Influence of serum protein on polycarbonate-based copolymer micelles as a delivery system for a hydrophobic anti-cancer agent

Polycaprolactone - Vitamin E TPGS micelles for delivery of paclitaxel: In vitro and in vivo evaluation

This study aimed to present findings on a paclitaxel (PTX)-loaded polymeric micellar formulation based on polycaprolactone-vitamin E TPGS (PCL-TPGS) and evaluate its in vitro anticancer activity as well as its in vivo pharmacokinetic profile in healthy mice in comparison to a marketed formulation. Micelles were prepared by a co-solvent evaporation method. The micelle's average diameter and polydispersity were determined using dynamic light scattering (DLS) technique. Drug encapsulation efficiency was assessed using an HPLC assay. The in vitro cytotoxicity was performed on human breast cancer cells (MCF-7 and MDA-MB-231) using MTT assay. The in vivo pharmacokinetic profile was characterized following a single intravenous dose of 4 mg/kg to healthy mice. The mean diameters of the prepared micelles were ≤ 100 nm. Moreover, these micelles increased the aqueous solubility of PTX from ∼0.3 μg/mL to reach nearly 1 mg/mL. While the PTX-loaded micelles showed an in vitro cytotoxicity comparable to the marketed formulation (Ebetaxel), drug-free PCL-TPGS micelles did not show any cytotoxic effects on both types of breast cancer cells (∼100% viability). Pharmacokinetics of PTX as part of PCL-TPGS showed a significant increase in its volume of distribution compared to PTX conventional formulation, Ebetaxel, which is in line with what was reported for clinical nano formulations of PTX, i.e., Abraxane, Genexol-PM, or Apealea. The findings of our studies indicate a significant potential for PCL-TPGS micelles to act as an effective system for solubilization and delivery of PTX.

Hybrid Nanoplatforms Comprising Organic Nanocompartments Encapsulating Inorganic Nanoparticles for Enhanced Drug Delivery and Bioimaging Applications

Organic and inorganic nanoparticles (NPs) have attracted significant attention due to their unique physico-chemical properties, which have paved the way for their application in numerous fields including diagnostics and therapy. Recently, hybrid nanomaterials consisting of organic nanocompartments (e.g., liposomes, micelles, poly (lactic-co-glycolic acid) NPs, dendrimers, or chitosan NPs) encapsulating inorganic NPs (quantum dots, or NPs made of gold, silver, silica, or magnetic materials) have been researched for usage in vivo as drug-delivery or theranostic agents. These classes of hybrid multi-particulate systems can enable or facilitate the use of inorganic NPs in biomedical applications. Notably, integration of inorganic NPs within organic nanocompartments results in improved NP stability, enhanced bioavailability, and reduced systemic toxicity. Moreover, these hybrid nanomaterials allow synergistic interactions between organic and inorganic NPs, leading to further improvements in therapeutic efficacy. Furthermore, these platforms can also serve as multifunctional agents capable of advanced bioimaging and targeted delivery of therapeutic agents, with great potential for clinical applications. By considering these advancements in the field of nanomedicine, this review aims to provide an overview of recent developments in the use of hybrid nanoparticulate systems that consist of organic nanocompartments encapsulating inorganic NPs for applications in drug delivery, bioimaging, and theranostics.

Enzyme/pH dual stimuli-responsive nanoplatform co-deliver disulfiram and doxorubicin for effective treatment of breast cancer lung metastasis

OBJECTIVES

Metastasis is still one of the main obstacles in the treatment of breast cancer. This study aimed to develop disulfiram (DSF) and doxorubicin (DOX) co-loaded nanoparticles (DSF-DOX NPs) with enzyme/pH dual stimuli-responsive characteristics to inhibit breast cancer metastasis.

METHODS

DSF-DOX NPs were prepared using the amphiphilic poly(ε-caprolactone)-b-poly(L-glutamic acid)-g-methoxy poly(ethylene glycol) (PCL-b-PGlu-g-mPEG) copolymer by a classical dialysis method. In vitro release tests, in vitro cytotoxicity assay, and anti-metastasis studies were conducted to evaluate pH/enzyme sensitivity and therapeutic effect of DSF-DOX NPs.

RESULTS

The specific pH and enzyme stimuli-responsiveness of DSF-DO NPs can be attributed to the transformation of secondary structure and the degradation of amide bonds in the PGlu segment, respectively. This accelerated drug release significantly increased the cytotoxicity to 4T1 cells. Compared with the control group, the DSF-DOX NPs showed a strong inhibition of in vitro metastasis with a wound healing rate of 36.50% and a migration rate of 18.39%. Impressively, in vivo anti-metastasis results indicated that the metastasis of 4T1 cells was almost completely suppressed by DSF-DOX NPs.

CONCLUSION

DSF-DOX NPs with controllable tumor site delivery of DOX and DSF were a prospectively potential strategy for metastatic breast cancer treatment.

Scavenger receptor A-mediated nanoparticles target M1 macrophages for acute liver injury

Acute liver injury (ALI) has an elevated fatality rate due to untimely and ineffective treatment. Although, schisandrin B (SchB) has been extensively used to treat diverse liver diseases, its therapeutic efficacy on ALI was limited due to its high hydrophobicity. Palmitic acid-modified serum albumin (PSA) is not only an effective carrier for hydrophobic drugs, but also has a superb targeting effect via scavenger receptor-A (SR-A) on the M1 macrophages, which are potential therapeutic targets for ALI. Compared with the common macrophage-targeted delivery systems, PSA enables site-specific drug delivery to reduce off-target toxicity. Herein, we prepared SchB-PSA nanoparticles and further assessed their therapeutic effect on ALI. In vitro, compared with human serum albumin encapsulated SchB nanoparticles (SchB-HSA NPs), the SchB-PSA NPs exhibited more potent cytotoxicity on lipopolysaccharide (LPS) stimulated Raw264.7 (LAR) cells, and LAR cells took up PSA NPs 8.79 times more than HSA NPs. As expected, the PSA NPs also accumulated more in the liver. Moreover, SchB-PSA NPs dramatically reduced the activation of NF-κB signaling, and significantly relieved inflammatory response and hepatic necrosis. Notably, the high dose of SchB-PSA NPs improved the survival rate in 72 h of ALI mice to 75%. Hence, SchB-PSA NPs are promising to treat ALI.

Exploring the Application of Micellar Drug Delivery Systems in Cancer Nanomedicine

Various formulations of polymeric micelles, tiny spherical structures made of polymeric materials, are currently being investigated in preclinical and clinical settings for their potential as nanomedicines. They target specific tissues and prolong circulation in the body, making them promising cancer treatment options. This review focuses on the different types of polymeric materials available to synthesize micelles, as well as the different ways that micelles can be tailored to be responsive to different stimuli. The selection of stimuli-sensitive polymers used in micelle preparation is based on the specific conditions found in the tumor microenvironment. Additionally, clinical trends in using micelles to treat cancer are presented, including what happens to micelles after they are administered. Finally, various cancer drug delivery applications involving micelles are discussed along with their regulatory aspects and future outlooks. As part of this discussion, we will examine current research and development in this field. The challenges and barriers they may have to overcome before they can be widely adopted in clinics will also be discussed.

The in vivo fate of polymeric micelles

This review aims to provide a systemic analysis of the in vivo, as well as subcellular, fate of polymeric micelles (PMs), starting from the entry of PMs into the body. Few PMs are able to cross the biological barriers intact and reach the circulation. In the blood, PMs demonstrate fairly good stability mainly owing to formation of protein corona despite controversial results reported by different groups. Although the exterior hydrophilic shells render PMs "long-circulating", the biodistribution of PMs into the mononuclear phagocyte systems (MPS) is dominant as compared with non-MPS organs and tissues. Evidence emerges to support that the copolymer poly(ethylene glycol)-poly(lactic acid) (PEG-PLA) is first broken down into pieces of PEG and PLA and then remnants to be eliminated from the body finally. At the cellular level, PMs tend to be internalized via endocytosis due to their particulate nature and disassembled and degraded within the cell. Recent findings on the effect of particle size, surface characteristics and shape are also reviewed. It is envisaged that unraveling the in vivo and subcellular fate sheds light on the performing mechanisms and gears up the clinical translation of PMs.

A Review of Polymeric Micelles and Their Applications

Self-assembly of amphiphilic polymers with hydrophilic and hydrophobic units results in micelles (polymeric nanoparticles), where polymer concentrations are above critical micelle concentrations (CMCs). Recently, micelles with metal nanoparticles (MNPs) have been utilized in many bio-applications because of their excellent biocompatibility, pharmacokinetics, adhesion to biosurfaces, targetability, and longevity. The size of the micelles is in the range of 10 to 100 nm, and different shapes of micelles have been developed for applications. Micelles have been focused recently on bio-applications because of their unique properties, size, shape, and biocompatibility, which enhance drug loading and target release in a controlled manner. This review focused on how CMC has been calculated using various techniques. Further, micelle importance is explained briefly, different types and shapes of micelles are discussed, and further extensions for the application of micelles are addressed. In the summary and outlook, points that need focus in future research on micelles are discussed. This will help researchers in the development of micelles for different applications.

Elucidating the Stability of Single-Chain Polymeric Nanoparticles in Biological Media and Living Cells

The controlled folding of synthetic polymer chains into single-chain polymeric nanoparticles (SCPNs) of defined size and shape in water is a viable way to create compartmentalized, nanometer-sized structures for a range of biological applications. Understanding the relationship between the polymer's microstructure and the stability of folded structures is crucial to achieving desired applications. Here, we introduce the solvatochromic dye Nile red into SCPNs and apply a combination of spectroscopic and microscopic techniques to relate polymer microstructure to nanoparticle stability in complex biological media and cellular environments. Our experimental data show that the polymer's microstructure has little effect on the stability of SCPNs in biological media and cytoplasm of living cells, but only SCPNs comprising supramolecular benzene-1,3,5-tricarboxamide (BTA) motifs showed good stability in lysosomes. The results indicate that the polymer's microstructure is vital to ensure nanoparticle stability in highly competitive environments: both hydrophobic collapse and a structured interior are required. Our study provides an accessible way of probing the stability of SCPNs in cellular environments and paves the way for designing highly stable SCPNs for efficient bio-orthogonal catalysis and sensing applications.

Cancer nanotechnology: current status and perspectives

Modern medicine has been waging a war on cancer for nearly a century with no tangible end in sight. Cancer treatments have significantly progressed, but the need to increase specificity and decrease systemic toxicities remains. Early diagnosis holds a key to improving prognostic outlook and patient quality of life, and diagnostic tools are on the cusp of a technological revolution. Nanotechnology has steadily expanded into the reaches of cancer chemotherapy, radiotherapy, diagnostics, and imaging, demonstrating the capacity to augment each and advance patient care. Nanomaterials provide an abundance of versatility, functionality, and applications to engineer specifically targeted cancer medicine, accurate early-detection devices, robust imaging modalities, and enhanced radiotherapy adjuvants. This review provides insights into the current clinical and pre-clinical nanotechnological applications for cancer drug therapy, diagnostics, imaging, and radiation therapy.

Multifunctional polymeric micellar nanomedicine in the diagnosis and treatment of cancer

Polymeric micelles are a prevalent topic of research for the past decade, especially concerning their fitting ability to deliver drug and diagnostic agents. This delivery system offers outstanding advantages, such as biocompatibility, high loading efficiency, water-solubility, and good stability in biological fluids, to name a few. The multifunctional polymeric micellar architect offers the added capability to adapt its surface to meet the looked-for clinical needs. This review cross-talks the recent reports, proof-of-concept studies, patents, and clinical trials that utilize polymeric micellar family architectures concerning cancer targeted delivery of anticancer drugs, gene therapeutics, and diagnostic agents. The manuscript also expounds on the underlying opportunities, allied challenges, and ways to resolve their bench-to-bedside translation for allied clinical applications.

Harnessing amphiphilic polymeric micelles for diagnostic and therapeutic applications: Breakthroughs and bottlenecks

Amphiphilic block copolymers are widely utilized in the design of formulations owing to their unique physicochemical properties, flexible structures and functional chemistry. Amphiphilic polymeric micelles (APMs) formed from such copolymers have gained attention of the drug delivery scientists in past few decades for enhancing the bioavailability of lipophilic drugs, molecular targeting, sustained release, stimuli-responsive properties, enhanced therapeutic efficacy and reducing drug associated toxicity. Their properties including ease of surface modification, high surface area, small size, and enhanced permeation as well as retention (EPR) effect are mainly responsible for their utilization in the diagnosis and therapy of various diseases. However, some of the challenges associated with their use are premature drug release, low drug loading capacity, scale-up issues and their poor stability that need to be addressed for their wider clinical utility and commercialization. This review describes comprehensively their physicochemical properties, various methods of preparation, limitations followed by approaches employed for the development of optimized APMs, the impact of each preparation technique on the physicochemical properties of the resulting APMs as well as various biomedical applications of APMs. Based on the current scenario of their use in treatment and diagnosis of diseases, the directions in which future studies need to be carried out to explore their full potential are also discussed.

Polymeric micelles in drug delivery: An insight of the techniques for their characterization and assessment in biorelevant conditions

Polymeric micelles, i.e. aggregation colloids formed in solution by self-assembling of amphiphilic polymers, represent an innovative tool to overcome several issues related to drug administration, from the low water-solubility to the poor drug permeability across biological barriers. With respect to other nanocarriers, polymeric micelles generally display smaller size, easier preparation and sterilization processes, and good solubilization properties, unfortunately associated with a lower stability in biological fluids and a more complicated characterization. Particularly challenging is the study of their interaction with the biological environment, essential to predict the real in vivo behavior after administration. In this review, after a general presentation on micelles features and properties, different characterization techniques are discussed, from the ones used for the determination of micelles basic characteristics (critical micellar concentration, size, surface charge, morphology) to the more complex approaches used to figure out micelles kinetic stability, drug release and behavior in the presence of biological substrates (fluids, cells and tissues). The techniques presented (such as dynamic light scattering, AFM, cryo-TEM, X-ray scattering, FRET, symmetrical flow field-flow fractionation (AF4) and density ultracentrifugation), each one with their own advantages and limitations, can be combined to achieve a deeper comprehension of polymeric micelles in vivo behavior. The set-up and validation of adequate methods for micelles description represent the essential starting point for their development and clinical success.

Thymoquinone-Loaded Soluplus®-Solutol® HS15 Mixed Micelles: Preparation, In Vitro Characterization, and Effect on the SH-SY5Y Cell Migration

Thymoquinone (TQ) is the main active ingredient of Nigella sativa essential oil, with remarkable anti-neoplastic activities with anti-invasive and anti-migratory abilities on a variety of cancer cell lines. However, its poor water solubility, high instability in aqueous solution and pharmacokinetic drawbacks limits its use in therapy. Soluplus^® and Solutol^® HS15 were employed as amphiphilic polymers for developing polymeric micelles (SSM). Chemical and physical characterization studies of micelles are reported, in terms of size, homogeneity, zeta potential, critical micelle concentration (CMC), cloud point, encapsulation efficiency (EE%), load capacity (DL), in vitro release, and stability. This study reports for the first time the anti-migratory activity of TQ and TQ loaded in SSM (TQ-SSM) in the SH-SY5Y human neuroblastoma cell line. The inhibitory effect was assessed by the wound-healing assay and compared with that of the unformulated TQ. The optimal TQ-SSM were provided with small size (56.71 ± 1.41 nm) and spherical shape at ratio of 1:4 (Soluplus:Solutol HS15), thus increasing the solubility of about 10-fold in water. The entrapment efficiency and drug loading were 92.4 ± 1.6% and 4.68 ± 0.12, respectively, and the colloidal dispersion are stable during storage for a period of 40 days. The TQ-SSM were also lyophilized to obtain a more workable product and with increased stability. In vitro release study indicated a prolonged release of TQ. In conclusion, the formulation of TQ into SSM allows a bio-enhancement of TQ anti-migration activity, suggesting that TQ-SSM is a better candidate than unformulated TQ to inhibit human SH-SY5Y neuroblastoma cell migration.

Isolation methods for particle protein corona complexes from protein-rich matrices

Background: Nanoparticles become rapidly encased by a protein layer when they are in contact with biological fluids. This protein shell is called a corona. The composition of the corona has a strong influence on the surface properties of the nanoparticles. It can affect their cellular interactions, uptake and signaling properties. For this reason, protein coronae are investigated frequently as an important part of particle characterization. Main body of the abstract: The protein corona can be analyzed by different methods, which have their individual advantages and challenges. The separation techniques to isolate corona-bound particles from the surrounding matrices include centrifugation, magnetism and chromatographic methods. Different organic matrices, such as blood, blood serum, plasma or different complex protein mixtures, are used and the approaches vary in parameters such as time, concentration and temperature. Depending on the investigated particle type, the choice of separation method can be crucial for the subsequent results. In addition, it is important to include suitable controls to avoid misinterpretation and false-positive or false-negative results, thus allowing the achievement of a valuable protein corona analysis result. Conclusion: Protein corona studies are an important part of particle characterization in biological matrices. This review gives a comparative overview about separation techniques, experimental parameters and challenges which occur during the investigation of the protein coronae of different particle types.

Computer-assisted engineering of programmed drug releasing multilayer nanomedicine via indomethacin-mediated ternary complex for therapy against a multidrug resistant tumor

Nanomedicine with programmed drug release can give full play to the synergistic effect of multi-component system in complicated tumor environment. However, the construction of these programmed drug delivery systems often depends on the sophisticated materials design and synthesis. In this study, we successfully designed an indomethacin (IND)-mediated ternary complex system based on a PEG cleavable polyethyleneimine (PEI), indomethacin (IND) and benzene ring containing chemotherapeutic drugs (such as paclitaxel (PTX), doxorubicin and docetaxel). Based on the difference of hydrophobicity in these components, these components were one-pot self-assembled into drug-loaded IND mediated PEGylation cleavable nanoassemblies (IPCNs) in multilayer structure. In drug-loaded IPCNs, PEG fragments, PEI/IND, and chemotherapeutic drug were respectively distributed from the out layer to core of nanomedicine. When drug-loaded IPCNs reached tumor site through EPR effect, the PEG fragment would firstly responsively release to the acidic tumor microenvironment to expose the intermediate layer of drug-loaded IPCNs that composed by mixture of PEI and IND for increasing the surface potential to promote the uptake by tumor cells. After entering cells, IND would be released faster than chemotherapeutic drug encapsulated in core to efficiently inhibit the expression of multidrug resistance protein 1 to reverse MDR of tumor cells before chemotherapeutic drug releasing. Contributed by the staged responsively releasing of PEG fragments, IND and encapsulated chemotherapeutic drug, the drug-loaded IPCNs exhibited a superior antitumor efficacy against A549/MDR tumor cells both in vitro and in vivo. STATEMENT OF SIGNIFICANCE: The way to develop programmed released drug delivery system is commonly relied on complicated material design and synthesis. Herein, under the computer-assist design, we successfully designed a ternary complex derived from indomethacin (IND), paclitaxel (PTX) and a pH-responsive PEGylated polyethyleneimine (PEG-s-PEI), and employed this ternary complex to successfully prepare a high drug loading and multilayer structured nanomedicine of PTX (PTX IPCNs). Contribute by the different location of PTX, IND and PEG-s-PEI in PTX IPCNs, PEG fragments, IND and PTX molecules could programmed release after reaching tumor for perfectly realizing the synergistic anti-tumor effect of tumor targeting, reversal of MDR and chemotherapy. Based on a fusion of these multiple mechanisms, PTX IPCNs showed a superior antitumor efficacy in mice loading A549/MDR tumor.

Clinical developments of antitumor polymer therapeutics

Polymer therapeutics encompasses polymer-drug conjugates that are nano-sized, multicomponent constructs already in the clinic as antitumor compounds, either as single agents or in combination with other organic drug scaffolds. Nanoparticle-based polymer-conjugated therapeutics are poised to become a leading delivery strategy for cancer treatments as they exhibit prolonged half-life, higher stability and selectivity, water solubility, longer clearance time, lower immunogenicity and antigenicity and often also specific targeting to tissues or cells. Compared to free drugs, polymer-tethered drugs preferentially accumulate in the tumor sites unlike conventional chemotherapy which does not discriminate between the cancer cells and healthy cells, thereby causing severe side-effects. It is also desirable that the drug reaches its site of action at a particular concentration and the therapeutic dose remains constant over a sufficiently long period of time. This can be achieved by opting for new formulations possessing polymeric systems of drug carriers. However, many challenges still remain unanswered in polymeric drug conjugates which need to be readdressed and therefore, can broaden the scope of this field. This review highlights some of the antitumor polymer therapeutics including polymer-drug conjugates, polymeric micelles, polymeric liposomes and other polymeric nanoparticles that are currently under investigation.

Formulation of Nanomicelles to Improve the Solubility and the Oral Absorption of Silymarin

Two novel nanomicellar formulations were developed to improve the poor aqueous solubility and the oral absorption of silymarin. Polymeric nanomicelles made of Soluplus and mixed nanomicelles combining Soluplus with d-α-tocopherol polyethylene glycol 1000 succinate (vitamin E TPGS) were prepared using the thin film method. Physicochemical parameters were investigated, in particular the average diameter, the homogeneity (expressed as polydispersity index), the zeta potential, the morphology, the encapsulation efficiency, the drug loading, the critical micellar concentration and the cloud point. The sizes of ~60 nm, the narrow size distribution (polydispersity index ≤0.1) and the encapsulation efficiency >92% indicated the high affinity between silymarin and the core of the nanomicelles. Solubility studies demonstrated that the solubility of silymarin increased by ~6-fold when loaded into nanomicelles. Furthermore, the physical and chemical parameters of SLM-loaded formulations stored at room temperature and in refrigerated conditions (4 °C) were monitored over three months. In vitro stability and release studies in media miming the physiological conditions were also performed. In addition, both formulations did not alter the antioxidant properties of silymarin as evidenced by the 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH) assay. The potential of the nanomicelles to increase the intestinal absorption of silymarin was firstly investigated by the parallel artificial membrane permeability assay. Subsequently, transport studies employing Caco-2 cell line demonstrated that mixed nanomicelles statistically enhanced the permeability of silymarin compared to polymeric nanomicelles and unformulated extract. Finally, the uptake studies indicated that both nanomicellar formulations entered into Caco-2 cells via energy-dependent mechanisms.

Albumin Submicron Particles with Entrapped Riboflavin-Fabrication and Characterization

Although riboflavin (RF) belongs to the water-soluble vitamins of group B, its solubility is low. Therefore, the application of micro-formulations may help to overcome this limiting factor for the delivery of RF. In this study we immobilized RF in newly developed albumin submicron particles prepared using the Co-precipitation Crosslinking Dissolution technique (CCD-technique) of manganese chloride and sodium carbonate in the presence of human serum albumin (HSA) and RF. The resulting RF containing HSA particles (RF-HSA-MPs) showed a narrow size distribution in the range of 0.9 to 1 μm, uniform peanut-like morphology, and a zeta-potential of -15 mV. In vitro release studies represented biphasic release profiles of RF in a phosphate buffered saline (PBS) pH 7.4 and a cell culture medium (RPMI) 1640 medium over a prolonged period. Hemolysis, platelet activation, and phagocytosis assays revealed a good hemocompatibility of RF-HSA-MPs.

Non-Viral Delivery To Enable Genome Editing

Genome-editing technologies such as zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENS), and the clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein system have revolutionized biological research. Each biotechnology consists of a DNA-binding protein that can be programmed to recognize and initiate double-strand breaks (DSBs) for site-specific gene modification. These technologies have the potential to be harnessed to cure diseases caused by aberrant gene expression. To be successful therapeutically, their functionality depends on their safe and efficient delivery into the cell nucleus. This review discusses the challenges in the delivery of genome-editing tools, and highlights recent innovations in non-viral delivery that have potential to overcome these limitations and advance the translation of genome editing towards patient care.

Synergistic breast tumor cell killing achieved by intracellular co-delivery of doxorubicin and disulfiram via core-shell-corona nanoparticles

Combination therapy with different functional chemotherapeutic agents based on nano-drug delivery systems is an effective strategy for the treatment of breast cancer. However, co-delivery of drug molecules with different physicochemical properties still remains a challenge. In this study, an amphiphilic poly (ε-caprolactone)-b-poly (l-glutamic acid)-g-methoxy poly (ethylene glycol) (PCL-b-PGlu-g-mPEG) copolymer was designed and synthesized to develop a nanocarrier for the co-delivery of hydrophilic doxorubicin (DOX) and hydrophobic disulfiram (DSF). The amphiphilic copolymer self-assembled into core-shell-corona structured nanoparticles with the hydrophobic PCL core for DSF loading (hydrophobic interaction) and anionic poly (glutamic acid) shell for DOX loading (electrostatic interaction). DSF and DOX co-loaded nanoparticles (Co-NPs) resulted in high drug loading and precisely controlled DSF/DOX ratio via formulation optimization. Compared with free drug solutions, DSF and DOX delivered by the Co-NPs were found to have improved intracellular accumulation. Results of cytotoxicity assays showed that DSF/DOX delivered at the weight ratio of 0.5 and 1 could achieve a synergistic cytotoxic effect on breast cancer cell lines (MCF-7 and MDA-MB-231). In vivo imaging confirmed that the core-shell-corona nanoparticles could efficiently accumulate in tumors. In vivo anti-tumor effect results indicated that Co-NPs showed an improved drug synergistic effect on antitumor activity compared with the free drug combination. Therefore, it can be concluded that core-shell-corona nanoparticles prepared by PCL-b-PGlu-g-mPEG could be a promising co-delivery system for drug combination therapy in the treatment of breast cancer.

Multiseed liposomal drug delivery system using micelle gradient as driving force to improve amphiphilic drug retention and its anti-tumor efficacy

To improve drug retention in carriers for amphiphilic asulacrine (ASL), a novel active loading method using micelle gradient was developed to fabricate the ASL-loaded multiseed liposomes (ASL-ML). The empty ML were prepared by hydrating a thin film with empty micelles. Then the micelles in liposomal compartment acting as ‘micelle pool’ drove the drug to be loaded after the outer micelles were removed. Some reasoning studies including critical micelle concentration (CMC) determination, influencing factors tests on entrapment efficiency (EE), structure visualization, and drug release were carried out to explore the mechanism of active loading, ASL location, and the structure of ASL-ML. Comparisons were made between pre-loading and active loading method. Finally, the extended drug retention capacity of ML was evaluated through pharmacokinetic, drug tissue irritancy, and in vivo anti-tumor activity studies. Comprehensive results from fluorescent and transmission electron microscope (TEM) observation, encapsulation efficiency (EE) comparison, and release studies demonstrated the formation of ML-shell structure for ASL-ML without inter-carrier fusion. The location of drug mainly in inner micelles as well as the superiority of post-loading to the pre-loading method , in which drug in micelles shifted onto the bilayer membrane was an additional positive of this delivery system. It was observed that the drug amphiphilicity and interaction of micelles with drug were the two prerequisites for this active loading method. The extended retention capacity of ML has been verified through the prolonged half-life, reduced paw-lick responses in rats, and enhanced tumor inhibition in model mice. In conclusion, ASL-ML prepared by active loading method can effectively load drug into micelles with expected structure and improve drug retention.

Leveraging Colloidal Aggregation for Drug-Rich Nanoparticle Formulations

While limited drug loading continues to be problematic for chemotherapeutics formulated in nanoparticles, we found that we could take advantage of colloidal drug aggregation to achieve high loading when combined with polymeric excipients. We demonstrate this approach with two drugs, fulvestrant and pentyl-PABC doxazolidine (PPD; a prodrug of doxazolidine, which is a DNA cross-linking anthracycline), and two polymers, polysorbate 80 (UP80) and poly(d,l-lactide-co-2-methyl-2-carboxytrimethylene carbonate)-graft-poly(ethylene glycol) (PLAC-PEG; a custom-synthesized, self-assembling amphiphilic polymer). In both systems, drug-loaded nanoparticles had diameters < 200 nm and were stable for up to two days in buffered saline solution and for up to 24 h in serum-containing media at 37 °C. While colloidal drug aggregates alone are typically unstable in saline and serum-containing media, we attribute the colloid stability observed herein to the polymeric excipients and consequent decreased protein adsorption. We expect this strategy of polymer-stabilized colloidal drug aggregates to be broadly applicable in delivery formulations.

Redox-Activated Light-Up Nanomicelle for Precise Imaging-Guided Cancer Therapy and Real-Time Pharmacokinetic Monitoring

Simultaneous tumor imaging, therapy, and pharmacokinetic monitoring can offer a safe and effective strategy for cancer therapy. This work describes the design of a fluorescence light-up nanomicelle that can afford precise imaging-guided drug delivery and pharmacokinetic monitoring in a real-time fashion for cancer chemotherapy. The nanomicelle, which contains a boron dipyrromethene based fluorescent probe as the hydrophobic core and a redox-triggered detachable poly(ethylene glycol) (PEG) shell, can accumulate at the tumor site via enhanced permeation and retention effect. The PEG detachment induced by tumoral and intracellular glutathione can destabilize the nanomicelle, leading to fluorescence light up and simultaneous drug release. Importantly, the fluorescence intensities generated by the nanomicelles in different organs are well-correlated with released drug concentrations in both temporal and spatial manners, suggesting its precise role for imaging-guided drug delivery and pharmacokinetic monitoring in vivo. The tumor growth can be effectively inhibited by the docetaxel-loaded nanomicelle formulation, and the nanomicelles are monitored to be excreted via hepatobiliary routes. This nanomicelle for precise imaging-guided chemotherapy provides a safe and robust theranostic strategy for the evaluation of cancer nanomedicine.

Development and optimization of self-assembling nanosystem for intra-articular delivery of indomethacin

Osteoarthritis is a propagated debilitating condition affecting patients' quality of life. Intra-articular injection approach was investigated as a localized treatment strategy providing: site-specific delivery, decreased side effects and, increased patient compliance. A 3² full factorial experimental design was employed to prepare the indomethacin-loaded self-assembling nanosystems (SANS). The surfactant (Poloxamer 407/Tetronic 90R4) ratio and the poly(lactic-co-glycolic acid) (PLGA) concentration significantly affected encapsulation efficiency and drug release (p<0.05). The optimized formula was subjected to modification by addition of different proteoglycans, as a compensatory treatment, to improve its pharmacological properties. The modified SANS, containing glucosamine (150mg), was selected for in-vivo studies as it had a sustained drug release profile and a small particle size (173.90nm). The effect of the optimized SANS, with or without PLGA, was compared with the modified formula containing glucosamine and, with the drug suspension on the arthritic knee joints of rats. It was found that the formulation containing PLGA and glucosamine showed significantly higher reduction in both, knee diameter and TNF-α levels, compared to other groups. Furthermore, all SANS showed histological improvement in the cellularity of the synovial membranes and joints. Our results indicate that SANS containing PLGA and glucosamine is capable of treating arthritic joints.

Development of shell cross-linked nanoparticles based on boronic acid-related reactions for self-regulated insulin delivery

Shell cross-linked nanoparticles were fabricated by the complexation of poly(3-methacrylamido phenylboronic acid) (PMAPBA) and thiolated chitosan (chitosan-SH) via boronic acid-related reactions. The formation of PMAPBA/chitosan-SH nanoparticles was confirmed by transmission electron microscopy, dynamic light scattering, and UV spectroscopy. The nanoparticles had a narrow size distribution with a relatively high positive charge density, and the size and zeta potential of the nanoparticles correlated with the chitosan-SH concentration. Furthermore, owing to the cross-linking of the nanoparticle shell, insulin was encapsulated in the nanoparticles with a loading capacity of up to 18%. The release of insulin from the nanoparticles slowed down because of the presence of disulfide bonds and increased with increasing glucose level in the medium. The structure of the released insulin was not distorted. More importantly, the nanoparticles had good cytocompatibility, as demonstrated by in vitro experiments. The simplicity of this strategy along with a high loading capacity, glucose sensitivity, and cytocompatibility of the produced nanoparticles should significantly boost their application in self-regulated insulin delivery.

GSH-targeted nanosponges increase doxorubicin-induced toxicity "in vitro" and "in vivo" in cancer cells with high antioxidant defenses

Several reports indicate that chemo-resistant cancer cells become highly adapted to intrinsic oxidative stress by up-regulating their antioxidant systems, which causes an increase of intracellular GSH content. Doxorubicin is one of the most widely used drugs for tumor treatment, able to kill cancer cells through several mechanisms. However, doxorubicin use is limited by its toxicity and cancer resistance. Therefore, new therapeutic strategies able to reduce doses and to overcome chemo-resistance are needed. A new class of glutathione-responsive cyclodextrin nanosponges (GSH-NS), is able to release anticancer drugs preferentially in cells having high GSH content. Doxorubicin-loaded GSH-NS, in the cancer cells with high GSH content, inhibited clonogenic growth, cell viability, topoisomerase II activity and induced DNA damage with higher effectiveness than free drug. Moreover, GSH-NS reduced the development of human tumor in xenograft models more than free drug. These characteristics indicate that GSH-NS can be a suitable drug delivery carrier for future applications in cancer therapy.

Microfluidic synthesis of dye-loaded polycaprolactone-block-poly(ethylene oxide) nanoparticles: Insights into flow-directed loading and in vitro release for drug delivery

Using the fluorescent probe dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) as a surrogate for hydrophobic drugs, we investigate the effects of water content and on-chip flow rate on the multiscale structure, loading and release properties of DiI-loaded poly(ε-caprolactone)-block-poly(ethylene oxide) (PCL-b-PEO) nanoparticles produced in a gas-liquid segmented microfluidic device. We find a linear increase in PCL crystallinity within the nanoparticle cores with increasing flow rate, while mean nanoparticle sizes first decrease and then increase with flow rate coincident with the disappearance and reappearance of long filament nanoparticles. Loading efficiencies at the lower water content (cwc+10wt%) are generally higher (up to 94%) compared to loading efficiencies (up to 53%) at the higher water content (cwc+75wt%). In vitro release times range between ∼2 and 4days for nanoparticles produced at cwc+10wt% and >15days for nanoparticles produced at cwc+75wt%. At the lower water content, slower release of DiI is found for nanoparticles produced at higher flow rate, while at high water content, release times first decrease and then increase with flow rate. Finally, we investigate the effects of the chemical and physical characteristics of the release medium on the kinetics of in vitro DiI release and nanoparticle degradation. This work demonstrates the general utility of dye-loaded nanoparticles as model systems for screening chemical and flow conditions for producing drug delivery formulations within microfluidic devices.

Recent advances in polymeric micelles for anti-cancer drug delivery

Block co-polymeric micelles receive increased attention due to their ability to load therapeutics, deliver the cargo to the site of action, improve the pharmacokinetic of the loaded drug and reduce off-target cytotoxicity. While polymeric micelles can be developed with improved drug loading capabilities by modulating hydrophobicity and hydrophilicity of the micelle forming block co-polymers, they can also be successfully cancer targeted by surface modifying with tumor-homing ligands. However, maintenance of the integrity of the self-assembled system in the circulation and disassembly for drug release at the site of drug action remain a challenge. Therefore, stimuli-responsive polymeric micelles for on demand drug delivery with minimal off-target effect has been developed and extensively investigated to assess their sensitivity. This review focuses on discussing various polymeric micelles currently utilized for the delivery of chemotherapeutic drugs. Designs of various stimuli-sensitive micelles that are able to control drug release in response to specific stimuli, either endogenous or exogenous have been delineated.

Synthesis, characterization and anti-cancer activity of Pluronic F68-curcumin conjugate micelles

Curcumin (CUR), a nontoxic polyphenol derived from the rhizome of turmeric (Curcuma longa), has been recognized as an anti-cancer and chemo-preventative agent. However, its clinical application for cancer treatment has been greatly limited due to its poor water-solubility and low bioavailability. To tackle this problem, Pluronic F68-CUR (F68-CUR) conjugate micelles, which are amphiphilic copolymers, were designed and synthesized in this study. These highly stable micelles with CUR concentrated in the core were formulated using the solvent evaporation method and were confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. Physicochemical characterization of F68-CUR conjugate micelles revealed that high drug loading content (DL%; 0.248 mg CUR/1 mg F68) was achieved, and the average particle size of micelles was 115.2 ± 3.0 nm. Compared with free CUR, a significantly higher cytotoxicity against human breast cancer cell line MDA-MB-231 was observed in F68-CUR conjugate micelles. The IC₅₀ value of F68-CUR conjugate micelles was 1.95-fold lower than that of free CUR, indicating that the anti-cancer activity of CUR was significantly improved in the micelles. Furthermore, apoptotic studies demonstrated that F68-CUR conjugate micelles induced more cell apoptosis than that of free CUR. Taken together, these results demonstrate that F68-CUR conjugate micelles are promising to improve the clinical effectiveness of CUR in cancer treatment.

Applications of polymer micelles for imaging and drug delivery

Polymeric micelles, self-assembling nano-constructs of amphiphilic copolymers, are widely considered as convenient nano-carriers for a variety of applications, such as diagnostic imaging, and drug and gene delivery. They have demonstrated a variety of favorable properties including biocompatibility, longevity, high stability in vitro and in vivo, capacity to effectively solubilize a variety of poorly soluble drugs, changing the release profile of the incorporated pharmaceutical agents, and the ability to accumulate in the target zone based on the enhanced permeability and retention effect. Moreover, additional functions can be imparted to the micelle-based delivery systems by engineering their surface for specific applications. Various targeting ligands can be attached for cell or intracellular accumulation at a site of interest. Also, the chelation or incorporation of imaging moieties into the micelle structure enables in vivo biodistribution studies. Moreover, pH-, thermo-, ultrasound-, enzyme- and light-sensitive block-copolymers allow for controlled micelle dissociation and triggered drug release in response to the pathological environment-specific stimuli and/or externally applied signals. The combination of these approaches can further improve specificity and efficacy of micelle-based drug delivery to promote the development of smart multifunctional micelles.

Innovative use of the taxol binding peptide overcomes key challenges of stable and high drug loading in polymeric nanomicelles

Incorporating a taxol binding peptide into the hydrophobic backbone of polymeric nanomicelles enhances docetaxel loading while maintaining serum stability.

Formation of DNA adducts by ellipticine and its micellar form in rats - a comparative study

The requirements for early diagnostics as well as effective treatment of cancer diseases have increased the pressure on development of efficient methods for targeted drug delivery as well as imaging of the treatment success. One of the most recent approaches covering the drug delivery aspects is benefitting from the unique properties of nanomaterials. Ellipticine and its derivatives are efficient anticancer compounds that function through multiple mechanisms. Formation of covalent DNA adducts after ellipticine enzymatic activation is one of the most important mechanisms of its pharmacological action. In this study, we investigated whether ellipticine might be released from its micellar (encapsulated) form to generate covalent adducts analogous to those formed by free ellipticine. The ³²P-postlabeling technique was used as a useful imaging method to detect and quantify covalent ellipticine-derived DNA adducts. We compared the efficiencies of free ellipticine and its micellar form (the poly(ethylene oxide)-block-poly(allyl glycidyl ether) (PAGE-PEO) block copolymer, P 119 nanoparticles) to form ellipticine-DNA adducts in rats in vivo. Here, we demonstrate for the first time that treatment of rats with ellipticine in micelles resulted in formation of ellipticine-derived DNA adducts in vivo and suggest that a gradual release of ellipticine from its micellar form might produce the enhanced permeation and retention effect of this ellipticine-micellar delivery system.

Sugar-based amphiphilic polymers for biomedical applications: from nanocarriers to therapeutics

Various therapeutics exhibit unfavorable physicochemical properties or stability issues that reduce their in vivo efficacy. Therefore, carriers able to overcome such challenges and deliver therapeutics to specific in vivo target sites are critically needed. For instance, anticancer drugs are hydrophobic and require carriers to solubilize them in aqueous environments, and gene-based therapies (e.g., siRNA or pDNA) require carriers to protect the anionic genes from enzymatic degradation during systemic circulation. Polymeric micelles, which are self-assemblies of amphiphilic polymers (APs), constitute one delivery vehicle class that has been investigated for many biomedical applications. Having a hydrophobic core and a hydrophilic shell, polymeric micelles have been used as drug carriers. While traditional APs are typically comprised of nondegradable block copolymers, sugar-based amphiphilic polymers (SBAPs) synthesized by us are comprised of branched, sugar-based hydrophobic segments and a hydrophilic poly(ethylene glycol) chain. Similar to many amphiphilic polymers, SBAPs self-assemble into polymeric micelles. These nanoscale micelles have extremely low critical micelle concentrations offering stability against dilution, which occurs with systemic administration. In this Account, we illustrate applications of SBAPs for anticancer drug delivery via physical encapsulation within SBAP micelles and chemical conjugation to form SBAP prodrugs capable of micellization. Additionally, we show that SBAPs are excellent at stabilizing liposomal delivery systems. These SBAP-lipid complexes were developed to deliver hydrophobic anticancer therapeutics, achieving preferential uptake in cancer cells over normal cells. Furthermore, these complexes can be designed to electrostatically complex with gene therapies capable of transfection. Aside from serving as a nanocarrier, SBAPs have also demonstrated unique bioactivity in managing atherosclerosis, a major cause of cardiovascular disease. The atherosclerotic cascade is usually triggered by the unregulated uptake of oxidized low-density lipoprotein, a cholesterol carrier, in macrophages of the blood vessel wall; SBAPs can significantly inhibit oxidized low-density lipoprotein uptake in macrophages and abrogate the atherosclerotic cascade. By modification of various functionalities (e.g., branching, stereochemistry, hydrophobicity, and charge) in the SBAP chemical structure, SBAP bioactivity was optimized, and influential structural components were identified. Despite the potential of SBAPs as atherosclerotic therapies, blood stability of the SBAP micelles was not ideal for in vivo applications, and means to stabilize them were pursued. Using kinetic entrapment via flash nanoprecipitation, SBAPs were formulated into nanoparticles with a hydrophobic solute core and SBAP shell. SBAP nanoparticles exhibited excellent physiological stability and enhanced bioactivity compared with SBAP micelles. Further, this method enables encapsulation of additional hydrophobic drugs (e.g., vitamin E) to yield a stable formulation that releases two bioactives. Both as nanoscale carriers and as polymer therapeutics, SBAPs are promising biomaterials for medical applications.

TPGS-g-PLGA/Pluronic F68 mixed micelles for tanshinone IIA delivery in cancer therapy

Tanshinone IIA (TAN) has few clinical applications for anti-cancer therapy mainly due to its high lipophicity, low cellular uptake, and poor bioavailability. To improve the anti-cancer effect and bioavailability of TAN, we developed a mixed micelle system constituted with D-α-tocopheryl polyethylene glycol succinate-graft-poly(D,L-lactide-co-glycolide) (TPGS-g-PLGA) copolymer and Pluronic F68. TAN was encapsulated in the TPGS-g-PLGA/Pluronic F68 mixed micelles by using the thin film hydration technology optimized by the central composite design/response surface method (CCD/RSM). TAN-loaded mixed micelles were highly stable in the presence or absence of bovine serum albumin (BSA) and achieved sustained drug release in vitro. Compared with free TAN, TAN mixed micelles had higher cytotoxicity and pro-apoptotic effects against human hepatocellular carcinoma HepG2 cells. The significant enhancement on pro-apoptosis by TAN micelles was evidenced by increased chromosome condensation, mitochondria membrane potential loss, cell apoptosis, and cleavages of caspase-3 and PARP. Furthermore, pharmacokinetic studies revealed that TAN mixed micelles significantly prolonged the circulation time and improved bioavailability of TAN in rats. These results demonstrated that TAN-loaded TPGS-g-PLGA/F68 mixed micelles are an effective strategy to deliver TAN for cancer therapy.

Amphiphilic nanoparticles repress macrophage atherogenesis: novel core/shell designs for scavenger receptor targeting and down-regulation

Atherosclerosis, an inflammatory lipid-rich plaque disease is perpetuated by the unregulated scavenger-receptor-mediated uptake of oxidized lipoproteins (oxLDL) in macrophages. Current treatments lack the ability to directly inhibit oxLDL accumulation and foam cell conversion within diseased arteries. In this work, we harness nanotechnology to design and fabricate a new class of nanoparticles (NPs) based on hydrophobic mucic acid cores and amphiphilic shells with the ability to inhibit the uncontrolled uptake of modified lipids in human macrophages. Our results indicate that tailored NP core and shell formulations repress oxLDL internalization via dual complementary mechanisms. Specifically, the most atheroprotective molecules in the NP cores competitively reduced NP-mediated uptake to scavenger receptor A (SRA) and also down-regulated the surface expression of SRA and CD36. Thus, nanoparticles can be designed to switch activated, lipid-scavenging macrophages to antiatherogenic phenotypes, which could be the basis for future antiatherosclerotic therapeutics.

Preparation of pH-responsive polymer core-shell nanospheres for delivery of hydrophobic antineoplastic drug ellipticine

Antineoplastic drug ellipticine and its derivatives are used in human cancer therapy. However, their clinical applications have been limited by its great hydrophobicity and severe side effects. An efficient delivery system is therefore very desirable. In this research, an ellipticine-loaded core-shell structured nanosphere namely poly(DEAEMA)-poly(PEGMA) is designed as a drug carrier and prepared via a two-step semibatch emulsion polymerization method where DEAEMA and PEGMA represent 2-(diethylamino)ethyl methacrylate and poly(ethylene glycol) methacrylate, respectively. The in-vitro release profiles of ellipticine towards the different pH liposome vesicles are recorded as a function of time at 37 °C. It is found that release of ellipticine from the core-shell polymer matrix is a pH-responsive and controlled release process. The three pH's of 3, 4, and 5 trigger a significant ellipticine release of 88% after 98 h, 83% after 98 h, and 79% after 122 h, respectively. The release mechanism of ellipticine from the core-shell polymer matrix under acidic conditions is explored. The synthesis and encapsulation process developed herein provides a new perspective for the development of appropriate delivery systems to deliver the ellipticine and its analogues, as well as other types of hydrophobic drugs to a given target cell or tumor tissue.

Polymeric curcumin nanoparticle pharmacokinetics and metabolism in bile duct cannulated rats

The objective of this study was to compare the pharmacokinetics and metabolism of polymeric nanoparticle-encapsulated (nanocurcumin) and solvent-solubilized curcumin formulations in Sprague-Dawley (SD) rats. Nanocurcumin is currently under development for cancer therapy. Since free, unencapsulated curcumin is rapidly metabolized and excreted in rats, upon intravenous (i.v.) administration of nanocurcumin only nanoparticle-encapsulated curcumin can be detected in plasma samples. Hence, the second objective of this study was to utilize the metabolic instability of curcumin to assess in vivo drug release from nanocurcumin. Nanocurcumin and solvent-solubilized curcumin were administered at 10 mg curcumin/kg by jugular vein to bile duct-cannulated male SD rats (n = 5). Nanocurcumin increased the plasma Cmax of curcumin 1749 fold relative to the solvent-solubilized curcumin. Nanocurcumin also increased the relative abundance of curcumin and glucuronides in bile but did not dramatically alter urine and tissue metabolite profiles. The observed increase in biliary and urinary excretion of both curcumin and metabolites for the nanocurcumin formulation suggested a rapid "burst" release of curcumin. Although the burst release observed in this study is a limitation for targeted tumor delivery, nanocurcumin still exhibits major advantages over solvent-solubilized curcumin, as the nanoformulation does not result in the lung accumulation observed for the solvent-solubilized curcumin and increases overall systemic curcumin exposure. Additionally, the remaining encapsulated curcumin fraction following burst release is available for tumor delivery via the enhanced permeation and retention effect commonly observed for nanoparticle formulations.