pH-sensitive carbonate apatite nanoparticles as DNA vaccine carriers enhance humoral and cellular immunity

Co-Delivery of Methotrexate and Nanohydroxyapatite with Polyethylene Glycol Polymers for Chemotherapy of Osteosarcoma

Neoadjuvant chemotherapy is an alternative treatment modality for tumors. Methotrexate (MTX) has been often used as a neoadjuvant chemotherapy reagent for osteosarcoma surgery. However, the large dosage, high toxicity, strong drug resistance, and poor improvement of bone erosion restricted the utilization of methotrexate. Here, we developed a targeted drug delivery system using nanosized hydroxyapatite particles (nHA) as the cores. MTX was conjugated to polyethylene glycol (PEG) through the pH-sensitive ester linkage and acted as both the folate receptor-targeting ligand and the anti-cancer drug due to the similarity to the structure of folic acid. Meanwhile, nHA could increase the concentration of calcium ions after being uptake by cells, thus inducing mitochondrial apoptosis and improving the efficacy of medical treatment. In vitro drug release studies of MTX-PEG-nHA in phosphate buffered saline at different pH values (5, 6.4 and 7.4) indicated that the system showed a pH-dependent release feature because of the dissolution of ester bonds and nHA under acidic conditions. Furthermore, the treatment on osteosarcoma cells (143B, MG63, and HOS) by using MTX-PEG-nHA was demonstrated to exhibit higher therapeutic efficacy. Therefore, the developed platform possesses the great potential for osteosarcoma therapy.

Krebs Cycle Intermediate-Modified Carbonate Apatite Nanoparticles Drastically Reduce Mouse Tumor Burden and Toxicity by Restricting Broad Tissue Distribution of Anticancer Drugs

The morphology, size, and surface area of nanoparticles (NPs), with the existence of functional groups on their surface, contribute to the drug binding affinity, distribution of the payload in different organs, and targeting of a particular tumor for exerting effective antitumor activity in vivo. However, the inherent chemical structure of NPs causing unpredictable biodistribution with a toxic outcome still poses a serious challenge in clinical chemotherapy. In this study, carbonate apatite (CA), citrate-modified CA (CMCA) NPs, and α-ketoglutaric acid-modified CA (α-KAMCA) NPs were employed as carriers of anticancer drugs for antitumor, pharmacokinetic, and toxicological analysis in a murine breast cancer model. The results demonstrated almost five-fold enhanced tumor regression in the cyclophosphamide (CYP)-loaded α-KAMCA NP-treated group compared to the group treated with CYP only. Also, NPs promoted much higher drug accumulation in blood and tumor in comparison with the drug injected without a carrier. In addition, doxorubicin (DOX)-loaded NPs exhibited less accumulation in the heart, indicating less potential myocardial toxicity in mice compared to free DOX. Our findings, thus, conclude that CA, CMCA, and α-KAMCA NPs extended the circulation half-life and enhanced the anticancer effect with reduced toxicity of conventional chemotherapeutics in healthy organs, signifying that they are promising drug delivery devices in breast cancer treatment.

Citrate- and Succinate-Modified Carbonate Apatite Nanoparticles with Loaded Doxorubicin Exhibit Potent Anticancer Activity against Breast Cancer Cells

Biodegradable inorganic apatite-based particle complex is popular for its pH-sensitivity at the endosomal acidic environment to facilitate drug release following cellular uptake. Despite being a powerful anticancer drug, doxorubicin shows severe off-target effects and therefore would need a carrier for the highest effectiveness. We aimed to chemically modify carbonate apatite (CA) with Krebs cycle intermediates, such as citrate and succinate in order to control the growth of the resultant particles to more efficiently carry and transport the anticancer drug into the cancer cells. Citrate- or succinate-modified CA particles were synthesized with different concentrations of sodium citrate or sodium succinate, respectively, in the absence or presence of doxorubicin. The drug loading efficiency of the particles and their cellular uptake were observed by quantifying fluorescence intensity. The average diameter and surface charge of the particles were determined using Zetasizer. Cell viability was assessed by MTT assay. Citrate-modified carbonate apatite (CMCA) exhibited the highest (31.38%) binding affinity for doxorubicin and promoted rapid cellular uptake of the drug, leading to the half-maximal inhibitory concentration 1000 times less than that of the free drug in MCF-7 cells. Hence, CMCA nanoparticles with greater surface area enhance cytotoxicity in different breast cancer cells by enabling higher loading and more efficient cellular uptake of the drug.

High quality β-FeOOH nanostructures constructed by a biomolecule-assisted hydrothermal approach and their pH-responsive drug delivery behaviors

High-quality akaganeite nanostructures with diverse well-defined morphologies and promising pH-responsive drug delivery behaviors were obtained by a facile wet chemistry method.