Adsorption of nucleotides on biomimetic apatite: The case of cytidine 5' monophosphate (CMP)

Development of calcium phosphate-chitosan composites with improved removal capacity toward tetracycline antibiotic: Adsorption and electrokinetic properties

Two eco-friendly and highly efficient adsorbents, namely brushite-chitosan (DCPD-CS), and monetite-chitosan (DCPA-CS) composites were synthesized via a simple and low-cost method and used for tetracycline (TTC) removal. The removal behavior of TTC onto the composite particles was studied considering various parameters, including contact time, pollutant concentration, and pH. The maximum TTC adsorption capacity was 138.56 and 112.48 mg/g for the DCPD-CS and DCPA-CS, respectively. Increasing the pH to 11 significantly enhanced the adsorption capacity to 223.84 mg/g for DCPD-CS and 205.92 mg/g for DCPA-CS. The antibiotic adsorption process was well-fitted by the pseudo-second-order kinetic and Langmuir isotherm models. Electrostatic attractions, complexation, and hydrogen bonding are the main mechanisms governing the TTC removal process. Desorption tests demonstrated that the (NH4)2HPO4 solution was the most effective desorbing agent. The developed composites were more efficient than DCPD and DCPA reference samples and could be used as valuable adsorbents of TTC from contaminated wastewater.

Interaction of Folic Acid with Nanocrystalline Apatites and Extension to Methotrexate (Antifolate) in View of Anticancer Applications

Nanocrystalline apatites mimicking bone mineral represent a versatile platform for biomedical applications thanks to their similarity to bone apatite and the possibility to (multi)functionalize them so as to provide "à la carte" properties. One relevant domain is in particular oncology, where drug-loaded biomaterials and engineered nanosystems may be used for diagnosis, therapy, or both. In a previous contribution, we investigated the adsorption of doxorubicin onto two nanocrystalline apatite substrates, denoted HA and FeHA (superparamagnetic apatite doped with iron ions), and explored these drug-loaded systems against tumor cells. To widen their applicability in the oncology field, here we examine the interaction between the same two substrates and two other molecules: folic acid (FA), often used as cell targeting agent, and the anticancer drug methotrexate (MTX), an antifolate analogue. In a first stage, we investigated the adsorptive behavior of FA (or MTX) on both substrates, evidencing their specificities. At low concentration, typically under 100 mmol/L, adsorption onto HA was best described using the Sips isotherm model, while the formation of a calcium folate secondary salt was evidenced at high concentration by Raman spectroscopy. Adsorption onto FeHA was instead fitted to the Langmuir model. A larger adsorptive affinity was found for the FeHA substrate compared to HA; accordingly, a faster release was noticed from HA. In vitro tests carried out on human osteosarcoma cell line (SAOS-2) allowed us to evaluate the potential of these compounds in oncology. Finally, in vivo (subcutaneous) implantations in the mouse were run to ascertain the biocompatibility of the two substrates. These results should allow a better understanding of the interactions between FA/MTX and bioinspired nanocrystalline apatites in view of applications in the field of cancer.

Laminin functionalized biomimetic apatite to regulate the adhesion and proliferation behaviors of neural stem cells

Background

Functionalizing biomaterial substrates with biological signals shows promise in regulating neural stem cell (NSC) behaviors through mimicking cellular microenvironment. However, diverse methods for immobilizing biological molecules yields promising results but with many problems. Biomimetic apatite is an excellent carrier due to its non-toxicity, good biocompatibility, biodegradability, and favorable affinity to plenty of molecules. Therefore, it may provide a promising alternative in regulating NSC behaviors.

Methods

Biomimetic apatite immobilized with the extracellular protein - laminin (LN) was prepared through coprecipitation process in modified Dulbecco's phosphate-buffered saline (DPBS) containing LN. The amount of coprecipitated LN and their release kinetics were examined. The adhesion and proliferation behaviors of NSC on biomimetic apatite immobilized with LN were investigated.

Results

The coprecipitation approach provided well retention of LN within biomimetic apatite up to 28 days, and supported the adhesion and proliferation of NSCs without cytotoxicity. For long-term cultivation, NSCs formed neurosphere-like aggregates on non-functionalized biomimetic apatite. A monolayer of proliferated NSCs on biomimetic apatite with coprecipitated LN was observed and even more stable than the positive control of LN coated tissue-culture treated polystyrene (TCP).

Conclusion

The simple and reproducible method of coprecipitation suggests that biomimetic apatite is an ideal carrier to functionalize materials with biological molecules for neural-related applications.

Functional calcium phosphate composites in nanomedicine

Calcium phosphate (CaP) materials have many peculiar and intriguing properties. In nature, CaP is found in nanostructured form embedded in a soft proteic matrix as the main mineral component of bones and teeth. The extraordinary stoichiometric flexibility, the different stabilities exhibited by its different forms as a function of pH and the highly dynamic nature of its surface ions, render CaP one of the most versatile materials for nanomedicine. This review summarizes some of the guidelines so far emerged for the synthesis of CaP composites in aqueous media that endow the material with tailored crystallinity, morphology, size, and functional properties. First, we introduce very briefly the areas of application of CaP within the nanomedicine field. Then through some selected examples, we review some synthetic routes where the presence of functional units (small templating molecules like surfactants, or oligomers and polymers) assists the synthesis and at the same time impart the functionality or the responsiveness desired for the end-application of the material. Finally, we illustrate two examples from our laboratory, where CaP is decorated by biologically active polymers or prepared within a thermo- and magneto-responsive hydrogel, respectively.

Experimental and computational modeling studies on silica-embedded NiO/MgO nanoparticles for adsorptive removal of organic pollutants from wastewater

This study presents newly-prepared silica-embedded NiO/MgO nanoparticles with a new experimental and computational adsorption approach for wastewater treatment.

Superparamagnetic iron-doped nanocrystalline apatite as a delivery system for doxorubicin

Iron-doped superparamagnetic apatite nanoparticles are promising materials for magnetic drug delivery systems due to their ability to strongly bind the anticancer doxorubicin and provide an active control over the drug release by using a low-frequency pulsed electromagnetic field.

Effect of nanosized and surface-structural-modified nano-pyroxene on adsorption of violanthrone-79

A new environmentally sound and low-cost yet highly efficient pyroxene nanoparticles employed for the first time as nanoadsorbents for violanthrone-79.