Polymeric micelles for multidrug delivery and combination therapy

Supramolecular 3 in 1: A Lubrication and Co-Delivery System for Synergistic Advanced Osteoarthritis Therapy

The complexity, heterogeneity, and drug resistance of diseases necessitate a shift in therapeutic paradigms from monotherapy to combination therapy, which could augment treatment efficiency. Effective treatment of advanced osteoarthritis (OA) requires addressing three key factors contributing to its deterioration: chronic joint inflammation, lubrication dysfunction, and cartilage-tissue degradation. Herein, we present a supramolecular nanomedicine of multifunctionality via molecular recognition and self-assembly. The employed macrocyclic carrier, zwitterion-modified cavitand (CV-2), not only accurately loads various drugs but also functions as a therapeutic agent with lubricating properties for the treatment of OA. Kartogenin (KGN), a drug for articular cartilage regeneration and protection, and flurbiprofen (FP), an anti-inflammatory agent, were coloaded onto CV-2 assembly, forming a supramolecular nanomedicine KGN&FP@CV-2. The three-in-one combination therapy of KGN&FP@CV-2 addresses the three pathological features for treating OA collectively, and thus provides long-term therapeutic benefits for OA through sustained drug release and intrinsic lubrication in vivo. The multifunctional integration of macrocyclic delivery and therapeutics provides a simple, flexible, and universal platform for the synergistic treatment of diseases involving multiple drugs.

Multifactorial drug carrier system bringing both chemical and physical therapeutics to the treatment of tumor heterogeneity

Tumor heterogeneity and drug resistance have been invincible features of cancer for its complete cure. Despite the advent of immunotherapy, the expansion and diversification of cancer cells evolved even in the absence or presence of drug treatment discourage additional therapeutic interventions. For the eradication of cancer cells, therefore, an 'all-at-once' strategy is required, which exploits both target-selective chemotherapy and non-selective physicotherapy. Multifactorial microcapsules comprising gold nanoparticles (AuNPs) and a self-assembly protein of α-synuclein (αS) were fabricated, in which hydrophobic and hydrophilic drugs could be separately encapsulated by employing lipid-based inverted micelles (IMs). Their combined physico-chemical therapeutic effects were examined since they also contained both membrane-disrupting IMs and heat-generating AuNPs upon irradiation as physicotherapeutic agents. For the optimal enclosure of IMs containing hydrophilic drugs, a porous inner skeleton made of poly(lactic-co-glycolic acid) was introduced, which would play the roles of not only compartmentalizing the internal space but also enhancing proteolytic disintegration of the microcapsules to discharge and stabilize IMs to the outside. In fact, hydrophobic paclitaxel and hydrophilic doxorubicin showed markedly enhanced drug efficacy when delivered in the IM-containing microcapsules exhibiting the 'quantal' release of both drugs into the cells whose integrity could be also affected by the IMs. In addition, the remnants of αS-AuNP microcapsules produced via proteolysis also caused cell death through photothermal effect. The multifactorial microcapsules are therefore considered as a promising anti-cancer drug carrier capable of performing combinatorial selective and non-selective chemical and physical therapies to overcome tumor heterogeneity and drug resistance.

Evaluation of pH-Sensitive Polymeric Micelles Using Citraconic Amide Bonds for the Co-Delivery of Paclitaxel, Etoposide, and Rapamycin

Paclitaxel (PTX), etoposide (ETP), and rapamycin (RAPA) have different mechanisms, allowing multiple pathways to be targeted simultaneously, effectively treating various cancers. However, these drugs have a low hydrosolubility, limiting clinical applications. Therefore, we used pH-sensitive polymeric micelles to effectively control the drug release in cancer cells and to improve the water solubility of PTX, ETP, and RAPA. The synergistic effect of PTX, ETP, and RAPA was evaluated in gastric cancer, and the combination index values were evaluated. Thin-film hydration was used to prepare PTX/ETP/RAPA-loaded mPEG-pH-PCL micelles, and various physicochemical properties of these micelles were evaluated. In vitro cytotoxicity, pH-sensitivity, drug release profiles, in vivo pharmacokinetics, and biodistribution studies of PTX/ETP/RAPA-loaded mPEG-pH-PCL micelles were evaluated. In the pH-sensitivity evaluation, the size of the micelles increased more rapidly at a pH of 5.5 than at a pH of 7.4. The release rate of each drug increased with decreasing pH values in PTX/ETP/RAPA-loaded mPEG-pH-PCL micelles. In vitro and in vivo studies demonstrated that PTX/ETP/RAPA-loaded mPEG-pH-PCL micelles exhibit different drug release behaviors depending on the pH of the tumor and normal tissues and increased bioavailability and circulation time in the blood than solutions. Therefore, we propose that PTX/ETP/RAPA- loaded mPEG-pH-PCL micelles are advantageous for gastric cancer treatment in drug delivery systems.

Nanoparticles Loaded with Docetaxel and Resveratrol as an Advanced Tool for Cancer Therapy

A growing interest in the use of a combination of chemosensitizers and cytostatics for overcoming cancer resistance to treatment and the development of their delivery systems has been observed. Resveratrol (Res) presents antioxidant, anti-inflammatory and chemopreventive properties but also limits multidrug resistance against docetaxel (Dtx), which is one of the main causes of failure in cancer therapy with this drug. However, the use of both drugs presents challenges, including poor bioavailability, the unfavourable pharmacokinetics and chemical instability of Res and the poor water solubility and dose-limiting toxicity of Dtx. In order to overcome these difficulties, attempts have been made to create different forms of delivery for both agents. This review is focused on the latest developments in nanoparticles for the delivery of Dtx, Res and for the combined delivery of those two drugs. The aim of this review was also to summarize the synergistic mechanism of action of Dtx and Res on cancer cells. According to recent reports, Dtx and Res loaded in a nano-delivery system exhibit better efficiency in cancer treatment compared to free drugs. Also, the co-delivery of Dtx and Res in one actively targeted delivery system providing the simultaneous release of both drugs in cancer cells has a chance to fulfil the requirements of effective anticancer therapy and reduce limitations in therapy caused by multidrug resistance (MDR).

Supramolecular Hydrogels Developed from Mafenide and Indomethacin as a Plausible Multidrug Self-Delivery System as Antibacterial and Anti-inflammatory Topical Gels

Following a structural rationale, a series of simple organic salts derived from mafenide (a drug for treating burn wounds) and n-alkyl carboxylic acids (Me-(CH₂)_n-COOH; n = 1-3, 10-15) and various nonsteroidal anti-inflammatory drugs (NSAIDs), namely, indomethacin (IND), diclofenac (DIC), meclofenamic acid (MEC), tolfenamic acid (TOL), and flufenamic acid (FLU) (designated as salts 1-14, respectively) were synthesized as potential hydrogelators. Gelation studies revealed that mafenide n-alkyl carboxylates with n = 11-14, i.e., salts 5-8, and the indomethacin salt of mafenide, i.e., salt 10, were hydrogelators. The corresponding hydrogels, namely, 5(HG)-8(HG) and 10(HG), were characterized by table-top and dynamic rheology and high-resolution transmission electron microscopy (HR-TEM). Single-crystal structures of the nongelator salts 1-3 and the gelator salt 10 were determined by X-ray diffraction. The results obtained from various studies, which included the solubility, biostability, biocompatibility (MTT assay), and anti-inflammatory (PGE₂ assay) response of salt 10, the antibacterial response (zone inhibition assay) of salt 10, its components, and 10(HG), and the release of salt 10 in vitro from the corresponding hydrogel bed to the bulk solvent at 37 °C in 24 h, suggested their plausible use in developing multidrug-derived topical hydrogels for self-delivery applications.

Optimization and Pharmacokinetic Evaluation of Synergistic Fenbendazole and Rapamycin Co-Encapsulated in Methoxy Poly(Ethylene Glycol)-b-Poly(Caprolactone) Polymeric Micelles

Purpose

We aimed to develop a nanocarrier formulation incorporating fenbendazole (FEN) and rapamycin (RAPA) with strong efficacy against A549 cancer cells. As FEN and RAPA are poorly soluble in water, it is difficult to apply them clinically in vivo. Therefore, we attempted to resolve this problem by encapsulating these drugs in polymeric micelles.

Methods

We evaluated drug synergy using the combination index (CI) values of various molar ratios of FEN and RAPA. We formed and tested micelles composed of different polymers. Moreover, we conducted cytotoxicity, stability, release, pharmacokinetic, and biodistribution studies to investigate the antitumor effects of FEN/RAPA-loaded mPEG-b-PCL micelles.

Results

We selected mPEG-b-PCL-containing FEN and RAPA at a molar ratio of 1:2 because these particles were consistent in size and had high encapsulation efficiency (EE, %) and drug loading (DL, %) capacity. The in vitro cytotoxicity was assessed for various FEN, RAPA, and combined FEN/RAPA formulations. After long-term exposures, both the solutions and the micelles had similar efficacy against A549 cancer cells. The in vivo pharmacokinetic study revealed that FEN/RAPA-loaded mPEG-b-PCL micelles had a relatively higher area under the plasma concentration–time curve from 0 to 2 h (AUC_{0–2 h}) and 0 to 8 h (AUC_{0–8 h}) and plasma concentration at time zero (C_o) than that of the FEN/RAPA solution. The in vivo biodistribution assay revealed that the IV injection of FEN/RAPA-loaded mPEG-b-PCL micelles resulted in lower pulmonary FEN concentration than the IV injection of the FEN/RAPA solution.

Conclusion

When FEN and RAPA had a 1:2 molar ratio, they showed synergism. Additionally, using data from in vitro cytotoxicity, synergism between a 1:2 molar ratio of FEN and RAPA was observed in the micelle formulation. The FEN/RAPA-loaded mPEG-b-PCL micelle had enhanced bioavailability than the FEN/RAPA solution.

Self-assembly of binary solutions to complex structures

Self-assembly in natural and synthetic molecular systems can create complex aggregates or materials whose properties and functionalities rise from their internal structure and molecular arrangement. The key microscopic features that control such assemblies remain poorly understood, nevertheless. Using classical density functional theory, we demonstrate how the intrinsic length scales and their interplay in terms of interspecies molecular interactions can be used to tune soft matter self-assembly. We apply our strategy to two different soft binary mixtures to create guidelines for tuning intermolecular interactions that lead to transitions from a fully miscible, liquid-like uniform state to formation of simple and core-shell aggregates and mixed aggregate structures. Furthermore, we demonstrate how the interspecies interactions and system composition can be used to control concentration gradients of component species within these assemblies. The insight generated by this work contributes toward understanding and controlling soft multi-component self-assembly systems. Additionally, our results aid in understanding complex biological assemblies and their function and provide tools to engineer molecular interactions in order to control polymeric and protein-based materials, pharmaceutical formulations, and nanoparticle assemblies.

Hyaluronic acid functionalized biodegradable mesoporous silica nanocomposites for efficient photothermal and chemotherapy in breast cancer

Chemotherapy is one of conventional treatment methods for breast cancer, but drug toxicity and side effects have severely limited its clinical applications. Photothermal therapy has emerged as a promising method that, upon combination with chemotherapy, can better treat breast cancer. In this context, a biodegradable mesoporous silica nanoparticle (bMSN NPs) system was developed for loading doxorubicin (DOX) and IR780, to be potentially applied in the treatment of breast cancer. IR780 is encapsulated in the pores of bMSN NPs by hydrophobic adsorption, while DOX is adsorbed on the surface of the bMSN NPs by hyaluronic acid electrostatically, to form the bMID NPs. Transmission electron microscopy, fluorescence spectrum and UV absorption spectrum are used to prove the successful encapsulation of IR780 and the loading of DOX. In vitro experiments have shown bMID NPs present an excellent therapeutic effect on breast cancer cells. In vivo fluorescence imaging results have indicated that bMID NPs can accumulate in tumor sites gradually and achieve in vivo long-term circulation and continuous drug release. Furthermore, bMID NPs have provided obvious antitumor effects in breast cancer mouse models, thus evolving as an efficient platform for breast cancer therapy.

Evaluation of the Physicochemical Properties, Pharmacokinetics, and In Vitro Anticancer Effects of Docetaxel and Osthol Encapsulated in Methoxy Poly(ethylene glycol)-b-Poly(caprolactone) Polymeric Micelles

Docetaxel (DTX), a taxane-based anticancer drug, and osthol (OTH), a coumarin-derivative compound, have shown anticancer effects against different types of cancers through various mechanisms. However, these drugs have low solubility in water and low oral bioavailability, and thus their clinical application is difficult. To overcome these problems, we encapsulated DTX and OTH in methoxy poly(ethylene glycol)-b-poly(caprolactone) (mPEG-b-PCL) and conducted studies in vitro and in vivo. We selected a 1:4 ratio as the optimal ratio of DTX and OTH, through combination index analysis in A549 cancer cells, and prepared micelles to evaluate the encapsulation efficiency, drug loading, particle size, and zeta potential. The in vitro drug-release profile showed that DTX/OTH-loaded mPEG-b-PCL micelles could slowly release DTX and OTH. In the clonogenic assay, DTX/OTH-loaded mPEG-b-PCL micelles showed 3.7 times higher inhibitory effect than the DTX/OTH solution. Pharmacokinetic studies demonstrated that micelles in combination with DTX and OTH exhibited increased area under curve and decreased clearance values, as compared with single micelles.

Opportunities and challenges in managing antibiotic resistance in bacteria using plant secondary metabolites

Development of antibiotic resistance (ABR) in bacteria and its multidimensional spread is an emerging global threat that needs immediate attention. Extensive antibiotics (AB) usage results in development of ABR in bacteria by target modification, production of AB degrading enzymes, porin modifications, efflux pumps overexpression, etc. To counter this, apart from strict regulation of AB use and behavioural changes, research and development (R&D) of newer antimicrobials are in place. One such emerging approach to combat ABR is the use of structurally and functionally diverse plant secondary metabolites (PSMs) in combination with the conventional AB. Either the PSMs are themselves antimicrobial or they potentiate the activity of the AB through a range of mechanisms. However, their use is lagging due to poor knowledge of mode of action, structure-activity relationships, pharmacokinetics, etc. This review paper discussed the opportunities and challenges in managing ABR using PSMs. Mechanisms of ABR development in bacteria and current strategies to counter them were studied and the areas where PSMs can play an important role were highlighted. The use of PSMs, both as an anti-resistance and anti-virulence agent in combination therapy to counter multi-drug resistance along with their mechanisms of action, has been discussed in detail. The difficulties in the commercialisation of PSMs and strategies to overcome them along with future priority areas of research have also been given. Following the given R&D path will definitely help in better understanding and utilising the full potential of PSMs in solving the problem of antimicrobial resistance (AMR).

Novel Chitosan Derivatives with Reversible Cationization and Hydrophobicization for Tumor Cytoplasm-Specific Burst Co-delivery of siRNA and Chemotherapeutics

Despite the great potential of combination therapy based on siRNA and chemotherapeutics, an efficient vehicle with abilities of well drug co-loading, synchronizing in vivo trafficking, and target-specific co-burst release remains elusive, which results in a suboptimal synergistic potency. Herein, a novel chitosan amphiphile (PEI-ss-HECS-ss-OA, HSPO) with glutathione (GSH)-reversible cationization and hydrophobicization by polyethylenimine (PEI) and octylamine (OA), respectively, was developed for this purpose. HSPO spontaneously assembled in aqueous solution to be a micellar system and effectively co-encapsulated the two drugs with an adjustable dosage ratio. With a surface charge inversion strategy by hyaluronic acid (HA) coating, the HA(HSPO) co-delivery micelles with a negative surface charge (-21.45 ± 1.44 mV) and suitable size (192.52 ± 7.41 nm) selectively accumulated into CD44 overexpressed A549 tumors through a combination of passive and active targeting mechanism. Then, tumor cytoplasm-selective co-burst release was obtained through GSH triggered collapse of the amphiphilic assembly alongside a decrease of positive charge condensation, finally leading to an enhanced synergistic antitumor effect with a superior inhibition ratio of 86.63%. Overall, this study validated the great promise of HSPO as an efficient site-specific rapid co-trafficking vehicle of siRNA and chemotherapeutics for a remarkable synergistic tumor inhibition.

Revolutionizing technologies of nanomicelles for combinatorial anticancer drug delivery

Insufficient efficacy of current single drug therapy of cancers have led to the advancement of combination drug-loaded formulations. Specifically, polymeric micelles have been focused on as efficient injectable vehicles for the delivery of several anticancer drugs simultaneously to cancer cells. These nano delivery systems have evolved with advancements in the area of nanotechnology. The current review presents a summary of the past events that have led to the procession of nanomicelles and novel nanotechnologies for combinatorial drug delivery. It also focuses on the advantages, disadvantages, and considerations for the design of nanotechnologies for combinatorial drug delivery systems. The opportunities and challenges of nanotechnologies in drug delivery to overcome current disadvantages are also discussed. Furthermore, we have added findings regarding the trends and perspectives regarding nanotechnologies for combinatorial anticancer drug delivery.

Nanoparticles characterization using the CAM assay

The current chapter highlights the use of chorioallantoic membrane (CAM) of fertilized chicken egg for the characterization of nanoparticles applied in cancer nanomedicine. The CAM assay represents a promising alternative to mouse models in term of costs, ease of use, rapidity and ethical issues in particular for the screening of nanoformulations. Hence, the features of nanoparticles including blood retention, biocompatibility, active targeting or tumor accumulation, angiogenic activity, drug delivery and tumor elimination might be simply evaluated via the CAM model. In particular, in this model, embryo organs and morphology, CAM vasculature and blood cells, transplanted tumors on CAM were typically monitored and used for the evaluation of the nanomaterials. With the above advantages, the CAM assay, as highly valuable in vivo model, could be used regularly in pharmaceutical industries.

E-jet 3D printed drug delivery implants to inhibit growth and metastasis of orthotopic breast cancer

Drug-loaded implants have attracted considerable attention in cancer treatment due to their precise delivery of drugs into cancer tissues. Contrary to injected drug delivery, the application of drug-loaded implants remains underutilized given the requirement for a surgical operation. Nevertheless, drug-loaded implants have several advantages, including a reduction in frequency of drug administration, minimal systemic toxicity, and increased delivery efficacy. Herein, we developed a new, precise, drug delivery device for orthotopic breast cancer therapy able to suppress breast tumor growth and reduce pulmonary metastasis using combination chemotherapy. Poly-lactic-co-glycolic acid scaffolds were fabricated by 3D printing to immobilize 5-fluorouracil and NVP-BEZ235. The implantable scaffolds significantly reduced the required drug dosages and ensured curative drug levels near tumor sites for prolonged period, while drug exposure to normal tissues was minimized. Moreover, long-term drug release was achieved, potentially allowing one-off implantation and, thus, a major reduction in the frequency of drug administration. This drug-loaded scaffold has great potential in anti-tumor treatment, possibly paving the way for precise, effective, and harmless cancer therapy.

Discovery of fluorescent coumarin-benzo[b]thiophene 1, 1-dioxide conjugates as mitochondria-targeting antitumor STAT3 inhibitors

STAT3 has been extensively studied as a potential antitumor target. Though studies on regulating STAT3 mainly focus on the inhibition of STAT3 phosphorylation at Tyr705 residue, the phosphorylation at Ser727 residue of STAT3 protein is also closely associated with the mitochondrial import of STAT3 protein. N, N-diethyl-7-aminocoumarin is a fluorescent mitochondria-targeting probe. In this study, a series of STAT3 inhibitors were developed by connecting N, N-diethyl-7-aminocoumarin fluorophore with benzo [b]thiophene 1, 1-dioxide moiety. All designed compounds displayed potent anti-proliferative activity against cancer cells. The representative compound 7a was mainly accumulated in mitochondria visualized by its fluorescence. STAT3 phosphorylation was inhibited by compound 7a at both Tyr705 and Ser727 residues. Compound 7a inhibited STAT3 phosphorylation whereas had no influence on the phosphorylation levels of STAT1, JAK2, Src and Erk1/2, indicating good selectivity of compound 7a. Moreover, compound 7a down-regulated the expression of STAT3 target genes Bcl-2 and Cyclin D1, increased ROS production and remarkably reduced the mitochondrial membrane potential to induce mitochondrial apoptotic pathway. Furthermore, compound 7ain vivo suppressed breast cancer 4T1 implanted tumor growth. Taken together, these results highlighted that compound 7a might be a promising mitochondria-targeting STAT3 inhibitor for cancer therapy.

Liposome and polymeric micelle-based delivery systems for chlorophylls: Photodamage effects on Staphylococcus aureus

Chlorophyll derivatives (Chls), loaded in F-127 polymeric micelles and DPPC liposomes as drug delivery systems (DDS), have been shown to be remarkable photosensitizers for photodynamic inactivation (PDI). Assays of photoinactivation of Staphylococcus aureus bacteria (as biological models) showed that the effectiveness of Chls in these nanocarriers is dependent on photobleaching processes, photosensitizer locations in DDS, singlet oxygen quantum yields, and Chl uptake to bacteria. These are factors related to changes in Chl structure, such as the presence of metals, charge, and the phytyl chain. The photodynamic activity was significantly greater for Chls without the phytyl chain, i.e., phorbides derivatives. Furthermore, the inactivation of S. aureus was increased by the use of liposomes compared to micelles. Therefore, this research details and shows the high significance of the Chl structure and delivery system to enhance the photodynamic activity. It also highlights the chlorophylls (particularly phorbides) in liposomes as promising photosensitizers for PDI.

Transferrin-decorated thymoquinone-loaded PEG-PLGA nanoparticles exhibit anticarcinogenic effect in non-small cell lung carcinoma via the modulation of miR-34a and miR-16

The detailed molecular mechanism of transferrin-tagged thymoquinone nanoparticle mediated apoptotic induction in non-small cell lung carcinoma showing the involvement of p53 dependent synergistic activation of miR-34a and miR-16 in the pathway.

Investigation of magnetic silica with thermoresponsive chitosan coating for drug controlled release and magnetic hyperthermia application

In this study, a drug delivery system for chemo-hyperthermia applications is proposed and fabricated. The delivery system consists of magnetic-silica (MagSi) particles being encapsulated within a pH/thermo-responsive chitosan‑g‑N‑isopropylacrylamide (Chi-g-NIPAAm) polymer matrix. The as-prepared MagSi@Chi-g-NIPAAm particles exhibit superparamagnetic behavior with a saturation magnetization (Ms) of 20.14 emu/g. In addition, the MagSi@Chi-g-NIPAAm particles can act as a heat source when subject to an alternating magnetic field (AMF) and have a specific absorptions rate (SAR) of 8.36 Wg^-1. The release of the drug DOX from the synthesized particles is sensitive to both the pH and temperature of its environment. We have compared the drug release when the solution is externally heated up and when it is heated up by the AMF (internal heating). For external heating (when the pH/temperature is 4.0/45 °C), 83.30 ± 2.92% of the DOX were released within the first 5 h. The release of the DOX by the particles in pH 7.4 (temperature of 37 °C) was much slower (around 25.87 ± 1.30% after 25 h). The release of the DOX was much higher (under an acidic condition pH = 4.0) around 57.13 ± 2.36% within 1 h in the presence of AMF heating. The in vitro cytotoxicity tests of the of DOX-loaded MagSi@Chi-g-NIPAAm particles towards HeLa cancer cells. In general, the toxicities of the drug DOX as part of a MagSi@Chi-g-NIPAAm particles were less than those of the standalone DOX until the concentration of DOX-loaded particles reached 250 μg/mL, after which the toxicity of DOX in both forms were the same.

Bacterial microbots for acid-labile release of hybrid micelles to promote the synergistic antitumor efficacy

Bacteria have inherent properties of self-propelled navigation and specific infiltration into solid tumors. In the current study, we investigate a novel type of bacterial microbots for delivery of hybrid micelles to promote the synergistic antitumor efficacy. Escherichia coli Nissle 1917 (EcN) is used as a bacterial carrier to immobilize amphiphilic copolymers through acid-labile 2-propionic-3-methylmaleic anhydride (CDM) linkers. Doxorubicin (DOX) and α-tocopheryl succinate (TOS) are conjugated with poly(ethylene glycol) through disulfide linkers to obtain amphiphilic promicelle polymers (PM_TOS and PM_DOX). Tetrazine and norbornene terminals are grafted on EcN and PM_TOS/PM_DOX copolymers, respectively, and the mild and site-specific bioorthogonal reaction between them maintains the viability, motion ability, and tumor accumulation capability of the conjugated EcN. The PM_TOS/PM_DOX copolymers are released from bacterial microbots in response to the slightly acidic tumor microenvironment, followed by in situ formation of these copolymers as hybrid micelles (M_D/T). The self-assembled micelles from PM_TOS/PM_DOX with a ratio of 1:2 demonstrate the most significant synergistic efficacy, and the released M_D/T hybrid micelles exhibit cellular uptake efficiency, glutathione (GSH)-sensitive drug release, and cytotoxicities similar to those exhibited by micelles prepared by solvent evaporation. Because of the consecutive process of the self-propelling nature of bacteria and preferential accumulation of EcN in tumors, in situ formation of M_D/T hybrid micelles, and intracellular drug release, bacterial microbots have shown remarkable antitumor efficacy with regard to animal survival, tumor growth, and apoptosis induction in tumor cells. Therefore, we demonstrate a feasible strategy for the construction of bacterial microbots to achieve tumor accumulation and on-demand release of multiple therapeutic agents for synergistic antitumor efficacy.

STATEMENT OF SIGNIFICANCE

Challenges remain in the targeted delivery of nanoparticles to solid tumors and the realization of synergistic efficacy in cancer chemotherapy. In the current study, we explore a novel class of bacterial microbots to load, deliver, and release hybrid micelles. Escherichia coli Nissle 1917 (EcN) is used as a bacterial carrier to immobilize amphiphilic copolymers through acid-labile linkers, and the released copolymers are self-assembled into micelles. The resulting bacterial microbots integrate self-propelling bacteria and self-assembling amphiphilic polymers into micelles and realize pH-responsive release of promicelle polymers from bacterial microbots and glutathione-responsive intracellular release of drugs. A synergistic antitumor efficacy is achieved using hybrid micelles, which release both doxorubicin and α-tocopheryl succinate to display toxicities in the nucleus and mitochondria, respectively.

HSA-based multi-target combination therapy: regulating drugs' release from HSA and overcoming single drug resistance in a breast cancer model

Multi-drug delivery systems, which may be promising solution to overcome obstacles, have limited the clinical success of multi-drug combination therapies to treat cancer. To this end, we used three different anticancer agents, Cu(BpT)Br, NAMI-A, and doxorubicin (DOX), to build human serum albumin (HSA)-based multi-drug delivery systems in a breast cancer model to investigate the therapeutic efficacy of overcoming single drug (DOX) resistance to cancer cells in vivo, and to regulate the drugs' release from HSA. The HSA complex structure revealed that NAMI-A and Cu(BpT)Br bind to the IB and IIA sub-domain of HSA by N-donor residue replacing a leaving group and coordinating to their metal centers, respectively. The MALDI-TOF mass spectra demonstrated that one DOX molecule is conjugated with lysine of HSA by a pH-sensitive linker. Furthermore, the release behavior of three agents form HSA can be regulated at different pH levels. Importantly, in vivo results revealed that the HSA-NAMI-A-Cu(BpT)Br-DOX complex not only increases the targeting ability compared with a combination of the three agents (the NAMI-A/Cu(BpT)Br/DOX mixture), but it also overcomes DOX resistance to drug-resistant breast cancer cell lines.

Polypeptide self-assemblies: nanostructures and bioapplications

Polypeptide copolymers can self-assemble into diverse aggregates. The morphology and structure of aggregates can be varied by changing molecular architectures, self-assembling conditions, and introducing secondary components such as polymers and nanoparticles. Polypeptide self-assemblies have gained significant attention because of their potential applications as delivery vehicles for therapeutic payloads and as additives in the biomimetic mineralization of inorganics. This review article provides an overview of recent advances in nanostructures and bioapplications related to polypeptide self-assemblies. We highlight recent contributions to developing strategies for the construction of polypeptide assemblies with increasing complexity and novel functionality that are suitable for bioapplications. The relationship between the structure and properties of the polypeptide aggregates is emphasized. Finally, we briefly outline our perspectives and discuss the challenges in the field.

Nanoparticles of Titanium and Zinc Oxides as Novel Agents in Tumor Treatment: a Review

Cancer has become a global problem. On all continents, a great number of people are diagnosed with this disease. In spite of the progress in medical care, cancer still ends fatal for a great number of the ill, either as a result of a late diagnosis or due to inefficiency of therapies. The majority of the tumors are resistant to drugs. Thus, the search for new, more effective therapy methods continues. Recently, nanotechnology has been attributed with big expectations in respect of the cancer fight. That interdisciplinary field of science creates nanomaterials (NMs) and nanoparticles (NPs) that can be applied, e.g., in nanomedicine. NMs and NPs are perceived as very promising in cancer therapy since they can perform as drug carriers, as well as photo- or sonosensitizers (compounds that generate the formation of reactive oxygen species as a result of either electromagnetic radiation excitation with an adequate wavelength or ultrasound activation, respectively). Consequently, two new treatment modalities, the photodynamic therapy (PDT) and the sonodynamic therapy (SDT) have been created. The attachment of ligands or antibodies to NMs or to NPs improve their selective distribution into the targeted organ or cell; hence, the therapy effectiveness can be improved. An important advantage of the targeted tumor treatment is lowering the cyto- and genotoxicity of active substance towards healthy cells. Therefore, both PDT and SDT constitute a valuable alternative to chemo- or radiotherapy. The vital role in cancer eradication is attributed to two inorganic sensitizers in their nanosized scale: titanium dioxide and zinc oxide.

Synthesis and biological evaluation of novel steroidal 5α,8α-epidioxyandrost-6-ene-3β-ol-17-(O-phenylacetamide)oxime derivatives as potential anticancer agents

Inspired by the significant anti-cancer activity of our previously screened natural ergosterol peroxide (EP, 1), we synthesized and characterized a series of novel 5α,8α-epidioxyandrost-3β-ol-17-(O-phenylacetamide)oxime derivatives (9a-o). The anti-proliferative activity of the synthesized compounds against human hepatocellular carcinoma cells (HepG2, Sk-Hep1) and human breast cancer cells (MCF-7, MDA-MB231) were investigated. Compounds 9d, 9f, 9h, 9j and 9m displayed good anti-proliferative activity (most IC₅₀<20μM) in vitro. Furthermore, fluorescence imaging showed that the designed coumarin-9d conjugate (12) localized mainly in mitochondria, leading to enhanced anticancer activities over the parent structure.

Synthesis of 5α,8α-Ergosterol Peroxide 3-Carbamate Derivatives and a Fluorescent Mitochondria-Targeting Conjugate for Enhanced Anticancer Activities

Inspired by the significant anticancer activity of our previously screened natural ergosterol peroxide (1), we synthesized and characterized a series of novel ergosterol peroxide 3-carbamate derivatives. The antiproliferative activities of the synthesized compounds against human hepatocellular carcinoma cells (HepG2, SK-Hep1) and human breast cancer cells (MCF-7, MDA-MB231) were investigated. 5α,8α-Epidioxyergosta-3-yl-(piperazine-1)carbamate (3 d) and 5α,8α-epidioxyergosta-3-yl-(piperidin-4-methylamine)carbamate (3 f) and their hydrochloride salts exhibited significant in vitro antiproliferative activities against the tested tumor cell lines, with IC₅₀ values ranging from 0.85 to 4.62 μm. Furthermore, fluorescent imaging showed that the designed coumarin-3 d conjugate (5) localized mainly in mitochondria, leading to enhanced anticancer activities over the parent structure 1. As a whole, it appeared that substituent changes at the C3 position could serve as a promising launch point for further design of this type of steroidal anticancer agent.

Iminoboronate-based dual-responsive micelles via subcomponent self-assembly for hydrophilic 1,2-diol-containing drug delivery

Iminoboronate-based dual-responsive micelles were fabricated via simple subcomponent self-assembly for delivery of hydrophilic 1,2-diol-containing drugs.

Nanosystem composed with MSNs, gadolinium, liposome and cytotoxic peptides for tumor theranostics

A dual-functional delivery system, based on mesoporous silica nanoparticles (MSNs) with the integration of Magnetic Resonance (MR) imaging and therapeutic peptide delivery, is reported in this paper. A lipid bilayer is attached onto the surface of the nanoparticles, following the doping of Gadolinium (Gd), a paramagnetic lanthanide ion. The liposome-coated GdMSNs exhibit improved colloidal stability, better biocompatibility and more efficient cellular uptake. The Gd renders the nano carrier a potential T1 contrast agent, confirmed by the MR imaging. A pro-apoptotic peptide, KLA (HGGKLAKLAKKLAKLAK), is encapsulated into the GdMSNs-LP and enters into the cells successfully to induce mitochondrial swelling and apoptosis, while it is nontoxic outside the cells. The synthesis procedure is convenient and free of toxic organic reagents. The nanosystem we construct may contribute to a promising theranostic platform for therapeutic peptide delivery in cancer treatment.

Pluronic® P123/F127 mixed micelles delivering sorafenib and its combination with verteporfin in cancer cells

Here, we developed Pluronic® P123/F127 (poloxamer) mixed micelles for the intravenous delivery of the anticancer drug sorafenib (SRB) or its combination with verteporfin (VP), a photosensitizer for photodynamic therapy that should complement well the cytotoxicity profile of the chemotherapeutic. SRB loading inside the core of micelles was governed by the drug:poloxamer weight ratio, while in the case of the SRB-VP combination, a mutual interference between the two drugs occurred and only specific ratios could ensure maximum loading efficiency. Coentrapment of SRB did not alter the photophysical properties of VP, confirming that SRB did not participate in any bimolecular process with the photosensitizer. Fluorescence resonance energy-transfer measurement of micelles in serum protein-containing cell-culture medium demonstrated the excellent stability of the system in physiologically relevant conditions. These results were in line with the results of the release study showing a release rate of both drugs in the presence of proteins slower than in phosphate buffer. SRB release was sustained, while VP remained substantially entrapped in the micelle core. Cytotoxicity studies in MDA-MB231 cells revealed that at 24 hours, SRB-loaded micelles were more active than free SRB only at very low SRB concentrations, while at 24+24 hours a prolonged cytotoxic effect of SRB-loaded micelles was observed, very likely mediated by the block in the S phase of the cell cycle. The combination of SRB with VP under light exposure was less cytotoxic than both the free combination and VP-loaded micelles + SRB-loaded micelles combination. This behavior was clearly explainable in terms of micelle uptake and intracellular localization. Besides the clear advantage of delivering SRB in poloxamer micelles, our results provide a clear example that each photochemotherapeutic combination needs detailed investigations on their particular interaction, and no generalization on enhanced cytotoxic effects should be derived a priori.

Titanium wire implants with nanotube arrays: A study model for localized cancer treatment

Adverse complications associated with systemic administration of anti-cancer drugs are a major problem in cancer therapy in current clinical practice. To increase effectiveness and reduce side effects, localized drug delivery to tumour sites requiring therapy is essential. Direct delivery of potent anti-cancer drugs locally to the cancer site based on nanotechnology has been recognised as a promising alternative approach. Previously, we reported the design and fabrication of nano-engineered 3D titanium wire based implants with titania (TiO2) nanotube arrays (Ti-TNTs) for applications such as bone integration by using in-vitro culture systems. The aim of present study is to demonstrate the feasibility of using such Ti-TNTs loaded with anti-cancer agent for localized cancer therapy using pre-clinical cancer models and to test local drug delivery efficiency and anti-tumour efficacy within the tumour environment. TNF-related apoptosis-inducing ligand (TRAIL) which has proven anti-cancer properties was selected as the model drug for therapeutic delivery by Ti-TNTs. Our in-vitro 2D and 3D cell culture studies demonstrated a significant decrease in breast cancer cell viability upon incubation with TRAIL loaded Ti-TNT implants (TRAIL-TNTs). Subcutaneous tumour xenografts were established to test TRAIL-TNTs implant performance in the tumour environment by monitoring the changes in tumour burden over a selected time course. TRAIL-TNTs showed a significant regression in tumour burden within the first three days of implant insertion at the tumour site. Based on current experimental findings these Ti-TNTs wire implants have shown promising capacity to load and deliver anti-cancer agents maintaining their efficacy for cancer treatment.

Co-delivery of chemotherapeutics and proteins for synergistic therapy

Combination therapy with chemotherapeutics and protein therapeutics, typically cytokines and antibodies, has been a type of crucial approaches for synergistic cancer treatment. However, conventional approaches by simultaneous administration of free chemotherapeutic drugs and proteins lead to limitations for further optimizing the synergistic effects, due to the distinct in vivo pharmacokinetics and distribution of small drugs and proteins, insufficient tumor selectivity and tumor accumulation, unpredictable drug/protein ratios at tumor sites, short half-lives, and serious systemic adverse effects. Consequently, to obtain optimal synergistic anti-tumor efficacy, considerable efforts have been devoted to develop the co-delivery systems for co-incorporating chemotherapeutics and proteins into a single carrier system and subsequently releasing the dual or multiple payloads at desired target sites in a more controllable manner. The co-delivery systems result in markedly enhanced blood stability and in vivo half-lives of the small drugs and proteins, elevated tumor accumulation, as well as the capability of delivering the multiple agents to the same target sites with rational drug/protein ratios, which may facilitate maximizing the synergistic effects and therefore lead to optimal antitumor efficacy. This review emphasizes the recent advances in the co-delivery systems for chemotherapeutics and proteins, typically cytokines and antibodies, for systemic or localized synergistic cancer treatment. Moreover, the proposed mechanisms responsible for the synergy of chemotherapeutic drugs and proteins are discussed.

Evaluation of the potential synergism of imatinib-related poly kinase inhibitors using growth factor stimulated proteoglycan synthesis as a model response

INTRODUCTION

Tyrosine kinase inhibitors were the first class of smart drugs being specifically designed to inhibit a disease causing target. There is a very important but unresolved question as whether or not the overall therapeutic role of an individual tinib results from an action at its primary target, a single most likely, tyrosine kinase, or from the combined or aggregate action at the multiple targets which each tinib addresses.

METHODS

We selected a series of ten tinibs (gefitinib, sunitinib, lapatinib, erlotinib, imatinib, sorafenib, axitinib, vanitinib, bosutinib, dasatinib) with various known targets and investigated their activities in the inhibition of proteoglycan synthesis and GAG hyperelongation stimulated by a tyrosine kinase receptor agonist, platelet derived growth factor (PDGF) and for contrast, a serine/threonine kinase receptor agonist, TGF β and some downstream signalling pathways.

RESULTS

The inhibitory activity varied from little to total inhibition. The actions of the tinibs were directed more towards inhibition of the tyrosine kinase, PDGF receptor signalling pathway compared to the TGF β.

CONCLUSION

There was no suggestion of any synergistic effect arising from inhibition of multiple kinases as the most potent compound, dasatinib, is known to inhibit the broadest spectrum of kinases.

Salt metathesis for developing injectable supramolecular metallohydrogelators as a multi-drug-self-delivery system

Salt metathesis has been exploited to generate a series of non-steroidal anti-inflammatory drug (NSAID) based Zn(ii) metallohydrogels displaying both anti-inflammatory and anti-bacterial properties.

Polyaspartamide-based multi-responsive micelle with sheddable shell for antitumor drug delivery

A multi-stimuli (pH/thermo/reduction) responsive graft copolymer based on a polyaspartamide derivative is reported for Dox delivery.

Synthesis of doxorubicin-PLGA loaded chitosan stabilized (Mn, Zn)Fe2O4 nanoparticles: Biological activity and pH-responsive drug release

We have synthesized Mn1-xZnxFe2O4 ((Mn, Zn) ferrite) magnetic nanoparticles (MNPs) having radius of 25nm to act as platforms for delivering drugs. The Mn0.9Zn0.1Fe2O4 MNPs exhibit superparamagnetic behavior with large saturation magnetization (MS). They were encapsulated in polymer so that they can be developed into PLGA-coated chitosan stabilized (Mn, Zn) MNPs, i.e., DOX-PLGA@CS@Mn0.9Zn0.1Fe2O4 which can serve as an effective carrier of the anti-cancer drug doxorubicin (DOX) whose release would be controlled by the pH in the environment surrounding the cancer tumor. The structure of the as-prepared particles is of a magnetic core-encapsulated by polymer shell layer of around 50nm thick. At a pH of 4.0, the DOX release within the first 5h is fast (around 57%). It becomes slower (around 46% over the next 25h) when the pH is increased to 7.4. The DOX-PLGA@CS@Mn0.9Zn0.1Fe2O4 (for concentrations lower than 125μgmL(-1)) shows lower toxicity against HeLa cells using DOX only. When the DOX-PLGA@CS@Mn0.9Zn0.1Fe2O4 is increased to 250μgmL(-1), the DOX-PLGA@CS@Mn0.9Zn0.1Fe2O4 shows greater anti-cancer activity and has satisfactory therapeutic effect. The slow sustained release of the DOX by the drug loaded particles when they are in the physiological pH environment (7.4) of normal tissues and mild toxicity of DOX against cancer cell at low concentration point to the DOX loaded PLGA@CS@Mn0.9Zn0.1Fe2O4 being safely used for treating cancer. The higher dosage of DOX needed to kill the cancer cells will be released when the synthesized carriers are subject to the pH stimuli surrounding these cells.

Mesoporous-Silica-Functionalized Nanoparticles for Drug Delivery

The ever-growing interest for finding efficient and reliable methods for treatment of diseases has set a precedent for the design and synthesis of new functional hybrid materials, namely porous nanoparticles, for controlled drug delivery. Mesoporous silica nanoparticles (MSNPs) represent one of the most promising nanocarriers for drug delivery as they possess interesting chemical and physical properties, thermal and mechanical stabilities, and are biocompatibile. In particular, their easily functionalizable surface allows a large number of property modifications further improving their efficiency in this field. This Concept article deals with the advances on the novel methods of functionalizing MSNPs, inside or outside the pores, as well as within the walls, to produce efficient and smart drug carriers for therapy.