Paclitaxel Nanocrystals Research Articles

Effect of Process Parameters on the Particle Size Distribution of Paclitaxel Nanocrystals

The main intention of this work was to study the effect of process variables on the particle size distribution of paclitaxel nanocrystals. Paclitaxel nanocrystals were prepared by using anti-solvent precipitation method. Box Behnken design was used to optimize the process parameters including the Ratio (v/v) of two phases (A), Ulatrasonication time in min (B) and Surfactant concentration (%w/v) (C). A response surface methodology comprising 17 runs was carried out to optimize the nanocrystal formulation of paclitaxel. Two dependent variables particle size and polydispersity index (PDI) were identified as responses. Polynomial equations and response surface curves were used to relate the dependent and independent variables. The optimization model predicted a mean particle size of 147.653 nm and PDI of 0.1706 with A, B and C levels of 5, 15 min and 0.03% w/v respectively. The observed values were in close agreement with the predicted values. The optimized batches of nanocrystals were analyzed by FTIR, DSC and XRPD techniques. The optimized batch revealed irregular morphology as assessed by transmission electron microscopy and was crystalline as determined by thermal analysis and XRPD studies. Paclitaxel nanocrystals exhibited a considerable increase in solubility as well as dissolution rate in comparison with the pure drug. The present work thoroughly explored the influence of process parameters on the physicochemical characteristics of the produced drug nanocrystals.

Synergistic Antitumor Effects on Drug-Resistant Breast Cancer of Paclitaxel/Lapatinib Composite Nanocrystals.

Drug resistance presents serious difficulties for cancer treatment. A combination of paclitaxel (PTX) and lapatinib (LAPA) shows potentials in multiple drug resistant cancers in the clinic, but it is almost impossible to deliver these two drugs to the tumor at the same time with the best proportion by simple co-administration of the respective current formualtions for their different pharmacokinetic profiles. Here composite nanocrystals of PTX and LAPA (cNC) were designed with a ratio of 2:1 (w/w), which was their intracellular ratio at the best synergistic efficacy on a drug-resistant cancer cell line (MCF-7/ADR). Such cNC were prepared using a bottom-up method to achieve a nearly spherical appearance and a narrow size distribution of 95.1 ± 2.1 nm. For nanocrystal stabilization, Polyethylene glycol (PEG) coating was introduced into the cNC via polydopamine (PDA) coating in order to get a PEGylated composite nanocrystal (cNC@PDA-PEG) with nanoscale size (170.5 ± 1.4 nm), considerable drug loading (PTX: 21.33 ± 1.48%, LAPA: 10.95 ± 1.24%) and good stability for at least 4 days in plasma-containing buffers. Differential scanning calorimeter (DSC) and XRD data both indicated the different crystalline states of the cNC as well as the cNC@PDA-PEG in comparison with bulk drugs. In vitro release data showed that PTX and LAPA were gradually and completely released from cNC@PDA-PEG in 3 days, while drug release from bulk drugs or cNC was only 30%. cNC@PDA-PEG also showed negligible hemolysis in vitro. Cellular uptake experiments in the MCF-7/ADR cell line showed that the nanocrystals entered the cells in a complete form through endocytosis and then released the drug in the cell. cNC@PDA-PEG inhibits the growth of this drug-resistant cell more effectively than the unmodified version (cNC). In summary, PEGylated PTX and LAPA composite nanocrystals showed the potential for treament of drug-resistant tumors by simultaneously delivering two drugs to tumor cells with the best proportion.

Improving systemic circulation of paclitaxel nanocrystals by surface hybridization of DSPE-PEG2000

This paper aims to improve the systemic circulation of paclitaxel (PTX) by modifying nanocrystals with DSPE-PEG 2000. PTX nanocrystals (PNCs) were prepared by an anti-solvent method and DSPE-PEG 2000 was inserted into PNCs by hybridization. The average size of DSPE-PEG-PNCs did not change obviously compared to the naked PNCs, but the negative charge increased after hybridization. The saturated attachment ratio of DSPE-PEG 2000 was 0.4%. In vitro release rate of DSPE-PEG-PNCs was significantly slower than that of PTX solution and the naked PNCs, which indicated that DSPE-PEG 2000 hindered the release of PTX. Moreover, pharmacokinetics results showed that DSPE-PEG-PNCs achieved a higher area-under-the-curve (AUC, 4.43 ± 0.19 mg/L*h) and lower clearance rate (1.08 ± 0.16 L/h/kg) compared to PNCs with an AUC of 2.48 ± 0.18 mg/L*h and a clearance rate of 1.89 ± 0.15 L/h/kg. Therefore, DSPE-PEG-PNCs could have a significant potential in clinical use by improving the systemic circulation of the drug.

"Locked" cancer cells are more sensitive to chemotherapy.

The treatment of metastatic cancer is a great challenging issue throughout the world. Conventional chemotherapy can kill the cancer cells and, whereas, would exacerbate the metastasis and induce drug resistance. Here, a new combinatorial treatment strategy of metastatic cancer was probed via subsequentially dosing dual nanomedicines, marimastat‐loaded thermosensitive liposomes (MATT‐LTSLs) and paclitaxel nanocrystals (PTX‐Ns), via intravenous and intratumoral injection. First, the metastasis was blocked and cancer cells were locked in the tumor microenvironment (TME) by delivering the matrix metalloproteinase (MMP) inhibitor, MATT, to the tumor with LTSLs, downregulating the MMPs by threefold and reducing the degradation of the extracellular matrix. And then, the “locked” cancer cells were efficiently killed via intratumoral injection of the other cytotoxic nanomedicine, PTX‐Ns, along with no metastasis and 100% inhibition of tumor growth. This work highlights the importance of the TME's integrity in the chemotherapy duration. We believe this is a generalized strategy for cancer treatment and has potential guidance for the clinical administration.

Silica Coated Paclitaxel Nanocrystals Enable Neural Stem Cell Loading For Treatment of Ovarian Cancer.

Ovarian cancer is commonly diagnosed only after it has metastasized to the abdominal cavity (stage III). While the current standard of care of intraperitoneal (IP) administration of cisplatin and paclitaxel (PTX) combination chemotherapy has benefit, patient 5-year survival rates are low and have not significantly improved in the past decade. The ability to target chemotherapy selectively to ovarian tumors while sparing normal tissue would improve efficacy and decrease toxicities. We have previously shown that cisplatin-loaded nanoparticles (NPs) loaded within neural stem cells (NSCs) are selectively delivered to ovarian tumors in the abdominal cavity following IP injection, with no evidence of localization to normal tissue. Here we extended the capabilities of this system to also include PTX delivery. NPs that will be loaded into NSCs must contain a high amount of drug by weight but constrain the release of the drug such that the NSCs are viable after loading and can successfully migrate to tumors. We developed silica coated PTX nanocrystals (Si[PTX-NC]) meeting these requirements. Si[PTX-NC] were more effective than uncoated PTX-NC or Abraxane for loading NSCs with PTX. NSCs loaded with Si[PTX-NC] maintained their migratory ability and, for low dose PTX, were more effective than free PTX-NC or Si[PTX-NC] at killing ovarian tumors in vivo. This work demonstrates that NSC/NP delivery is a platform technology amenable to delivering different therapeutics and enables the pursuit of NSC/NP targeted delivery of the entire preferred chemotherapy regimen for ovarian cancer. It also describes efficient silica coating chemistry for PTX nanocrystals that may have applications beyond our focus on NSC transport.

RGD-modified PEGylated paclitaxel nanocrystals with enhanced stability and tumor-targeting capability

Nanocrystals has been constructed for insoluble drugs as a novel type of nanoscale drug delivery systems with high drug loading. How to prepare nanocrystals with good stability and tumor targeting capability is still challenging. This study was to modify paclitaxel nanocrystals with polyethylene glycol (PEG) for stabilization and RGD peptide for tumor targeting. Inspired by the structure of mussel's foot protein, polydopamine (PDA) was introduced to the drug delivery system for the modification of nanocrystals. Briefly, PDA was coated on the surface of nanocrystals to form a reaction platform for further PEGylation and RGD peptide conjugation. PEGylated nanocrystals with RGD peptide modification (NC@PDA-PEG-RGD) were prepared with near-spheroid shape, drug loading 45.12 ± 1.81% and a hydrodynamic diameter 419.9 ± 80.9 nm. The size of NC@PDA-PEG-RGD remained basically unchanged for at least 72 h in the presence of plasma while the size of unmodified nanocrystals (NC) increased and exceeded 1000 nm in 12 h. Cellular uptake and cellular growth inhibition experiments using the lung cancer cell line A549 demonstrated the superiority of NC@PDA-PEG-RGD over NC or PEGylated nanocrystals without RGD modification (NC@PDA-PEG). In A549 model tumor bearing-mice, NC@PDA-PEG-RGD showed significantly higher intratumor accumulation and slower tumor growth than NC@PDA-PEG or free paclitaxel. In summary, our study suggested the superiority of RGDmodified PEGylated paclitaxel nanocrystals as a lung cancer-targeted delivery system and the potential of PDA coating technique for targeting functionalization of nanocrystals.

A personalized and long-acting local therapeutic platform combining photothermal therapy and chemotherapy for the treatment of multidrug-resistant colon tumor.

BackgroundLocal photothermal therapy (PTT) provides an easily applicable, noninvasive adjunctive therapy for colorectal cancer (CRC), especially when multidrug resistance (MDR) occurs. However, using PTT alone does not result in complete tumor ablation in many cases, thus resulting in tumor recurrence and metastasis.Materials and methodsIn this study, we aim to develop a personalized local therapeutic platform combining PTT with long-acting chemotherapy for the treatment of MDR CRC. The platform consists of polyethylene glycol (PEG)-coated gold nanorods (PEG-GNRs) and D-alpha-tocopheryl PEG 1000 succinate (TPGS)-coated paclitaxel (PTX) nanocrystals (TPGS-PTX NC), followed by the incorporation into an in situ hydrogel (gel) system (GNRs-TPGS-PTX NC-gel) before injection. After administration, PEG-GNRs can exert quick and efficient local photothermal response under near-infrared laser irradiation to shrink tumor; TPGS-PTX NC then provides a long-acting chemotherapy due to the sustained release of PTX along with the P-glycoprotein inhibitor TPGS to reverse the drug resistance.ResultsThe cytotoxicity studies showed that the IC50 of GNRs-TPGS-PTX NC-gel with laser irradiation decreased to ~178-folds compared with PTX alone in drug-resistant SW620 AD300 cells. In the in vivo efficacy test, after laser irradiation, the GNRs-TPGS-PTX NC-gel showed similar tumor volume inhibition compared with GNRs-gel at the beginning. However, after 14 days, the tumor volume of the mice treated with GNRs-gel quickly increased, while that of the mice treated with GNRs-TPGS-PTX NC-gel remained controllable due to the long-term chemotherapeutic effect of TPGS-PTX NC. The mice treated with GNRs-TPGS-PTX NC-gel also showed no weight loss and obvious organ damages and lesions during the treatment, indicating a low systemic side effect profile and a good biocompatibility.ConclusionOverall, the nano-complex may serve as a promising local therapeutic patch against MDR CRC with one-time dosing to achieve a long-term tumor control. The doses of PEG-GNRs and TPGS-PTX NC can be easily adjusted before use according to patient-specific characteristics potentially making it a personalized therapeutic platform.

Triphenylphosphonium-modified mitochondria-targeted paclitaxel nanocrystals for overcoming multidrug resistance

Mitochondria are currently known as novel targets for treating cancer, especially for tumors displaying multidrug resistance (MDR). This present study aimed to develop a mitochondria-targeted delivery system by using triphenylphosphonium cation (TPP+)-conjugated Brij 98 as the functional stabilizer to modify paclitaxel (PTX) nanocrystals (NCs) against drug-resistant cancer cells. Evaluations were performed on 2D monolayer and 3D multicellular spheroids (MCs) of MCF-7 cells and MCF-7/ADR cells. In comparison with free PTX and the non-targeted PTX NCs, the targeted PTX NCs showed the strongest cytotoxicity against both 2D MCF-7 and MCF-7/ADR cells, which was correlated with decreased mitochondrial membrane potential. The targeted PTX NCs exhibited deeper penetration on MCF-7 MCs and more significant growth inhibition on both MCF-7 and MCF-7/ADR MCs. The proposed strategy indicated that the TPP+-modified NCs represent a potentially viable approach for targeted chemotherapeutic molecules to mitochondria. This strategy might provide promising therapeutic outcomes to overcome MDR.

Development of carrier-free nanocrystals of poorly water-soluble drugs by exploring metastable zone of nucleation

There has been increasing interest in research and development of nanocrystals for the delivery of poorly water-soluble drugs that can be directly produced from solution. Compared with traditional carrier-based or encapsulation designs, drug nanocrystals circumvent possible side-effects due to carrier polymers and poor stability issues associated with encapsulation. The production of carrier-free nanocrystals requires careful control of nucleation and thus a thorough understanding of the relevant solution's metastable zone. A solution may stay supersaturated without forming any nuclei and become metastable. The maximal degree of supersaturation is known as the metastable zone width. When nucleation is triggered directly from the metastable zone, it helps to produce homogeneous nuclei leading to uniform nanocrystals. Herein, we report a study in which the solubility and metastable limit of paclitaxel (PTX) in ethanol aqueous solution were measured at 40 °C. A wide range of metastable compositions were studied to prepare carrier-free PTX nanocrystals with particle size smaller than 250 nm and PDI less than 0.25. Compared with the raw material, dissolution rate of PTX nanocrystals was significantly increased. The study enables production of high-quality drug nanocrystals for treating patients.

Nanoscale partitioning of paclitaxel in hybrid lipid-polymer membranes.

Paclitaxel is a powerful drug against restenosis and many forms of cancer. However, its clinical application hinges on the ability to achieve suitable stabilized drug concentrations in an aqueous suspension while hindering drug crystallization. To engineer such formulations, it is imperative to understand paclitaxel's partitioning and crystallization within the carrier matrix. Lipid-polymer hybrid films have been recently shown to accommodate large paclitaxel loads and suppress crystallization. Additionally, such hybrid materials promote synergistic drug release compared to the pure constituents. Here, we leverage the composition sensitive photo-thermal induced resonance (PTIR) technique to study paclitaxel partitioning within hybrid films at the nanoscale. PTIR data reveal that paclitaxel nano-crystals segregate from lipid-only films but are well dispersed in polymer-only films. Remarkably, lipid-polymer hybrid films show enhanced partitioning of paclitaxel at the lipid-polymer phase boundaries, but still stifle crystallization, thus paving the way towards compositional and microstructural engineering of small-drug delivery systems.

Evaluation of Paclitaxel Nanocrystals In Vitro and In Vivo.

We created a novel paclitaxel (PTX) nanoparticle drug delivery system and compared this to acommercial injection preparation to evaluate the antitumor effects for both formulations in vivo and in vitro.PTXnanocrystals were 194.9 nm with potential of -29.6 mV. Cytotoxicity tests indicated that both formulations had similar effects and cytotoxicity was dose- and time-dependent.Pharmacodynamics indicated that the drug concentration at the tumor was greater with PTX nanocrystals compared to commercial injection (P<0.01) and that drug accumulated more and for a longer duration. In vivo antitumor evaluation indicated significant antitumor effects and low toxicity of PTX nanocrystals. Moreover, bioimaging indicated that the PTX retention time in MCF-7-bearing mice was longer, especially at the tumor site, and this high drug concentration was maintained for a long time.Overall, PTX nanocrystalsare feasible and superior to traditional injection formulation chemotherapy.

Study on orally delivered paclitaxel nanocrystals: modification, characterization and activity in the gastrointestinal tract.

Drug nanocrystals (NCs) can improve the solubility and bioavailability of insoluble drugs for oral administration. However, the biocompatibility and mechanisms of transmittance of drug NCs through the intestinal epithelial tissue are still not well understood. In this work, the physico-chemical properties and interactions with biomolecules in oral delivery pathways, as well as the transmittance through mimical intestinal epithelial cells, of NCs of paclitaxel (PTX) are investigated. PTX was previously demonstrated to be an effective anti-cancer drug. It is found that maximum 1% (w/v) poly(styrenesulfonate) is sufficient to keep PTX NCs monodisperse in varied biological environments and presents no significant interaction with extracellular biomolecules for at least 24 h. The concentration of PTX NCs is kept carefully controlled to avoid serious toxicity to cells (10 µg ml−1 in our experiments but this also depends on NC size). The transmittance of PTX NCs through mimical intestinal epithelial reached 25% in 6 h, demonstrating its comparatively high oral bioavailability in the human body. This work demonstrates the great potential of PTX NC treated in oral delivery.

Exploring intracellular fate of drug nanocrystals with crystal-integrated and environment-sensitive fluorophores

Formulating a poorly water-soluble drug substance into nanocrystals offers many advantages. Understanding of the in vivo fate of drug nanocrystals is however very limited. In this study, we utilized the hybrid nanocrystal concept and studied the kinetic process of dissolution in cancer cells. By taking advantage of aggregation-induced emission (AIE), hybrid paclitaxel (PTX) nanocrystals integrated with tetraphenylethene (TPE) enabled a novel way for estimating the intracellular dissolution process of the nanocrystals. When TPE is entrapped in a nanocrystal, fluorescence is emitted when the nanocrystal is optically excited. When an entrapped TPE molecule is released to a liquid medium due to the dissolution of the nanocrystal, its fluorescence is quenched. By monitoring the change in fluorescence, it is possible to quantify the dissolution of nanocrystals in a biological environment. Cellular uptake studies of hybrid nanocrystals were conducted with KB and HT-29 cell lines and characterized by confocal microscopy, flow cytometry, and HPLC. The results suggest that drug nanocrystals were taken up directly by the cells, and subsequently dissolved in the cytoplasm. The extent to which the drug nanocrystal dissolved was estimated according to the fluorescence measurement. The cellular uptake and intracellular dissolution could be influenced by drug concentration, incubation time, and surface coating, as well as the type of cell line.

Transmembrane Pathways and Mechanisms of Rod-like Paclitaxel Nanocrystals through MDCK Polarized Monolayer.

Drug nanocrystals (NCs) appear to be favorable to improving oral bioavailability of poorly water-soluble drugs as evidenced by the great success they have had in the market. However, the pathway and mechanism of drug NCs through epithelial membrane are still unclear. In an attempt to clarify their transport features, paclitaxel nanocrystals (PTX-NCs), and paclitaxel hybrid NCs with lipophilic carbocyanine dyes, were prepared and characterized as the models. The endocytosis, intracellular trafficking, paracellular transport, and transcytosis of PTX-NCs were carefully investigated with Förster resonance energy transfer (FRET) analysis, as well as a colocalization assay, flow cytometry, gene silencing, Western-blot, transepithelial electrical resistance (TEER) study and other approaches on MDCK cells. It was found that rod-like PTX-NCs could transport through the monolayer intact, and the process of endocytosis proved to be time and energy dependent. Endoplasmic reticulum (ER) and Golgi complexes were colocalized with PTX-NCs in cells, so the ER-Golgi complexes/Golgi complexes-basolateral membrane pathway may be involved in the intracellular trafficking and transcytosis of PTX-NCs. It was demonstrated here that cav-1, dynamin, and actin filament modulated the endocytosis process, and Cdc 42 regulated the transcytosis process. In addition, no paracellular transport of PTX-NCs was observed. These findings demonstrated that the rod-like nanocrystals not only enhanced the transcytosis of PTX compared with microparticles of raw drug materials but also changed the pathways of drug delivery. This study certainly provides insight for the oral absorption mechanism of nanocrystals of poorly soluble drugs.

Development and evaluation of targeting ligands surface modified paclitaxel nanocrystals

To overcome the toxicity of excipient or blank nanoparticles for drug delivery nano-system, the surface modified paclitaxel nanocrystals (PTX-NC) have been developed. PTX-NCs were prepared by nano-precipitation method. The surface of PTX-NCs were modified by grafting with apo-transferrin (Tf) or hyaluronic acid (HA). The physical properties of PTX-NCs were evaluated by field emission scanning electron microscope (FE-SEM), zeta-sizer, zeta-potential, differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectrometry. In vitro drug release study was performed in phosphate buffered saline (PBS) with or without 0.5% (w/v) Tween 80 for 24h. Cellular uptake was studied at time intervals of 0.5, 1, and 2h in MCF-7 cells, and cell growth inhibition study was performed for 24h using MCF-7 cells (cancer cells), and HaCaT cells (normal cells).Three different types of PTX-NCs with a mean size of 236.0±100.6nm (PTX-NC), 302.0±152.0nm (Tf-PTX-NC) and 339±180.6nm (HA-PTX-NC) were successfully prepared. The drug release profiles showed 29.1%/6.9% (PTX (pure)), 40.7%/23.9% (PTX-NC), 50.5%/25.1% (Tf-PTX-NC) and 46.8/24.8% (HA-PTX-NC) in PBS with/without 0.5% (w/v) Tween 80 for 24h, respectively. As per the results, the drug release of PTX-NCs showed the faster release as compared to that of PTX (pure). Surface modified PTX-NCs exhibited higher values for cell permeability than unmodified PTX-NC in the cellular uptake study. Surface modified PTX-NCs inhibited the cell growth approximately to 60% in MCF-7 cells, however effect of surface modified PTX-NCs on normal cell line was lower than the PTX-NC and PTX (pure). In conclusion, biological macromolecules (Tf or HA) surface modified PTX-NC enhanced the cellular uptake and the cell growth inhibition.

Direct in vivo evidence on the mechanism by which nanoparticles facilitate the absorption of a water insoluble, P-gp substrate

Here we examine the mechanisms by which nanoparticles enable the oral absorption of water-insoluble, P-glycoprotein efflux pump (P-gp) substrates, without recourse to P-gp inhibitors. Both 200nm paclitaxel N-(2-phenoxyacetyl)-6-O-glycolchitosan (GCPh) nanoparticles (GCPh-PTX) and a simulated Taxol formulation, facilitate drug dissolution in biorelevant media, unlike paclitaxel nanocrystals. Verapamil (40mgkg−1) increased the oral absorption from low dose Taxol (6 or 10mgkg−1) by 100%, whereas the oral absorption from high dose Taxol (20mgkg−1) or low dose GCPh-PTX (6 or 10mgkg−1) was largely unchanged by verapamil. There was virtually no absorption from control paclitaxel nanocrystals (20mgkg−1). Imaging of ex-vivo rat ileum samples showed that fluorescently labelled GCPh nanoparticles are mucoadhesive and are taken up by ileum epithelial cells. GCPh nanoparticles were also found to open Caco-2 cell tight junctions. In conclusion, mucoadhesive, drug solubilising GCPh nanoparticles enable the oral absorption of paclitaxel via the saturation of the P-gp pump (by high local drug concentrations) and by particle uptake and tight junction opening mechanisms.

In Vitro and In Vivo Evaluation of PEGylated Layer-by-Layer Polyelectrolyte-Coated Paclitaxel Nanocrystals.

Drug nanocrystals (NCs) are colloidal dispersions composed almost entirely of drug. As such, there is substantial interest in targeting them to diseased tissues, where they can locally deliver high doses of the therapeutic. However, because of their uncontrolled dissolution characteristics in vivo and uptake by the monomolecular phagocyte system, achieving tumor accumulation is challenging. To address these issues, a layer-by-layer approach is adopted to coat paclitaxel NCs with alternating layers of oppositely charged polyelectrolytes, using a PEGylated copolymer as the top layer. The coating successfully slows down dissolution in comparison to the noncoated NCs and to Abraxane (an approved paclitaxel nanoformulation), provides colloidal stability in physiologically relevant media, and has no intrinsic effect on cell viability at the concentrations tested. Nevertheless, their pharmacokinetic and biodistribution profile indicates that the NCs are rapidly cleared from the bloodstream followed by accumulation in the mononuclear phagocyte system organs (i.e., liver and spleen). This is hypothesized to be a consequence of the shedding of the PEGylated polyelectrolyte from the NCs' surface. While therapeutic efficacy was not investigated (due to poor tumor accumulation), overall, this work questions whether approaches that rely solely on electrostatic interactions for retaining coatings on the surfaces of NCs are appropriate for use in vivo.

Biological effect on restenosis and vascular healing of encapsulated paclitaxel nanocrystals delivered via coated balloon technology in the familial hypercholesterolaemic swine model of in-stent restenosis.

The aim of this study was to evaluate the biological efficacy of a novel lower-dose (2.5 µg/mm2) encapsulated paclitaxel nanocrystal-coated balloon (Nano-PCB) in the familial hypercholesterolaemic swine (FHS) model of iliofemoral in-stent restenosis. Nano-PCB pharmacokinetics were assessed in 20 femoral arteries (domestic swine). Biological efficacy was evaluated in ten FHS: 14 days following bare metal stent implantation each stent segment was randomised to a clinically available PCB (IN.PACT, n=14), the Nano-PCB (n=14) or an uncoated balloon (n=12). Angiographic, optical coherence tomography and histological evaluation was performed at 28 days after treatment. Arterial paclitaxel concentration was 120.7 ng/mg at one hour and 7.65 ng/mg of tissue at 28 days with the Nano-PCB. Compared to the control uncoated group, both PCBs significantly reduced percent area stenosis (Nano-PCB: 36.0±14.2%, IN.PACT: 29.3±9.2% vs control: 67.9±15.1%, p<0.001). Neointimal distribution in the entire stent length was more homogenous in the Nano-PCB. Histological evaluation showed comparable degrees of neointimal proliferation in both PCBs; however, the Nano-PCB showed slightly higher levels of neointimal maturity and endothelialisation. Lower-dose encapsulated paclitaxel nanocrystals delivered via a coated balloon displayed comparable biological efficacy with superior healing features compared to a clinically validated PCB technology.

Herceptin-functionalized pure paclitaxel nanocrystals for enhanced delivery to HER2-postive breast cancer cells

The objective of this study was to prepare Herceptin (HCT)-functionalized paclitaxel nanocrystals and evaluated their cell-specific interactions, cellular accumulation, and growth inhibition in HER2-positve breast cancer cells as a tumor-targeted delivery module. Paclitaxel (PTX) was fabricated in the form of nanocrystals (PNCs) by a sono-precipitation method, and HCT were coated using a facile non-covalent method (PNCs-HCT). Our results showed that the PNCs-HCT were stable for at least 1month at 4°C with no noticeable desorption of HCT. The release test showed that PNCs-HCT exhibited sustained drug release similar to only PNCs but with a higher release rate than only PTX powder. Cellular uptake, cytotoxicity, and cell cycle arrest studies revealed that PNCs-HCT exhibit greater binding affinity and higher cell-specific internalization to HER2-positive breast cancer cell lines as compared to PNCs, followed by enhanced cell growth inhibition. HCT-functionalized PNCs presented in this study offer a promising strategy for targeted pure drug nanocrystal delivery and enhancing the efficiency of anticancer therapy.

Effects of paclitaxel nanocrystals surface charge on cell internalization

In this study, we investigated the influence of paclitaxel nanocrystals (PTX-NC) surface charge on cell internalization and cell cytotoxicity. PTX-NCs were prepared using the nano-precipitation method. The surface-modified PTX-NCs were prepared using an absorption method with positively charged poly(allylamine hydrochloride) (PAH) and negatively charged poly(sodium 4-styrenesulfonate) (PSS). The morphologies of the surface-modified and unmodified PTX-NCs were characterized by field emission scanning electron microscopy. An in vitro drug release study was performed in phosphate-buffered saline (pH 7.4) containing 0.5% (w/v) Tween 80 for 48h. Cell internalization was evaluated at time intervals of 0.5, 1, and 2h, and cell cytotoxicity was analyzed for 24h using A549 cells. Three different types of PTX-NCs with a mean size of around 300-400nm were successfully prepared. The zeta-potential revealed PSS-PTX-NCs (-22.7±5.1 mV), PTX-NCs (− 2.4±2.9 mV), and PAH-PTX-NCs (+ 19.3±3.4 mV). The three types of PTX-NC exhibited higher drug release than pure PTX. The positive charge on PTX-NC resulted in higher cell uptake and cell cytotoxicity than the negative charge on PTX-NC. Moreover, the positive charge on PTX-NC showed stronger interactions with bovine serum albumin. In conclusion, the positive charge on PTX-NCs improved cell internalization, cell cytotoxicity, and interactions with bovine serum albumin.