Disulfide-Linked Amphiphilic Polymer-Docetaxel Conjugates Assembled Redox-Sensitive Micelles for Efficient Antitumor Drug Delivery

Bioreducible Amphiphilic Hyperbranched Polymer-Drug Conjugate for Intracellular Drug Delivery

This paper reports synthesis of a bioreducible hyperbranched (HB) polymer by A2+B3 approach from commercially available dithiothreitol (DTT) (A2) and an easily accessible trifunctional monomer (B3) containing three reactive pyridyl-disulfide groups. Highly efficient thiol-activated disulfide exchange reaction leads to the formation of the HB polymer (Mw = 21000; Đ = 2.3) with bioreducible disulfide linkages in the backbone and two different functional groups, namely, hydroxyl and pyridyl-disulfide in the core and periphery, respectively, of the HB-polymer. Postpolymerization functionalization of the hydroxyl-groups with camptothecin (CPT), a topoisomerase inhibitor and known anticancer drug, followed by replacing the terminal pyridyl-disulfide groups with oligo-oxyethylene-thiol resulted in easy access to an amphiphilic HB polydisulfide-CPT conjugate (P1) with a very high drug loading content of ∼40%. P1 aggregated in water (above ∼10 μg/mL) producing drug-loaded nanoparticles (Dh ∼ 135 nm), which showed highly efficient glutathione (GSH)-triggered release of the active CPT. Mass spectrometry analysis of the GSH-treated P1 showed the presence of the active CPT drug as well as a cyclic monothiocarbonate product, which underpins the cascade-degradation mechanism involving GSH-triggered cleavage of the labile disulfide linkage, followed by intramolecular nucleophilic attack by the in situ generated thiol to the neighboring carbonate linkage, resulting in release of the active CPT drug. The P1 nanoparticle showed excellent cellular uptake as tested by confocal fluorescence microscopy in HeLa cells by predominantly endocytosis mechanism, resulting in highly efficient cell killing (IC50 ∼ 0.6 μg/mL) as evident from the results of the MTT assay, as well as the apoptosis assay. Comparative studies with an analogous linear polymer-CPT conjugate showed much superior intracellular drug delivery potency of the hyperbranched polymer.

Construction of intelligent drug delivery system based on polysaccharide-derived polymer micelles: A review

Micelles are nanostructures developed via the spontaneous assembly of amphiphilic polymers in aqueous systems, which possess the advantages of high drug stability or active-ingredient solubilization, targeted transport, controlled release, high bioactivity, and stability. Polysaccharides have excellent water solubility, biocompatibility, and degradability, and can be modified to achieve a hydrophobic core to encapsulate hydrophobic drugs, improve drug biocompatibility, and achieve regulated delivery of the loaded drug. Micelles drug delivery systems based on polysaccharides and their derivatives show great potential in the biomedical field. This review discusses the principles of self-assembly of amphiphilic polymers and the formation of micelles; the preparation of amphiphilic polysaccharides is described in detail, and an overview of common polysaccharides and their modifications is provided. We focus on the review of strategies for encapsulating drugs in polysaccharide-derived polymer micelles (PDPMs) and building intelligent drug delivery systems. This review provides new research directions that will help promote future research and development of PDPMs in the field of drug carriers.

Interplay between Diffusion and Bond Cleavage Reaction for Determining Release in Polymer-Drug Conjugates

In conjugated polymeric drug delivery systems, both the covalent bond degradation rate and the diffusion of the freely moving drug particles affect the release profile of the formulation. Using Monte Carlo simulations in spherical matrices, the release kinetics resulting from the competition between the reaction and diffusion processes is discussed. For different values of the relative bond cleavage rate, varied over four orders of magnitude, the evolution of (i) the number of bonded drug molecules, (ii) the fraction of the freely moved detached drug within the polymer matrix, and (iii) the resulting fractional release of the drug is presented. The characteristic release time scale is found to increase by several orders of magnitude as the cleavage reaction rate constant decreases. The two extreme rate-limiting cases where either the diffusion or the reaction dominates the release are clearly distinguishable. The crossover between the diffusion-controlled and reaction-controlled regimes is also examined and a simple analytical formula is presented that can describe the full dependence of the release time on the bond cleavage rate constant. This simple relation is provided simply by the sum of the characteristic time for purely diffusional release and the bond cleavage decay time, which equals the inverse of the reaction rate constant.

A novel micellar carrier to reverse multidrug resistance of tumours: TPGS derivatives with end-grafted cholesterol

D-α-tocopherol polyethylene glycol succinate (TPGS) has good biocompatibility, low immunogenicity, prolonged circulation time, and it can reverse multidrug resistance of tumours. However, the micelle concentration (CMC) of TPGS is too high (0.2 mg/mL) to develop the formulation of the micelle. In this study, TPGS was modified with cholesterol to obtain a new carrier material, TPGS-CHMC. The CMC of TPGS-CHMC was 2 μg/mL, which was extremely lower than that of TPGS. Docetaxel (DTX)-loaded TPGS-CHMC micelles (TPGS-CHMC/DTX) exhibited an average size of approximately 13 nm, a zeta potential of approximately -4.66 mV, and high encapsulation efficiency (99.2 ± 0.6%). TPGS-CHMC reduced mitochondrial membrane potential and cell membrane fluidity in paclitaxel-resistant ovarian cancer cells (A2780/T). In vivo, DiR-loaded TPGS-CHMC micelles were selectively distributed in A2780/T tumour-bearing nude mice. In A2780/T tumour-bearing nude mice, TPGS-CHMC/DTX micelles displayed significantly higher anti-tumour activity and less toxicity than the free DTX solution. In summary, TPGS-CHMC has various advantages, and provides a new option for developing functional polymeric micelles.

Study of Cytotoxicity and Internalization of Redox-Responsive Iron Oxide Nanoparticles on PC-3 and 4T1 Cancer Cell Lines

Redox-responsive and magnetic nanomaterials are widely used in tumor treatment separately, and while the application of their combined functionalities is perspective, exactly how such synergistic effects can be implemented is still unclear. This report investigates the internalization dynamics of magnetic redox-responsive nanoparticles (MNP-SS) and their cytotoxicity toward PC-3 and 4T1 cell lines. It is shown that MNP-SS synthesized by covalent grafting of polyethylene glycol (PEG) on the magnetic nanoparticle (MNP) surface via SS-bonds lose their colloidal stability and aggregate fully in a solution containing DTT, and partially in conditioned media, whereas the PEGylated MNP (MNP-PEG) without S-S linker control remains stable under the same conditions. Internalized MNP-SS lose the PEG shell more quickly, causing enhanced magnetic core dissolution and thus increased toxicity. This was confirmed by fluorescence microscopy using MNP-SS dual-labeled by Cy3 via labile disulfide, and Cy5 via a rigid linker. The dyes demonstrated a significant difference in fluorescence dynamics and intensity. Additionally, MNP-SS demonstrate quicker cellular uptake compared to MNP-PEG, as confirmed by TEM analysis. The combination of disulfide bonds, leading to faster dissolution of the iron oxide core, and the high-oxidative potential Fe³⁺ ions can synergically enhance oxidative stress in comparison with more stable coating without SS-bonds in the case of MNP-PEG. It decreases the cancer cell viability, especially for the 4T1, which is known for being sensitive to ferroptosis-triggering factors. In this work, we have shown the effect of redox-responsive grafting of the MNP surface as a key factor affecting MNP-internalization rate and dissolution with the release of iron ions inside cancer cells. This kind of synergistic effect is described for the first time and can be used not only in combination with drug delivery, but also in treatment of tumors responsive to ferroptosis.

Mollification of Doxorubicin (DOX)-Mediated Cardiotoxicity Using Conjugated Chitosan Nanoparticles with Supplementation of Propionic Acid

Doxorubicin is an extensively prescribed antineoplastic agent. It is also known for adverse effects, among which cardiotoxicity tops the list. The possible mechanism underlying doxorubicin (DOX)-mediated cardiotoxicity has been investigated in this study. Further, to reduce the DOX-mediated cardiotoxicity, DOX was conjugated with Chitosan Nanoparticles (DCNPs) and supplemented with propionic acid. Initially, the drug loading efficacy and conjugation of DOX with chitosan was confirmed by UV–Visible Spectroscopy (UV) and Fourier Transform Infrared Spectroscopy (FTIR). The average sizes of the synthesized Chitosan Nanoparticles (CNPs) and DCNPs were measured by Dynamic Light Scattering (DLS) analysis as 187.9 ± 1.05 nm and 277.3 ± 8.15 nm, respectively, and the zeta potential values were recorded as 55.2 ± 0.7 mV and 51.9 ± 1.0 mV, respectively. The size and shape of CNPs and DCNPs were recorded using a High-Resolution Electron Microscopy (HRTEM). The particles measured <30 nm and 33–84 nm, respectively. The toxic effects of DCNPs and propionic acid were evaluated in rat model. The data from the electrocardiogram (ECG), cardiac biomarkers, Peroxisome proliferator-activated receptor gamma (PPARγ) and histological observations indicated evidence of DOX-mediated cardiotoxicity, whereas the administration of DCNPs, as well as Propionic Acid (PA), brought about a restoration to normalcy and offered protection in the context of DOX-induced cardiotoxicity.

Effect of the disulfide bond and polyethylene glycol on the degradation and biophysicochemical properties of polyurethane micelles

The disulfide bond has emerged as a promising redox-sensitive switch for smart polymeric micelles, due to its properties of rapid response to the reductive environment and spatiotemporally-controlled therapeutic agent delivery. However, the dilemma of multifunctional nanomedicine is that the more intelligent the functionalities integrated into a system, the vaguer the understanding of the structure and interaction between the multi-functional moieties becomes. To better understand the interaction between the disulfide bond and methoxy polyethylene glycol (mPEG), and their effects on the biophysicochemical characterization of micelles, we developed a series of polyurethane micelles containing various densities of disulfide bonds and bearing different molecular weights of mPEG. In this work, we found that the critical factor determining the degradation rate of polymer micelles was the hydrophobic/hydrophilic ratio of broken polymer segments triggered by disulfide bond breaking. The higher density of the disulfide bond and longer mPEG chain accelerate the degradation process due to the disproportionate hydrophobic/hydrophilic ratio of the broken chain, which is the key factor to determine the micellization and stabilization of polymer micelles. This work provides a fundamental understanding of the interaction between the complex functional groups and a new insight into the mechanism of the micelle degradation process, offering guidance on the rational design and fabrication of multifunctional nanoformulations.

Improved Synthesis of a Novel Biodegradable Tunable Micellar Polymer Based on Partially Hydrogenated Poly(β-malic Acid-co-benzyl Malate)

Poly(benzyl malate) (PBM), together with its derivatives, have been studied as nanocarriers for biomedical applications due to their superior biocompatibility and biodegradability. The acquisition of PBM is primarily from chemical routes, which could offer polymer-controlled molecular weight and a unique controllable morphology. Nowadays, the frequently used synthesis from L-aspartic acid gives an overall yield of 4.5%. In this work, a novel synthesis route with malic acid as the initiator was successfully designed and optimized, increasing the reaction yield up to 31.2%. Furthermore, a crystalline form of PBM (PBM-2) that polymerized from high optical purity benzyl-β-malolactonate (MLABn) was discovered during the optimization process. X-ray diffraction (XRD) patterns revealed that the crystalline PBM-2 had obvious diffraction peaks, demonstrating that its internal atoms were arranged in a more orderly manner and were different from the amorphous PBM-1 prepared from the racemic MLABn. The differential scanning calorimetry (DSC) curves and thermogravimetric curves elucidated the diverse thermal behaviors between PBM-1 and PBM-2. The degradation curves and scanning electron microscopy (SEM) images further demonstrated the biodegradability of PBM, which have different crystal structures. The hardness of PBM-2 implied the potential application in bone regeneration, while it resulted in the reduction of solubility when compared with PBM-1, which made it difficult to be dissolved and hydrogenated. The solution was therefore heated up to 75 °C to achieve benzyl deprotection, and a series of partially hydrogenated PBM was sequent prepared. Their optimal hydrogenation rates were screened to determine the optimal conditions for the formation of micelles suitable for drug-carrier applications. In summary, the synthesis route from malic acid facilitated the production of PBM for a shorter time and with a higher yield. The biodegradability, biosafety, mechanical properties, and adjustable hydrogenation widen the application of PBM with tunable properties as drug carriers.

Glutathione sensitive vesicles prepared from supramolecular amphiphiles

Glutathione (GSH) sensitive vesicles were prepared by the self-assembly of amphiphilic inclusion complexes. These novel chemically sensitive supramolecular amphiphiles are anticipated to have applications in drug delivery; the nanocarriers can protect the encapsulated cargo and release it via triggered degradation in high concentrations of GSH. Additionally, the sensitivity of the vesicles to GSH indicates that the dynamic covalent disulfide bond at the vesicle surface can be used for post-modification of the nanocarrier via a thiol-disulfide exchange, a strategy that can be exploited to introduce targeting moieties to increase treatment specificity. Supramolecular amphiphiles containing a dynamic covalent disulfide bond were prepared via the host-guest inclusion complexes between alkylated β-cyclodextrin (β-CD) hosts and adamantane terminated polyethylene glycol derivatives. The significant difference between the critical micelle concentrations of the supramolecular amphiphiles and the individual host and guest components confirmed that a unique supramolecular amphiphile was formed. Fluorescence experiments and dynamic light scattering (DLS) revealed that the supramolecular amphiphiles self-assembled into vesicles of 130 nm diameter which were stable for 8 months. Degradation of the vesicles after incubation with GSH was monitored using DLS and by the release of encapsulated 5,6-carboxyfluorescein (CF), observed by an increase in fluorescence intensity. Degradation of the nanocarrier was faster at intracellular GSH concentrations than at extracellular GSH concentrations.

Bioresponsive nanomedicines based on dynamic covalent bonds

Trends in the development of modern medicine necessitate the efficient delivery of therapeutics to achieve the desired treatment outcomes through precise spatiotemporal accumulation of therapeutics at the disease site. Bioresponsive nanomedicine is a promising platform for this purpose. Dynamic covalent bonds (DCBs) have attracted much attention in studies of the fabrication of bioresponsive nanomedicines with an abundance of combinations of therapeutic modules and carrier function units. DCB-based nanomedicines could be designed to maintain biological friendly synthesis and site-specific release for optimal therapeutic effects, allowing the complex to retain an integrated structure before accumulating at the disease site, but disassembling into individual active components without compromising function in the targeted organs or tissues. In this review, we focus on responsive nanomedicines containing dynamic chemical bonds that can be cleaved by various specific stimuli, enabling achievement of targeted drug release for optimal therapy in various diseases.

Nanoplatforms for Targeted Stimuli-Responsive Drug Delivery: A Review of Platform Materials and Stimuli-Responsive Release and Targeting Mechanisms

To achieve the promise of stimuli-responsive drug delivery systems for the treatment of cancer, they should (1) avoid premature clearance; (2) accumulate in tumors and undergo endocytosis by cancer cells; and (3) exhibit appropriate stimuli-responsive release of the payload. It is challenging to address all of these requirements simultaneously. However, the numerous proof-of-concept studies addressing one or more of these requirements reported every year have dramatically expanded the toolbox available for the design of drug delivery systems. This review highlights recent advances in the targeting and stimuli-responsiveness of drug delivery systems. It begins with a discussion of nanocarrier types and an overview of the factors influencing nanocarrier biodistribution. On-demand release strategies and their application to each type of nanocarrier are reviewed, including both endogenous and exogenous stimuli. Recent developments in stimuli-responsive targeting strategies are also discussed. The remaining challenges and prospective solutions in the field are discussed throughout the review, which is intended to assist researchers in overcoming interdisciplinary knowledge barriers and increase the speed of development. This review presents a nanocarrier-based drug delivery systems toolbox that enables the application of techniques across platforms and inspires researchers with interdisciplinary information to boost the development of multifunctional therapeutic nanoplatforms for cancer therapy.

Judging Enzyme-Responsive Micelles by Their Covers: Direct Comparison of Dendritic Amphiphiles with Different Hydrophilic Blocks

Enzymatically degradable polymeric micelles have great potential as drug delivery systems, allowing the selective release of their active cargo at the site of disease. Furthermore, enzymatic degradation of the polymeric nanocarriers facilitates clearance of the delivery system after it has completed its task. While extensive research is dedicated toward the design and study of the enzymatically degradable hydrophobic block, there is limited understanding on how the hydrophilic shell of the micelle can affect the properties of such enzymatically degradable micelles. In this work, we report a systematic head-to-head comparison of well-defined polymeric micelles with different polymeric shells and two types of enzymatically degradable hydrophobic cores. To carry out this direct comparison, we developed a highly modular approach for preparing clickable, spectrally active enzyme-responsive dendrons with adjustable degree of hydrophobicity. The dendrons were linked with three different widely used hydrophilic polymers—poly(ethylene glycol), poly(2-ethyl-2-oxazoline), and poly(acrylic acid) using the CuAAC click reaction. The high modularity and molecular precision of the synthetic methodology enabled us to easily prepare well-defined amphiphiles that differ either in their hydrophilic block composition or in their hydrophobic dendron. The micelles of the different amphiphiles were thoroughly characterized and their sizes, critical micelle concentrations, drug loading, stability, and cell internalization were compared. We found that the micelle diameter was almost solely dependent on the hydrophobicity of the dendritic hydrophobic block, whereas the enzymatic degradation rate was strongly dependent on the composition of both blocks. Drug encapsulation capacity was very sensitive to the type of the hydrophilic block, indicating that, in addition to the hydrophobic core, the micellar shell also has a significant role in drug encapsulation. Incubation of the spectrally active micelles in the presence of cells showed that the hydrophilic shell significantly affects the micellar stability, localization, cell internalization kinetics, and the cargo release mechanism. Overall, the high molecular precision and the ability of these amphiphiles to report their disassembly, even in complex biological media, allowed us to directly compare the different types of micelles, providing striking insights into how the composition of the micelle shells and cores can affect their properties and potential to serve as nanocarriers.

Robust and smart polypeptide-based nanomedicines for targeted tumor therapy

Nanomedicines based on synthetic polypeptides are among the most versatile and advanced platforms for tumor therapy. Notably, several polypeptide-based nanodrugs are currently under human clinical assessments. The previous (pre)clinical studies clearly show that dynamic stability (i.e. stable in circulation while destabilized in tumor) of nanomedicines plays a vital role in their anti-tumor performance. Various strategies have recently been developed to design dynamically stabilized polypeptide-based nanomedicines by e.g. crosslinking the nanovehicles with acid, reactive oxygen species (ROS), glutathione (GSH), or photo-sensitive linkers, inter-crosslinking between vehicles and drugs, introducing π-π stacking or lipid-lipid interactions in the nanovehicles, chemically conjugating drugs to vehicles, and forming unimolecular micelles. Interestingly, these robust and smart nanodrugs have demonstrated improved tumor targetability, anti-tumor efficacy, as well as safety profiles in different tumor models. In this review, representative strategies to robust and smart polypeptide-based nanomedicines for targeted treatment of varying malignancies are highlighted. The exciting development of dynamic nanomedicines will foresee further increasing clinical translation in the future.

Enzymatic multifunctional biodegradable polymers for pH- and ROS-responsive anticancer drug delivery

A new family of multifunctional biodegradable block copolymers, PEG-poly(ω-pentadecalactone-co-N-methyldiethyleneamine sebacate-co-2,2'-thiodiethylene sebacate) (PEG-PMT), were synthesized via lipase-catalyzed copolymerization procedures. Amphiphilic PEG-PMT copolymers can be readily transformed into stable micellar nanoparticles through self-assembling processes in aqueous medium. The particle sizes increase dramatically after exposure of the particles to the acidic pH and high reactive oxygen species (ROS) conditions in tumor microenvironments, due to protonation of thioether groups and oxidation of amino groups in the PMT micelle cores, respectively. For example, docetaxel (DTX)-loaded PEG-PM-19 % TS micelles were triggered synergistically by acidic pH and ROS stimuli to release over 85 % of the anti-cancer drug. In particular, DTX/PEG-PMT-19 % TS and DTX/PEG-PMT-48 % TS micelles performed better than commercial Duopafei formulation in prohibiting growth of CT-26 tumors xenografed in vivo (70 % of tumor-inhibiting efficiency). Biosafety analysis revealed that DTX-loaded PEG-PMT nanoparticles possessed minimal toxicity towards normal organs, such as liver and kidney. These experimental data demonstrated that the pH- and ROS-responsive PEG-PMT micelles are promising vectors for both delivery of anti-tumor drugs and their controlled release at tumor intracellular sites.

Design, in silico modelling and functionality theory of folate-receptor-targeted myricetin-loaded bovine serum albumin nanoparticle formulation for cancer treatment

Targeted drug delivery systems are a promising field of research. Nano-engineered material-mediated drug delivery possesses remarkable potential for the treatment of various malignancies. Here, folic acid (FA)-conjugated bovine serum albumin (BSA) nanoparticles (NPs) were used to encapsulate myricetin (Myr). Subsequently, the delivery of Myr via naturally overexpressed folate receptor (FR) to FR-positive breast cancer cells was studied. Myr-loaded BSA NPs were assembled by modified desolvation cross-linking technique. An FA-conjugated carrier, N-hydroxysuccinimide (NHS)-FA ester, was successfully synthesized. Its functional and structural characteristics were confirmed by ultraviolet, Fourier-transform infrared, and proton nuclear magnetic resonance spectroscopy. Biocompatible FA-conjugated, Myr-loaded BSA NPs (FA-Myr-BSA NPs) were successfully formulated using a carbonate/bicarbonate buffer. Their morphology, size, shape, physiological stability, and drug release kinetics were studied. Molecular docking studies revealed that FA-Myr-BSA NPs readily bound non-covalently to folate receptors and facilitated active drug endocytosis. FA-Myr-BSA NPs could trigger fast release of Myr in an acidic medium (pH 5.4), and showed high biocompatibility in a physiological medium. FA-Myr-BSA NPs effectively decreased the viability of MCF-7 cells after 24 h with 72.45 μg ml^-1 IC₅₀ value. In addition, FA-Myr-BSA NPs enhanced the uptake of Myr in MCF-7 cells. After incubation, a typical apoptotic morphology of condensed nuclei and distorted membrane bodies was observed. The NPs also targeted mitochondria of MCF-7 cells, significantly increasing reactive oxygen species release and contributing to the loss of mitochondrial membrane integrity. The observed results confirm that the newly developed FA-Myr-BSA NPs can serve as a potential carrier for Myr to increase the anticancer activity of this chemotherapeutic.

Antitumor Efficacy of Focused Ultrasound-MFL Nanoparticles Combination Therapy in Mouse Breast Cancer Xenografts

High doses of chemotherapy agents can cause adverse effects. To address this issue, drug-loaded vesicles with minimum drug loss, guided by an external element for precise delivery, are desired. Combinational therapy of both a focused ultrasound-induced drug delivery method and membrane fusogenic liposomes (MFLs) as drug delivery vehicles can satisfy such premises. In this study, we confirmed that the use of a small quantity of docetaxel-loaded membrane fusogenic liposomes (DTX-MFL) with focused ultrasound can induce better antitumor response in a xenograft mouse model compared to conventional docetaxel monotherapy and DTX-MFL only.

Ditelluride-Bridged PEG-PCL Copolymer as Folic Acid-Targeted and Redox-Responsive Nanoparticles for Enhanced Cancer Therapy

The development of the nanosized delivery systems with targeting navigation and efficient cargo release for cancer therapy has attracted great attention in recent years. Herein, a folic acid (FA) modified PEGylated polycaprolactone containing ditelluride linkage was synthesized through a facile coupling reaction. The hydrophobic doxorubicin (DOX) can be encapsulated into the polymeric micelles, and such nanoparticles (F-TeNPDOX) exhibited redox-responsive drug release under abundant glutathione (GSH) condition due to the degradation of ditelluride bonds. In addition, flow cytometric analyses showed that the FA ligands on F-TeNPDOX could facilitate their cellular uptake in 4T1 breast cancer cells. Therefore, F-TeNPDOX led to the promoted drug accumulation and enhanced growth inhibition on 4T1 tumor in vivo. The obtained results suggest F-TeNPDOX excellent potential as nanocarriers for anticancer drug delivery.

Bio-responsive Bletilla striata polysaccharide-based micelles for enhancing intracellular docetaxel delivery

The aim of this study was to design a pH- and redox-dual responsive Bletilla striata polysaccharide (BSP)-based copolymer to enhance anti-tumor drugs release at tumor sites and improve the therapeutic effect. The copolymer was synthesized using stearic acid (SA) and cystamine via a disulfide linkage and characterized using 1H-Nuclear Magnetic Resonance spectroscopy and Fourier Transform Infrared spectroscopy. The BSP-ss-SA copolymer could self-assemble into micelle in an aqueous environment and could encapsulate docetaxel therein. Its inhibitory effects on HepG2 cells and 4 T1 cells were determined. Besides, the anti-cancer effects in vivo and histopathological study of 4 T1-bearing tumor mice were also evaluated. Docetaxel-loaded BSP-ss-SA micelles showed significant pH-sensitive release behavior, supplying a greater drug release percentage in pH 5.0 media compared to pH 7.4 media. BSP-ss-SA micelles exhibited a clear redox-responsive release property in pH 7.4 media whereas the similar cumulative release percentage of docetaxel from BSP-ss-SA micelles in pH 5.0 media in the presence and absence of DL-dithiothreitol. The Docetaxel-loaded BSP-ss-SA micelles clearly inhibited the proliferation of HepG2 and 4 T1 cells compared with docetaxel solution. The results of MTT and histopathological study indicated that BSP-ss-SA copolymer exhibited good blood compatibility. The BSP-ss-SA copolymer may be used as carriers to deliver anti-tumor drugs to special tumor tissues.

Synthetic copolymer conjugates of docetaxel and in vitro assessment of anticancer efficacy

Docetaxel (DTX) is a widely used chemotherapy drug that is associated with numerous side effects and limited bioavailability. We show synthetic copolymer conjugates of docetaxel with drug loading up to 20% and assess their efficacy in MCF-7 cells.

Development of Traceable Rituximab-Modified PEO-Polyester Micelles by Postinsertion of PEG-phospholipids for Targeting of B-cell Lymphoma

The objective of this work was to develop rituximab (RTX)-modified polymeric micelles for targeting of B-cell lymphoma cells, through postinsertion of RTX-poly(ethylene glycol)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (RTX-PEG-DSPE) into methoxy poly(ethylene oxide)-poly(ε-caprolactone) (PEO-PCL) or methoxy poly(ethylene oxide)-poly(ε-benzylcarboxylate-ε-caprolactone) (PEO-PBCL) micelles. Mixed micelles were made traceable by introducing Cy5.5 to RTX and conjugating Cy3 to propargyl moiety, end-capped PCL or PBCL. Successful adaptation of the postinsertion method for the formation of immunomicelles was evidenced by measurement of RTX levels on the micellar surface, purified from free RTX by size exclusion chromatography, using microBSA assay. A change in the micellar diameter, from 50-70 nm for PEO-PCL and PEO-PBCL micelles and 20 nm for PEG-DSPE micelles, to 80-95 nm for the mixed micellar population as well as the critical micellar concentration of mixed micelles provided further proof for the success of the postinsertion method applied here. Mixed micelles containing PCL or PBCL with a degree of polymerization of 22 (PCL₂₂ and PBCL₂₂) were thermodynamically and kinetically more stable than those with PCL₁₅. Accordingly, RTX micelles containing PCL₂₂ or PBCL₂₂ showed a higher percentage of Cy³⁺/Cy^5.5+ cell population in CD20⁺ KG-15 cells, than those with PCL₁₅. The percentage of Cy³⁺/Cy^5.5+ cell population drastically reduced in the presence of competing RTX for micelles containing PCL₂₂ or PBCL₂₂ cores, indicating the superiority of these structures for active targeting of CD20⁺ cells. No significant difference in the cytotoxicity of paclitaxel in RTX-micelles versus plain ones was observed, reflecting the noninternalizing function of CD20. The results show that traceable mixed micelles prepared through postinsertion of RTX-PEG-DSPE to PEO-PCL₂₂ or PEO-PBCL₂₂ micelles can be used for targeting and/or imaging of CD20⁺ B cell lymphoma cells. The postinsertion method can be adopted to prepare other PEO-poly(ester)-based immunomicelles for active targeting of other diseased cells.

Improved chemotherapeutic efficacy against resistant human breast cancer cells with co-delivery of Docetaxel and Thymoquinone by Chitosan grafted lipid nanocapsules: Formulation optimization, in vitro and in vivo studies

In recent years, multi-targeted chemotherapeutic combinations have received considerable attention in solid tumor chemotherapy. Here, we optimized low-molecular-weight chitosan (CS)-grafted lipid nanocapsules (LNCs, referred to as CLNCs) for the co-delivery of docetaxel (DTX) and thymoquinone (THQ) to treat drug-resistant breast cancer. We first screened size reduction techniques (homogenization vs ultrasonication), and then the 3³-Box-Behnken design was employed to determine optimal conditions of the final LNCs with the desired quality attributes. Uncoated LNCs had a particle size of 141.7 ± 2.8 nm (Polydispersity index, PdI: 0.17 ± 0.02) with entrapment efficiency (%EE) of 66.1 ± 3.5 % and 85.3 ± 3.1 % for DTX and THQ, respectively. The CS functionalization of LNCs improved the uptake and endosomal escape effect, and led to a significantly higher cytotoxicity against MCF-7 and triple-negative (MDA-MB-231) breast cancer cells. Furthermore, an enhanced antiangiogenic effect was observed with DTX- and THQ-carrying CLNCs in the Chick embryo chorioallantoic membrane (CAM) assay.

Self-assembled nanoparticles of reduction-sensitive poly (lactic-co-glycolic acid)-conjugated chondroitin sulfate A for doxorubicin delivery: preparation, characterization and evaluation

In this study, reduction-sensitive self-assembled polymer nanoparticles based on poly (lactic-co-glycolic acid) (PLGA) and chondroitin sulfate A (CSA) were developed and characterized. PLGA was conjugated with CSA via a disulfide linkage (PLGA-ss-CSA). The critical micelle concentration (CMC) of PLGA-ss-CSA conjugate is 3.5 µg/mL. The anticancer drug doxorubicin (DOX) was chosen as a model drug, and was effectively encapsulated into the nanoparticles (PLGA-ss-CSA/DOX) with high loading efficiency of 15.1%. The cumulative release of DOX from reduction-sensitive nanoparticles was only 34.8% over 96 h in phosphate buffered saline (PBS, pH 7.4). However, in the presence of 20 mM glutathione-containing PBS environment, DOX release was notably accelerated and almost complete from the reduction-sensitive nanoparticles up to 96 h. Moreover, efficient intracellular DOX release of PLGA-ss-CSA/DOX nanoparticles was confirmed by CLSM assay in A549 cells. In vitro cytotoxicity study showed that the half inhibitory concentrations of PLGA-ss-CSA/DOX nanoparticles and free DOX against A549 cells were 1.141 and 1.825 µg/mL, respectively. Therefore, PLGA-ss-CSA/DOX nanoparticles enhanced the cytotoxicity of DOX in vitro. These results suggested that PLGA-ss-CSA nanoparticles could be a promising carrier for drug delivery.

Block copolymer prodrugs: Synthesis, self-assembly, and applications for cancer therapy

Block copolymer prodrugs (BCPs) have emerged as one of the most promising anticancer drug delivery strategies, which can self-assemble into nanoparticles with optimal physicochemical properties including sizes, morphologies, surface properties, and integration of multifunction for improved in vivo applications. Moreover, the utility of stimuli-responsive linkages to conjugate drugs onto the polymer backbones can achieve efficient and targeting drug release. Several BCP micellar delivery systems have been pushed ahead into the clinical trials, which showed great promising potentials for cancer therapy. In recent years, various novel and more efficient BCP systems have been developed for better in vivo performance. In this focus article, we focus on the recent advances of BCPs including the synthesis, self-assembly, and applications for cancer therapy. The synthetic methods are first introduced, and the self-assembly of BCPs for in vivo anticancer applications is discussed along the line of varying endogenous stimuli-responsive linkages including amide or ester bonds, pH, reduction, and oxidation-responsive linkages. Finally, conclusions along with the brief future perspectives are presented. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Cysteine-based redox-responsive nanoparticles for small-molecule agent delivery

As a significant part of molecular-targeted therapies, small-molecule agents (SMAs) have been increasingly used for cancer treatment. Nevertheless, most SMAs are currently administered orally due to their poor solubility, resulting in a low bioavailability and unavoidable side effects. Herein, we proposed a promising SMA delivery strategy using a biocompatible and redox-responsive nanoparticle (NP) delivery system to improve their bioavailability, alleviate side effects and enhance therapeutic performance. To demonstrate the feasibility of this strategy, a type of cysteine-based hydrophobic polymer was employed to construct a redox-sensitive nanoplatform for the delivery of various hydrophobic oral SMAs. These SMA-loaded nanoparticles (SMA-NPs) all have a small particle size and good drug-loading capacity. Particularly, lapatinib-loaded nanoparticles (LAP-NPs) with a minimal particle size (79.71 nm) and an optimal drug-loading capacity (12.5%) were utilized as a model to systemically explore the in vitro and in vivo anticancer potential of SMA-NPs. As expected, the LAP-NPs exhibited rapid redox-responsive drug release, enhanced in vitro cytotoxicity and cell apoptosis, and demonstrated notable anti-metastasis ability and desirable intracellular localization. Additionally, the in vivo results demonstrated the preferential accumulation of LAP-NPs in tumor tissues and the significant suppression of tumor growth. Therefore, the generated SMA-NP delivery system shows great SMA delivery potential for advanced molecular-targeted therapies.

Dual Stable Nanomedicines Prepared by Cisplatin-Crosslinked Camptothecin Prodrug Micelles for Effective Drug Delivery

A polymer micelle-based drug delivery system has faced many challenges due to the lack of stability especially after being diluted in blood, resulting in a premature release. Herein, we developed camptothecin (CPT)-conjugated prodrug (CPTP) micelles in which CPT was grafted to the poly(ethylene glycol)-poly(glutamic acid) block copolymer via a disulfide bond linker for a redox-triggered drug release. Then, the cisplatin (CDDP)-crosslinked CPT-prodrug micelles (CPTP/CDDP) with a hybrid complex as a stable structure were successfully established via the CDDP (Pt)-carboxyl (COOH) chelate interaction. The resulting dual CPTP/CDDP had an average hydrodynamic radius of about 50 nm with a narrow distribution, which was conducive to the promotion of solid tumor accumulation. Importantly, CPT chemical bonding to the polymer backbone obviously stabilizes the CPT-prodrug micelles and prolongs their circulation time. Moreover, both CPT and CDDP are clinically used antitumor drugs; CDDP not only behaves as an ancillary anticarcinogen but also serves as a crosslinker to restrain the untimely burst release of CPT and to achieve synergistic antitumor efficacy. In addition, the CPTP/CDDP also exhibited a sustained reduction responsive release of CPT accompanied by the dissociation of the CDDP-COOH complex. This design ingeniously solved the contradiction between the stability and release of polymer micelle-based nanomedicines. Both in vitro and in vivo tests demonstrated an amazing antineoplastic efficacy compared with free drugs (CPT or CDDP) and just their physical mixing, indicating great promise for cancer treatment.

pH responsible and fluorescent Cy5.5-PEG-g-A-HA/CDDP complex nanoparticles: synthesis, characterization, and application for targeted drug delivery

Clinical application of cisplatin (CDDP) against various solid tumors is often limited due to its poor selectivity and severe side effect. Considering this, in our study, CDDP was incorporated in fluorescent PEG amine grafted aldehyde hyaluronic acid by imine bond and metal ion coordination bond linking and formed a complex, the complex was then self-assembled into nanoparticles in water simply. FT-IR, XRD, DLS and SEM analysis demonstrated that the nanoparticles were prepared successfully and exhibited a spherical structure with size ranged from 216.4 to 372.3 nm in diameter. CDDP releasing from the nanoparticles was in a controlled manner, and had faster release rate at lower pH, indicating the nanoparticles were responsive to tumor micro-acid environment. Since fluorescent Cy5.5 and targeting hyaluronic acid existed on the surface of the nanoparticles, CLSM images clearly showed that the nanoparticles could target and internalize into HeLa cells, and then inhibited the growth of HeLa cells. In addition, MTT, AO-EB staining, and hemolysis assay showed that the nanoparticles had good cyto-/hemo-compatibility. Hence, the nanoparticles had the potential to be used for cancer therapy and diagnosis. The further in vivo experiment will be shown in the next work. pH responsible and fluorescent Cy5.5-PEG-g-A-HA/CDDP complex nanoparticles were facilely fabricated for controlled and targeted delivery of CDDP.

Dual-Responsive Size-Shrinking Nanocluster with Hierarchical Disassembly Capability for Improved Tumor Penetration and Therapeutic Efficacy

It is generally known that, for nanoparticles in cancer therapy, sufficient tumor penetration needs a minor particle size, while long in vivo circulation time needs a larger particle size. It is hard to balance them because they are standing on either side of a seesaw. To address these two different requirements, a dual-responsive size-shrinking nanocluster can self-adaptively respond to a complicated tumor microenvironment and transform its particulate property to overcome sequential in vivo barriers and reach a preferable antitumor activity. The nanocluster (RPSPT@SNCs) could preferentially accumulate into tumor tissue and dissociate under extracellular matrix metalloproteinase-2 (MMP-2) to release small-sized micelle formulations (RPSPTs). RPSPT possesses favorable tumor penetration and tumor targeting capability to deliver the antitumor agent paclitaxel (PTX) into deep regions of solid tumor. The intracellular redox microenvironment can also accelerate drug accumulation. The prepared RPSPT@SNCs possesses enhanced cell cytotoxicity and tumor penetration capability on MCF-7 cells and a favorable antitumor activity on the xenograft tumor mouse model.

Release of Pharmaceutical Peptides in an Aggregated State: Using Fibrillar Polymorphism to Modulate Release Levels

Traditional approaches to achieve sustained delivery of pharmaceutical peptides traditionally use co-excipients (e.g., microspheres and hydrogels). Here, we investigate the release of an amyloidogenic glucagon analogue (3474) from an aggregated state and the influence of surfactants on this process. The formulation of peptide 3474 in dodecyl maltoside (DDM), rhamnolipid (RL), and sophorolipid (SL) led to faster fibrillation. When the aggregates were subjected to multiple cycles of release by repeated resuspension in fresh buffer, the kinetics of the release of soluble peptide 3474 from different surfactant aggregates all followed a simple exponential decay fit, with half-lives of 5–18 min and relatively constant levels of release in each cycle. However, different amounts of peptide are released from different aggregates, ranging from 0.015 mg/mL (3475-buffer) up to 0.03 mg/mL (3474-DDM), with 3474-buffer and 3474-RL in between. In addition to higher release levels, 3474-DDM aggregates showed a different amyloid FTIR structure, compared to 3474-RL and 3474-SL aggregates and a faster rate of degradation by proteinase K. This demonstrates that the stability of organized peptide aggregates can be modulated to achieve differences in release of soluble peptides, thus coupling aggregate polymorphism to differential release profiles. We achieved aggregate polymorphism by the addition of different surfactants, but polymorphism may also be reached through other approaches, including different excipients as well as changes in pH and salinity, providing a versatile handle to control release profiles.

Design and synthesis of mixed micellar system for enhanced anticancer efficacy of Paclitaxel through its co-delivery with Naringin

Emergence of multidrug resistance (MDR) has limited the success of chemotherapeutic agents. Reversal of drugs efflux systems through combination therapy has got wider attention for increasing anticancer drugs efficacy. This study aims at co-encapsulation of Paclitaxel with Naringin in mixed polymeric micelles for enhanced anticancer activity of the drug. Drug-loaded micelles were prepared using two different amphiphilic block co-polymers and were characterized for morphology, size, zeta potential, drug encapsulation, in vitro release and stability using atomic force microscope (AFM), zetasizer, UV spectrophotometer, and FT-IR. MTT assay and fluorescence microscopy were used for in vitro cytotoxicity and cellular uptake studies. Nano-size micelles with spherical morphology and negative charge encapsulated 76.52 ± 0.94% and 32.87 0.61% Paclitaxel and Naringin, respectively. The micelles were thermally stable and retained 87.05 ± 0.69% and 92.88 ± 2.17% Paclitaxel and Naringin upon one-month storage. Maximum drug release was achieved at fourth hour of the study for both the loaded drugs. Paclitaxel co-encapsulation with Naringin synergistically improved its intracellular uptake and 65% in vitro cytotoxicity against breast cancer cells was achieved at its lower dose of 15 µg/mL. Results suggest that co-encapsulation of Paclitaxel with Naringin in mixed micelles is an effective strategy for achieving its higher anticancer activity.

A Smart pH-Sensitive Delivery System for Enhanced Anticancer Efficacy via Paclitaxel Endosomal Escape

Micelles are highly attractive nano-drug delivery systems for targeted cancer therapy. While they have been demonstrated to significantly alleviate the side-effects of their cargo drugs, the therapy outcomes are usually suboptimal partially due to ineffective drug release and endosome entrapment. Stimulus-responsive nanoparticles have allowed controlled drug release in a smart fashion, and we want to use this concept to design novel micelles. Herein, we reported pH-sensitive paclitaxel (PTX)-loaded poly (ethylene glycol)-phenylhydrazone-dilaurate (PEG-BHyd-dC12) micelles (PEG-BHyd-dC12/PTX). The micelles were spherical, with an average particle size of ∼135 nm and a uniform size distribution. The pH-responsive properties of the micelles were certified by both colloidal stability and drug release profile, where the particle size was strikingly increased accompanied by faster drug release as pH decreased from 7.4 to 5.5. As a result, the micelles exhibited much stronger cytotoxicity than the pH-insensitive counterpart micelles against various types of cancer cells due to the hydrolysis of the building block polymers and subsequent rapid PTX release. Overall, these results demonstrate that the PEG-BHyd-dC12 micelle is a promising drug delivery system for cancer therapy.

Stimuli-responsive nanoscale drug delivery systems for cancer therapy

Currently, with the rapid development of nanotechnology, novel drug delivery systems (DDSs) have made rapid progress, in which nanocarriers play an important role in the tumour treatment. In view of the conventional chemotherapeutic drugs with many restrictions such as nonspecific systemic toxicity, short half-life and low concentration in the tumour sites, stimuli-responsive DDSs can deliver anti-tumour drugs targeting to the specific sites of tumours. Owing to precise stimuli response, stimuli-responsive DDSs can control drug release, so as to improve the curative effects, reduce the damage of normal tissues and organs, and decrease the side effects of traditional anticancer drugs. At present, according to the physicochemical properties and structures of nanomaterials, they can be divided into three categories: (1) endogenous stimuli-responsive materials, including pH, enzyme and redox responsive materials; (2) exogenous stimuli-responsive materials, such as temperature, light, ultrasound and magnetic field responsive materials; (3) multi-stimuli responsive materials. This review mainly focuses on the researches and developments of these novel stimuli-responsive DDSs based on above-mentioned nanomaterials and their clinical applications.

Biodegradable Micelles for NIR/GSH-Triggered Chemophototherapy of Cancer

The chemotherapy of stimuli-responsive drug delivery systems (SDDSs) is a promising method to enhance cancer treatment effects. However, the low efficiency of chemotherapy drugs and poor degradation partly limit the application of SDDSs. Herein, we report doxorubicin (DOX)-loading mixed micelles for biotin-targeting drug delivery and enhanced photothermal/photodynamic therapy (PTT/PDT). Glutathione (GSH)-responsive mixed micelles were prepared by a dialysis method, proportionally mixing polycaprolactone-disulfide bond-biodegradable photoluminescent polymer (PCL-SS-BPLP) and biotin-polyethylene glycol-cypate (biotin-PEG-cypate). Chemically linking cypate into the mixed micelles greatly improved cypate solubility and PTT/PDT effect. The micelles also exhibited good monodispersity and stability in cell medium (~119.7 nm), low critical micelles concentration, good biodegradation, and photodecomposition. The high concentration of GSH in cancer cells and near-infrared light (NIR)-mediated cypate decomposition were able to achieve DOX centralized release. Meanwhile, the DOX-based chemotherapy combined with cypate-based NIR-triggered hyperthermia and reactive oxygen species could synergistically induce HepG2 cell death and apoptosis. The in vivo experiments confirmed that the micelles generated hyperthermia and achieved a desirable therapeutic effect. Therefore, the designed biodegradable micelles are promising safe nanovehicles for antitumor drug delivery and chemo/PTT/PDT combination therapy.

Glutathione Triggered Cascade Degradation of an Amphiphilic Poly(disulfide)-Drug Conjugate and Targeted Release

A bioreducible poly(disulfide)-derived amphiphilic block copolymer-drug conjugate (loading content 31%) was synthesized by post-polymerization modification. It shows redox-responsive polymersome assembly in water with aggregation induced emission property arising from the appended Camptothecin (CPT) drug. Glutathione (GSH), a tripeptide overexpressed in cancer cells, triggers a cascade reaction resulting in simultaneous degradation of the polymer backbone (consisting of disulfide linkage) and the release of the pendant drug. The cascade reaction involves GSH trigger cleavage of the backbone disulfide bond producing free thiol followed by its intrachain nucleophilic attack to the adjacent carbonate group that links the appended drug molecule. The polymeric pro-drug exhibits killing efficiency to a cancer cell with remarkably low IC₅₀ value of 3.1 μg/mL (based on the CPT concentration) while it shows negligible toxicity to a normal cell up to polymer concentration 300 μg/mL.

Sericin nanomicelles with enhanced cellular uptake and pH-triggered release of doxorubicin reverse cancer drug resistance

Drug resistance is the major challenge facing cancer chemotherapy and nanoscale delivery systems based on natural materials, such as sericin, are a promising means of overcoming drug resistance. Yet, no attempt of introducing synthetic poly(γ-benzyl-L-glutamate) (PBLG) onto sericin polypeptide to fabricate a facile biocompatible and biodegradable micelle has been tried. Here, we prepared a polypeptide-based amphiphilic polymer containing hydrophilic sericin polypeptide backbone and PBLG side chains via ring-opening polymerization (ROP) strategy. The introduction of PBLG side chains remarkably enhances the stability of sericin micelles in water. Meanwhile, the micelles exhibited a high loading capacity and pH-responsive release ability for antitumor drug doxorubicin (DOX), called sericin-PBLG-DOX. Owing to the excellent cell membrane penetration of sericin-PBLG, the cellular uptake of DOX when loaded into micelles was improved. Subsequently, sericin-PBLG-DOX was transferred into perinuclear lysosomes, where the release rate of DOX was accelerated. Compared to the same dose of DOX, sericin-PBLG-DOX could induce a more efficient anti-tumor effect both in vitro and in vivo, and these micelles have promise for future clinical applications in overcoming cancer drug resistance with good biosafety, enhanced cellular uptake, pH-triggered drug release, efficient anti-tumor effects, and minimized systemic toxicity.

Hypoxia-activated prodrugs and redox-responsive nanocarriers

Hypoxia is one of the marked features of malignant tumors, which is associated with several adaptation changes in the microenvironment of tumor cells. Therefore, targeting tumor hypoxia is a research hotspot for cancer therapy. In this review, we summarize the developing chemotherapeutic drugs for targeting hypoxia, including quinones, nitroaromatic/nitroimidazole, N-oxides, and transition metal complexes. In addition, redox-responsive bonds, such as nitroimidazole groups, azogroups, and disulfide bonds, are frequently used in drug delivery systems for targeting the redox environment of tumors. Both hypoxia-activated prodrugs and redox-responsive drug delivery nanocarriers have significant effects on targeting tumor hypoxia for cancer therapy. Hypoxia-activated prodrugs are commonly used in clinical trials with favorable prospects, while redox-responsive nanocarriers are currently at the experimental stage.

In situ misemgel as a multifunctional dual-absorption platform for nasal delivery of raloxifene hydrochloride: formulation, characterization, and in vivo performance

BACKGROUND

Raloxifene hydrochloride (RLX) is approved by the US Food and Drug Administration for the treatment and prevention of osteoporosis, in addition to reducing the risk of breast cancer in postmenopausal women. RLX has the disadvantages of low aqueous solubility, extensive presystemic intestinal glucuronidation, and first-pass metabolism, resulting in a limited bio-availability of only 2%. The aim of this work was to enhance the bioavailability of RLX via the formulation of an in situ nasal matrix (misemgel) comprising micelles made of vitamin E and D-α-tocopheryl polyethylene glycol 1000 succinate and nanosized self-emulsifying systems (NSEMS).

MATERIALS AND METHODS

Optimization of the RLX-loaded NSEMS was performed using a mixture design. The formulations were characterized by particle size and then incorporated into an in situ nasal gel. Transmission electron microscopy, bovine nasal mucosa ex vivo permeation, and visualization using a fluorescence laser microscope were carried out on the RLX in situ misemgel comparing with raw RLX in situ gel. In addition, the in vivo performance was studied in rats.

RESULTS

The results revealed improved permeation parameters for RLX misemgel compared with control gel, with an enhancement factor of 2.4. In vivo studies revealed a 4.79- and 13.42-fold increased bioavailability for RLX in situ misemgel compared with control RLX in situ gel and commercially available tablets, respectively. The obtained results highlighted the efficacy of combining two different formulations to enhance drug delivery and the benefits of utilizing different possible paths for drug absorption.

CONCLUSION

The developed in situ misemgel matrix could be considered as a promising multifunctional platform for nasal delivery which works based on a dual-absorption mechanism.

Lactoferrin-conjugated pH and redox-sensitive polymersomes based on PEG-S-S-PLA-PCL-OH boost delivery of bacosides to the brain

In the present study, engineered lactoferrin (Lf)-conjugated pH and redox-sensitive polymersomes derived from the triblock copolymer polyethylene glycol-S-S-polylactic acid-polycaprolactone (PEG-S-S-PLA-PCL-OH) have been used to deliver bacosides to the brain. Bacosides are classified as triterpenoid saponins and are used in Indian Ayurveda for reversal of amnesia; however, no study has extensively demonstrated their efficacy as a nano-formulation in an animal model. The polymer was synthesized by ring opening polymerization of lactide and ε-caprolactone. The nanoparticles obtained by nanoprecipitation showed a core-shell morphology, with an average size of 110 nm, by transmission electron microscopy (TEM). The colloidal stability, hemocompatibility and cytocompatibility of the polymersomes proved their biocompatibility. pH and disulfide linkages in the polymeric chain accelerated the disintegration of the polymersomes at pH 6.6 and at pH 6.6 with glutathione (GSH) in comparison to pH 7.4, supporting their degradation behavior. Supermagnetic iron oxide nanoparticles (SPIONs, 74.99 μg mg-1 polymer) encapsulated into the polymersomes demonstrated their uptake in a mouse model by MRI. Furthermore, bacosides encapsulated in the polymersomes (10% loading) showed significant memory loss reversal in chemically induced amnesic mice, supported by the gene expression profiles of Arc, BDNF and CREB as well as by histopathology.