, antibacterial or barrier properties, antistatic to conductive electrical characteristics, etc., are required by different end-use sectors. The addition of different nanofillers represents an attractive way to develop and enhance the properties of neat PLA. Numerous nanofillers with different architectures and properties have been investigated, with satisfactory achievements, in the design of PLA nanocomposites. This review paper overviews the current advances in the synthetic routes of PLA nanocomposites, the imparted properties of each nano-additive, as well as the numerous applications of PLA nanocomposites in various industrial fields.

The advance anticancer role of polymeric core-shell ZnO nanoparticles containing oxaliplatin in colorectal cancer

We evaluated the activity of core-shell ZnO nanoparticles (ZnO-NPs@polymer shell) containing Oxaliplatin via polymerization through in vitro studies and in vivo mouse models of colorectal cancer. ZnO NPs were synthesized in situ when the polymerization step was completed by co-precipitation. Gadolinium coordinated-ZnONPs@polymer shell (ZnO-Gd NPs@polymer shell) was synthesized by exploiting Gd's oxophilicity (III). The biophysical properties of the NPs were studied using powder X-ray diffraction (PXRD), Fourier transforms infrared spectroscopy, Ultraviolet-visible spectroscopy (UV-Vis), field emission electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy, dynamic light scattering, and z-potential. (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) was used to determine the antiproliferative activity of ZnO-Gd-OXA. Moreover, a xenograft mouse model of colon cancer was exerted to survey its antitumor activity and effect on tumor growth. In the following, the model was also evaluated by histological staining (H-E; Hematoxylin & Eosin and trichrome staining) and gene expression analyses through the application of RT-PCR/ELISA, which included biochemical evaluation (MDA, thiols, SOD, CAT). The formation of ZnO NPs, which contained a crystallite size of 16.8 nm, was confirmed by the outcomes of the PXRD analysis. The Plate-like morphology and presence of Pt were obtained in EDX outcomes. TEM analysis displayed the attained ZnO NPs in a spherical shape and a diameter of 33 ± 8.5 nm, while the hydrodynamic sizes indicated that the particles were highly aggregated. The biological results demonstrated that ZnO-Gd-OXA inhibited tumor growth by inducing reactive oxygen species and inhibiting fibrosis, warranting further research on this novel colorectal cancer treatment agent.

Biodegradable Microcapsules of Poly(Butylene Adipate-co-Terephthalate) (PBAT) as Isocyanate Carriers and the Effect of the Process Parameters

Poly(butylene adipate-co-terephthalate) (PBAT), a biodegradable flexible, and tough polymer is herein used, for the first time, to encapsulate and protect isocyanate derivatives. Isocyanates are essential building blocks widely employed in the chemical industry for the production of high-performing materials. Microencapsulation of isocyanates eliminates the risks associated with their direct handling and protects them from moisture. In light of this, and having in mind eco-innovative products and sustainability, we present a straightforward process to encapsulate isophorone diisocyanate (IPDI) using this biodegradable polymer. Spherical and core-shell microcapsules (MCs) were produced by an emulsion system combined with the solvent evaporation method. The MCs present a regular surface, without holes or cracks, with a thin shell and high isocyanate loadings, up to 79 wt%. Additionally, the MCs showed very good isocyanate protection if not dispersed in organic or aqueous solutions. Effects of various process parameters were systematically studied, showing that a higher stirring speed (1000 rpm) and emulsifier amount (2.5 g), as well as a smaller PBAT amount (1.60 g), lead to smaller MCs and narrower size distribution.

Hybrid Systems of Nanofibers and Polymeric Nanoparticles for Biological Application and Delivery Systems

Nanomedicine is a new discipline resulting from the combination of nanotechnology and biomedicine. Nanomedicine has contributed to the development of new and improved treatments, diagnoses, and therapies. In this field, nanoparticles have notable importance due to their unique properties and characteristics, which are useful in different applications, including tissue engineering, biomarkers, and drug delivery systems. Electrospinning is a versatile technique used to produce fibrous mats. The high surface area of the electrospun mats makes them suitable for applications in fields using nanoparticles. Electrospun mats are used for tissue engineering, wound dressing, water-treatment filters, biosensors, nanocomposites, medical implants, protective clothing materials, cosmetics, and drug delivery systems. The combination of nanoparticles with nanofibers creates hybrid systems that acquire properties that differ from their components' characteristics. By utilizing nanoparticles and nanofibers composed of dissimilar polymers, the two synergize to improve the overall performance of electrospinning mats and nanoparticles. This review summarizes the hybrid systems of polymeric nanoparticles and polymeric nanofibers, critically analyzing how the combination improves the properties of the materials and contributes to the reduction of some disadvantages found in nanometric devices and systems.

Immunogenic evaluation of multi-epitope peptide-loaded PCPP microparticles as a vaccine candidate against Toxoplasma Gondii

Toxoplasmosis is a major health problem and socioeconomic burden, affecting around 30-50% of the global population. Poly(dicarboxylatophenoxy)phosphazene (PCPP) polymer was chosen as adjuvant for the immunogenic peptide antigen. Peptide-loaded PCPP microparticles were synthesized via the coacervation method and the characterization studies of microparticles were conducted to determine their size, charge, morphology, encapsulation efficacy, and loading capacity. To evaluate in vivo efficacy of the vaccine candidate, Balb/c mice were immunized with the formulations. Brain and spleen tissues were isolated from animals to investigate cytokine levels, lymphocyte proliferation, and brain cyst formation. As a result, antibody and cytokine responses in groups immunized with peptide-loaded PCPP microparticles were found to be significantly higher when compared to the control group. In conclusion, our novel multi-epitope peptide-loaded PCPP microparticle-based vaccine formulation demonstrated considerable humoral and cellular immune responses against T. gondii and protected mice against T. gondii infection during Toxoplasmosis.

Nanoparticles in Drug Delivery: From History to Therapeutic Applications

Current research into the role of engineered nanoparticles in drug delivery systems (DDSs) for medical purposes has developed numerous fascinating nanocarriers. This paper reviews the various conventionally used and current used carriage system to deliver drugs. Due to numerous drawbacks of conventional DDSs, nanocarriers have gained immense interest. Nanocarriers like polymeric nanoparticles, mesoporous nanoparticles, nanomaterials, carbon nanotubes, dendrimers, liposomes, metallic nanoparticles, nanomedicine, and engineered nanomaterials are used as carriage systems for targeted delivery at specific sites of affected areas in the body. Nanomedicine has rapidly grown to treat certain diseases like brain cancer, lung cancer, breast cancer, cardiovascular diseases, and many others. These nanomedicines can improve drug bioavailability and drug absorption time, reduce release time, eliminate drug aggregation, and enhance drug solubility in the blood. Nanomedicine has introduced a new era for drug carriage by refining the therapeutic directories of the energetic pharmaceutical elements engineered within nanoparticles. In this context, the vital information on engineered nanoparticles was reviewed and conferred towards the role in drug carriage systems to treat many ailments. All these nanocarriers were tested in vitro and in vivo. In the coming years, nanomedicines can improve human health more effectively by adding more advanced techniques into the drug delivery system.

PLGA-Based Nanomedicine: History of Advancement and Development in Clinical Applications of Multiple Diseases

Research on the use of biodegradable polymers for drug delivery has been ongoing since they were first used as bioresorbable surgical devices in the 1980s. For tissue engineering and drug delivery, biodegradable polymer poly-lactic-co-glycolic acid (PLGA) has shown enormous promise among all biomaterials. PLGA are a family of FDA-approved biodegradable polymers that are physically strong and highly biocompatible and have been extensively studied as delivery vehicles of drugs, proteins, and macromolecules such as DNA and RNA. PLGA has a wide range of erosion times and mechanical properties that can be modified. Many innovative platforms have been widely studied and created for the development of methods for the controlled delivery of PLGA. In this paper, the various manufacturing processes and characteristics that impact their breakdown and drug release are explored in depth. Besides different PLGA-based nanoparticles, preclinical and clinical applications for different diseases and the PLGA platform types and their scale-up issues will be discussed.

Poly(Glycerol Succinate) as Coating Material for 1393 Bioactive Glass Porous Scaffolds for Tissue Engineering Applications

BACKGROUND

Aliphatic polyesters are widely used for biomedical, pharmaceutical and environmental applications due to their high biodegradability and cost-effective production. Recently, star and hyperbranched polyesters based on glycerol and ω-carboxy fatty diacids have gained considerable interest. Succinic acid and bio-based diacids similar to glycerol are regarded as safe materials according to the US Food and Drug Administration (FDA). Bioactive glass scaffolds utilized in bone tissue engineering are relatively brittle materials. However, their mechanical properties can be improved by using polymer coatings that can further control their degradation rate, tailor their biocompatibility and enhance their performance. The purpose of this study is to explore a new biopolyester poly(glycerol succinate) (PGSuc) reinforced with mesoporous bioactive nanoparticles (MSNs) as a novel coating material to produce hybrid scaffolds for bone tissue engineering.

METHODS

Bioactive glass scaffolds were coated with neat PGSuc, PGSuc loaded with dexamethasone sodium phosphate (DexSP) and PGSuc loaded with DexSP-laden MSNs. The physicochemical, mechanical and biological properties of the scaffolds were also evaluated.

RESULTS

Preliminary data are provided showing that polymer coatings with and without MSNs improved the physicochemical properties of the 1393 bioactive glass scaffolds and increased the ALP activity and alizarin red staining, suggesting osteogenic differentiation potential when cultured with adipose-derived mesenchymal stem cells.

CONCLUSIONS

PGSuc with incorporated MSNs coated onto 1393 bioactive glass scaffolds could be promising candidates in bone tissue engineering applications.

A Macrophage Membrane-Polymer Hybrid Biomimetic Nanoplatform for Therapeutic Delivery of Somatostatin Peptide to Chronic Pancreatitis

The clinical translation of therapeutic peptides is generally challenged by multiple issues involving absorption, distribution, metabolism and excretion. In this study, a macrophage membrane-coated poly(lactic-co-glycolic acid) (PLGA) nanodelivery system was developed to enhance the bioavailability of the somatostatin (SST) peptide, which faces the hurdles of short half-life and potential side effects in the treatment of chronic pancreatitis. Using a facile nanoprecipitation strategy, SST was loaded in the nanoparticles with an encapsulation efficiency (EE) and a loading efficiency (LE) of 73.68 ± 3.56% and 1.47 ± 0.07%, respectively. The final formulation of SST-loaded nanoparticles with the camouflage of macrophage membrane (MP-SST) showed a mean diameter of 151 ± 4 nm and an average zeta potential of −29.6 ± 0.3 mV, which were stable long term during storage. With an above 90% cell viability, a hemolysis level of about 2% (<5%) and a preference for being ingested by activated endothelial cells compared to macrophages, the membrane−polymer hybrid nanoparticle showed biocompatibility and targeting capability in vitro. After being intravenously administered to mice with chronic pancreatitis, the MP-SST increased the content of SST in the serum (123.6 ± 13.6 pg/mL) and pancreas (1144.9 ± 206.2 pg/g) compared to the treatment of (Dulbecco’s phosphate-buffered saline) DPBS (61.7 ± 6.0 pg/mL in serum and 740.2 ± 172.4 pg/g in the pancreas). The recovery of SST by MP-SST downregulated the expressions of chronic pancreatitis-related factors and alleviated the histologic severity of the pancreas to the greatest extent compared to other treatment groups. This augmentation of SST therapeutic effects demonstrated the superiority of integrating the synthetic polymer with biological membranes in the design of nanoplatforms for advanced and smart peptide delivery. Other peptides like SST can also be delivered via the membrane−polymer hybrid nanosystem for the treatment of diseases, broadening and promoting the potential clinical applications of peptides as therapeutics.

Biodegradable polymeric materials for flexible and degradable electronics

Biodegradable electronics have great potential to reduce the environmental footprint of electronic devices and to avoid secondary removal of implantable health monitors and therapeutic electronics. Benefiting from the intensive innovation on biodegradable nanomaterials, current transient electronics can realize full components’ degradability. However, design of materials with tissue-comparable flexibility, desired dielectric properties, suitable biocompatibility and programmable biodegradability will always be a challenge to explore the subtle trade-offs between these parameters. In this review, we firstly discuss the general chemical structure and degradation behavior of polymeric biodegradable materials that have been widely studied for various applications. Then, specific properties of different degradable polymer materials such as biocompatibility, biodegradability, and flexibility were compared and evaluated for real-life applications. Complex biodegradable electronics and related strategies with enhanced functionality aimed for different components including substrates, insulators, conductors and semiconductors in complex biodegradable electronics are further researched and discussed. Finally, typical applications of biodegradable electronics in sensing, therapeutic drug delivery, energy storage and integrated electronic systems are highlighted. This paper critically reviews the significant progress made in the field and highlights the future prospects.

Formulation optimization, in vitro and in vivo evaluation of agomelatine-loaded nanostructured lipid carriers for augmented antidepressant effects

The present study was intended to prepare and optimize agomelatine-loaded nanostructured lipid carriers (AGM-NLCs) for augmented in vivo antidepressant potential. AGM-NLCs were optimized on several parameters including cumulative hydrophilic-lipophilic balance of surfactants, proportions of solid and liquid lipids, total amounts of drug and surfactants. AGM-NLCs were assessed for their physicochemical properties, in vitro AGM release and in vivo antidepressant effects in mice model. The optimized AGM-NLCs demonstrated spherical morphology with average particle size of 99.8 ± 2.6 nm, PDI of 0.142 ± 0.017, zeta potential of - 23.2 ± 1.2 mV and entrapment efficiency of 97.1 ± 2.1%. Thermal and crystallinity studies depict amorphous nature of AGM after its incorporation into NLCs. AGM-NLCs exhibit a sustained drug release profile after initial 2 h. Mice treated with AGM-NLCs exhibited reduced immobility time in behavioral analysis. Furthermore, cresyl violet staining demonstrated an improved neuronal morphology and survival in AGM-NLCs group. The concentrations and the expression of inflammatory markers (TNF-α and COX-2) in mice brain were significantly reduced by AGM-NLCs. Taken together, therapeutic effectiveness of AGM was markedly augmented in AGM-NLCs and thereby they could be promising nanocarriers for the effective delivery of antidepressants to brain.

Physicochemical Characterization and Finite Element Analysis-Assisted Mechanical Behavior of Polylactic Acid- Montmorillonite 3D Printed Nanocomposites

This work aims to improve the properties of poly(lactic acid) (PLA) for future biomedical applications by investigating the effect of montmorillonite (MMT) nanoclay on physicochemical and mechanical behavior. PLA nanocomposite filaments were fabricated using different amounts of MMT (1.0, 2.0, and 4.0 wt.%) and 2 wt.% Joncryl chain extenders. The 3D-printed specimens were manufactured using Fused Filament Fabrication (FFF). The composites were characterized by Gel Permeation Chromatography (GPC), Melt Flow Index (MFI), X-ray Diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The thermal properties were studied by means of Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Moreover, the hydrophilicity of the PLA/MMT nanocomposites was investigated by measuring the water contact angle. The mechanical behavior of the PLA/MMT nanocomposites was examined with nanoindentation, compression tests, and Dynamic Mechanical Analysis (DMA). The presence of Joncryl, as well as the pretreatment of MMT before filament fabrication, improved the MMT distribution in the nanocomposites. Furthermore, MMT enhanced the printability of PLA and improved the hydrophilicity of its surface. In addition, the results of nanoindentation testing coupled with Finite Element Analysis showed that as the MMT weight fraction increased, as well as an increased Young’s modulus. According to the results of the mechanical analysis, the best mechanical behavior was achieved for PLA nanocomposite with 4 wt.% MMT.

Anti-Inflammatory and Mineralization Effects of an ASP/PLGA-ASP/ACP/PLLA-PLGA Composite Membrane as a Dental Pulp Capping Agent

Dental pulp is essential for the development and long-term preservation of teeth. Dental trauma and caries often lead to pulp inflammation. Vital pulp therapy using dental pulp-capping materials is an approach to preserving the vitality of injured dental pulp. Most pulp-capping materials used in clinics have good biocompatibility to promote mineralization, but their anti-inflammatory effect is weak. Therefore, the failure rate will increase when dental pulp inflammation is severe. The present study developed an amorphous calcium phosphate/poly (L-lactic acid)-poly (lactic-co-glycolic acid) membrane compounded with aspirin (hereafter known as ASP/PLGA-ASP/ACP/PLLA-PLGA). The composite membrane, used as a pulp-capping material, effectively achieved the rapid release of high concentrations of the anti-inflammatory drug aspirin during the early stages as well as the long-term release of low concentrations of aspirin and calcium/phosphorus ions during the later stages, which could repair inflamed dental pulp and promote mineralization. Meanwhile, the composite membrane promoted the proliferation of inflamed dental pulp stem cells, downregulated the expression of inflammatory markers, upregulated the expression of mineralization-related markers, and induced the formation of stronger reparative dentin in the rat pulpitis model. These findings indicate that this material may be suitable for use as a pulp-capping material in clinical applications.

Research Progress of Conjugated Nanomedicine for Cancer Treatment

The conventional cancer therapeutic modalities include surgery, chemotherapy and radiotherapy. Although immunotherapy and targeted therapy are also widely used in cancer treatment, chemotherapy remains the cornerstone of tumor treatment. With the rapid development of nanotechnology, nanomedicine is believed to be an emerging field to further improve the efficacy of chemotherapy. Until now, there are more than 17 kinds of nanomedicine for cancer therapy approved globally. Thereinto, conjugated nanomedicine, as an important type of nanomedicine, can not only possess the targeted delivery of chemotherapeutics with great precision but also achieve controlled drug release to avoid adverse effects. Meanwhile, conjugated nanomedicine provides the platform for combining several different therapeutic approaches (chemotherapy, photothermal therapy, photodynamic therapy, thermodynamic therapy, immunotherapy, etc.) with the purpose of achieving synergistic effects during cancer treatment. Therefore, this review focuses on conjugated nanomedicine and its various applications in synergistic chemotherapy. Additionally, the further perspectives and challenges of the conjugated nanomedicine are also addressed, which clarifies the design direction of a new generation of conjugated nanomedicine and facilitates the translation of them from the bench to the bedside.

In Vitro Cell Behavior and Antibiotic Activity under Sustained Release of Doxycycline-Loaded Poly(lactic-co-glycolic acid) Microspheres

The state-of-the-art sustained drug delivery systems are related to features to improve pharmacological transport through a controlled ratio between drug release and the desired therapeutic effect. Microspheres of biodegradable polymers, such as poly(lactic-co-glycolic acid) (PLGA), play an important role in these approaches, directing the release in a specific region of interest. In this way, the encapsulation of doxycycline (DOX) as a microbial agent turns the PLGA microspheres into a potential device for the treatment of topic oral diseases. Thus, this work aimed to produce DOX-loaded PLGA microspheres and see how they interfered with mesenchymal stem cell viability and in the sustained release in antimicrobial assays. Scanning electron microscopy showed the spherical microstructured pattern, revealing assorted sized distribution, with major diameters ranging 1–3 µm. The encapsulation efficiency presented a mean of 80% in both methods to obtain the microspheres (sonication and magnetic rotation). The DOX release test revealed a gradual and continuous profile of 30–40% between 120 and 168 h. Mesenchymal stem cells cultured in PLGA with or without DOX at several concentrations revealed no effect on the cell metabolic activity. Striking morphology changes were observed by confocal microscopy after 1 to 3 days under culture. The live/dead assay indicated that when microsphere densities were increased (from 10 to 100 µg/mL) cultured cells presented an internalized pattern of microspheres in both groups of PLGA containing DOX or not, while slight cell death signals were identified nearby microsphere clusters. Microbiological assays performed by the agar diffusion test pointed out that an inhibition zone was identified in Staphylococcus aureus (S. aureus) cultures at earlier times of DOX release. Despite the well-known use of PLGA as a drug delivery vehicle, when synthesized with DOX, it presents both characteristics of the desired treatment to prevent healthy tissue damage while avoiding bacterial growth in a microenvironment with anatomical features, such as grooves, projections, and other tough conditions that favor the development of oral diseases.

Direct and indirect effects on molecular mobility in renewable polylactide-poly(propylene adipate) block copolymers as studied via dielectric spectroscopy and calorimetry

In this work, we study a series of sustainable block copolymers based on polylactide, PLA, and poly(propylene adipate), PPAd, both polymers being prepared from renewable resources. Envisaging a wide range of future applications in the frame of a green and circular economy, e.g., packaging materials replacing conventional petrochemicals, the employment of PPAd aims at lowering the glass transition and melting temperatures of PLA and, finally, facilitation of the enzymatic degradation and compostability. The copolymers have been synthesized via ring opening polymerization of lactides in the presence of propylene adipate oligomers (5, 15 and 25%). The direct effects on the molecular mobility by the structure/composition are assessed in the amorphous state employing broadband dielectric spectroscopy (BDS) and calorimetry. BDS allowed the recording of local PLA and PPAd dynamics in all cases. The effects on local relaxations suggest favoring of interchain interactions, both PLA-PPAd and PPAd-PPAd. Regarding the more important segmental dynamics, the presence of PPAd leads to faster polymer chain diffusion, as monitored by the significant lowering of the dielectric and calorimetric glass transition temperature, T_g. This suggests the plasticizing role of PPAd on PLA (majority) in combination with the lowering of the average molar mass, M_n, in the copolymers from ∼75 to ∼30 kg mol^-1, which is the actual scope for the synthesis of these materials. Interestingly, a strong suppression in fragility (chain cooperativity) is additionally recorded. In contrast to calorimetry and due to the high resolving power of BDS, for the higher PPAd fraction, the weak segmental relaxation of PPAd was additionally recorded. Overall, the recordings suggest a strong increase in free volume and two individual dynamic states, one for 0 and 5% PPAd and another for 15 and 25% PPAd. Within the latter, we gained indications for partial phase nano-separation of PPAd. Regarding indirect effects, these were followed via crystallization. Independent of the method of crystallization, namely, melt or cold, the presence of PPAd led to the systematic lowering of crystallization and melting temperatures and enthalpies. The effects reflect the decrease of crystalline nuclei, which is confirmed by optical microscopy as in the copolymers fewer although larger crystals are formed.

Dual Coating of Chitosan and Albumin Negates the Protein Corona-Induced Reduced Vascular Adhesion of Targeted PLGA Microparticles in Human Blood

Vascular-targeted carriers (VTCs) have the potential to localize therapeutics and imaging agents to inflamed, diseased sites. Poly (lactic-co-glycolic acid) (PLGA) is a negatively charged copolymer commonly used to construct VTCs due to its biodegradability and FDA approval. Unfortunately, PLGA VTCs experienced reduced adhesion to inflamed endothelium in the presence of human plasma proteins. In this study, PLGA microparticles were coated with chitosan (CS), human serum albumin (HSA), or both (HSA-CS) to improve adhesion. The binding of sialyl Lewis A (a ligand for E-selectin)-targeted PLGA, HSA-PLGA, CSPLGA, and HSA-CSPLGA to activated endothelial cells was evaluated in red blood cells in buffer or plasma flow conditions. PLGA VTCs with HSA-only coating showed improvement and experienced 35–52% adhesion in plasma compared to plasma-free buffer conditions across all shear rates. PLGA VTCs with dual coating—CS and HSA—maintained 80% of their adhesion after exposure to plasma at low and intermediate shears and ≈50% at high shear. Notably, the protein corona characterization showed increases at the 75 and 150 kDa band intensities for HSA-PLGA and HSA-CSPLGA, which could correlate to histidine-rich glycoprotein and immunoglobulin G. The changes in protein corona on HSA-coated particles seem to positively influence particle binding, emphasizing the importance of understanding plasma protein–particle interactions.

Magnetite Nanoparticles Functionalized with Therapeutic Agents for Enhanced ENT Antimicrobial Properties

In the context of inefficient antibiotics, antibacterial alternatives are urgently needed to stop the increasing resistance rates in pathogens. This study reports the fabrication and characterization of four promising magnetite-based antibiotic delivery systems for ENT (ear, nose and throat) applications. Magnetite nanoparticles were functionalized with streptomycin and neomycin and some were entrapped in polymeric spheres. The obtained nanomaterials are stable, with spherical morphology, their size ranging from ~2.8 to ~4.7 nm for antibiotic-coated magnetite nanoparticles, and from submicron sizes up to several microns for polymer-coated magnetite–antibiotic composites. Cell viability and antimicrobial tests demonstrated their biocompatibility on human diploid cells and their antibacterial effect against Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) opportunistic bacteria. The presence of the polymeric coat proved an enhancement in biocompatibility and a slight reduction in the antimicrobial efficiency of the spheres. Our results support the idea that functional NPs and polymeric microsystems containing functional NPs could be tailored to achieve more biocompatibility or more antimicrobial effect, depending on the bioactive compounds they incorporate and their intended application.

Modified Release of the Pineal Hormone Melatonin from Matrix Tablets Containing Poly(L-lactic Acid) and Its PLA-co-PEAd and PLA-co-PBAd Copolymers

In terms of drug delivery, the attractive properties of poly(L-lactic acid) (PLA) and its aliphatic polyesters, poly(ethylene adipate) (PEAd) and poly(butylene adipate) (PBAd), render them ideal co-formulants for the preparation of modified-release pharmaceutical formulations. Furthermore, we have previously demonstrated that by adding a “softer” aliphatic polyester onto the macromolecular chain of PLA, i.e., PEAd or PBAd, resulting in the formation of the PLA’s copolymers (PLA-co-PEAd and PLA-co-PBAd, in 95/5, 90/10, 75/25 and 50/50 weight ratios), the hydrolysis rate is also severely affected, leading to improved dissolution rates of the active pharmaceutical ingredients (API). In the present report, we communicate our findings on the in vitro modified release of the chronobiotic hormone melatonin (MLT), in aqueous media (pH 1.2 and 6.8), from poly(L-lactic acid) and the aforementioned copolymer matrix tablets, enriched with commonly used biopolymers, such as hydroxypropylmethylcellulose (HPMC K15), lactose monohydrate, and sodium alginate. It was found that, depending on the composition and the relevant content of these excipients in the matrix tablets, the release of MLT satisfied the sought targets for fast sleep onset and sleep maintenance. These findings constitute a useful background for pursuing relevant in vivo studies on melatonin in the future.

Novel Biodegradable Poly (Lactic Acid)/Wood Leachate Composites: Investigation of Antibacterial, Mechanical, Morphological, and Thermal Properties

This research aimed to investigate the effects of using wood leachate (WL) powder as a cost-effective filler added to novel poly (lactic acid) biocomposites and evaluate their mechanical, thermal, morphological, and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), tensile test, Charpy impact test, Shore hardness, scanning electron microscope (SEM), differential scanning calorimetry (DSC), contact angle, and bacterial growth inhibition tests were employed to characterize the developed biocomposites. The SEM results indicated a proper filler dispersion in the polymer matrix. WL powder improved the hydrophobic nature in the adjusted sample’s contact angle experiment. Markedly, the results showed that the addition of WL filler improved the mechanical properties of the fabricated biocomposites. The thermal analysis determined the development in crystallization behavior and a decline in glass transition temperature (Tg) from 60.1 to 49.3 °C in 7% PLA-WL biocomposites. The PLA-WL biocomposites exhibited an antibacterial activity according to the inhibition zone for Escherichia coli bacteria. The developed novel PLA-WL composites can be effectively utilized in various value-added industrial applications as a sustainable and functional biopolymer material.

Special Features of Polyester-Based Materials for Medical Applications

This article presents current possibilities of using polyester-based materials in hard and soft tissue engineering, wound dressings, surgical implants, vascular reconstructive surgery, ophthalmology, and other medical applications. The review summarizes the recent literature on the key features of processing methods and potential suitable combinations of polyester-based materials with improved physicochemical and biological properties that meet the specific requirements for selected medical fields. The polyester materials used in multiresistant infection prevention, including during the COVID-19 pandemic, as well as aspects covering environmental concerns, current risks and limitations, and potential future directions are also addressed. Depending on the different features of polyester types, as well as their specific medical applications, it can be generally estimated that 25-50% polyesters are used in the medical field, while an increase of at least 20% has been achieved since the COVID-19 pandemic started. The remaining percentage is provided by other types of natural or synthetic polymers; i.e., 25% polyolefins in personal protection equipment (PPE).

A review on Biopolymer-derived Electrospun Nanofibers for Biomedical and Antiviral Applications

Unique aspects of polymer-derived nanofibers provide significant potential in the area of biomedical and health care applications. Much research has demonstrated several plausible nanofibers to overcome the modern-day challenges in...