Doxorubicin hydrochloride-oleic acid conjugate loaded nanostructured lipid carriers for tumor specific drug release

Recent developments in sustained-release and targeted drug delivery applications of solid lipid nanoparticles

Solid Lipid Nanoparticles (SLNs) are versatile nano-carriers for wide range of applications. The advantages of SLNs include ease of preparation, low toxicity, high active compound bioavailability, flexibility of incorporating hydrophilic and lipophilic drugs, and feasibility of large-scale production. This review provides an overview on the preparation methods of the SLNs, the micro and nanostructure characteristics of the SLNs, and the different factors influencing sustained release and targeted drug delivery. The applications in agriculture and environment, cosmetics, wound healing, malarial treatment, gene therapy and nano-vaccines, and cancer therapy, are elaborated. The mechanisms such as passive, active, and co-delivery are discussed. The issues, challenges and the way forward with ionisable SLNs for delivery of gene and vaccines, RAS-targeted therapy, and bioactive compounds, are highlighted. In combination with multiple compounds and the potential for integration with nature/bio-based solutions, SLNs are proven to be effective, and practical for diverse applications.

Ternary lipids-based novel thermoresponsive lipid nanoparticles for targeting doxorubicin to breast cancer cells

Conventional thermoresponsive liposomes have failed to meet cancer targeting potential due to poor safety profile, unpredictable fate, and low therapeutic response in clinical studies. Recently, we reported phase-change nanostructured lipid carriers, termed thermoresponsive lipid nanoparticles (TLNs), for targeting cancer cells under hyperthermia. Herein, we have prepared ternary eutectic mixtures of myristic, stearic, and palmitic acid at a ratio of 2.5:1:1.5 yielded a melting point or solid-liquid phase transition temperature of 41°C. Doxorubicin (DOX)-loaded TLNs were fabricated and optimized using Box-Behnken Design Expert® software and exhibited desirable particle size (191.7±2.88 nm), polydispersity index (0.213±0.025), zeta-potential (-21.2±2.29 mV), spherical shape, high entrapment efficiency (92.24±1.05), and desirable physicochemical stability. In-vitro drug release studies showed hyperthermia-aided abrupt DOX release within 2 h at 41°C and 43°C while sustained drug release pattern for 12 h at 37°C. In-vitro cytotoxicity studies of TLN also exhibited the highest breast cancer (MCF-7) cells killing at hyperthermia (41°C), more than 3-fold compared to 37°C and free DOX solution. A 23-fold higher cell uptake in breast cancer cells further confirmed that ternary eutectic mixture-based DOX-loaded TLNs are an excellent candidate for breast cancer targeting and may be preferred over other nano-carriers due to the feasible preparation and superior stability.

Chemosensitizer Loaded NIR-Responsive Nanostructured Lipid Carriers: A Tool for Drug-Resistant Breast Cancer Synergistic Therapy

Although numerous technical advances have been made in cancer treatment, chemotherapy is still a viable treatment option. However, it is more effective when used in combination with photothermal therapy for resistant breast cancer cells. This study introduces a smart drug delivery system, (DOX-OA+VERA+AuNRs)@NLC, which is designed for dual chemo/photothermal therapy of multiple-drug-resistant breast cancer. Type-III nanostructured lipid carriers (NLCs) were used as drug delivery systems, where nano-in-nano structures offer several advantages. Doxorubicin (DOX) was used as the antitumor agent by ion-pairing it with oleic acid (OA) to increase the DOX loading capacity, as well as to reduce the burst release of the drug. Verapamil (VERA), which was used as a chemosensitizer to overcome the multiple-drug resistance, was co-loaded with DOX-OA. Gold nanorods (AuNRs) were exploited as the photothermal therapy agent in photothermal therapy (PTT) application, which would have a synergistic relation with chemotherapy. The release of DOX-OA and VERA from NLCs was studied in vitro by triggering with NIR laser irradiation. Thus, an all-in-one drug delivery system was designed to release the active pharmaceutical ingredients (APIs) at higher concentrations in the desired region and provide both chemo/PTT. Besides, the application of a folic acid-chitosan (FA-CS) coating to NLCs has facilitated the development of systems capable of targeting and specifically releasing their cargo within cancerous tissues while preserving their surrounding environment.

β-cyclodextrin-modified carboxymethyl chitosan/hyaluronic acid-based crosslinked composite nanogels as a dual responsive carrier for targeting anti-tumor therapy

Advanced nanosized drug delivery systems can significantly improve efficacy and safety of first-line chemotherapeutics by enhancing tumor targeting. Herein, one-pot covalent crosslinking approach was developed to generate biodegradable tumor-targeted composite Nanogels from carboxymethyl chitosan, hyaluronic acid, cystamine and 6-ethylene-diamine-6-deoxy-β-cyclodextrin loaded with doxorubicin (DOX) for controlled intracellular DOX release. The optimized synthetic procedures generated Nanogels of about 190 nm in size and 28.3 % drug loading capability. DOX-loaded Nanogels was effectively internalized into tumor cells mainly by CD44 receptor-mediated endocytosis and rapidly released DOX in response to the high level of GSH in cytoplasm and acidic intracellular environments. DOX-loaded Nanogels significantly inhibited the tumor growth especially without appreciable side toxicities in 4 T1 tumor-bearing mice model owing to CD44 receptor-mediated active targeting and the passive targeting of Nanogels by enhanced permeation and retention effect. Overall, our newly developed composite Nanogels might be employed as a potentially effective therapeutic strategy for tumor therapy.

pH-Sensitive doxorubicin delivery using zinc oxide nanoparticles as a rectified theranostic platform: in vitro anti-proliferative, apoptotic, cell cycle arrest and in vivo radio-distribution studies

Despite enormous advancements in its management, cancer is the world's primary cause of mortality. Therefore, tremendous strides were made to produce intelligent theranostics with mitigated side effects and improved specificity and efficiency. Thus, we developed a pH-sensitive theranostic platform composed of dextran immobilized zinc oxide nanoparticles, loaded with doxorubicin and radiolabeled with the technetium-99m radionuclide (99mTc-labelled DOX-loaded ZnO@dextran). The platform measured 11.5 nm in diameter with -12 mV zeta potential, 88% DOX loading efficiency and 98.5% radiolabeling efficiency. It showed DOX release in a pH-responsive manner, releasing 93.1% cumulatively at pH 5 but just 7% at pH 7.4. It showed improved intracellular uptake, which resulted in a high growth suppressive effect against MCF-7 cancer cells as compared to the free DOX. It boasted a 4 times lower IC50 than DOX, indicating its significant anti-proliferative potential (0.14 and 0.55 μg ml-1, respectively). The in vitro biological evaluation revealed that its molecular mode of anti-proliferative action included downregulating Cdk-2, which provoked G1/S cell cycle arrest, and upregulating both the intracellular ROS level and caspase-3, which induced apoptosis and necrosis. The in vivo experiments in Ehrlich-ascites carcinoma bearing mice demonstrated that DOX-loaded ZnO@dextran showed a considerable 4-fold increase in anti-tumor efficacy compared to DOX. Moreover, by utilizing the diagnostic radionuclide (99mTc), the radiolabeled platform (99mTc-labelled DOX-loaded ZnO@dextran) was in vivo monitored in tumor-bearing mice, revealing high tumor accumulation (14% ID g-1 at 1 h p.i.) and reduced uptake in non-target organs with a 17.5 T/NT ratio at 1 h p.i. Hence, 99mTc-labelled DOX-loaded ZnO@dextran could be recommended as a rectified tumor-targeted theranostic platform.

Evaluation of Doxorubicin-loaded Echogenic Macroemulsion for Targeted Drug Delivery

BACKGROUND

The latest technology trend in targeted drug delivery highlights stimuliresponsive particles that can release an anticancer drug in a solid tumor by responding to external stimuli.

OBJECTIVE

This study aims to design, fabricate, and evaluate an ultrasound-responsive drug delivery vehicle for an ultrasound-mediated drug delivery system.

METHODS

The drug-containing echogenic macroemulsion (eME) was fabricated by an emulsification method using the three phases (aqueous lipid solution as a shell, doxorubicin (DOX) contained oil, and perfluorohexane (PFH) as an ultrasound-responsive agent). The morphological structure of eMEs was investigated using fluorescence microscopy, and the size distribution was analyzed by using DLS. The echogenicity of eME was measured using a contrast-enhanced ultrasound device. The cytotoxicity was evaluated using a breast cancer cell (MDA-MB-231) via an in vitro cell experiment.

RESULTS

The obtained eME showed an ideal morphological structure that contained both DOX and PFH in a single particle and indicated a suitable size for enhancing ultrasound response and avoiding complications in the blood vessel. The echogenicity of eME was demonstrated via an in vitro experiment, with results showcasing the potential for targeted drug delivery. Compared to free DOX, enhanced cytotoxicity and improved drug delivery efficiency in a cancer cell were proven by using DOX-loaded eMEs and ultrasound.

CONCLUSION

This study established a platform technology to fabricate the ultrasound-responsive vehicle. The designed drug-loaded eME could be a promising platform with ultrasound technology for targeted drug delivery.

Sequential targeting dual-responsive magnetic nanoparticle for improved therapy of lung metastatic breast cancer

Lung metastatic breast cancer is a leading cause of cancer-related death in women and difficult to treat due to non-specific drug delivery. Herein a sequential targeting dual-responsive magnetic nanoparticle was fabricated, where Fe3O4 nanoparticle was used as magnetic core, then sequentially coated with tetraethyl orthosilicate, bis[3-(triethoxy-silyl)propyl] tetrasulfide, and 3-(trimethoxysilyl) propylmethacrylate to afford -C = C- on the surface for further polymerisation with acrylic acid, acryloyl-6-ethylenediamine-6-deoxy-β-cyclodextrin using N, N-bisacryloylcy- stamine as cross-linker, obtaining pH/redox dual-responsive magnetic nanoparticle (MNPs-CD) to delivery doxorubicin (DOX) for suppressing lung metastatic breast cancer. Our results suggested DOX-loaded nanoparticle could target the lung metastases site by sequential targeting, in which they first be delivered to the lung and even the metastatic nodules through size-driven, electrical interaction, and magnetic field-guided mechanisms, then be effectively internalised into the cancer cells followed by intelligently triggering DOX release. MTT analysis demonstrated DOX-loaded nanoparticle exhibited high anti-tumour activity against 4T1 and A549 cells. 4T1 tumour-bearing mice were employed to confirm the higher specific accumulation in lung and improved anti-metastatic therapy efficiency of DOX by focussing an extracorporeal magnetic field on the biological target. Our findings suggested the as-proposed dual-responsive magnetic nanoparticle offered a prerequisite to inhibit lung metastasis of breast cancer tumours.

Tumor microenvironment stimuli-responsive lipid-drug conjugates for cancer treatment

Lipid drug conjugates (LDCs) have attracted considerable attention in the fields of drug delivery and pharmacology due to their ability to target specific cells, increase drug solubility, reduce toxicity, and improve therapeutic efficacy. These unique features make LDCs promising candidates for the treatment cancer, inflammation, and infectious diseases. In fact, by choosing specific linkers between the lipid and drug molecules, stimuli-responsive LDCs can be designed to target cancer cells based on the unique properties of the tumor microenvironment. Despite the fact that many reviews have described LDCs, few articles have focused on tumor microenvironmental stimuli-responsive LDCs for cancer treatment. Therefore, the key elements of these types of LDCs in cancer treatment will be outlined and discussed in this paper. Our paper goes into detail on the concepts and benefits of LDCs, the various types of tumor microenvironment stimuli-responsive LDCs (such as pH, redox, enzyme, or reactive oxygen species-responsive LDCs), and the current status of LDCs in clinical trials.

Preparation and physicochemical properties of cisplatin and doxorubicin encapsulated by niosome alginate nanocarrier for cancer therapy

Alginate (AL), in the form of a hydrogel, is extensively used in drug delivery. In the current study, an optimum formulation of alginate-coated niosome-based nanocarriers for co-delivery of doxorubicin (Dox) and cisplatin (Cis) was obtained for the treatment of breast and ovarian cancers in an attempt to decrease drug doses and overcome multidrug resistance. The physiochemical characteristics of uncoated niosomes containing Cis and Dox (Nio-Cis-Dox) compared to alginate-coated niosomes formulation (Nio-Cis-Dox-AL). The three-level Box-Behnken method was examined to optimize the particle size, polydispersity index, entrapment efficacy (%), and percent drug release of nanocarriers. Nio-Cis-Dox-AL showed appropriate encapsulation efficiencies of 65.54 ± 1.25 % and 80.65 ± 1.80 % for Cis and Dox, respectively. Maximum drug release decreased from niosomes in case coated by alginate. Also, the zeta potential value of Nio-Cis-Dox nanocarriers decreased after coating with alginate. In vitro cellular and molecular experiments were performed to investigate the anticancer activity of Nio-Cis-Dox and Nio-Cis-Dox-AL. MTT assay showed the IC₅₀ of Nio-Cis-Dox-AL was much lower than the Nio-Cis-Dox formulations and free drugs. Cellular and molecular assays demonstrated that Nio-Cis-Dox-AL caused significant increase in apoptosis induction rate and cell cycle arrest in MCF-7 and A2780 cancer cells, as compared to Nio-Cis-Dox and free drugs. Also, the Caspase 3/7 activity increased after treatment with coated niosomes compared to uncoated nisomes and the drug-free case. Synergetic cell proliferation inhibitory impacts of Cis and Dox were demonstrated against MCF-7 and A2780 cancer cells. All anticancer experimental data demonstrated that the co-delivery of Cis and Dox through alginate-coated niosomal nanocarriers was effective for ovarian and breast cancer treatment.

Meropenem-Loaded Nanostructured Lipid Carriers For Skin and Soft Tissue Infection Caused by Staphylococcus aureus: Formulation, Design, and Evaluation

AIM

Meropenem hydrochloride (MpM)-loaded nanostructured lipid carriers were designed for the effective management of skin infection caused by Staphylococcus aureus via topical route. The solvent evaporation tactic was preferred to develop nanostructured lipid carriers (NLCs). Stearic acid was used as a solid fatty acid; oleic acid was used as liquid fatty acid and Tween 80 as a surfactant. The Staphylococcus aureus burden was analyzed by pharmacodynamic studies. The skin retention was analyzed by fluorescence microscopy. Spherical shape of NLCs was confirmed by TEM. The optimum particle size of the MpM-NLCs was ~ 126.5 ± 0.9 nm with 79.1 ± 2.3% entrapment (EE) and 0.967 mV zeta potential. The in vitro release studies revealed 81.5 ± 3.1% release of drug in 48 h, while the pure drug was almost completely released (98.4 ± 1.4%) within 24 h confirming the potential of NLCs for sustained topical drug delivery. Skin permeation study also revealed better permeation of drug from NLCs than of plain drug. The prepared MpM-NLCs when stored at 4 ± 2°C for 90 days were found to be more stable when the formulation was stored at 28 ± 2°C. The S. aureus burden was analyzed by evaluating the zone of inhibition (ZOI). The ZOI of MpM alone and MpM-NLC gel was measured and compared with that of the control group. The MpM was found significantly effective when its gel was prepared with NLCs because of its enhanced adhesion property occlusion and ability to sustain release. In overall, the study's outcomes validated the relevance of NLC's composition as a vehicle for topical MpM administration in skin diseases caused by Staphylococcus aureus.

Advanced Nano-Carriers for Anti-Tumor Drug Loading

Chemotherapy is one of the important means of tumor therapy. However, most of the anti-tumor drugs that currently used in clinic are hydrophobic non-specific drugs, which seriously affect the efficacy of drugs. With the development of nanotechnology, drug efficacy can be improved by selecting appropriate biodegradable nanocarriers for achieving the controlled release, targeting and higher bioavailability of drugs. This paper reviewed the research progress of anti-tumor drug nanoparticle carriers, which mainly summarized the materials used for anti-tumor drug nanoparticle carriers and their effects in anti-tumor drugs, as well as the targeted drug delivery methods of anti-tumor drugs based on nanocarriers.

Nanoencapsulated Doxorubicin Prevents Mucositis Development in Mice

Doxorubicin (DOX), a chemotherapy drug successfully used in the therapy of various types of cancer, is currently associated with the mucositis development, an inflammation that can cause ulcerative lesions in the mucosa of the gastrointestinal tract, abdominal pain and secondary infections. To increase the safety of the chemotherapy, we loaded DOX into nanostructured lipid carriers (NLCs). The NLC-DOX was characterized by HPLC, DLS, NTA, Zeta potential, FTIR, DSC, TEM and cryogenic-TEM. The ability of NLC-DOX to control the DOX release was evaluated through in vitro release studies. Moreover, the effect of NLC-DOX on intestinal mucosa was compared to a free DOX solution in C57BL/6 mice. The NLC-DOX showed spherical shape, high drug encapsulation efficiency (84.8 ± 4.6%), high drug loading (55.2 ± 3.4 mg/g) and low average diameter (66.0-78.8 nm). The DSC and FTIR analyses showed high interaction between the NLC components, resulting in controlled drug release. Treatment with NLC-DOX attenuated DOX-induced mucositis in mice, improving shortening on villus height and crypt depth, decreased inflammatory parameters, preserved intestinal permeability and increased expression of tight junctions (ZO-1 and Ocludin). These results indicated that encapsulation of DOX in NLCs is viable and reduces the drug toxicity to mucosal structures.

Long chain fatty acids can form aggregates and affect the membrane integrity

Stearic acid (SA) and oleic acid (OA) which are inherently existing fatty acids (FAs) in the body can alter cell membrane function and interact with each other. However, discrepancies arise as to whether these effects are beneficial or harmful on the body. To resolve this ambiguity, there is a dire need to study how FAs can affect the etiology of diseases and their treatment. In this study, we aimed to investigate long chain FAs aggregation behaviors and their effects on membrane integrity and cell viability. We determined the critical aggregation concentration (CAC) of SA and OA (1110 μM and 300 μM, respectively which were less amount than that used in nanocarriers). In TEM images, hexagonal overlapped or fused structures of SA were seen, whereas quite small spherical clusters of OA were obtained. Membrane integrity assessments demonstrated that SA and OA at their own CAC and below could crack the lipid junctions on membrane mimicking systems. Moreover, they completely disrupt the membrane integrity above the CAC at pH 7.2. Cell viabilities on various cell lines were assessed after exposed to SA or OA aggregates. SA was more aggressive than OA on cell death in all cell lines. The effect of SA on PC3 cell lines was in a concentration-dependent manner. The effect of SA above CAC boosted the inhibition of cell viability. Furthermore, OA showed a proliferation effect on PC3 cells. Consequently, the aggregation behavior of FAs should be considered as a noteworthy factor in physiological functions.

Enhanced oral bioavailability of nintedanib esylate with nanostructured lipid carriers by lymphatic targeting: In vitro, cell line and in vivo evaluation

The present research work was aimed to explore the ability of nanostructured lipid carriers (NLCs) to improve oral bioavailability of Nintedanib esylate (NE) via lymphatic uptake. The NE loaded NLCs (NE-NLCs) were fabricated using high speed homogenization followed by probe sonication method and physiochemically characterized. The NE-NLCs had particle size of 125.7 ± 5.5 nm, entrapment efficiency of 88.5 ± 2.5% and zeta potential of -17.3 ± 3.5 mV. DSC and XRD studies indicated that NE was converted to amorphous form. TEM images showed uniformly distributed spherical shaped particles. In vitro release study of NE-NLCs showed drug release of 6.87 ± 2.72% in pH 1.2 and 92.72 ± 3.40% in phosphate buffer pH 6.8 and obeyed higuchi model. Lipolysis study showed higher amount of drug in aqueous layer in NE-NLCs compared to NE-suspension. Tissue distribution study showed deeper penetration of FITC loaded NLCs compared to FITC solution. The cellular uptake across Caco-2 cells exhibited more uptake of FITC loaded NLCs. Cytotoxicity study using A549 cell line revealed higher potential of NE-NLCs in inhibiting tumor cell growth in comparison to that of suspension. The oral bioavailability of NE was ameliorated over 26.31 folds after inclusion into NLCs in contrast to NE-suspension. Intestinal lymphatic uptake of NE-NLCs in cycloheximide treated mice was lower as compared to control without cycloheximide treatment. Thus, the developed NE-NLCs can be an encouraging delivery strategy for increasing oral bioavailability of NE via lymphatic uptake.

Co-delivery of doxorubicin, docosahexaenoic acid, and α-tocopherol succinate by nanostructured lipid carriers has a synergistic effect to enhance antitumor activity and reduce toxicity

Doxorubicin (DOX) is widely used in cancer treatment, however, its use is often limited due to its side effects. To avoid these shortcomings, the encapsulation of DOX into nanocarriers has been suggested. Herein, we proposed a novel nanostructured lipid carrier (NLC) formulation loading DOX, docosahexaenoic acid (DHA), and α-tocopherol succinate (TS) for cancer treatment. DHA is an omega-3 fatty acid and TS is a vitamin E derivative. It has been proposed that these compounds can enhance the antitumor activity of chemotherapeutics. Thus, we hypothesized that the combination of DOX, DHA, and TS in NLC (NLC-DHA-DOX-TS) could increase antitumor efficacy and also reduce toxicity. NLC-DHA-DOX-TS was prepared using emulsification-ultrasound. DOX was incorporated after preparing the NLC, which prevented its degradation during manufacture. High DOX encapsulation efficiency was obtained due to the ion-pairing with TS. This ion-pairing increases lipophilicity of DOX and reduces its crystallinity, contributing to its encapsulation in the lipid matrix. Controlled DOX release from the NLC was observed in vitro, with increased drug release at the acidic environment. In vitro cell studies indicated that DOX, DHA, and TS have synergistic effects against 4T1 tumor cells. The in vivo study showed that NLC-DHA-DOX-TS exhibited the greatest antitumor efficacy by reducing tumor growth in 4T1 tumor-bearing mice. In addition, this formulation reduced mice mortality, prevented lung metastasis, and decreased DOX-induced toxicity to the heart and liver, which was demonstrated by hematologic, biochemical, and histologic analyses. These results indicate that NLC-DHA-DOX-TS may be a promising carrier for breast cancer treatment.

Lipid-based Nanoplatforms in Cancer Therapy: Recent Advances and Applications

Though modern available cancer therapies are effective, they possess major adverse effects, causing non-compliance to patients. Furthermore, the majority of the polymeric-based medication platforms are certainly not universally acceptable, due to their several restrictions. With this juxtaposition, lipid-based medication delivery systems have appeared as promising drug nanocarriers to replace the majority of the polymer-based products because they are in a position to reverse polymer as well as, drug-associated restrictions. Furthermore, the amalgamation of the basic principle of nanotechnology in designing lipid nanocarriers, which are the latest form of lipid carriers, has tremendous chemotherapeutic possibilities as tumor-targeted drug-delivery pertaining to tumor therapy. Apart from this, it is reported that nearly 40% of the modern medication entities are lipophilic. Moreover, research continues to be efficient in attaining a significant understanding of the absorption and bioavailability of the developed lipids systems.

99mTc-doxorubicin-loaded gallic acid-gold nanoparticles (99mTc-DOX-loaded GA-Au NPs) as a multifunctional theranostic agent

The development of cancer theranostic nanomedicines is recommended to concurrently achieve and evaluate the therapeutic benefit and progress. The current work aims to develop gallic acid-gold nanoparticles (GA-Au NPs) as a theranostic probe for ^99mTc-Doxorubicin (^99mTc-DOX) based on the spatiotemporal release pattern induced intra-tumoral (IT) delivery. DOX-loaded GA-Au NPs were developed and identified via UV-Vis spectroscopy. The system was characterized for drug loading efficiency%, particle size, zeta potential, topography, in vitro DOX release and anti-proliferative activity against the MCF-7 cell-line. The factors influencing radiolabeling efficiency of DOX with ^99mTc (DOX concentration, stannous chloride concentration, reaction time and pH) were optimized. The in vitro stability in mice serum and in vivo distribution studies in mice of ^99mTc-DOX-loaded GA-Au NPs were investigated following IV and IT administration. Dox-loaded GA-Au NPs had a loading efficiency of 91%, a small particle size (≈50 nm), a promising zeta potential (-20 mV) and a sustained drug release profile at pH 5.3. GA-Au NPs exhibited increased anti-proliferative activity, with approximately a four-fold lower IC₅₀ value (0.15 μg/ml) than free DOX. The optimized radiolabeling efficiency of ^99mTc-DOX was ≈93%. It showed good physiological stability in mice serum for at least 8 h. The IT delivery of ^99mTc-DOX-loaded GA-Au NPs in tumor-induced mice showed dramatic tumor accumulation. A maximum magnitude of 86.73%ID/g was achieved, at 15 min post-injection, with a target/non-target ratio of ≈56. ^99mTc-DOX-loaded GA-Au NPs could be used for the selective IT delivery of a chemotherapeutic agent and an imaging agent to a target organ.

Strategies to Obtain Encapsulation and Controlled Release of Small Hydrophilic Molecules

The therapeutic effect of small hydrophilic molecules is limited by the rapid clearance from the systemic circulation or a local site of administration. The unsuitable pharmacokinetics and biodistribution can be improved by encapsulating them in drug delivery systems. However, the high-water solubility, very hydrophilic nature, and low molecular weight make it difficult to encapsulate small hydrophilic molecules in many drug delivery systems. In this mini-review, we highlight three strategies to efficiently encapsulate small hydrophilic molecules and achieve controlled release: physical encapsulation in micro/nanocapsules, physical adsorption via electronic interactions, and covalent conjugation. The principles, advantages, and disadvantages of each strategy are discussed. This review paper could be a guide for scientists, engineers, and medical doctors who want to improve the therapeutic efficacy of small hydrophilic drugs.

Hydrophobic ion pairing: encapsulating small molecules, peptides, and proteins into nanocarriers

Hydrophobic ion pairing has emerged as a method to modulate the solubility of charged hydrophilic molecules ranging in class from small molecules to large enzymes. Charged hydrophilic molecules are ionically paired with oppositely-charged molecules that include hydrophobic moieties; the resulting uncharged complex is water-insoluble and will precipitate in aqueous media. Here we review one of the most prominent applications of hydrophobic ion pairing: efficient encapsulation of charged hydrophilic molecules into nano-scale delivery vehicles - nanoparticles or nanocarriers. Hydrophobic complexes are formed and then encapsulated using techniques developed for poorly-water-soluble therapeutics. With this approach, researchers have reported encapsulation efficiencies up to 100% and drug loadings up to 30%. This review covers the fundamentals of hydrophobic ion pairing, including nomenclature, drug eligibility for the technique, commonly-used counterions, and drug release of encapsulated ion paired complexes. We then focus on nanoformulation techniques used in concert with hydrophobic ion pairing and note strengths and weaknesses specific to each. The penultimate section bridges hydrophobic ion pairing with the related fields of polyelectrolyte coacervation and polyelectrolyte-surfactant complexation. We then discuss the state of the art and anticipated future challenges. The review ends with comprehensive tables of reported hydrophobic ion pairing and encapsulation from the literature.

Co-delivery of doxorubicin and shRNA of Beclin1 by folate receptor targeted pullulan-based multifunctional nanomicelles for combinational cancer therapy

Doxorubicin (DOX) is a widely-used effective antitumor agent. However, its clinical application is limited due to its side effects including anti-apoptotic defense of cancer cells caused by DOX-induced autophagy and deleterious effects in normal tissues. Therefore, in this study, a new folate (FA)-decorated amphiphilic bifunctional pullulan-based copolymer (named as FPDP) was developed as an efficient nano-carrier for the co-delivery of DOX and short hairpin RNA of Beclin1, a pivotal autophage-related gene, to enhance the anticancer effect of DOX by the blockade of the Beclin1 protein mediated autophagy process. In FPDP molecules, pullulan was modified with lipophilic desoxycholic acid for the formation of micelles, the introduced low molecular weight (1 kDa) branched polyethylenimine (PEI) was for shBeclin1 delivery, and folate (FA) was employed as the tumor-targeting group. FPDP micelles demonstrated an average diameter of 161.9 nm, good biocompatibility, applicable storage stability, excellent loading capacities for both DOX and shBeclin1 and a sustained drug release profile. In vitro cell culture experiments demonstrated that the uptake amount of FPDP/DOX micelles in folate receptor positive (FR⁺) HeLa cells was more than that in folate receptor negative (FR⁻) HepG2 cells, leading to significantly higher cytotoxicity against FR⁺ HeLa cells. The simultaneous co-delivery of shBeclin1 and DOX to HeLa cells with FPDP micelles led to efficient reduction in the expression level of Beclin1 as well as synergistic cell apoptotic induction. Furthermore, in vivo studies revealed superior antitumor efficacy of tumor-targeted FPDP/DOX/shBeclin1 in comparison with non-FR-targeted PDP micelles and free DOX. These results highlighted that co-delivery of DOX and shRNA of Beclin1 with FPDP micelles has the potential to overcome the limitations of DOX in clinical cancer therapy.

New folate receptor targeted nano-micelles enhanced the anticancer effect of doxorubicin by shBeclin1 with the blockade of the autophagy process.

Doxorubicin-loaded nanocarriers: A comparative study of liposome and nanostructured lipid carrier as alternatives for cancer therapy

Nowadays cancer is one of the most common causes of deaths worldwide. Conventional antitumor agents still present various problems related to specificity for tumor cells often leading to therapeutic failure. Nanoscale particles are considered potential alternative to direct access of drugs into tumor cells, therefore increasing the drug accumulation and performance. The aim of this study was to evaluate the antitumor activity of doxorubicin (DOX)-loaded nanostructured lipid carriers (NLC) versus liposomes against a breast cancer animal experimental model. NLC-DOX and liposomes-DOX were successfully prepared and characterized. Tumor-bearing mice were divided into five groups (blank-NLC, blank-liposome, DOX, NLC-DOX, liposome-DOX). Each animal received by the tail vein four doses of antitumoral drugs (total dose, 16mg/kg), every 3 days. Antitumor efficacy was assessed by measuring 1) tumor volume, calculating the inhibitory ratio (TV-IR, see after) and 2) acquiring scintigraphic images of the tumor using doxorubicin radiolabeled with technetium-99m as an imaging tumor probe. Liposome-DOX and free DOX did not showed differences in the tumor mean volume, whereas NLC-DOX proved to be the best treatments in controlling the tumor growth. NLC-DOX showed an inhibition ration (TV-IR) of 73.5% while free DOX and liposome-DOX decreased TV-RI of 48.8% and 68.0%, respectively. Tumor was clearly visualized in controls, DOX, and liposome-DOX groups. Yet, regarding the NLC-DOX group, tumor was barely identified by the image, indicating antitumor efficacy. Moreover, both NLC and liposomes proved to be able to delay the occurrence of lung metastasis. In conclusion, results of this study indicated that NLC-DOX might be an alternative strategy to achieve an efficient antitumor activity.

Hyaluronic acid-coated, prodrug-based nanostructured lipid carriers for enhanced pancreatic cancer therapy

CONTEXT

Gemcitabine (GEM) and Baicalein (BCL) are reported to have anti-tumor effects including pancreatic cancer. Hyaluronic acid (HA) can bind to over-expressed receptors in various kinds of cancer cells.

OBJECTIVE

The aim of this study is to develop prodrugs containing HA, BCL and GEM, and construct nanomedicine incorporate GEM and BCL in the core and HA on the surface. This system could target the cancer cells and co-deliver the drugs.

METHODS

GEM-stearic acid lipid prodrug (GEM-SA) and hyaluronic acid-amino acid-baicalein prodrug (HA-AA-BCL) were synthesized. Then, GEM and BCL prodrug-based targeted nanostructured lipid carriers (HA-GEM-BCL NLCs) were prepared by the nanoprecipitation technique. The in vitro cytotoxicity studies of the NLCs were evaluated on AsPC1 pancreatic cancer cell line. In vivo anti-tumor effects were observed on the murine-bearing pancreatic cancer model.

RESULTS

HA-GEM-BCL NLCs were effective in entering pancreatic cancer cells over-expressing HA receptors, and showed cytotoxicity of tumor cells in vitro. In vivo study revealed significant tumor growth inhibition ability of HA-GEM-BCL NLCs in murine pancreatic cancer model.

CONCLUSION

It could be concluded that HA-GEM-BCL NLCs could be featured as promising co-delivery, tumor-targeted nanomedicine for the treatment of cancers.

Controlled drug release from lung-targeted nanocarriers via chemically mediated shell permeabilisation

Nanocarriers can aid therapeutic agent administration to the lung, but controlling drug delivery from these systems after deposition in the airways can be problematic. The aim of this study was to evaluate if chemically mediated shell permeabilisation could help manipulate the rate and extent of nanocarrier drug release. Rifampicin was loaded into lipid shell (loading efficiency 41.0±11.4%, size 50nm) and polymer shell nanocarriers (loading efficiency 25.9±2.3%, size 250nm). The drug release at pH 7.4 (lung epithelial pH) and 4.2 (macrophage endosomal pH) with and without the chemical permeabilisers (Pluronic L62D - lipid nanocarriers; H(+)- polymer nanocarriers) was then tested. At pH 7.4 the presence of the permeabilisers increased nanocarrier drug release rate (from 3.2μg/h to 6.8μg/h for lipid shell nanocarriers, 2.3μg/h to 3.4μg/h for polymer shell nanocarriers) and drug release extent (from 50% to 80% for lipid shell nanocarriers, from 45% to 76% for polymer shell nanocarriers). These effects were accompanied by lipid nanocarrier distension (from 50 to 240nm) and polymer shell hydrolysis. At pH 4.2 the polymer nanocarriers did not respond to the permeabiliser, but the lipid nanocarrier maintained a robust drug release enhancement response and hence they demonstrated that the manipulation of controlled drug release from lung-targeted nanocarriers was possible through chemically mediated shell permeabilisation.