Enhanced degradation of methylene blue by a solution plasma process catalyzed by incidentally co-generated copper nanoparticles.

This study presents a catalytic organic pollution treatment using the solution plasma process (SPP) with incidentally co-generated copper (Cu) nanoparticles via Cu electrode erosion. Methylene blue (MB) was used as a model organic contaminant. The treatment time was from 0 to 60 minutes at the plasma frequencies of 15 and 30 kHz. The treatment efficacy using the Cu electrode was compared with that of the tungsten (W) electrode. The high erosion-resistant W electrode provided no W nanoparticles, while the low erosion-resistant Cu electrode yielded incidental nanoparticles (10-20 nm), hypothesized to catalyze the MB degradation during the SPP. The percentage of MB degradation and the hydrogen peroxide (H2O2) generation were determined by an ultraviolet-visible spectrophotometer. The results showed that, after the SPP by the Cu electrode for 60 minutes, the MB was degraded up to 96%. Using the Cu electrode at a high plasma frequency strongly accelerated the Cu nanoparticle generation and MB treatment, although the amount of H2O2 generated during the SPP using the Cu electrode was less than that of the W electrode. The Cu nanoparticles were hypothesized to enhance MB degradation via both homogeneous (release of dissolved Cu ions) and heterogeneous (on the surface of the particles) catalytic processes.

Production of reducing sugar from cassava starch waste (CSW) using solution plasma process (SPP).

The cassava starch processing plays an important role in food industries. During starch processing stage, a large amount of cassava starch waste (CSW) which mainly contains lost starch product and solid residue such as cassava bagasse are produced. Starch and cassava bagasse can be hydrolyzed into fermentable sugar such as glucose. In the present study, the solution plasma process (SPP) is used to treat CSW to prepare reducing sugar. The investigated parameters are treatment time, solvent concentration, applied pulsed frequency, and CSW concentration. The %yield of total reducing sugar (TRS) and glucose were calculated by DNS method and glucose assay kit, respectively. The chemical structure, morphology, and crystal structure of plasma-treated CSW were investigated. The results showed that the %yield of TRS was greatly enhanced by SPP treatment compared to that of acid hydrolysis. The CSW powder completely broke down into pieces after SPP treatment was applied. The amorphous and crystalline regions of CSW were destroyed during SPP treatment. SPP treatment of CSW with light sulfuric acid concentration of 0.08 M, applied pulsed frequency of 30 kHz, and CSW concentration of 0.5%w/v provided 99.0% TRS and 47.9% glucose.

Vetiver plantlets in aerated system degrade phenol in illegally dumped industrial wastewater by phytochemical and rhizomicrobial degradation.

This research evaluated the feasibility of using vetiver plantlets (Vetiveria zizanioides (L.) Nash) on a floating platform with aeration to degrade phenol (500 mg/L) in illegally dumped industrial wastewater (IDIWW). The IDIWW sample was from the most infamous illegal dumping site at Nong Nae subdistrict, Phanom Sarakham district, Chachoengsao province, Thailand. Laboratory results suggested that phenol degradation by vetiver involves two phases: Phase I, phytopolymerization and phyto-oxidation assisted by root-produced peroxide (H2O2) and peroxidase (POD), followed by phase II, a combination of phase I with enhanced rhizomicrobial degradation. The first 360-400 h of phenol degradation were dominated by phytopolymerization and phyto-oxidation yielding particulate polyphenols (PPP) or particulate organic matter (POM) as by-products, while phenol decreased to around 145 mg/L. In Phase II, synergistically, rhizomicrobial growth was ∼100-folds greater on the roots of the vetiver plantlets than in the IDIWW and participated in the microbial degradation of phenol at this lower phenol concentration, increasing the phenol degradation rate by more than three folds. This combination of phytochemical and rhizomicrobiological processes eliminated phenol in IDIWW in less than 766 h (32 days), while without the vetiver plantlets, phenol degradation by aerated microbial degradation alone may require 235 days. To our knowledge, this is the first that systematically reveals the complete phenol degradation mechanism by vetiver plantlets in real aerated wastewater.

A two-step method using air plasma and carbodiimide crosslinking to enhance the biocompatibility of polycaprolactone.

In this study, polycaprolactone (PCL) film, a high potential material used in biomedical applications, was treated by air plasma prior to a conjugation by carbodiimide cross-linking with various types of proteins, including type A gelatin, type B gelatin, and collagen hydrolysate. The properties of modified PCL films were characterized by X-ray photoelectron spectroscopy (XPS), contact angle measurement, and atomic force microscopy. The XPS results showed that oxygen and nitrogen atoms were successfully introduced on the air plasma-treated PCL surface. Primary amine was found on the air plasma-treated PCL films. All proteins were shown to be successfully cross-linked on air plasma-treated PCL films. The wettability and roughness of protein-conjugated PCL films were significantly increased compared to those of neat PCL film. In vitro biocompatibility test using L929 mouse fibroblast showed that the attachment percentage and spreading area of attached cells on all protein-conjugated PCL films were markedly increased. Comparing among modified PCL films, no significant difference on the attachment of L929 on modified PCL films was noticed. However, the spreading areas of cells after 24 hours of culture on type A gelatin- and type B gelatin-modified PCL surfaces were higher than that on collagen hydrolysate-modified surface, possibly related to the lower percentage of amide bond on collagen hydrolysate-conjugated surface compared to those on both gelatin-conjugated PCL ones. This indicated that the two-step modification of PCL film via air plasma and carbodiimide cross-linking with collagen-derived proteins could enhance the biocompatibility of PCL films. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1658-1666, 2017.

The effects of pulsed inductively coupled plasma (PICP) on physical properties and biocompatibility of crosslinked gelatin films.

In this work, pulsed inductively coupled plasma (PICP) device is introduced to treat crosslinked gelatin film. The effects of plasma on the properties of gelatin film were investigated. Type A gelatin film crosslinked by dehydrothermal process was treated by PICP. The properties of crosslinked gelatin were characterized by differential scanning calorimetry (DSC), amino acid content assay (TNBS), contact angle measurement and atomic force microscopy (AFM). The results showed that pulsed inductively coupled plasma did not significantly affect the thermal behavior and the degree of crosslinking of crosslinked gelatin film. The contact angle by both water and ethylene glycol of crosslinked gelatin films treated with nitrogen plasma was decreased in comparison with untreated film. The surface energy was slightly increased when increasing number of repeated discharges were applied from 1 to 20 times. This implied that nitrogen plasma could improve hydrophilicity of the crosslinked gelatin surface. The result from AFM revealed that surface roughness of crosslinked gelatin film was introduced when PICP treatment was applied. In vitro test using L929 mouse fibroblast revealed that, the number of cells proliferated on PICP-treated samples was higher than that on untreated samples. The results indicated that PICP is a potential method for crosslinked gelatin surface modification for future tissue engineering applications.

Development of acellular dermis from porcine skin using periodic pressurized technique.

In this work, a new method for producing acellular dermis (ADM), a natural scaffold used for dermal replacement, from porcine skin was developed. Fresh porcine skin from local slaughterhouse was dehaired by sodium sulphide following by epidermis removal using glycerol. After fat removal by chloroform/methanol (2/1 v/v) solvent, cellular components were removed using enzymatic treatment incorporated with a periodic pressurized technique. The effects of enzyme type (trypsin and dispase II) and periodic pressurized conditions on the efficiency of cell removal were investigated. When periodic pressure was applied, enzymatic treatment time could be shorten since the enzyme solution was able to penetrate into tight dermis. As a result, cells could be easily removed from porcine skin as noticed quantitatively by DNA assay and qualitatively by H&E staining. When enzyme refreshment was introduced into the decellularized process, the percentage of cell removal was further enhanced. This ensured that no inhibitions effect from the removed cells on enzyme-substrate interaction. Moreover, short-time enzymatic treatment with periodic pressurized technique could prevent the disruption of dermal structure, as observed by SEM. Dispase II can be used to remove cell better than trypsin in the periodic pressurized technique. However, in vivo study indicated that numerous fibroblast from the host tissue infiltrated into ADM prepared using both enzymes. Neo-collagen and neo-capillaries were produced in both implanted ADMs. The result elucidated that the use of periodic pressurized technique with enzymatic treatment has a high potential to be a new method to produce ADM for skin tissue engineering.