Enzyme and Thermal Dual Responsive Amphiphilic Polymer Core–Shell Nanoparticle for Doxorubicin Delivery to Cancer Cells

Dual responsive polymer nanoscaffolds for administering anticancer drugs both at the tumor site and intracellular compartments are made for improving treatment in cancers. The present work reports the design and development of new thermo- and enzyme-responsive amphiphilic copolymer core–shell nanoparticles for doxorubicin delivery at extracellular and intracellular compartments, respectively. A hydrophobic acrylate monomer was tailor-made from 3-pentadecylphenol (PDP, a natural resource) and copolymerized with oligoethylene glycol acrylate (as a hydrophilic monomer) to make new classes of thermo and enzyme dual responsive polymeric amphiphiles. Both radical and reversible addition–fragmentation chain transfer (RAFT) methodologies were adapted for making the amphiphilic copolymers. These amphiphilic copolymers were self-assembled to produce spherical core–shell nanoparticles in water. Upon heating, the core–shell nanoparticles underwent segregation to produce larger sized aggregates above the lower critical solution temperature (LCST). The dual responsive polymer scaffold was found to be capable of loading water insoluble drug, such as doxorubicin (DOX), and fluorescent probe-like Nile Red. The drug release kinetics revealed that DOX was preserved in the core–shell assemblies at normal body temperature (below LCST, ≤ 37 °C). At closer to cancer tissue temperature (above LCST, ∼43 °C), the polymeric scaffold underwent burst release to deliver 90% of loaded drugs within 2 h. At the intracellular environment (pH 7.4, 37 °C) in the presence of esterase enzyme, the amphiphilic copolymer ruptured in a slow and controlled manner to release >95% of the drugs in 12 h. Thus, both burst release of cargo at the tumor microenvironment and control delivery at intracellular compartments were accomplished in a single polymer scaffold. Cytotoxicity assays of the nascent and DOX-loaded polymer were carried out in breast cancer (MCF-7) and cervical cancer (HeLa) cells. Among the two cell lines, the DOX-loaded polymers showed enhanced killing in breast cancer cells. Furthermore, the cellular uptake of the DOX was studied by confocal and fluorescence microscopes. The present investigation opens a new enzyme and thermal-responsive polymer scaffold approach for DOX delivery in cancer cells

Aspirin Delimits Platelet Life Span by Proteasomal Inhibition

<div><p>Aspirin is widely used in clinical settings as an anti-inflammatory and anti-platelet drug due its inhibitory effect on cyclooxygenase activity. Although the drug has long been considered to be an effective and safe therapeutic regime against inflammatory and cardiovascular disorders, consequences of its cyclooxygenase-independent attributes on platelets, the key players in thrombogenesis, beg serious investigation. In this report we explored the effect of aspirin on platelet lifespan in murine model and its possible cytotoxicity against human platelets <i>in vitro</i>. Aspirin administration in mice led to significant reduction in half-life of circulating platelets, indicative of enhanced rate of platelet clearance. Aspirin-treated human platelets were found to be phagocytosed more efficiently by macrophages, associated with attenuation in platelet proteasomal activity and upregulation of conformationally active Bax, which were consistent with enhanced platelet apoptosis. Although the dosage of aspirin administered in mice was higher than the therapeutic regimen against cardiovascular events, it is comparable with the recommended anti-inflammatory prescription. Thus, above observations provide cautionary framework to critically re-evaluate prophylactic and therapeutic dosage regime of aspirin in systemic inflammatory as well as cardiovascular ailments.</p></div

Study of apoptosis-like features in platelets following aspirin treatment.

<p>Mitochondrial transmembrane potential (red/green ratio) (A), PS exposure (PE-annexin V binding) (B) and ROS generation (C) were studied in control platelets, as well as in cells pre-treated with aspirin as indicated. In (A), CCCP (mitochondrial protonophore) has been employed as the positive control. Data are representative of five different experiments and expressed as mean±SD. (*p<0.05 as compared to ethanol-pretreated resting platelets).</p

Aspirin affects lifespan and phagocytic uptake of platelets (A), Platelet count in control as well as aspirin-administered mice on different days.

<p>(B), Proportion of biotinylated platelets (%) in peripheral blood sample drawn from ethanol (vehicle) or aspirin (10 and 15 mg/kg) pre-administered mice 0, 24, 48, 72, and 96 h after administration of NHS-biotin. t_1/2 (h) represents platelet half-life in hours. (C) and (D), phagocytic uptake of platelets by autologous macrophages. Flow cytometry (C) and epifluorescence microscopy (D) of macrophages co-incubated with calcein-labeled platelets pretreated either with aspirin (5 mM) or ethanol (control). Scale bars, 10 µm. Data are representative of five different experiments.</p

Study of proteosome and caspase-3 activities in aspirin-treated platelets (A), Western blots showing expression level of active Bax in platelets pretreated with ethanol, aspirin, ABT737, epoxomicin, PSI and bortezomib, as indicated (upper panel) normalized against β-actin (lower panel).

<p>(B), Quantitative representation of active Bax levels in platelet whole cell lysates determined by densitometry of Western blots. (C), caspase-3 activity from the extent of cleavage of fluorigenic substrate AC-DEVD-AMC. (D), Assay of proteasome enzymatic activity in platelets pretreated with ethanol, PSI (proteasome inhibitor) (10 µM) and aspirin. Data are representative of five different experiments and expressed as mean±SD. (*p<0.05 as compared to ethanol-pretreated resting platelets).</p

Polyurethane-Grafted Chitosan as New Biomaterials for Controlled Drug Delivery

The present investigation focuses on the grafting of chitosan (CHT) with diisocyanate terminated polyurethane. Solid state ¹³C NMR spectroscopy confirms the grafting reaction and the degree of substitution (DS) was calculated from the deconvoluted area of the corresponding NMR peak. Solubility studies, swelling behavior and contact angle measurements support the hydrophobic chemical modification on CHT molecules and higher DS leads to the cross-linking of CHT molecules having polyurethane bridges resulting insolubility and regulated swelling in the graft copolymer. Molecular relaxations phenomena due to the constraint associated with the grafting have been revealed using spin–lattice relaxation tine (<i>T</i>₁) and shifting of peak position in tan δ curve toward lower temperature in dynamic mechanical measurement at constant frequency indicating flexible nature of graft copolymers as compared to pure CHT. The sustained drug delivery has been achieved using graft copolymers vis-à-vis pure CHT following the Fickian diffusion behavior (<i>n</i> ≤ 0.45) and the release rate can be tuned by altering the DS. In depth biocompatibility studies through platelet aggregation, platelet adhesion, reactive oxygen species of the developed graft copolymers, and <i>in vitro</i> hemolysis assay and cell viability have been performed to understand its potential use in biomedical applications and compared the improved properties with respect to pure CHT. Hence, bio- and hemocompatible CHT graft copolymers have been developed with the capability of controlled and sustained drug release

Supplemental Material, Supplementary_File - Chemical modification of nitrile rubber in the latex stage by functionalizing phosphorylated cardanol prepolymer: A bio-based plasticizer and a renewable resource

<p>Supplemental Material, Supplementary_File for Chemical modification of nitrile rubber in the latex stage by functionalizing phosphorylated cardanol prepolymer: A bio-based plasticizer and a renewable resource by Satyajit Samantarai, Ahindra Nag, Nitesh Singh, Debabrata Dash, Amit Basak, Golok B. Nando and Narayan Ch Das in Journal of Elastomers & Plastics</p

Screening for the Biochemical Profile and Biological Activity in Cephalotaxus and Taxus Collected from North-Eastern Himalayas

Cephalotaxus and Taxus both possess significant medicinal values in the traditional medicine system. Even though the tribal communities in the Himalayas have used these genera extensively, little is known about their ethnopharmacological properties. The study aims to investigate the biochemical profile and biological activities of various extracts of Cephalotaxus and Taxus. This study examined six different accessions of Cephalotaxus and Taxus growing in the northeastern Himalayan region of India for their biochemical components and biological activities. This report considers three species of Cephalotaxus, namely, C. mannii, C. sinensis, and C. griffithii, and one species of Taxus viz. Taxus wallichiana. The stem and leaf extracts of all six selected accessions were biochemically characterized using HPLC/LC–MS. Results have demonstrated the presence of several medicinally important chemicals like harringtonine, rutin, caffeic acid, gallic acid, and a few other biologically active compounds. The isolates were tested for their antibacterial and anti-plasmodial properties. The zone of inhibitions for various extracts ranged from 3–11 mm in the case of Cephalotaxus and 3–6 mm for Taxus. Leaf and stem extracts of all six accessions were found negative for antiplasmodial properties. The data from this study can further serve as a framework for a thorough analysis of various compounds and their antibacterial and antimalarial properties