PLGA-based nanoparticles: A new paradigm in biomedical applications

Gold nanoparticles for sustained antileukemia drug release: development, optimization and evaluation by quality-by-design approach

AIM

To design, develop, optimize and evaluate sustained-release dasatinib-loaded gold nanoparticles (DSB-GNPs) to treat chronic myeloid leukemia (CML) by using quality by design.

MATERIALS & METHODS

In this study, we performed risk assessment, optimization, in vitro characterizations, stability study, drug release studies, cytotoxicity study and in vivo pharmacokinetic evaluation.

RESULTS

DSB-GNPs of desired size, entrapment, smooth, spherical, stable and sustained drug release for 48 h were achieved. DSB-GNPs exhibited significantly more percentage growth inhibition and enhanced systemic bioavailability compared with pure DSB.

CONCLUSION

The in vitro and in vivo evaluation exhibited that the DSB-GNPs have a potential cytotoxic effect, systemic bioavailability and sustained release making them a promising system of DSB delivery in the treatment of chronic myeloid leukemia.

Dual-drug loaded nanoparticles of Epigallocatechin-3-gallate (EGCG)/Ascorbic acid enhance therapeutic efficacy of EGCG in a APPswe/PS1dE9 Alzheimer's disease mice model

Epigallocatechin-3-gallate (EGCG) is a candidate for treatment of Alzheimer's disease (AD) but its inherent instability limits bioavailability and effectiveness. We found that EGCG displayed increased stability when formulated as dual-drug loaded PEGylated PLGA nanoparticles (EGCG/AA NPs). Oral administration of EGCG/AA NPs in mice resulted in EGCG accumulation in all major organs, including the brain. Pharmacokinetic comparison of plasma and brain accumulation following oral administration of free or EGCG/AA NPs showed that, whilst in both cases initial EGCG concentrations were similar, long-term (5–25 h) concentrations were ca. 5 fold higher with EGCG/AA NPs. No evidence was found that EGCG/AA NPs utilised a specific pathway across the blood-brain barrier (BBB). However, EGCG, empty NPs and EGCG/AA NPs all induced tight junction disruption and opened the BBB in vitro and ex vivo. Oral treatment of APPswe/PS1dE9 (APP/PS1) mice, a familial model of AD, with EGCG/AA NPs resulted in a marked increase in synapses, as judged by synaptophysin (SYP) expression, and reduction of neuroinflammation as well as amyloid β (Aβ) plaque burden and cortical levels of soluble and insoluble Aβ_(1-42) peptide. These morphological changes were accompanied by significantly enhanced spatial learning and memory. Mechanistically, we propose that stabilisation of EGCG in NPs complexes and a destabilized BBB led to higher therapeutic EGCG concentrations in the brain. Thus EGCG/AA NPs have the potential to be developed as a safe and strategy for the treatment of AD.

Preparation and Evaluation of Irinotecan Poly(Lactic-co-Glycolic Acid) Nanoparticles for Enhanced Anti-tumor Therapy

Irinotecan (IRT), the pro-drug of SN-38, has exhibited potent cytotoxicity against various tumors. In order to enhance the anti-tumor effect of IRT, we prepared IRT-loaded PLGA nanoparticles (IRT-PLGA-NPs) by emulsion-solvent evaporation method. Firstly, IRT-PLGA-NPs were characterized through drug loading (DL), entrapment efficiency (EE), particle size, zeta potential, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). We next studied the in vitro release characteristics of IRT-PLGA-NPs. Finally, the pharmacokinetics and pharmacodynamics profiles of IRT-PLGA-NPs were investigated. The results revealed that IRT-PLGA-NPs were spherical with an average size of (169.97 ± 6.29) nm and its EE and DL were (52.22 ± 2.41)% and (4.75 ± 0.22)%, respectively. IRT-PLGA-NPs could continuously release drug for 14 days in vitro. In pharmacokinetics studies, for pro-drug IRT, the t_1/2β of IRT-PLGA-NPs was extended from 0.483 to 3.327 h compared with irinotecan solution (IRT-Sol), and for its active metabolite SN-38, the t_1/2β was extended from 1.889 to 4.811 h, which indicated that IRT-PLGA-NPs could prolong the retention times of both IRT and SN-38. The pharmacodynamics results revealed that the tumor doubling time, growth inhibition rate, and specific growth rate of IRT-PLGA-NPs were 2.13-, 1.30-, and 0.47-fold those of IRT-Sol, respectively, which demonstrated that IRT-PLGA-NPs could significantly inhibit the growth of tumor. In summary, IRT-PLGA-NPs, which exhibited excellent therapeutic effect against tumors, might be used as a potential carrier for tumor treatment in clinic.

Recent Advances in Polymeric Nanomedicines for Cancer Immunotherapy

Immunotherapy has emerged as a promising approach to treat cancer, since it facilitates eradication of cancer by enhancing innate and/or adaptive immunity without using cytotoxic drugs. Of the immunotherapeutic approaches, significant clinical potentials are shown in cancer vaccination, immune checkpoint therapy, and adoptive cell transfer. Nevertheless, conventional immunotherapies often involve immune-related adverse effects, such as liver dysfunction, hypophysitis, type I diabetes, and neuropathy. In an attempt to address these issues, polymeric nanomedicines are extensively investigated in recent years. In this review, recent advances in polymeric nanomedicines for cancer immunotherapy are highlighted and thoroughly discussed in terms of 1) antigen presentation, 2) activation of antigen-presenting cells and T cells, and 3) promotion of effector cells. Also, the future perspectives to develop ideal nanomedicines for cancer immunotherapy are provided.

Docetaxel-loaded human serum albumin (HSA) nanoparticles: synthesis, characterization, and evaluation

Background

Docetaxel (DTX) is an anticancer drug that is currently formulated with polysorbate 80 and ethanol (50:50, v/v) in clinical use. Unfortunately, this formulation causes hypersensitivity reactions, leading to severe side-effects, which have been primarily attributed to polysorbate 80.

Methods

In this study, a DTX-loaded human serum albumin (HSA) nanoparticle (DTX-NP) was designed to overcome the hypersensitivity reactions that are induced by polysorbate 80. The methods of preparing the DTX-NPs have been optimized based on factors including the drug-to-HSA weight ratio, the duration of HSA incubation, and the choice of using a stabilizer. Synthesized DTX-NPs were characterized with regard to their particle diameters, drug loading capacities, and drug release kinetics. The morphology of the DTX-NPs was observed via scanning electron microscopy (SEM) and the successful preparation of DTX-NPs was confirmed via differential scanning calorimetry (DSC). The cytotoxicity and cellular uptake of DTX-NPs were investigated in the non-small cell lung cancer cell line A549 and the maximum tolerated dose (MTD) of DTX-NPs was evaluated via investigations with BALB/c mice.

Results

The study showed that the loading capacity and the encapsulation efficiency of DTX-NPs prepared under the optimal conditions was 11.2 wt% and 63.1 wt%, respectively and the mean diameter was less than 200 nm, resulting in higher permeability and controlled release. Similar cytotoxicity against A549 cells was exhibited by the DTX-NPs in comparison to DTX alone while higher maximum tolerated dose (MTD) with the DTX-NPs (75 mg/kg) than with DTX (30 mg/kg) was demonstrated in mice, suggesting that the DTX-NPs prepared with HSA yielded similar anti-tumor activity but were accompanied by less systemic toxicity than solvent formulated DTX.

Conclusions

DTX-NPs warrant further investigation and are promising candidates for clinical applications.

PLGA-Based Nanoparticles in Cancer Treatment

Nanomedicines can be used for a variety of cancer therapies including tumor-targeted drug delivery, hyperthermia, and photodynamic therapy. Poly (lactic-co-glycolic acid) (PLGA)-based materials are frequently used in such setups. This review article gives an overview of the properties of previously reported PLGA nanoparticles (NPs), their behavior in biological systems, and their use for cancer therapy. Strategies are emphasized to target PLGA NPs to the tumor site passively and actively. Furthermore, combination therapies are introduced that enhance the accumulation of NPs and, thereby, their therapeutic efficacy. In this context, the huge number of reports on PLGA NPs used as drug delivery systems in cancer treatment highlight the potential of PLGA NPs as drug carriers for cancer therapeutics and encourage further translational research.

AS1411 aptamer-decorated cisplatin-loaded poly(lactic-co-glycolic acid) nanoparticles for targeted therapy of miR-21-inhibited ovarian cancer cells

AIM

The overexpression of miRNA-21 correlates with the cisplatin (CIS) resistance in the ovarian cancers.

METHODS

AS1411 antinucleolin aptamer-decorated PEGylated poly(lactic-co-glycolic acid) nanoparticles containing CIS (Ap-CIS-NPs) and anti-miR-21 (Ap-anti-miR-21-NPs) were prepared, physicochemically investigated and their cancer-targeting ability was confirmed. CIS-resistant A2780 cells (A2780 R) were infected with anti-miR-21 using Ap-anti-miR-21-NPs to decrease the drug resistance and sensitize the cells to CIS. Afterward, miR-21-inhibited cells were exposed to the Ap-CIS-NPs.

RESULTS

Ap-anti-miR-21-NPs could infect the A2780 R cells mainly through nucleolin-mediated endocytosis and inhibit the endogenous miR-21. Targeted delivery of CIS using Ap-CIS-NPs into the miR-21-inhibited cells caused an enhanced mortality.

CONCLUSION

The targeted delivery of chemotherapeutics to the oncomiR-inhibited cells may find a robust application in cancer chemo/gene therapy.

PLGA: From a classic drug carrier to a novel therapeutic activity contributor

Poly(lactic-co-glycolic acid) (PLGA) is well known for its biocompatibility and minimal toxicity. It is one of the most promising biodegradable polymeric drug delivery systems able to get endorsement from regulatory bodies to enter market. For many decades, PLGA has been functioning as an excipient, which by definition is pharmaceutically inert at a given dose of formulation. Lactate (one of the hydrolysis products of PLGA) has a key role in biochemical pathways and could improve physiological activities in certain illnesses by exerting therapeutic effects such as angiogenesis and promotion of healing. These activities, however, depend on the released amounts and metabolic clearance of lactate and route of formulation delivery. In the current commentary, along with several key notes on the lactate interactions, we would like to inform the PLGA research community that lactate (resulting from local delivery of physiologically significant amount of PLGA) may positively or negatively affect therapeutic efficacy of certain drugs. Hence, the excipient role of PLGA may be investigated for its potential pharmacological contributions in some biomedical applications.

Antibiofilm Coatings Based on PLGA and Nanostructured Cefepime-Functionalized Magnetite

The aim of our study was to obtain and evaluate the properties of polymeric coatings based on poly(lactic-co-glycolic) acid (PLGA) embedded with magnetite nanoparticles functionalized with commercial antimicrobial drugs. In this respect, we firstly synthesized the iron oxide particles functionalized (@) with the antibiotic Cefepime (Fe₃O₄@CEF). In terms of composition and microstructure, the as-obtained powdery sample was investigated by means of grazing incidence X-ray diffraction (GIXRD), thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM, respectively). Crystalline and nanosized particles (~5 nm mean particle size) with spherical morphology, consisting in magnetite core and coated with a uniform and reduced amount of antibiotic shell, were thus obtained. In vivo biodistribution studies revealed the obtained nanoparticles have a very low affinity for innate immune-related vital organs. Composite uniform and thin coatings based on poly(lactide-co-glycolide) (PLGA) and antibiotic-functionalized magnetite nanoparticles (PLGA/Fe₃O₄@CEF) were subsequently obtained by using the matrix assisted pulsed laser evaporation (MAPLE) technique. Relevant compositional and structural features regarding the composite coatings were obtained by performing infrared microscopy (IRM) and SEM investigations. The efficiency of the biocompatible composite coatings against biofilm development was assessed for both Gram-negative and Gram-positive pathogens. The PLGA/Fe₃O₄@CEF materials proved significant and sustained anti-biofilm activity against staphylococcal and Escherichia coli colonisation.

Carcinoembryonic antigen-targeted nanoparticles potentiate the delivery of anticancer drugs to colorectal cancer cells

Bioengineered functionalized nanoparticles have extensively been proposed in recent years to efficiently deliver anti-cancer drugs to the tumour site, by targeting the cancer cells and improving the therapeutic efficiency of active molecules. In this work, polymeric poly (lactic-co- glycolic)-polyethyleneglycol (PLGA-PEG) nanoparticles were produced by nanoprecipitation and loaded with paclitaxel, following surface-functionalized with a monoclonal antibody targeting the carcinoembryonic antigen (CEA) of intestinal epithelial cells. Physicochemical properties, cytotoxicity and targeting ability of the nanoparticles against two intestine epithelial carcinoma cell lines, CEA-expressing Caco-2 clone and non-CEA-expressing SW480, were assessed. Results showed successful production of nanoparticles around 200 nm, and close to charge neutrality, encapsulating up to 99% of paclitaxel. Functionalized nanoparticles were further constructed, demonstrating to be non-cytotoxic against intestinal cells. The targeting ability of functionalized nanoparticles to Caco-2 CEA expressing cells was confirmed by flow cytometry, in opposite to SW480 cells. Overall, the surface-modified PLGA-PEG nanoparticles with the CEA-targeting antibody were successfully developed as nanocarriers for paclitaxel and interacted with CEA expressing cells. This specific interaction provide these particles ability to be used as targeted systems for colorectal cancer therapeutics.

Improvement of N-Acetylcysteine Loaded in PLGA Nanoparticles by Nanoprecipitation Method

N-Acetylcysteine (NAC) is a hydrophilic compound with a low bioavailability. It has been used as an effective antioxidant agent. This research seeks to enhance the entrapment of NAC in PLGA nanoparticles for drug delivery systems. The nanoparticles were made using the nanoprecipitation method and changing the following parameters: the solvent/nonsolvent nature, its viscosity, pH, NAC addition to the nonsolvent, the polymer concentration and molecular weight, and NAC concentration in the solvent. The results showed that an increase in the nonsolvent viscosity produces NAC concentration in the solvent, and the nonsolvent rises its entrapment in the nanoparticles. Nanoparticles with 235.5 ± 11.4 nm size with an entrapment efficiency of 0.4 ± 0.04% and a specific load of 3.14 ± 0.33% were obtained. The results suggest that besides efficiently entrapping hydrophobic compounds, the nanoprecipitation method also has a high potential as an alternative entrapment method for hydrophilic compounds as well. However, its use in the pharmaceutical industry, as a proper specific load vehicle, still depends on the improvement of the load capacity.

Therapeutic Contact Lenses with Polymeric Vehicles for Ocular Drug Delivery: A Review

The eye has many barriers with specific anatomies that make it difficult to deliver drugs to targeted ocular tissues, and topical administration using eye drops or ointments usually needs multiple instillations to maintain the drugs’ therapeutic concentration because of their low bioavailability. A drug-eluting contact lens is one of the more promising platforms for controllable ocular drug delivery, and, among various manufacturing methods for drug-eluting contact lenses, incorporation of novel polymeric vehicles with versatile features makes it possible to deliver the drugs in a sustained and extended manner. Using the diverse physicochemical properties of polymers for nanoparticles or implants that are selected according to the characteristics of drugs, enhancement of encapsulation efficiency and prolonged drug release are possible. Even though therapeutic contact lenses with polymeric vehicles allow us to achieve sustained ocular drug delivery, drug leaching during storage and distribution and the possibility of problems related to surface roughness due to the incorporated vehicles still need to be discussed before application in a real clinic. This review highlights the overall trends in methodology to develop therapeutic contact lenses with polymeric vehicles and discusses the limitations including comparison to cosmetically tinted soft contact lenses.

Nanofiber technology in the ex vivo expansion of cord blood-derived hematopoietic stem cells

Umbilical cord blood (CB) can be used as an alternative source of hematopoietic stem cells (HSCs) for transplantation in hematological and non-hematological disorders. Despite several recognized advantages the limited cell number in CB one unit still restricts its clinical use. The success of transplantation greatly depends on the levels of total nucleated cell and CD34+ cell counts. Thus, many ex vivo strategies have been developed within the last decade in order to solve this obstacle, with more or less success, mainly determined by the degree of difficulty related with maintaining HSCs self-renewal and stemness properties after long-term expansion. Different research groups have developed very promising and diverse CB-derived HSC expansion strategies using nanofiber scaffolds. Here we review the state-of-the-art of nanofiber technology-based CB-derived HSC expansion.

Customizing poly(lactic-co-glycolic acid) particles for biomedical applications

Nano- and microparticles have increasingly widespread applications in nanomedicine, ranging from drug delivery to imaging. Poly(lactic-co-glycolic acid) (PLGA) particles are the most widely-applied type of particles due to their biocompatibility and biodegradability. Here, we discuss the preparation of PLGA particles, and various modifications to tailor particles for applications in biological systems. We highlight new preparation approaches, including microfluidics and PRINT method, and modifications of PLGA particles resulting in novel or responsive properties, such as Janus or upconversion particles. Finally, we describe how the preparation methods can- and should-be adapted to tailor the properties of particles for the desired biomedical application. Our aim is to enable researchers who work with PLGA particles to better appreciate the effects of the selected preparation procedure on the final properties of the particles and its biological implications.

STATEMENT OF SIGNIFICANCE

Nanoparticles are increasingly important in the field of biomedicine. Particles made of polymers are in the spotlight, due to their biodegradability, biocompatibility, versatility. In this review, we aim to discuss the range of formulation techniques, manipulations, and applications of poly(lactic-co-glycolic acid) (PLGA) particles, to enable a researcher to effectively select or design the optimal particles for their application. We describe the various techniques of PLGA particle synthesis and their impact on possible applications. We focus on recent developments in the field of PLGA particles, and new synthesis techniques that have emerged over the past years. Overall, we show how the chemistry of PLGA particles can be adapted to solve pressing biological needs.

CD44 targeted PLGA nanomedicines for cancer chemotherapy

In recent years scientific community has drawn a great deal of attention towards understanding the enigma of cluster of differentiation-44 (CD44) in order to deliver therapeutic agents more selectively towards tumor tissues. Moreover, its over-expression in variety of solid tumors has attracted drug delivery researchers to target this receptor with nanomedicines. Conventional nanomedicines based on biodegradable polymers such as poly(lactide-co-glycolide) (PLGA) are often associated with insufficient cellular uptake by cancer cells, due to lack of active targeting moiety on their surface. Therefore, to address this limitation, CD44 targeted PLGA nanomedicines has gained considerable interest for enhancing the efficacy of chemotherapeutic agents. In this review, we have elaborately discussed the recent progress in the design and synthesis of CD44 targeted PLGA nanomedicines used to improve tumor-targeted drug delivery. We have also discussed strategies based on co-targeting of CD44 with other targeting moieties such as folic acid, human epidermal growth factor 2 (HER2), monoclonal antibodies using PLGA based nanomedicines.

Fast Degradable Polycaprolactone for Drug Delivery

Polycaprolactone (PCL) was reported a long time ago; however, its biomedical applications has not been extensively investigated in comparison with poly(lactide- co-glycolide) (PLGA) due to its too slow degradation profile. Here, we are reporting an oxalate-connected oligocaprolactone multiblock copolymer (PCL-OX) as a fast degradable PCL while maintaining its crystalline properties and low melting point of PCL. The in vivo application of the paclitaxel-loaded PCL-OX microspheres provided a steady plasma drug concentration of 6-9 μg/mL over 28 days, similar to that of the PLGA microspheres. Both PCL and PLGA microspheres were completely cleared two months after in vivo implantation. The PCL-OX microspheres showed a similar tissue compatibility to that of PLGA microspheres in the subcutaneous layer of rats. These findings suggest that PCL-OX is a useful biomaterial that solves the slow degradation problems of PCL and, thus, may find uses in other biomedical applications as an alternative to PLGA.

Antifungal Activity of Chitosan-Coated Poly(lactic-co-glycolic) Acid Nanoparticles Containing Amphotericin B

Amphotericin B (AmB) is one of the most used drugs for the treatment of systemic fungal infections; however, the treatment causes several toxic manifestations, including nephrotoxicity and hemolytic anemia. Chitosan-coated poly(lactide-co-glycolide) (PLGA) nanoparticles containing AmB were developed with the aim to decrease AmB toxicity and propose the oral route for AmB delivery. In this work, the antifungal efficacy of chitosan-coated PLGA nanoparticles containing AmB was evaluated in 20 strains of fungus isolates from patients with vulvovaginal candidiasis (01 Candida glabrata and 03 Candida albicans), bloodstream infections (04 C. albicans and 01 C. tropicalis) and patients with urinary tract infection (04 Candida albicans, 02 Trichosporon asahii, 01 C. guilhermondii, 03 C. glabrata) and 01 Candida albicans ATCC 90028. Moreover, the cytotoxicity over erythrocytes was evaluated. The single-emulsion solvent evaporation method was suitable for obtaining chitosan-coated PGLA nanoparticles containing AmB. Nanoparticles were spherical in shape, presented mean particle size about 460 nm, positive zeta potential and encapsulation efficiency of 42%. Moreover, nanoparticles prolonged the AmB release. All the strains were susceptible to plain AmB and nanostructured AmB, according to EUCAST breakpoint version 8.1 (resistant > 1 μg/mL), using broth microdilution method. In C. albicans (urine, blood, and vulvovaginal secretion isolates, and 1 ATCC), the MIC value of AmB-loaded nanoparticles varied from 0.25 to 0.5 μg/mL and EUCAST varied from 0.03 to 0.5 μg/mL. In urine and vulvovaginal secretion isolates of C. glabrata, the MIC value of AmB-loaded nanoparticles varied from 0.25 to 0.5 μg/mL and EUCAST varied from 0.03 to 0.015 μg/mL. In urine isolates of C. guilhermondii, the MIC value of AmB-loaded nanoparticles was 0.12 μg/mL and EUCAST was 0.06 μg/mL. In blood isolates of C. tropicalis, the MIC value of AmB-loaded nanoparticles was 0.5 μg/mL and EUCAST was 0.25 μg/mL. Finally, in urine isolates of T asahii, the MIC value of AmB-loaded nanoparticles was 1 μg/mL and EUCAST varied from 0.5 to 1 μg/mL. In the cytotoxicity assay, plain AmB was highly hemolytic (100% in 24 h) while AmB-loaded chitosan/PLGA nanoparticles presented negligible hemolysis.

Epigallocatechin-3-gallate loaded PEGylated-PLGA nanoparticles: A new anti-seizure strategy for temporal lobe epilepsy

Temporal lobe epilepsy is the most common type of pharmacoresistant epilepsy in adults. Epigallocatechin-3-gallate has aroused much interest because of its multiple therapeutic effects, but its instability compromises the potential effectiveness. PEGylated-PLGA nanoparticles of Epigallocatechin-3-gallate were designed to protect the drug and to increase the brain delivery. Nanoparticles were prepared by the double emulsion method and cytotoxicity, behavioral, Fluoro-Jade C, Iba1 and GFAP immunohistochemistry studies were carried out to determine their effectiveness. Nanoparticles showed an average size of 169 nm, monodisperse population, negative surface charge, encapsulation efficiency of 95% and sustained release profile. Cytotoxicity assays exhibited that these nanocarriers were non-toxic. Behavioral test showed that nanoparticles reduced most than free drug the number of epileptic episodes and their intensity. Neurotoxicity and immunohistochemistry studies confirmed a decrease in neuronal death and neuroinflammation. In conclusion, Epigallocatechin-3-gallate PEGylated-PLGA nanoparticles could be a suitable strategy for the treatment of temporal lobe epilepsy.

Controlled-release biodegradable nanoparticles: From preparation to vaginal applications

This study aimed to prepare poly (d,l-lactide-co-glycolide) (PLGA) nanoparticles (NPs) with chitosan (CTS) surface modification to be used as a vaginal delivery system for antimycotic drugs. Clotrimazole was encapsulated with entrapment efficiencies of 86.1 and 68.9% into Clotrimazole-PLGA-NPs (CLT-PLGA-NPs) and PLGA-NPs with CTS-modified surface (CLT-PLGA-CTS-NPs), respectively. The later NPs exhibited a larger size and higher positive zeta potential (Z potential) in comparison to unmodified NPs. In vitro release kinetic studies indicated that Clotrimazole was released in percentages of >98% from both nanoparticulate systems after 18days. Antifungal activity and mucoadhesive properties of NPs were enhanced when CTS was added onto the surface. In summary, these results suggested that Clotrimazole loaded into PLGA-CTS-NPs has great potential for vaginal applications in treating vaginal infections generated by Candida albicans.

Preparation of particulate polymeric therapeutics for medical applications

Particulate therapeutics fabricated from polymeric materials have become increasingly popular over the past several decades. Generally, polymeric systems are easy to synthesize and have tunable parameters, giving them significant potential for wide use in the clinic. They come in many different forms, including as nanoparticles, microparticles, and colloidal gels. In this review, we discuss the current preparation methods for each type of platform, as well as some representative applications. To achieve enhanced performance, lipid coatings and other surface modification techniques for introducing additional functionality are also mentioned. We hope that, by outlining the various methods and techniques for their preparation, it will be possible to provide insights into the utility of these polymeric platforms and further encourage their development for biomedical applications.

Metabolic Reprogramming of Macrophages Exposed to Silk, Poly(lactic-co-glycolic acid), and Silica Nanoparticles

Monitoring macrophage metabolism in response to nanoparticle exposure provides new insights into biological outcomes, such as inflammation or toxicity, and supports the design of tailored nanomedicines. This paper describes the metabolic signature of macrophages exposed to nanoparticles ranging in diameter from 100 to 125 nm and made from silk, poly(lactic-co-glycolic acid) or silica. Nanoparticles of this size and type are currently at various stages of preclinical and clinical development for drug delivery applications. ¹ H NMR analysis of cell extracts and culture media is used to quantify the changes in the intracellular and extracellular metabolomes of macrophages in response to nanoparticle exposure. Increased glycolytic activity, an altered tricarboxylic acid cycle, and reduced ATP generation are consistent with a proinflammatory phenotype. Furthermore, amino acids possibly arising from autophagy, the creatine kinase/phosphocreatine system, and a few osmolytes and antioxidants emerge as important players in the metabolic reprogramming of macrophages exposed to nanoparticles. This metabolic signature is a common response to all nanoparticles tested; however, the direction and magnitude of some variations are clearly nanoparticle specific, indicating material-induced biological specificity. Overall, metabolic reprogramming of macrophages can be achieved with nanoparticle treatments, modulated through the choice of the material, and monitored using ¹ H NMR metabolomics.

Construction of poly(lactic-co-glycolic acid)/ZnO nanorods/Ag nanoparticles hybrid coating on Ti implants for enhanced antibacterial activity and biocompatibility

Poly(lactic-co-glycolic acid)/Ag/ZnO nanorods coating were successfully prepared on the surface of Ti metallic implants using a hydrothermal method and subsequent spin-coating of mixtures of poly(lactic-co-glycolic acid) and silver nanoparticles. The poly(lactic-co-glycolic acid)/Ag/ZnO nanorods coating exhibited excellent antibacterial efficacy of over 96% against both Staphylococcus aureus and Escherichia coli when the initial content of Ag nanoparticles was over 3wt%. In addition, the release of both silver and zinc could last for over a hundred days due to the enwrapping of poly(lactic-co-glycolic acid). Proliferation of mouse calvarial cells exhibited minimal cytotoxicity on the poly(lactic-co-glycolic acid)/Ag/ZnO coating with an initial content of Ag nanoparticles of 1wt% and 3wt%, while it inhibited cell proliferation once this value was increased to 6wt%. The results revealed that this poly(lactic-co-glycolic acid)/Ag/ZnO composite could provide a long-lasting antibacterial approach and good cytocompatibility, thus exhibiting considerable potential for biomedical application in orthopedic and dental implants with excellent self-antibacterial activity and good biocompatibility.

Novel strategies in the oral delivery of antidiabetic peptide drugs - Insulin, GLP 1 and its analogs

As diabetes is a complex disorder being a major cause of mortality and morbidity in epidemic rates, continuous research has been done on new drug types and administration routes. Up to now, a large number of therapeutic peptides have been produced to treat diabetes including insulin, glucagon-like peptide-1 (GLP-1) and its analogs. The most common route of administration of these antidiabetic peptides is parenteral. Due to several drawbacks associated with this invasive route, delivery of these antidiabetic peptides by the oral route has been a goal of pharmaceutical technology for many decades. Dosage form development should focus on overcoming the limitations facing oral peptides delivery as degradation by proteolytic enzymes and poor absorption in the gastrointestinal tract (GIT). This review focuses on currently developed strategies to improve oral bioavailability of these peptide based drugs; evaluating their advantages and limitations in addition to discussing future perspectives on oral peptides delivery. Depending on the previous reports and papers, the area of nanocarriers systems including polymeric nanoparticles, solid lipid nanoparticles, liposomes and micelles seem to be the most promising strategy that could be applied for successful oral peptides delivery; but still further potential attempts are required to be able to achieve the FDA approved oral antidiabetic peptide delivery system.

Proanthocyanidins-Loaded Nanoparticles Enhance Dentin Degradation Resistance

Previous studies reported that grapeseed extract (GSE), which is rich in proanthocyanidins (PAs), improves the biodegradation resistance of demineralized dentin. This study aimed to investigate the effect of a new GSE delivery strategy to demineralized dentin through loading into biodegradable polymer poly-[lactic-co-glycolic acid] (PLGA) nanoparticles on the biodegradation resistance in terms of structural stability and surface/bulk mechanical and biochemical properties with storage time in collagenase-containing solutions. GSE-loaded nanoparticles were synthetized by nanoprecipitation at PLGA/GSE (w/w) ratios of 100:75, 100:50, and 100:25 and characterized for their morphological/structural features, physicochemical characteristics, and drug loading, entrapment, and release. Nanoparticle suspensions in distilled water (12.5% w/v) were applied (1 min) to demineralized dentin specimens by simulating pulpal pressure. The nanoparticle delivery was investigated by scanning electron microscopy (SEM)/transmission electron microscopy (TEM), and the GSE release from the delivered nanoparticles was further characterized. The variations in surface and bulk mechanical properties were characterized in terms of reduced elastic-modulus, hardness, nanoindentation testing, and apparent elastic-modulus with a storage time up to 3 mo. Hydroxyproline release with exposure to collagenase up to 7 d was estimated. An etch-and-rinse dentin adhesive was applied to investigate the morphology of the resin-dentin interface after nanoparticle delivery. Treatment with the GSE-loaded nanoparticles enhanced the collagen fibril structural resistance, reflected from the TEM investigation, and improved the biomechanical and biochemical stability of demineralized dentin. Nanoparticles having PLGA/GSE of 100:75 (w/w) showed the highest cumulative GSE release and were associated with the best improvement in biodegradation resistance. TEM/SEM showed the ability of the nanoparticles to infiltrate dentinal tubules' main and lateral branches. SEM revealed the formation of a uniform hybrid layer and well-formed resin tags with the presence of numerous nanoparticles located within the dentinal tubules and/or attached to the resin tag. This study demonstrated the potential significance of delivering collagen crosslinkers loaded into biodegradable polymer nanoparticles through the dentinal tubules of demineralized dentin on the biodegradation resistance.

Surface spermidine functionalized PEGylated poly(lactide-co-glycolide) nanoparticles for tumor-targeted drug delivery

SPD functionalized nanoparticles could target the delivery of a drug into tumor cells by binding specifically with PTS.