Effect of the Folate Ligand Density on the Targeting Property of Folated-Conjugated Polymeric Nanoparticles

The effects of ligand distribution and density on the targeting properties of dual-targeting folate/biotin Pluronic F127/Poly (lactic acid) polymersomes

Targeted drug delivery systems modified with two or more ligands were expected to have better anti-tumor ability than those with just one ligand due to the complexity and heterogeneity of tumors. Thus, dual-targeting Pluronic/poly (lactic acid) polymersomes containing biotin (BT) and folic acid (FA) ligands (BT/FA-F127-PLA) were designed to study their targeting properties over human ovarian cancer cells (OVCAR-3). Two kinds of dual-ligand targeting polymersomes, BT/FA-F127-PLA and (BT + FA)-F127-PLA, were prepared to study the effect of the dual-ligand distribution on the cell targeting of polymersomes. BT/FA-F127-PLA had two ligands distributed in the same polymersomes whereas (BT + FA)-F127-PLA had two ligands distributed in different polymersomes. The in vitro cytotoxicity and cellular uptake, and in vivo pharmacokinetic behaviors of BT/FA-F127-PLA were superior to those of (BT + FA)-F127-PLA. It suggested that biotin and folate ligands distributed on the same polymersomes could have the targeting effect of synergistic promotion. Further experiments on cell uptake mechanisms of polymersomes showed that the uptake of targeted polymersomes was associated with energy-dependent endocytosis, involving clathrin, caveolin protein, macropinocytosis and ligand receptor-mediated endocytosis. In addition, the effect of different density ratios of dual ligands for BT/FA-F127-PLA was further studied. The results showed that the cellular targeting effect of BT/FA-F127-PLA was the strongest when the molar ratio of biotin to folic acid was 7.5 %: 7.5 %. In conclusion, BT/FA-F127-PLA dual-targeting polymersomes could be good candidates as targeted drug delivery carriers.

Glycyrrhetinic acid-modified redox-sensitive polymeric mixed micelles for tumor-specific intracellular delivery of cantharidin

Cantharidin (CTD) has been widely used to treat hepatocellular carcinoma (HCC) in clinical practice. However, the current CTD preparations may induce hepatic and renal damage due to their non-specific distribution. Therefore, redox-sensitive polymer Pluronic F127-disulfide bond-poly(d,l-lactide) (F127-SS-PDLA) and active targeting polymer F127-glycyrrhetinic acid (F127-GA) were synthesized to prepare mixed micelles (GA/F127-SS-PDLA/CTD) for effective delivery of CTD. Fourier transform infrared (FTIR) spectroscopy and 1H nuclear magnetic resonance (1H-NMR) spectroscopy were used to verify the successful synthesis of F127-SS-PDLA and F127-GA. During the preparation, this study was the first to screen the density of GA by cellular uptake assay. The results indicated that mixed micelles with 10% and 15% F127-GA (weight fraction) exhibited superior cellular uptake in comparison to micelles with 5% and 20% F127-GA. GA/F127-SS-PDLA/CTD micelles prepared by thin film hydration method demonstrated excellent drug loading capacity for CTD (16.12 ± 0.11%). The particle size and zeta potential of GA/F127-SS-PDLA/CTD micelles were 85.17 ± 1.24 nm and -11.71 ± 0.86 mV, respectively. Hemolysis and stability assay showed that the mixed micelles had good blood compatibility and could remain stable for 30 days at 4 °C. The redox-sensitivity of GA/F127-SS-PDLA/CTD micelles in vitro was verified under reducing conditions through dynamic light scattering (DLS) and an in vitro drug release experiment, which showed obvious particle size variation and rapid drug release ability. In cellular experiments, GA/F127-SS-PDLA/CTD micelles could induce superior cytotoxicity, apoptosis and intracellular reactive oxygen species (ROS) levels compared with free CTD, non-sensitive F127-PDLA/CTD micelles and redox-sensitive F127-SS-PDLA/CTD micelles. The cellular uptake ability of nile red-labeled GA/F127-SS-PDLA micelles, which was evaluated via fluorescent microscope and flow cytometry, indicated that the modification of GA significantly increased micelle uptake in HepG-2 cells. Consequently, GA/F127-SS-PDLA/CTD micelles could be considered as a satisfactory drug administration strategy in the treatment of HCC.

Recent Advances in Nanotechnology-Based Targeted Delivery Systems of Active Constituents in Natural Medicines for Cancer Treatment

Owing to high efficacy and safety, natural medicines have found their way into the field of cancer therapy over the past few decades. However, the effective ingredients of natural medicines have shortcomings of poor solubility and low bioavailability. Nanoparticles can not only solve the problems above but also have outstanding targeting ability. Targeting preparations can be classified into three levels, which are target tissues, cells, and organelles. On the premise of clarifying the therapeutic purpose of drugs, one or more targeting methods can be selected to achieve more accurate drug delivery and consequently to improve the anti-tumor effects of drugs and reduce toxicity and side effects. The aim of this review is to summarize the research status of natural medicines' nano-preparations in tumor-targeting therapies to provide some references for further accurate and effective cancer treatments.

Small molecules as cancer targeting ligands: Shifting the paradigm

Conventional chemotherapeutics exploration is hampered due to their nonspecific distribution leading to unintended serious toxicity. Toxicity is so severe that deciding to go for chemotherapy becomes a question of concern for many terminally ill cancer patients. However, with evolving times nanotechnology assisted in reducing the haywire distribution and channelizing the movement of drug-enclosing drug delivery systems to cancer cells to a greater extent, yet toxicity issues still could not be obliterated. Thus, active targeting appeared as a refuge, where ligands actively or specifically deliver linked chemotherapeutics and carriers to cancer cells. For a very long time, large molecule weight/macromolecular ligands (peptides and big polymers) were considered the first choice for ligand-directed active cancer targeting, due to their specificity towards overexpressed native cancer receptors. However, complex characterization, instability, and the expensive nature demanded to reconnoitre better alternatives for macromolecule ligands. The concept of small molecules as ligands emerged from the idea that few chemical molecules including chemotherapeutics have a higher affinity for cancer receptors, which are overexpressed on cell membranes, and may have the ability to assist in drug cellular uptake through endocytosis. But now the question is, can they assist the conjugated macro cargos to enter the cell or not? This present review will provide a holistic overview of the small molecule ligands explored till now.

Advances in the therapeutic delivery and applications of functionalized Pluronics: A critical review

Pluronic (PEO-PPO-PEO) block copolymers can form nano-sized micelles with a structure composed of a hydrophobic PPO core and hydrophilic PEO shell layer. Pluronics are U.S. Food and Drug Administration approved polymers, which are widely used for solubilization of drugs and their delivery, gene/therapeutic delivery, diagnostics, and tissue engineering applications due to their non-ionic properties, non-toxicity, micelle forming ability, excellent biocompatibility and biodegradability. Although Pluronics have been employed as drug carrier systems for several decades, numerous issues such as rapid dissolution, shorter residence time in biological media, fast clearance and weak mechanical strength have hindered their efficacy. Pluronics have been functionalized with pH-sensitive, biological-responsive moieties, antibodies, aptamers, folic acid, drugs, different nanoparticles, and photo/thermo-responsive hydrogels. These functionalization strategies enable Pluronics to act as stimuli responsive and targeted drug delivery vehicles. Moreover, Pluronics have emerged in nano-emulsion formulations and have been utilized to improve the properties of cubosomes, dendrimers and nano-sheets, including their biocompatibility and aqueous solubility. Functionalization of Pluronics results in the significant improvement of target specificity, loading capacity, biocompatibility of nanoparticles and stimuli responsive hydrogels for the promising delivery of a range of drugs. Therefore, this review presents an overview of all advancements (from the last 15 years) in functionalized Pluronics, providing a valuable tool for industry and academia in order to optimize their use in drug or therapeutic delivery, in addition to several other biomedical applications.

Development and evaluation of a novel biodegradable implants with excellent inflammatory response suppression effect by hot-melt extrusion

PURPOSE

Dexamethasone (Dex) is a widely used drug for the treatment of inflammatory and autoimmune conditions, however, long-term systemic use of Dex is associated with serious adverse effects. The objective of the present study was to develop an implantable device to avoid side effects and realize a controlled release of Dex at the implant site.

METHODS

Hydrophobic Dex was incorporated into biodegradable polyesters derived from PCL and Pluronic® L64 (PCL-Pluronic L64-PCL, PCLC) by hot-melt extrusion (HME) method to prepare Dex/PCLC implantable devices. Drug loading and encapsulation efficiency, a series of physicochemical properties, and in vivo features of the implants were studied.

RESULTS

The maximum value of the drug loading and encapsulation efficiency for the Dex/PCLC implants were up to 47% and 94%, respectively. Incorporation of Dex resulted in accelerated crystallization of PCLC, decreased the wettability, increased contact angles and viscosity, and accelerated Dex release rate and degradation rate from the implants in vivo. Moreover, Dex/PCLC implants showed excellent biocompatibility. Furthermore, the inflammatory response to the Dex/PCLC implants was less severe than that to the positive control group.

CONCLUSION

All these results suggested that Dex/PCLC implants might be a safe and controlled local drug delivery system with excellent inflammatory response suppression effect.

Paclitaxel-Loaded Folate-Targeted Albumin-Alginate Nanoparticles Crosslinked with Ethylenediamine. Synthesis and In Vitro Characterization

Among the different ways to reduce the secondary effects of antineoplastic drugs in cancer treatment, the use of nanoparticles has demonstrated good results due to the protection of the drug and the possibility of releasing compounds to a specific therapeutic target. The α-isoform of the folate receptor (FR) is overexpressed on a significant number of human cancers; therefore, folate-targeted crosslinked nanoparticles based on BSA and alginate mixtures and loaded with paclitaxel (PTX) have been prepared to maximize the proven antineoplastic activity of the drug against solid tumors. Nanometric-range-sized particles (169 ± 28 nm-296 ± 57 nm), with negative Z-potential values (between -0.12 ± 0.04 and -94.1± 0.4), were synthesized, and the loaded PTX (2.63 ± 0.19-3.56 ±0.13 µg PTX/mg Np) was sustainably released for 23 and 27 h. Three cell lines (MCF-7, MDA-MB-231 and HeLa) were selected to test the efficacy of the folate-targeted PTX-loaded BSA/ALG nanocarriers. The presence of FR on the cell membrane led to a significantly larger uptake of BSA/ALG-Fol nanoparticles compared with the equivalent nanoparticles without folic acid on their surface. The cell viability results demonstrated a cytocompatibility of unloaded nanoparticle-Fol and a gradual decrease in cell viability after treatment with PTX-loaded nanoparticle-Fol due to the sustainable PTX release.

Targeting Strategies for Enhancing Paclitaxel Specificity in Chemotherapy

Paclitaxel (PTX) has been used for cancer treatment for decades and has become one of the most successful chemotherapeutics in the clinic and financially. However, serious problems with its use still exist, owing to its poor solubility and non-selective toxicity. With respect to these issues, recent advances have addressed the water solubility and tumor specificity related to PTX application. Many measures have been proposed to remedy these limitations by enhancing tumor recognition via ligand-receptor-mediated targeting as well as other associated strategies. In this review, we investigated various kinds of ligands that have emerged as PTX tumor-targeting tools. In particular, this article highlights small molecule-, protein-, and aptamer-functionalized conjugates and nanoparticles (NPs), providing a promising approach for PTX-based individualized treatment prospects.

Targeting Strategies for Enhancing Paclitaxel Specificity in Chemotherapy

Paclitaxel (PTX) has been used for cancer treatment for decades and has become one of the most successful chemotherapeutics in the clinic and financially. However, serious problems with its use still exist, owing to its poor solubility and non-selective toxicity. With respect to these issues, recent advances have addressed the water solubility and tumor specificity related to PTX application. Many measures have been proposed to remedy these limitations by enhancing tumor recognition via ligand-receptor-mediated targeting as well as other associated strategies. In this review, we investigated various kinds of ligands that have emerged as PTX tumor-targeting tools. In particular, this article highlights small molecule-, protein-, and aptamer-functionalized conjugates and nanoparticles (NPs), providing a promising approach for PTX-based individualized treatment prospects.

Biotin-decorated all-HPMA polymeric micelles for paclitaxel delivery

To avoid poly(ethylene glycol)-related issues of nanomedicines such as accelerated blood clearance, fully N-2-hydroxypropyl methacrylamide (HPMAm)-based polymeric micelles decorated with biotin for drug delivery were designed. To this end, a biotin-functionalized chain transfer agent (CTA), 4-cyano-4-[(dodecylsulfanylthiocarbonyl)-sulfanyl]pentanoic acid (biotin-CDTPA), was synthesized for reversible addition-fragmentation chain-transfer (RAFT) polymerization. Amphiphilic poly(N-2-hydroxypropyl methacrylamide)-block-poly(N-2-benzoyloxypropyl methacrylamide) (p(HPMAm)-b-p(HPMAm-Bz)) with molecular weights ranging from 8 to 24 kDa were synthesized using CDTPA or biotin-CDTPA as CTA and 2,2'-azobis(2-methylpropionitrile) as initiator. The copolymers self-assembled in aqueous media into micelles with sizes of 40-90 nm which positively correlated to the chain length of the hydrophobic block in the polymers, whereas the critical micelle concentrations decreased with increasing hydrophobic block length. The polymer with a molecular weight of 22.1 kDa was used to prepare paclitaxel-loaded micelles which had sizes between 61 and 70 nm, and a maximum loading capacity of around 10 wt%. A549 lung cancer cells overexpressing the biotin receptor, internalized the biotin-decorated micelles more efficiently than non-targeted micelles, while very low internalization of both types of micelles by HEK293 human embryonic kidney cells lacking the biotin receptor was observed. As a consequence, the paclitaxel-loaded micelles with biotin decoration exhibited stronger cytotoxicity in A549 cells than non-targeted micelles. Overall, a synthetic pathway to obtain actively targeted poly(ethylene glycol)-free micelles fully based on a poly(HPMAm) backbone was established. These polymeric micelles are promising systems for the delivery of hydrophobic anticancer drugs.

Novel folated pluronic F127 modified liposomes for delivery of curcumin: preparation, release, and cytotoxicity

Aim: A novel folated pluronic F127 (FA-F127) was synthesised, so as to modify liposomes with FA group on the surface, and evaluate the effects of FA-F127 modification on the properties of the modified liposomes.Methods: FA was linked to one end of pluronic F127, via the terminal OH group, to obtain FA-F127 and the structure was characterised. FA-F127 modified curcumin liposomes (cur-FA-F127-Lps) were prepared. The physicochemical characteristics of cur-FA-F127-Lps, including morphology and particle size, were studied. The in vitro cytotoxicity of cur-FA-F127-Lps against KB cancer cells was determined by MTT tests.Results: The effects of FA-F127 modification on the average particle size, PDI, curcumin encapsulation efficiency and microstructure were not significant. Compared with nonfolated F127 liposomes (cur-F127-Lps), cur-FA-F127-Lps exhibited significantly higher cytotoxicity towards KB cells.Conclusions: Folic acid modified liposomes provide a novel strategy to improve the chemotherapeutic efficacy of hydrophobic bioactive compounds.