Spectroscopic monitoring of polyurethane-based nanocomposite as a potential catalyst for the reduction of dyes.

In this study, AgNPs-loaded polyurethane-sodium alginate (PU-S/Alg) composite polymers were prepared by precipitation polymerization and in-situ reduction method. Their catalytic potential was evaluated for the reduction of methyl orange (MO), brilliant blue (BB), Rhodamine B (RhB), 4-nitroaniline (4-NA), and 4-nitrophenol (4-NP). Successful preparation of samples was confirmed by UV-Visible spectrophotometry (UV-Visible), Fourier transform infrared (FTIR), and Scanning electron microscopy (SEM) analysis. During the catalytic study, the value of kapp for the reduction of MO in the presence of NaBH4 and catalyst was found 0.488 min-1 while, in the presence of NaBH4 and catalyst alone, were found as 0.9 × 10-4 and 0.8 × 10-5 min-1, respectively which indicates the role of catalyst in making the reaction speedy. The value of kapp for the reduction of BB, RhB, 4-NA, and 4-NP was found as 0.764, 0.475, 0.212 and 0.757 min-1, respectively. Simultaneous reduction of dyes induced a decreased reaction completion time under the same reaction conditions. A slight increase in the value of kapp for the catalytic reduction of MO was also observed when reactions were performed in the presence of ionic media of different salts such as NaCl, KCl, CaCl2, and MnCl2. The rate of reduction of MO was increased with the increase in ionic strength of the medium. However, the presence of SDS (surfactant) in the reaction mixture induced the decreased activity of the catalyst and increased reaction completion time. The same value of kapp for the reduction of MO was observed in the case of freshly prepared and several days old nanocomposite catalyst. These results illustrate the stability and maintained catalytic potential of metal NPs for a prolonged time. Our reported catalyst also showed good potential for the treatment of dyes-polluted textile industry wastewater.

Colon specific enzyme responsive oligoester crosslinked dextran nanoparticles for controlled release of 5-fluorouracil.

Targeting bioactives selectively to diseased sites is one of the most challenging aspects of cancer therapy. Herein, fabrication of colonic enzyme-responsive dextran based oligoester crosslinked nanoparticles is reported for the controlled release of 5-fluorouracil (5-FU) - an anticancer drug. The 5-FU drug loaded nanoparticles (DNPs, size ~237 ± 25 nm, ζ-potential -17.0 ± 3 mV) were developed by the in-situ crosslinking of dextran with a bifunctional telechelic oligoester followed by the physical drug encapsulation via nanoprecipitation. Drug encapsulation efficiency and drug loading capacity of DNPs were found to be ~76% (±0.1) and ~8% (±0.1), respectively. The DNPs were demonstrated to release the encapsulated drug selectively in the presence of dextranase enzyme. The in vitro release kinetics assay revealed that the DNPs released about 75% (±4) of the entrapped drug within 12 h of incubation with dextranase enzyme. No drug was released in a control experiment where DNPs were exposed to pH conditions encountered in the stomach and small intestine. Moreover, the treatment of HCT116 colon cancer cell line with the developed DNPs highlighted its biocompatibility as well as dextranase triggered cytotoxicity. The developed system offers an avenue to reduce the non-specific cytotoxicity of the encapsulated 5-FU, and a colon specific delivery of the encapsulated drug in response to the dextranase enzyme.

Ecological risk assessment of pharmaceuticals in the receiving environment of pharmaceutical wastewater in Pakistan.

The pharmaceutical industry of Pakistan is growing with an annual growth rate of 10%. Besides this growth, this industry is not complying with environmental standards, and discharging its effluent into domestic wastewater network. Only limited information is available about the occurrence of pharmaceutical compounds (PCs) in the environmental matrices of Pakistan that has motivated us to aim at the occurrence and ecological risk assessment of 11 PCs of different therapeutic classes in the wastewater of pharmaceutical industry and in its receiving environmental matrices such as sludge, solid waste and soil samples near the pharmaceutical formulation units along Shiekhupura road, Lahore, Pakistan. Target PCs (paracetamol, naproxen, diclofenac, ibuprofen, amlodipine, rosuvastatin, ofloxacin, ciprofloxacin, moxifloxacin, sparfloxacin and gemifloxacin) were quantified using in-house developed HPLC-UV. Ibuprofen (1673µg/L, 6046µg/kg, 1229µg/kg and 610µg/kg), diclofenac (836µg/L, 4968µg/kg, 6632µg/kg and 257µg/kg) and naproxen (464µg/L, 7273µg/kg, 4819µg/kg and 199µg/kg) showed the highest concentrations among 11 target PCs in wastewater, sludge, solid waste and soil samples, respectively. Ecological risk assessment, in terms of risk quotient (RQ), was also carried out based on the maximum measured concentration of PCs in wastewater. The maximum RQ values obtained were with paracetamol (64 against daphnia), naproxen (177 against fish), diclofenac (12,600 against Oncorhynchus mykiss), ibuprofen (167,300 against Oryzias latipes), ofloxacin (81,000 against Pseudomonas putida) and ciprofloxacin (440 against Microcystis aeruginosa). These results show a high level of ecological risk due to the discharge of untreated wastewater from pharmaceutical units. This risk may further lead to food web contamination and drug resistance in pathogens. Thus, further studies are needed to detect the PCs in crops as well as the government should strictly enforce environmental legislation on these pharmaceutical units.