Drug encapsulated polymeric microspheres for intracranial tumor therapy: A review of the literature

Preparation and Characterization of Injectable Augmentation Gels Containing Polycaprolactone and Hyaluronic Acid

BACKGROUND

Injectable augmentation gels are widely used in the treatment of soft tissue. The composition of these gels has to be continuously improved due to the limitations of the currently available formulations.

AIMS

This study focuses on the development of an innovative injectable gel designed to address current trends and specific needs within the field.

METHODS

The current study utilized a safer hyaluronic acid (HA) gel carrier, created with a less toxic cross-linker, in combination with polycaprolactone (PCL) microspheres at various concentrations. PCL microspheres were prepared using an emulsification-solvent evaporation technique. Six different gel formulations were developed using PCL microspheres and biphasic HA gel structures.

RESULTS

The produced microspheres had non-agglomerated, smooth surfaces with an average particle size of approximately 45 ± 0.14 μm. The rheological results of the PCL-HA6 such as storage modulus (G', Pa), loss modulus (G", Pa), complex viscosity (η*), and phase angle (°) at 1 Hz frequency were measured as 553.97 ± 32.48, 368.4 ± 12.24, 105.9 ± 5.27, and 33.65 ± 0.92, respectively, and the injection force was measured as 9.64 ± 1.46. In vitro tests revealed that the PCL-HA6 group showed the highest cell viability compared to the other groups and provided a relative increase in collagen production over time, as demonstrated by the relevant gene expression.

CONCLUSIONS

The developed PCL/HA gel exhibited biocompatibility and non-toxicity, making it a safe option for soft tissue augmentation. It demonstrated potential for medical applications and exhibited favorable rheological characteristics and injectability.

Nanoparticle-Based Approaches in the Diagnosis and Treatment of Brain Tumors

Glioblastomas are highly invasive brain tumors among perilous diseases. They are characterized by their fast proliferation and delayed detection that render them a significant focal point for medical research endeavors within the realm of cancer. Among glioblastomas, Glioblastoma multiforme (GBM) is the most aggressive and prevalent malignant brain tumor. For this, nanomaterials such as metallic and lipid nanoparticles and quantum dots have been acknowledged as efficient carriers. These nano-materials traverse the blood-brain barrier (BBB) and integrate and reach the necessary regions for neuro-oncology imaging and treatment purposes. This paper provides a thorough analysis on nanoparticles used in the diagnosis and treatment of brain tumors, especially for GBM.

Fabrication of polymeric microspheres for biomedical applications

Polymeric microspheres (PMs) have attracted great attention in the field of biomedicine in the last several decades due to their small particle size, special functionalities shown on the surface and high surface-to-volume ratio. However, how to fabricate PMs which can meet the clinical needs and transform laboratory achievements to industrial scale-up still remains a challenge. Therefore, advanced fabrication technologies are pursued. In this review, we summarize the technologies used to fabricate PMs, including emulsion-based methods, microfluidics, spray drying, coacervation, supercritical fluid and superhydrophobic surface-mediated method and their advantages and disadvantages. We also review the different structures, properties and functions of the PMs and their applications in the fields of drug delivery, cell encapsulation and expansion, scaffolds in tissue engineering, transcatheter arterial embolization and artificial cells. Moreover, we discuss existing challenges and future perspectives for advancing fabrication technologies and biomedical applications of PMs.

Polymer Microspheres and Their Application in Cancer Diagnosis and Treatment

Cancer is a significant global public health issue with increasing morbidity and mortality rates. To address this challenge, novel drug carriers such as nano-materials, liposomes, hydrogels, fibers, and microspheres have been extensively researched and utilized in oncology. Among them, polymer microspheres are gaining popularity due to their ease of preparation, excellent performance, biocompatibility, and drug-release capabilities. This paper categorizes commonly used materials for polymer microsphere preparation, summarizes various preparation methods (emulsification, phase separation, spray drying, electrospray, microfluidics, and membrane emulsification), and reviews the applications of polymer microspheres in cancer diagnosis, therapy, and postoperative care. The current status and future development directions of polymer microspheres in cancer treatment are analyzed, highlighting their importance and potential for improving patient outcomes.

Matrix Metalloproteinase- and pH-Sensitive Nanoparticle System Enhances Drug Retention and Penetration in Glioblastoma

Glioblastoma (GBM) is a primary malignant brain tumor with limited therapeutic options. One promising approach is local drug delivery, but the efficacy is hindered by limited diffusion and retention. To address this, we synthesized and developed a dual-sensitive nanoparticle (Dual-NP) system, formed between a dendrimer and dextran NPs, bound by a dual-sensitive [matrix metalloproteinase (MMP) and pH] linker designed to disassemble rapidly in the tumor microenvironment. The disassembly prompts the in situ formation of nanogels via a Schiff base reaction, prolonging Dual-NP retention and releasing small doxorubicin (Dox)-conjugated dendrimer NPs over time. The Dual-NPs were able to penetrate deep into 3D spheroid models and detected at the tumor site up to 6 days after a single intratumoral injection in an orthotopic mouse model of GBM. The prolonged presence of Dual-NPs in the tumor tissue resulted in a significant delay in tumor growth and an overall increase in survival compared to untreated or Dox-conjugated dendrimer NPs alone. This Dual-NP system has the potential to deliver a range of therapeutics for efficiently treating GBM and other solid tumors.

Innovative strategies for effective paclitaxel delivery: Recent developments and prospects

PURPOSE

Paclitaxel is an effective chemotherapeutic agent against a variety of cancer types. However, the clinical utility of paclitaxel is restricted by its poor solubility in water and high toxicity, resulting in low drug tolerance. These difficulties could be resolved by using suitable pharmacological carriers. Hence, it is essential to determine innovative methods of administering this effective medication to overcome paclitaxel's inherent limitations.

METHODS

An extensive literature search was conducted using multiple electronic databases to identify relevant studies published.

RESULTS

In this comprehensive analysis, many different paclitaxel delivery systems are covered and discussed, such as albumin-bound paclitaxel, polymeric micelles, paclitaxel-loaded liposomes, prodrugs, cyclodextrins, and peptide-taxane conjugates. Moreover, the review also covers various delivery routes of conventional paclitaxel or novel paclitaxel formulations, such as oral administration, local applications, and intraperitoneal delivery.

CONCLUSION

In addition to albumin-bound paclitaxel, polymeric micelles appear to be the most promising formulations for innovative drug delivery systems at present. A variety of variants of polymeric micelles are currently undergoing advanced phases of clinical trials.

Magnetic iron oxide nanoparticles@lecithin/poly (l-lactic acid) microspheres for targeted drug release in cancer therapy

The use of targeted chemotherapy is a promising solution to mitigate the side effects and dosage of drugs. This research focuses on the development of magnetic microspheres (MMS) based drug carriers for targeted chemotherapy, formulated with iron oxide nanoparticles (Fe3O4 NPs) and poly (l-lactic acid) (PLA) loaded with the antibiotic drug Ciprofloxacin (CIF). In this study, Fe3O4 NPs were synthesized using pomegranate peel extract as a natural reducing and stabilizing agent. The double emulsification method (W1/O/W2) was employed to produce Fe3O4@LEC-CIF-PLA-MMS, which were characterized using various spectral and microscopic techniques. The drug encapsulation efficiency for Fe3O4@LEC-CIF-PLA-MMS was found to be 80.7 %. The in vitro drug release of CIF from Fe3O4@LEC-CIF-PLA-MMS induced by H2O2 and GSH- stimuli was found to be 87.55 % and 82.32 %, respectively in acidic pH 4.5. Notably, the magnetically triggered drug release behaviour of Fe3O4@LEC-CIF-PLA-MMS (93.56 %) was assessed in acidic pH environment upon exposure to low-frequency alternating magnetic field (LF-AMF). Fe3O4@LEC-CIF-PLA-MMS demonstrated significantly enhanced in vitro cytotoxicity (IC50 = 0.8 ± 0.03 μg/mL) against the HeLa-S3 cancer cell lines. Nevertheless, these research findings highlight the potential of Fe3O4@LEC-CIF-PLA-MMS for further development as a chemotherapeutic agent and hold promise for the future of targeted cancer treatment.

Polymeric biomaterials: Advanced drug delivery systems in osteoarthritis treatment

Polymeric biomaterials have emerged as a highly promising candidate for drug delivery systems (DDS), exhibiting significant potential to enhance the therapeutic landscape of osteoarthritis (OA) therapy. Their remarkable capacity to manifest desirable physicochemical attributes, coupled with their excellent biocompatibility and biodegradability, has greatly expanded their utility in pharmacotherapeutic applications. Nevertheless, an urgent necessity exists for a comprehensive synthesis of the most recent advances in polymeric DDS, providing valuable guidance for their implementation in the context of OA therapy. This review is dedicated to summarizing and examining recent developments in the utilization of polymeric DDS for OA therapy. Initially, we present an overview of the intricate pathophysiology characterizing OA and underscore the prevailing limitations inherent to current treatment modalities. Subsequently, we introduce diverse categories of polymeric DDS, including hydrogels, nanofibers, and microspheres, elucidating their inherent advantages and limitations. Moreover, we discuss and summarize the delivery of bioactive agents through polymeric biomaterials for OA therapy, emphasizing key findings and emerging trends. Finally, we highlight prospective directions for advancing polymeric DDS, offering a promising approach to enhance their translational potential for OA therapy.

Properties of Poly (Lactic-co-Glycolic Acid) and Progress of Poly (Lactic-co-Glycolic Acid)-Based Biodegradable Materials in Biomedical Research

In recent years, biodegradable polymers have gained the attention of many researchers for their promising applications, especially in drug delivery, due to their good biocompatibility and designable degradation time. Poly (lactic-co-glycolic acid) (PLGA) is a biodegradable functional polymer made from the polymerization of lactic acid (LA) and glycolic acid (GA) and is widely used in pharmaceuticals and medical engineering materials because of its biocompatibility, non-toxicity, and good plasticity. The aim of this review is to illustrate the progress of research on PLGA in biomedical applications, as well as its shortcomings, to provide some assistance for its future research development.

Recent Advances in Pickering Double Emulsions and Potential Applications in Functional Foods: A Perspective Paper

Double emulsions are complex emulsion systems with a wide range of applications across different fields, such as pharmaceutics, food and beverage, materials sciences, personal care, and dietary supplements. Conventionally, surfactants are required for the stabilization of double emulsions. However, due to the emerging need for more robust emulsion systems and the growing trends for biocompatible and biodegradable materials, Pickering double emulsions have attracted increasing interest. In comparison to double emulsions stabilized solely by surfactants, Pickering double emulsions possess enhanced stability due to the irreversible adsorption of colloidal particles at the oil/water interface, while adopting desired environmental-friendly properties. Such advantages have made Pickering double emulsions rigid templates for the preparation of various hierarchical structures and as potential encapsulation systems for the delivery of bioactive compounds. This article aims to provide an evaluation of the recent advances in Pickering double emulsions, with a special focus on the colloidal particles employed and the corresponding stabilization strategies. Emphasis is then devoted to the applications of Pickering double emulsions, from encapsulation and co-encapsulation of a wide range of active compounds to templates for the fabrication of hierarchical structures. The tailorable properties and the proposed applications of such hierarchical structures are also discussed. It is hoped that this perspective paper will serve as a useful reference on Pickering double emulsions and will provide insights toward future studies in the fabrication and applications of Pickering double emulsions.

Dual-Nozzle 3D Printed Nano-Hydroxyapatite Scaffold Loaded with Vancomycin Sustained-Release Microspheres for Enhancing Bone Regeneration

Background

Successful treatment of infectious bone defect remains a major challenge in the orthopaedic field. At present, the conventional treatment for infectious bone defects is surgical debridement and long-term systemic antibiotic use. It is necessary to develop a new strategy to achieve effective bone regeneration and local anti-infection for infectious bone defects.

Methods

Firstly, vancomycin / poly (lactic acid-glycolic acid) sustained release microspheres (VAN/PLGA-MS) were prepared. Then, through the dual-nozzle 3D printing technology, VAN/PLGA-MS was uniformly loaded into the pores of nano-hydroxyapatite (n-HA) and polylactic acid (PLA) scaffolds printed in a certain proportion, and a composite scaffold (VAN/MS-PLA/n-HA) was designed, which can not only promote bone repair but also resist local infection. Finally, the performance of the composite scaffold was evaluated by in vivo and in vitro biological evaluation.

Results

The in vitro release test of microspheres showed that the release of VAN/PLGA-MS was relatively stable from the second day, and the average daily release concentration was about 15.75 μg/mL, which was higher than the minimum concentration specified in the guidelines. The bacteriostatic test in vitro showed that VAN/PLGA-MS had obvious inhibitory effect on Staphylococcus aureus ATCC-29213. Biological evaluation of VAN/MS-PLA/n-HA scaffolds in vitro showed that it can promote the proliferation of adipose stem cells. In vivo biological evaluation showed that VAN/MS-PLA/n-HA scaffold could significantly promote bone regeneration.

Conclusion

Our research shows that VAN/MS-PLA/n-HA scaffolds have satisfying biomechanical properties, effectively inhibit the growth of Staphylococcus aureus, with good biocompatibility, and effectiveness on repairing bone defects. The VAN/MS-PLA/n-HA scaffold provide the clinic with an application prospect in bone tissue engineering.

Recent advances of polymer based nanosystems in cancer management

Cancer is still one of the leading causes of death worldwide. Nanotechnology, particularly nanoparticle-based platforms, is at the leading edge of current cancer management research. Polymer-based nanosystems have piqued the interest of researchers owing to their many benefits over other conventional drug delivery systems. Polymers derived from both natural and synthetic sources have various biomedical applications due to unique qualities like porosity, mechanical strength, biocompatibility, and biodegradability. Polymers such as poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL), and polyethylene glycol (PEG) have been approved by the USFDA and are being researched for drug delivery applications. They have been reported to be potential carriers for drug loading and are used in theranostic applications. In this review, we have primarily focused on the aforementioned polymers and their conjugates. In addition, the therapeutic and diagnostic implications of polymer-based nanosystems have been briefly reviewed. Furthermore, the safety of the developed polymeric formulations is crucial, and we have discussed their biocompatibility in detail. This article also discusses recent developments in block co-polymer-based nanosystems for cancer treatment. The review ends with the challenges of clinical translation of polymer-based nanosystems in drug delivery for cancer therapy.

Perfluorooctylbromide-loaded fucoidan-chlorin e6 nanoparticles for tumor-targeted photodynamic therapy

Efficient delivery of a photosensitizer (PS) and oxygen to tumor tissue is critical for successful photodynamic therapy (PDT). For this purpose, we developed a fucoidan (Fu)-chlorin e6 (Ce6) nanoparticle (NP) containing perfluorooctylbromide (PFOB). Fu, a biopolymer derived from seaweed, made up the hydrophilic shell of the NP and provided specific targeting to tumor cells by P-selectin binding. Conjugation with the hydrophobic Ce6 enabled self-assembly and Ce6-generated cytotoxic reactive oxygen species to kill tumor cells upon laser irradiation. PF supplied oxygen to the hypoxic tumor tissue and increased the efficacy of the PDT. The developed Fu-Ce6-PF-NPs bound specifically to SCC7 tumor cells and killed them via a photodynamic effect on laser irradiation. High accumulation of the NPs in tumor tissue and improved tumor suppression by PDT were observed in SCC7 tumor-bearing mice. The overall data demonstrated the potential of Fu-Ce6-PF-NP as a tumor-targeting drug carrier for effective PDT.

Synthesis of novel combinatorial drug delivery system (nCDDS) for co-delivery of 5-Fluorouracil and Leucovorin calcium for colon targeting and controlled drug release

Objective: Purpose of the current study was to improve the oral effectiveness of 5-Fluorouracil (5-FU) by developing novel controlled, combinatorial drug delivery system (nCDDS) for co-delivery of 5-FU and Leucovorin (LC) for colon targeting.Significance: on the basis of results obtained, novel controlled, combinatorial drug delivery system (nCDDS) could be an effective strategy for the colon targeting of 5-FU and LC.Methods: Free radical polymerization method was tuned and used to fabricate this nCDDS. The nCDDS is synthesized in two steps, firstly synthesis of 5-fluoruracil/leucovorin calcium loaded nanogels and secondly, pre-synthesized 5-FU & LC loaded nanogels were dispersed in pectin based polymerized matrix hard gel. The nanogels and nCDD gels were characterized for network structure, thermal stability and surface morphology. Swelling and in-vitro release studies were carried out at different pH 1.2 and 7.4 both for naive nanogels and combined matrix gels. In-vivo study of combinatorial gel was performed on rabbits by using HPLC method to estimate plasma drug concentration and pharmacokinetics parameters.Results: Structure and thermal analysis confirmed the formation of stable polymeric network. SEM of nanogels and combinatorial gels showed that the spongy and rough edges particles and uniformly distributed in the combinatorial gel. The prepared nCDDS showed excellent water loving capacity and pH responsiveness. Combinatorial gel showed excellent characteristic for colonic delivery of drugs, which were confirmed by various in-vitro and in-vivo characterization. Acute oral toxicity study of combinatorial gel confirmed the biocompatible and non-toxic characteristics of developed formulation.Conclusion: Conclusively it can be found that nCDDS showed excellent properties regarding drug targeting in a controllable manner as compared to naive PEGylated nanogels.

Developed meloxicam loaded microparticles for colon targeted delivery: Statistical optimization, physicochemical characterization, and in-vivo toxicity study

The study aimed to fabricate and evaluate Meloxicam (MLX) loaded Hydroxypropyl Methylcellulose (HPMC) microparticles for colon targeting because MLX is a potent analgesic used in the treatment of pain and inflammation associated with colorectal cancer (CRC). Nevertheless, its efficiency is limited by poor solubility and gastrointestinal tracts (GIT) associated side effects. Seventeen formulations of MLX loaded HPMC microparticles were fabricated by the oil-in-oil (O/O)/ emulsion solvent evaporation (ESE) technique. A 3-factor, 3-level Box Behnken (BBD) statistical design was used to estimate the combined effects of the independent variables on the dependent variables (responses), such as the percent yield (R1), the entrapment efficiency (EE) (R2), mean particle size (R3) and in vitro percentage of cumulative drug release (R4). For physicochemical characterization FTIR, XRD, DSC, and SEM analyses were performed. Biocompatibility and non-toxicity were confirmed by in-vivo acute oral toxicity determination. The percentage yield and EE were 65.75-90.71%, and 70.62-88.37%, respectively. However, the mean particle size was 62.89-284.55 μm, and the in vitro cumulative drug release percentage was 74.25-92.64% for 24 hours. FTIR analysis showed that the composition of the particles was completely compatible, while XRD analysis confirmed the crystalline nature of the pure drug and its transition into an amorphous state after formulation. DSC analysis revealed the thermal stability of the formulations. The SEM analysis showed dense spherical particles. The toxicity study in albino rabbits showed no toxicity and was found biocompatible. The histopathological evaluation showed no signs of altered patterns. Results of this study highlighted a standard colonic drug delivery system with the ability to improve patient adherence and reduce GIT drug-associated side effects in CRC treatment.

Fabrication and Modelling of a Reservoir-Based Drug Delivery System for Customizable Release

Localized therapy approaches have emerged as an alternative drug administration route to overcome the limitations of systemic therapies, such as the crossing of the blood–brain barrier in the case of brain tumor treatment. For this, implantable drug delivery systems (DDS) have been developed and extensively researched. However, to achieve an effective localized treatment, the release kinetics of DDS needs to be controlled in a defined manner, so that the concentration at the tumor site is within the therapeutic window. Thus, a DDS, with patient-specific release kinetics, is crucial for the improvement of therapy. Here, we present a computationally supported reservoir-based DDS (rDDS) development towards patient-specific release kinetics. The rDDS consists of a reservoir surrounded by a polydimethylsiloxane (PDMS) microchannel membrane. By tailoring the rDDS, in terms of membrane porosity, geometry, and drug concentration, the release profiles can be precisely adapted, with respect to the maximum concentration, release rate, and release time. The release is investigated using a model dye for varying parameters, leading to different distinct release profiles, with a maximum release of up to 60 days. Finally, a computational simulation, considering exemplary in vivo conditions (e.g., exchange of cerebrospinal fluid), is used to study the resulting drug release profiles, demonstrating the customizability of the system. The establishment of a computationally supported workflow, for development towards a patient-specific rDDS, in combination with the transfer to suitable drugs, could significantly improve the efficacy of localized therapy approaches.

Advances in local therapy for glioblastoma - taking the fight to the tumour

Despite advances in neurosurgery, chemotherapy and radiotherapy, glioblastoma remains one of the most treatment-resistant CNS malignancies, and the tumour inevitably recurs. The majority of recurrences appear in or near the resection cavity, usually within the area that received the highest dose of radiation. Many new therapies focus on combatting these local recurrences by implementing treatments directly in or near the tumour bed. In this Review, we discuss the latest developments in local therapy for glioblastoma, focusing on recent preclinical and clinical trials. The approaches that we discuss include novel intraoperative techniques, various treatments of the surgical cavity, stereotactic injections directly into the tumour, and new developments in convection-enhanced delivery and intra-arterial treatments.

Heme Oxygenase-1 targeting exosomes for temozolomide resistant glioblastoma synergistic therapy

Glioblastoma (GBM) is a highly fatal and recurrent brain cancer without a complete prevailing remedy. Although the synthetic nanotechnology-based approaches exhibit excellent therapeutic potential, the associated cytotoxic effects and organ clearance failure rest major obstacles from bench to clinics. Here, we explored allogeneic bone marrow mesenchymal stem cells isolated exosomes (BMSC_Exo) decorated with heme oxygenase-1 (HMOX1) specific short peptide (HSSP) as temozolomide (TMZ) and small interfering RNA (siRNA) nanocarrier for TMZ resistant glioblastoma therapy. The BMSC_Exo had excellent TMZ and siRNA loading ability and could traverse the blood-brain barrier (BBB) by leveraging its intrinsic brain accumulation property. Notably, with HSSP decoration, the TMZ or siRNA encapsulated BMSC_Exo exhibited excellent TMZ resistant GBM targeting ability both in vitro and in vivo due to the overexpression of HMOX1 in TMZ resistant GBM cells. Further, the HSSP decorated BMSC_Exo delivered the STAT3 targeted siRNA to the TMZ resistant glioma and restore the TMZ sensitivity, consequently achieved the synergistically drug resistant GBM treatment with TMZ. Our results showed this biomimetic nanoplatform can serve as a flexible, robust and inert system for GBM treatment, especially emphasizing the drug resistant challenge.

GSH-sensitive polymeric prodrug: Synthesis and loading with photosensitizers as nanoscale chemo-photodynamic anti-cancer nanomedicine

Precisely delivering combinational therapeutic agents has become a crucial challenge for anti-tumor treatment. In this study, a novel redox-responsive polymeric prodrug (molecular weight, MW: 93.5 kDa) was produced by reversible addition-fragmentation chain transfer (RAFT) polymerization. The amphiphilic block polymer-doxorubicin (DOX) prodrug was employed to deliver a hydrophobic photosensitizer (PS), chlorin e6 (Ce6), and the as-prepared nanoscale system [NPs(Ce6)] was investigated as a chemo-photodynamic anti-cancer agent. The glutathione (GSH)-cleavable disulfide bond was inserted into the backbone of the polymer for biodegradation inside tumor cells, and DOX conjugated onto the polymer with a disulfide bond was successfully released intracellularly. NPs(Ce6) released DOX and Ce6 with their original molecular structures and degraded into segments with low MWs of 41.2 kDa in the presence of GSH. NPs(Ce6) showed a chemo-photodynamic therapeutic effect to kill 4T1 murine breast cancer cells, which was confirmed from a collapsed cell morphology, a lifted level in the intracellular reactive oxygen species, a reduced viability and induced apoptosis. Moreover, ex vivo fluorescence images indicated that NPs(Ce6) retained in the tumor, and exhibited a remarkable in vivo anticancer efficacy. The combinational therapy showed a significantly increased tumor growth inhibition (TGI, 58.53%). Therefore, the redox-responsive, amphiphilic block polymeric prodrug could have a great potential as a chemo-photodynamic anti-cancer agent.

PLGA-based biodegradable microspheres in drug delivery: recent advances in research and application

Biodegradable microspheres have been widely used in the field of medicine due to their ability to deliver drug molecules of various properties through multiple pathways and their advantages of low dose and low side effects. Poly (lactic-co-glycolic acid) copolymer (PLGA) is one of the most widely used biodegradable material currently and has good biocompatibility. In application, PLGA with a specific monomer ratio (lactic acid and glycolic acid) can be selected according to the properties of drug molecules and the requirements of the drug release rate. PLGA-based biodegradable microspheres have been studied in the field of drug delivery, including the delivery of various anticancer drugs, protein or peptide drugs, bacterial or viral DNA, etc. This review describes the basic knowledge and current situation of PLGA biodegradable microspheres and discusses the selection of PLGA polymer materials. Then, the preparation methods of PLGA microspheres are introduced, including emulsification, microfluidic technology, electrospray, and spray drying. Finally, this review summarizes the application of PLGA microspheres in drug delivery and the treatment of pulmonary and ocular-related diseases.

Reduction-sensitive polymeric micelles as amplifying oxidative stress vehicles for enhanced antitumor therapy

Chemotherapy-photodynamic therapy (PDT)-based combination therapy is a currently frequently used means in cancer treatment that photosensitizer was able to generate reactive oxygen species (ROS) for improving chemotherapy, owing to the high oxidative stress of the tumor microenvironment (TME). Whereas, cancer cells were accustomed to oxidative stress by overexpression of antioxidant such as glutathione (GSH), which would consume the damage of ROS, as well as it could result in ineffective treatment. Herein, amplification of oxidative stress preferentially in tumor cells by consuming GSH or generating ROS is a reasonable treatment strategy to develop anticancer drugs. To achieve excellent therapeutic effects, we designed a GSH-scavenging and ROS-generating polymeric micelle mPEG-S-S-PCL-Por (MSLP) for amplifying oxidative stress and enhanced anticancer therapy. The amphiphilic polymer of methoxy poly(ethylene glycol) (mPEG)-S-S-poly(ε-caprolactone) (PCL)-Protoporphyrin (Por) was self-assembled into polymeric micelles with the anticancer drug doxorubicin (DOX) for treatment and tracking via FRET. Spherical DOX/MSLP micelles with the average size of 88.76 ± 3.52 nm was procured with negatively charged surface, reduction sensitivity and high drug loading content (17.47 ± 1.53 %). The intracellular ROS detection showed that the MSLP could deplete glutathione and regenerate additional ROS. The cellular uptake of DOX/MSLP micelles was grabbed real-time monitoring by the Fluorescence resonance energy transfer (FRET) effect between DOX and MSLP. The reduction-sensitive polymeric micelles MSLP as amplifying oxidative stress vehicles combined chemotherapy and PDT exhibited significant antitumor activity both in vitro (IC50 = 0.041 μg/mL) and much better antitumor efficacy than that of mPEG-PCL-Por (MLP) micelles in vivo.

Polyvinyl alcohol based-drug delivery systems for cancer treatment

Polyvinyl alcohol (PVA) is a biodegradable semicrystalline synthetic polymer that has been used for biomedical applications for several years. In the pharmaceutical area, PVA has been widely used to prepare solid dispersions to improve the solubility of drugs. Furthermore, it has been demonstrated that PVA is highly biocompatible and non-toxic in in-vitro and in-vivo studies. Several reports provided in this review suggest a promising strategy for cancer treatment. Thus far, the current therapy includes a combination of surgery, chemotherapy, and radiotherapy, the effectivity can be limited due to the heterogeneous manifestations of the disease, dose-related toxicity, and side effects. A promising strategy is the implementation of a targeted therapy using hydrogels, microparticles, or nanoparticles (NPs), capable of encapsulating, protecting, transporting, and targeted administration of a therapeutic agent. Considering the relevance of the PVA in conjunction with their copolymers, it has become a promising biodegradable material to build novel functional composites used in the fabrication of hydrogels, microparticles, nanoparticles, and nanocomposites for drug delivery systems in cancer treatment.

Poly(ester-thioether) microspheres co-loaded with erlotinib and α-tocopheryl succinate for combinational therapy of non-small cell lung cancer

Polymer microspheres are attracting wide attention in localized cancer therapy owing to the excellent biocompatibility and drug loading capacity, controllable biodegradation speeds, and minimized systemic toxicity. Herein, we presented poly(ester-thioether) microspheres, porous and nonporous, as drug depots for localized therapy of non-small cell lung cancer (NSCLC). Specifically, erlotinib and α-tocopheryl succinate (α-TOS), which are respectively an epidermal growth factor receptor (EGFR) inhibitor and mitochondria destabilizer, were efficiently loaded into porous and nonporous poly(ester-thioether) microspheres for the treatment of EGFR-overexpressing NSCLC (A549 cells). The poly(ester-thioether) microspheres significantly improved the bioavailability of both erlotinib and α-TOS in comparison to the free drug combination, realizing synergistic inhibition of A549 cells both in vitro and in vivo. The porous microspheres displayed faster degradation and drug release than the nonporous counterpart, thereby showing better anticancer efficacy. Overall, our study reported a new anticancer strategy of erlotinib and α-TOS combination for therapy of NSCLC, and established that poly(ester-thioether) microspheres could be a robust and biodegradable reservoir for drug delivery and localized cancer therapy.

Shear Speed-Regulated Properties of Long-Acting Docetaxel Control Release Poly (Lactic-Co-Glycolic Acid) Microspheres

Advanced drug carriers for the controlled release of chemotherapeutics in the treatment of malignant tumors have drawn significant notice in recent years. In the current study, microspheres (MPs) loaded with docetaxel (DTX) were prepared using polylactic-co-glycolic acid copolymer (PLGA). The double emulsion solvent evaporation method is simple to perform, and results in high encapsulation efficiency. Electron micrographs of the MPs showed that controlling the shear rate can effectively control the size of the MPs. At present, most DTX sustained-release carriers cannot maintain stable and long-term local drug release. The 1.68 μm DTX-loaded microspheres (MP/DTX) with elastase was completely degraded in 14 d. This controlled degradation period is similar to a course of treatment for most cancers. The drug release profile of all kinds of MP/DTX demonstrated an initial rapid release, then slower and stable release to the end. The current study demonstrates that it is possible to create drug-loaded MPs with specific degradation times and drug release curves, which may be useful in achieving optimal treatment times and drug release rates for different diseases, and different drug delivery routes. The initial burst release reaches the effective concentration of the drug at the beginning of release, and then the drug concentration is maintained by stable release to reduce the number of injections and improve patient compliance.

Injectable biodegradation-visual self-healing citrate hydrogel with high tissue penetration for microenvironment-responsive degradation and local tumor therapy

Local tumor therapy through injectable biodegradable hydrogels with controlled drug release has attracted much attention recently, due to their easy operation, low side effect and efficiency. However, most of the reported therapeutic hydrogel system showed a lack of biodegradation tracking and tumor environment-responsive degradation/therapy. Herein, we developed a multifunctional injectable biodegradation-visual citric acid-based self-healing scaffolds with microenvironment-responsive degradation and drug release for safe and efficient skin tumor therapy (FPRC hydrogel). FPRC scaffolds possess multifunctional properties including thermosensitive, injectable, self-healing, photoluminescent and pH-responsive degradation/drug release. The FPRC scaffolds with strong red fluorescence which has good photostability, tissue penetration and biocompatibility can be tracked and monitored to evaluate the degradation of the scaffolds in vivo. Moreover, the FPRC scaffolds showed pH-responsive doxorubicin (DOX) release, efficiently killed the A375 cancer cell in vitro and suppressed the tumor growth in vivo. Compared to the free drug (DOX), the FPRC@DOX scaffolds displayed a significantly high therapeutic effect and less biotoxicity. This work provides an alternative strategy to design smart visual scaffolds for tumor therapy and regenerative medicine.

Current Status of Alginate in Drug Delivery

Alginate is one of the natural polymers that are often used in drug- and protein-delivery systems. The use of alginate can provide several advantages including ease of preparation, biocompatibility, biodegradability, and nontoxicity. It can be applied to various routes of drug administration including targeted or localized drug-delivery systems. The development of alginates as a selected polymer in various delivery systems can be adjusted depending on the challenges that must be overcome by drug or proteins or the system itself. The increased effectiveness and safety of sodium alginate in the drug- or protein-delivery system are evidenced by changing the physicochemical characteristics of the drug or proteins. In this review, various routes of alginate-based drug or protein delivery, the effectivity of alginate in the stem cells, and cell encapsulation have been discussed. The recent advances in the in vivo alginate-based drug-delivery systems as well as their toxicities have also been reviewed.

Designing Biodegradable Wafers Based on Poly(L-lactide-co-glycolide) and Poly(glycolide-co-ε-caprolactone) for the Prolonged and Local Release of Idarubicin for the Therapy of Glioblastoma Multiforme

PURPOSE

The blood-brain barrier limits the application of idarubicin in the therapy of glioblastoma multiforme. Biodegradable, intracranial wafers with prolonged release may increase therapy efficiency.

METHODS

Blank wafers, wafers containing 5% w/w and 10% w/w of idarubicin were formulated by solution casting from poly(L-lactide-co-glycolide) and poly(glycolide-co-ε-caprolactone). The following methods were used: NMR, GPC, DSC, FTIR, AFM, UV-VIS, and a viability and proliferation assay for idarubicin action (U87MG cell line).

RESULTS

Wafers showed a surface with numerous immersions and hills. A lack of interactions between idarubicin and the copolymers was observed. The substance was entrapped in the matrix and released in two phases for all wafers with the appropriate bolus and maintenance dose. The burst effect was observed for all wafers, however, the biggest bolus for poly(L-lactide-co-glycolide) wafers containing 5% w/w of idarubicin was noted. The stable and steady degradation of poly(glycolide-co-ε-caprolactone) wafers containing 5% w/w of idarubicin ensures the most optimal release profile and high inhibition of proliferation.

CONCLUSIONS

Copolymer wafers with idarubicin are an interesting proposition with great potential for the local treatment of glioblastoma multiforme. The release rate and dose may be regulated by the amount and kind of wafers for various effects.

Development of finasteride/PHBV@polyvinyl alcohol/chitosan reservoir-type microspheres as a potential embolic agent: from in vitro evaluation to animal study

Benign prostatic hyperplasia (BPH) is a prevalent urological disease affecting elders. Currently, the prostatic artery embolization (PAE) is considered as a minimally invasive and safe technique to treat BPH. However, various drug-loaded embolic agents have not been thoroughly investigated in BPH therapy. In this study, finasteride/poly(3-hydroxybutyrate-3-hydroxyvalerate)@polyvinyl alcohol/chitosan (FNS/PHBV@PVA/CS) reservoir-type microspheres were prepared via the solid-in-water-in-oil (S/W/O) emulsion crosslinking method with the aim to reduce the burst effect and control localized drug delivery. The structure and properties of the drug and resultant microspheres were characterized via field emission scanning electron microscopy (FESEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that the drug-loaded hybrid microspheres were well-dispersed and spherical with a mean diameter of 238.1 ± 27.3 μm. All samples exhibited excellent thermal stability. The FNS/PHBV microspheres were successfully encapsulated inside the PVA/CS polymeric matrix, which effectively suppressed the burst effect and prolonged the drug release up to 51 days. In vitro biocompatibility assessment indicated that the microspheres possessed excellent cytocompatibility and hemocompatibility. Furthermore, in vivo studies performed in the rabbit ear embolization model showed the formation of progressive ischemic necrosis after treatment for various periods. Histopathological studies revealed that the microspheres completely occluded the blood vessels with minimal foreign body response and formed the fibrotic area at the periphery of embolized arteries. Furthermore, the auricular vascular endothelial cells showed acute ultrastructural changes, associated with the ischemic necrosis induced by the embolization procedures. All these findings suggest that the FNS/PHBV@PVA/CS hybrid microspheres could be used as a promising drug delivery system for potential applications in BPH therapy.

[Preparation and characterization of paclitaxel microspheres in situ gel and its antitumor efficacy by local injection]

OBJECTIVE

The current difficulties in the treatment of tumor include repeated administration and high recurrence rate after tumor resection. In order to reduce the number of doses, avoid side effects of chemotherapeutic drugs, suppress tumor growth and delay tumor recurrence after surgery, a temperature-sensitive in situ gel with paclitaxel microspheres (PTX/M gel) was prepared. PTX/M gel was administered by intratumoral injection once a month.

METHODS

First of all, paclitaxel microspheres (PTX/M) were prepared by emulsion solvent evaporation method. A laser particle size distribution analyzer was used to investigate the size, distribution, specific surface area of microspheres. Paclitaxel content was determined by high performance liquid chromatography (HPLC). Then encapsulation efficiency of paclitaxel was calculated and in vitro release characteristics were studied. Secondly, PTX/M gel was prepared by cold dissolution method. The phase transition temperature, elastic modulus, dissolution curve, correlation between dissolution and release were measured. Finally, U87 MG and 4T1 subcutaneous tumor models were established respectively to study the efficacy of PTX/M gel in suppressing tumor growth and delaying tumor recurrence after surgery.

RESULTS

The median diameter of the selected PTX/M was (32.24±1.09) μm, the specific surface area was (206.61±10.23) m²/kg, the encapsulation efficiency was 85.29%±1.34%, and the cumulative release percentage of paclitaxel from PTX/M was 33.56%±3.33% in one month. Phase transition temperature of PTX/M gel was 33 °C. The elastic modulus of PTX/M gel at 25 °C and 37 °C were 4.2×103 Pa and 18×103 Pa, respectively. The gel could stay in the body for up to 48 hours. It could be seen from the results of animal experiments that were compared with the saline group and the Taxol group, and the tumor-bearing mice of the PTX/M gel group had the slowest tumor growth (P<0.05). Similarly, in the tumor recurrence experiments, the mice of PTX/M gel group had the latest tumor recurrence after surgery.

CONCLUSION

As a local sustained-release preparation, PTX/M gel can effectively suppress tumor growth and delay postoperative recurrence of tumors. It has potential advantages in tumor treatment.

Nanocarriers and nonviral methods for delivering antiangiogenic factors for glioblastoma therapy: the story so far

Angiogenesis, the formation of new blood vessels, is an essential component of glioblastoma (GB) progression. The development of angiogenesis inhibitor therapy, including treatments targeting vascular endothelial growth factor (VEGF) in particular, raised new hopes for the treatment of GB, but no Phase III clinical trial to date has reported survival benefits relative to standard treatment. There are several possible reasons for this limited efficacy, including VEGF-independent angiogenesis, induction of tumor invasion, and inefficient antiangiogenic factor delivery to the tumor. Efforts have been made to overcome these limitations by identifying new angiogenesis inhibitors that target angiogenesis through different mechanisms of action without inducing tumor invasion, and through the development of viral and nonviral delivery methods to improve antiangiogenic activity. Herein, we describe the nonviral methods, including convection-enhanced delivery devices, implantable polymer devices, nanocarriers, and cellular vehicles, to deliver antiangiogenic factors. We focus on those evaluated in intracranial (orthotopic) animal models of GB, the most relevant models of this disease, as they reproduce the clinical scenario of tumor progression and therapy response encountered in GB patients.

Embryonic Stem Cells-Derived Exosomes Endowed with Targeting Properties as Chemotherapeutics Delivery Vehicles for Glioblastoma Therapy

Exosomes are nanosized membrane vesicles (30-100 nm) that can easily penetrate the blood-brain barrier, safely deliver therapeutic drugs, and be modified with target ligands. Embryonic stem cells (ESCs) provide abundant exosome sources for clinical application due to their almost unlimited self-renewal. Previous studies show that exosomes secreted by ESCs (ESC-exos) have antitumor properties. However, it is not known whether ESC-exos inhibit glioblastoma (GBM) growth. In this study, the anti-GBM effect of ESC-exos is confirmed and then c(RGDyK)-modified and paclitaxel (PTX)-loaded ESC-exos, named cRGD-Exo-PTX are prepared. It is then investigated whether the engineered exosomes deliver more efficiently to GBM cells versus free drug alone and drug-loaded ESC-exos using an in vitro GBM model and in vivo subcutaneous and orthotopic xenografts model. The results show that cRGD-Exo-PTX significantly improves the curative effects of PTX in GBM via enhanced targeting. These data indicate that ESC-exos are potentially powerful therapeutic carriers for GBM and could have utility in many other diseases.

Electro-Assisted Bioprinting of Low-Concentration GelMA Microdroplets

Low-concentration gelatin methacryloyl (GelMA) has excellent biocompatibility to cell-laden structures. However, it is still a big challenge to stably fabricate organoids (even microdroplets) using this material due to its extremely low viscosity. Here, a promising electro-assisted bioprinting method is developed, which can print low-concentration pure GelMA microdroplets with low cost, low cell damage, and high efficiency. With the help of electrostatic attraction, uniform GelMA microdroplets measuring about 100 μm are rapidly printed. Due to the application of lower external forces to separate the droplets, cell damage during printing is negligible, which often happens in piezoelectric or thermal inkjet bioprinting. Different printing states and effects of printing parameters (voltages, gas pressure, nozzle size, etc.) on microdroplet diameter are also investigated. The fundamental properties of low-concentration GelMA microspheres are subsequently studied. The results show that the printed microspheres with 5% w/v GelMA can provide a suitable microenvironment for laden bone marrow stem cells. Finally, it is demonstrated that the printed microdroplets can be used in building microspheroidal organoids, in drug controlled release, and in 3D bioprinting as biobricks. This method shows great potential use in cell therapy, drug delivery, and organoid building.

Physicochemical Characterization and Pharmacokinetics of Agomelatine-Loaded PLGA Microspheres for Intramuscular Injection

PURPOSE

The aim of this study was to design agomelatine loaded long acting injectable microspheres, with an eventual goal of reducing the frequency of administration and improving patient compliance in treatment of depression.

METHODS

AGM-loaded microspheres were prepared by an O/W emulsion solvent evaporation method. The physicochemical properties and in vitro performance of the microspheres were characterized. The pharmacokinetics of different formulations with various particle sizes and drug loadings were evaluated.

RESULTS

AGM-loaded microspheres with drug loading of 23.7% and particle size of 60.2 μm were obtained. The in vitro release profiles showed a small initial burst release (7.36%) followed by a fast release, a period of lag time and a second accelerated release. Pore formation and pore closure were observed in vitro, indicating that the release of drug from microspheres is dominated by water-filled pores. Pharmacokinetic studies showed that AGM microspheres could release up to 30 days in vivo at a steady plasma concentration. As well, particle size and drug loading could significantly influence the in vivo release of AGM microspheres.

CONCLUSIONS

AGM-loaded microspheres are a promising carrier for the treatment of major depressant disorder.

Primary M1 macrophages as multifunctional carrier combined with PLGA nanoparticle delivering anticancer drug for efficient glioma therapy

Glioma remains difficult to treat because of the infiltrative growth of tumor cells and their resistance to standard therapy. Despite rapid development of targeted drug delivery system, the current therapeutic efficacy is still challenging. Based on our previous studies, macrophages have been proved to be promising drug carrier for active glioma delivery. To make full use of macrophage carrier, primary M1 macrophages were proposed to replace regular macrophage to deliver nanodrugs into glioma, because M1 macrophages not only have the natural ability to home into tumor tissues, but they also have stronger phagocytic capability than other types of macrophage, which can enable them to uptake enough drug-loaded nanoparticles for therapy. In addition, M1 macrophages are not easily affected by harsh tumor microenvironment and inhibit tumor growth themselves. In this study, M1 macrophage-loaded nanoparticles (M1-NPs) were prepared by incubating poly(lactide-co-glycolide) (PLGA) nanoparticles with primary M1 macrophages. In vitro cell assays demonstrated M1 macrophage still maintained good tumor tropism capability after particle loading, and could efficiently carry particles across endothelial barrier into tumor tissues. In vivo imaging verified that M1-NPs exhibited higher brain tumor distribution than free nanoparticles. DOX@M1-NPs (doxorubicin-loaded M1-NPs) presented significantly enhanced anti-glioma effect with prolonged survival median and increased cell apoptosis. In conclusion, the results provided a new strategy exploiting M1 macrophage as carrier for drug delivery, which improved targeting efficiency and therapeutic efficacy of chemodrugs for glioma therapy.

Using drug-loaded pH-responsive poly(4-vinylpyridine) microspheres as a new strategy for intelligent controlling of Lactobacillus plantarum contamination in bioethanol fermentation

Bioethanol fermentation is usually contaminated by bacteria, especially lactic acid bacteria (LAB), thereby leading to decrease of bioethanol yield and serious economic losses. Nisin is safer for controlling of bacterial contamination than antibiotics that are widely applied in industry. Moreover, in LAB contaminative bioethanol fermentation system, consistently decreased pH value provides opportunity to realize pH value responsive material-based release of anti-bacteria substances for intelligent and persistent controlling of bacterial contamination. In this study, nisin was embedded into pH-sensitive poly(4-vinylpyridine) (P4VP) microspheres synthesized by suspension polymerization to realize intelligent controlling of Lactobacillus plantarum contamination in bioethanol fermentation. Chloramphenicol with the highest antimicrobial activity and excellent stability was chosen as the model drug to be embedded into P4VP microspheres to test the drug release behavior. The drug release curve of chloramphenicol-loaded P4VP microspheres showed sustained and pH-responsive release properties. The diameters of the microspheres ranged from 40 to 100 µm. The encapsulation efficiency of nisin into P4VP microspheres was 47.67% and the drug-loading capacity of nisin was 2.5%. Nisin-loaded P4VP microspheres were added into the simulated contaminative fermentation system, and successfully reversed the decline of bioethanol yield secondary to L. plantarum contamination. The results in this study indicated that L. plantarum contamination in bioethanol fermentation could be effectively controlled by nisin-loaded P4VP microspheres.

Aggressive Man-Made Red Blood Cells for Hypoxia-Resistant Photodynamic Therapy

Extreme hypoxia of tumors represents the most notable barrier against the advance of tumor treatments. Inspired by the biological nature of red blood cells (RBCs) as the primary oxygen supplier in mammals, an aggressive man-made RBC (AmmRBC) is created to combat the hypoxia-mediated resistance of tumors to photodynamic therapy (PDT). Specifically, the complex formed between hemoglobin and enzyme-mimicking polydopamine, and polydopamine-carried photosensitizer is encapsulated inside the biovesicle that is engineered from the recombined RBC membranes. The mean corpuscular hemoglobin of AmmRBCs reaches about tenfold as high as that of natural RBCs. Owing to the same origin of outer membranes, AmmRBCs share excellent biocompatibility with parent RBCs. The introduced polydopamine plays the role of the antioxidative enzymes existing inside RBCs to effectively prevent the oxygen-carrying hemoglobin from the oxidation damage during the circulation. This biomimetic engineering can accumulate in tumors, permit in situ efficient oxygen supply, and impose strong PDT efficacy toward the extremely hypoxic tumor with complete tumor elimination. The man-made pseudo-RBC shows potentials as a universal oxygen-self-supplied platform to sensitize hypoxia-limited tumor treatment means, including but not limited to PDT. Meanwhile, this study offers ideas to the production of artificial substitutes of packed RBCs for clinical blood transfusion.

Design and Synthesis of a Biocompatible 1D Coordination Polymer as Anti-Breast Cancer Drug Carrier, 5-Fu: In Vitro and in Vivo Studies

Designable coordination polymers with suitable chemical diversities and biocompatible structures have been proposed as a promising class of vehicles for drug delivery systems. Here, we hydrothermally synthesized a novel one-dimensional (1D) coordination polymer, [Zn(H₂O)₆K₂(H₂BTC)₂(H₂O)₄](H₂BTC)₂·2H₂O, where H₃BTC = benzene-1,3,5-tricarboxylic acid (trimesic acid), cp.1. As the hydrogen bonds stabilized 1D chains in three dimensions, the cp.1 could be a good candidate for delivering small-molecule chemotherapeutics such as 5-fluorouracil (5-Fu). The synthesized cp.1 showed a remarkable 5-Fu loading of 66% with encapsulation efficiency of 98% and almost complete release process. The 5-Fu-loaded cp.1 displayed a time-dependent cytotoxicity effect against breast cancer cell lines MCF-7 and 4T1. The cellular uptake of cp.1 particles was investigated via confocal laser scanning microscopy using fluorescein isothiocyanate and LysoTracker Red staining. Furthermore, the in vivo antitumor impact of 5-Fu-loaded cp.1 was studied on 4T1 breast cancer BALB/c mice model. The intratumor treatment of 5-Fu-loaded cp.1 demonstrated beneficial antitumor efficacy by postponing tumor growth. These results suggest that the 5-Fu-loaded cp.1 microparticles with a great locoregional delivery can be efficient anticancer drug carriers for further clinical treatments.

Biodegradable polylactide and thermoplastic starch blends as drug release device – mass transfer study

Four different compositions of polylactide/thermoplastic starch blends (PLA/TPS blends) for application as drug carriers were examined. Initially, using cyanocobalamin (1.355 kDa) as a model compound, the blend with the highest starch content (wt. 60%) was selected for further research of mass transfer phenomenon. In this case, different concentrations of acetaminophen (0.151 kDa), doxorubicin hydrochloride (0.580 kDa) and cyanocobalamin (1.355 kDa) were used for determination of particular releasing profiles. Besides from the comparative analysis of obtained results, the values of the overall mass transfer coefficient (K) were calculated for each of tested drug molecules. Depending on the size and properties of used compound, determined values of the coefficient range from 10−11 to 10−13 m/s. Based on these outcomes, it could be stated that PLA/TPS blend selected in preliminary research, seems to be preferred material for fabrication of long-term drug delivery systems, which could be successfully applied for example in anti-cancer therapy.

Nanocomposite Microgels for the Selective Separation of Halogen Compounds from Aqueous Solution

Nanocomposite microgels that selectively adsorb and release halogen compounds were developed. These nanocomposite microgels consist of poly(2-methoxyethyl acrylate) (pMEA) and a poly(oligo ethylene glycol methacrylate) hydrogel matrix. Therefore, the methoxy groups of the former are crucial for the halogen bonding, while the presence of the latter adds colloidal stability and allows controlled uptake/release of the halogen compounds. Such nanocomposite microgels may not only be used as dispersed carriers, but also in films and columnar formations. Thus, these unprecedented polymer/polymer nanocomposite microgels resolve a variety of problems associated with, e.g., the removal of halogen compounds from wastewater, or with the delivery of halogen-containing drugs.

pH-Responsive Nanoscale Coordination Polymer for Efficient Drug Delivery and Real-Time Release Monitoring

Both excess dosages of drug and unwanted drug carrier can lead to severe side effects as well as the failure of tumor therapy. Here, an Fe³⁺ -gallic acid based drug delivery system is designed for efficient monitoring of drug release in tumor. Fe³⁺ and polyphenol gallic acid can form polygonal nanoscale coordination polymer in aqueous solution, which exhibits certain antitumor effect. Importantly, this coordination polymer possesses extremely high doxorubicin (DOX) loading efficacy (up to 48.3%). In vitro studies demonstrate that the fluorescence of DOX can be quenched efficiently when DOX is loaded on the coordination polymer. The acidity in lysosome also triggers the release of DOX and fluorescence recovery simultaneously, which realizes real-time monitoring of drug release in tumor cells. In vivo studies further indicate that this polyphenol-rich drug delivery system can significantly inhibit tumor growth with negligible heart toxicity of DOX. This system with minimal side effects should be a promising nanoplatform for tumor treatment.