Synthesis, NMR characterization and in vitro cytotoxicity evaluation of new poly(oxyethylene aminophosphonate)s

Multicomponent Synthesis of Poly(α-aminophosphine chalcogenide)s and Subsequent Depolymerization

Multicomponent reactions of primary phosphines (R-PH2), diimines (R'-N═C(H)-R-(H)C═N-R'), and chalcogens (O2, S8) generate poly(α-aminophosphine chalcogenide)s (4-7) through step-growth polymerization. Characterization of the linear polymers using 31P{1H} diffusion-ordered NMR spectroscopy (DOSY) experiments aided in determining the molecular weight (Mw) of the material. Subjecting the polyphosphine oxide or sulfide to reducing conditions in the presence of a Lewis acid resulted in complete depolymerization of the polymers, quantitatively releasing the 1° phosphine and diimine (2) starting materials, with concomitant reduction of diimine to diamine (9).

Synthesis and Characterization of Amphiphilic Diblock Polyphosphoesters Containing Lactic Acid Units for Potential Drug Delivery Applications

Multistep one-pot polycondensation reactions synthesized amphiphilic diblock polyphosphoesters containing lactic acid units in the polymer backbone. At the first step was synthesized poly[poly(ethylene glycol) H-phosphonate-b-poly(ethylene glycol)lactate H-phosphonate] was converted through one pot oxidation into poly[alkylpoly(ethylene glycol) phosphate-b-alkylpoly(ethylene glycol)lactate phosphate]s. They were characterized by ¹H, ¹³C {H},³¹P NMR, and size exclusion chromatography (SEC). The effects of the polymer composition on micelle formation and stability, and micelle size were studied via dynamic light scattering (DLS). The hydrophilic/hydrophobic balance of these polymers can be controlled by changing the chain lengths of hydrophobic alcohols. Drug loading and encapsulation efficiency tests using Sudan III and doxorubicin revealed that hydrophobic substances can be incorporated inside the hydrophobic core of polymer micelles. The micelle size was 72-108 nm when encapsulating Sudan III and 89-116 nm when encapsulating doxorubicin. Loading capacity and encapsulation efficiency depend on the length of alkyl side chains. Changing the alkyl side chain from 8 to 16 carbon atoms increased micelle-encapsulated Sudan III and doxorubicin by 1.6- and 1.1-fold, respectively. The results obtained indicate that these diblock copolymers have the potential as drug carriers.

Pharmacological Activities of Schiff Bases and Their Derivatives with Low and High Molecular Phosphonates

This review paper is focused on the design of anthracene and furan-containing Schiff bases and their advanced properties as ligands in complex transition metal ions The paper also provides a brief overview on a variety of biological applications, namely, potent candidates with antibacterial and antifungal activity, antioxidant and chemosensing properties. These advantageous properties are enhanced upon metal complexing. The subject of the review has been extended with a brief discussion on reactivity of Schiff bases with hydrogen phosphonates and the preparation of low and high molecular phosphonates, as well as their application as pharmacological agents. This work will be of interest for scientists seeking new challenges in discovering advanced pharmacological active molecules gaining inspiration from the versatile families of imines and aminophosphonates.

Tumor microenvironment and redox dual stimuli-responsive polymeric nanoparticles for the effective cisplatin-based cancer chemotherapy

The serious side effects of cisplatin hindered its clinical application and the nanotechnology might be the potential strategy to address the limitation. However, rapid clearance in the blood circulation and ineffective controlled drug release from nanocarriers hamper the therapeutic efficacy of the nano-delivery system. We constructed a tumor microenvironment and redox dual stimuli-responsive nano-delivery system PEG-c-(BPEI-SS-Pt) by cross-linking the disulfide-containing polymeric conjugate BPEI-SS-Pt with the dialdehyde group-modified PEG₂₀₀₀via Schiff base. After optimized the cross-linking time, 72 h was selected to get the nano-delivery system.¹H NMR and drug release assays showed that under the acidic tumor microenvironment (pH 6.5-6.8), the Schiff base can be broken and detached the PEG cross-linked outer shells, displaying the capability to release the drugs with a sequential pH- and redox-responsive manner. Moreover, PEG-c-(BPEI-SS-Pt) showed more effective anti-tumor therapeutic efficacyin vivowith no significant side effects when compared with the drug of cisplatin used in the clinic. This strategy highlights a promising platform with the dual stimuli-responsive profile to achieve better therapeutic efficacy and minor side effects for platinum-based chemotherapy.

CO2 Adsorption on the N- and P-Modified Mesoporous Silicas

SBA-15 and MCM-48 mesoporous silicas were modified with functionalized (3-aminopropyl)triethoxysilane (APTES) by using the post-synthesis method, thus introducing N- and P-containing groups to the pore surface. The structure of the newly synthesized modifiers (aldimine and aminophosphonate derivatives of (3-aminopropyl)triethoxysilane and their grafting onto the porous matrix were proved by applying multinuclear NMR and FTIR spectroscopies. The content of the grafted functional groups was determined via thermogravimetric analysis. The physicochemical properties of the adsorbent samples were studied by nitrogen physisorption and UV–Vis spectroscopy. The adsorption capacity of CO₂ was measured in a dynamic CO₂ adsorption regime. The modified silicas displayed an enhanced adsorption capacity compared to the initial material. The ¹³C NMR spectra with high-power proton decoupling proved the presence of physically captured CO₂. A value of 4.60 mmol/g was achieved for the MCM-48 material grafted with the Schiff base residues. The total CO₂ desorption was achieved at 40 °C. A slight decrease of about 5% in CO₂ adsorption capacities was registered for the modified silicas in three adsorption/desorption cycles, indicating their performance stability.

Synthesis of Polymers via Kabachnik-Fields Polycondensation

Kabachnik-Fields reaction was employed as a new method for polycondensation. For this purpose, polymers were prepared from a mixture of dialdehydes, diamines, and phosphites. Variation of different starting monomers allowed the synthesis of polymers with tunable properties. It not only allowed the variation of glass transition temperatures but also enabled the synthesis of highly functional polymers including zwitterionic polymers. Further, photodegradable polymers have been realized by utilizing a photolabile dialdehyde monomer, which renders the obtained polymers highly interesting for numerous applications.

Low cytotoxicity and clastogenicity of some polymeric aminophosphonate derivatives

Poly(oxyethylene aminophosphonate)s synthesized on the basis of biodegradable poly(phosphorester)s and Schiff bases were tested in vitro for antitumor activity against a panel of six human epithelial cancer cell lines, for cytotoxicity to mouse fibroblast cells and in vivo for clastogenicity and antiproliferative effects. The polymers showed lower cytotoxicity, both in vivo and in vitro and lower clastogenicity in vivo than the corresponding low-molecular aminophosphonates. The biological activities of the tested polymers correlate with their low in vitro antitumor activity.