Displaying publications 1 - 20 of 32 in total

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  1. Lee SY, Liu BL, Wu JY, Chang YK
    Food Chem, 2021 Feb 15;338:128144.
    PMID: 33092004 DOI: 10.1016/j.foodchem.2020.128144
    A weak ion-exchange membrane (P-COOH) was synthesized by alkaline hydrolysis of a polyacrylonitrile nanofiber membrane prepared by electrospinning process. The P-COOH membrane was characterized for its physical properties and its application for purification of lysozyme from chicken egg white was investigated. The lysozyme adsorption efficiency of the P-COOH membrane operating in a stirred cell contactor (Millipore, Model 8010) was evaluated. The effects of key parameters such as the feed concentration, the rotating speed, the flow rate of feed and the operating pressure were studied. The results showed successful purification of lysozyme with a high recovery yield of 98% and a purification factor of 63 in a single step. The purification strategy was scaled-up to the higher feedstock loading volume of 32.7 and 70 mL using stirred cell contactors of Model 8050 and 8200, respectively. The scale-up processes achieved similar purification results, proving linear scalability of the purification technique adopted.
  2. Nikol L, Kuan G, Ong M, Chang YK, Terry PC
    Front Psychol, 2018;9:1114.
    PMID: 30072929 DOI: 10.3389/fpsyg.2018.01114
    Running in high heat and humidity increases psychophysiological strain, which typically impairs running performance. Listening to synchronous music has been shown to provide psychophysiological benefits, which may enhance running performance. The present randomized, crossover study examined effects of listening to synchronous music on psychophysiological parameters and running performance in hot and humid conditions. Twelve male runners (21.7 ± 2.2 y; 166.17 ± 7.18 cm; 60.32 ± 9.52 kg; 59.29 ± 5.95 ml kg-1 min-1) completed two running trials in simulated conditions (31°C and 70% humidity) with and without synchronous music. Participants ran on a treadmill inside a climatic chamber for 60 min at 60%

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    O2max and continued to run to exhaustion at 80%

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    O2max. Time-to-exhaustion under the synchronous music condition was 66.59% longer (mean = 376.5 s vs. 226.0 s, p = 0.02, d = 0.63) compared to the no music condition. Ratings of perceived exertion were significantly lower for the synchronous music condition at each time point (15, 30, 45, and 60 min) of the steady state portion of the running trials. Small differences in heart rate were detected between conditions. No significant between-condition differences were found in urine specific gravity, percentage of body weight loss, thermal comfort, and blood lactate. Findings suggest that listening to synchronous music is beneficial to running performance and perceived exertion in hot and humid conditions.
  3. Hidrus A, Kueh YC, Norsa'adah B, Chang YK, Kuan G
    PMID: 34501562 DOI: 10.3390/ijerph18178972
    Brain Breaks® are structured physical activity (PA) web-based videos designed to promote an interest in learning and health promotion. The objective of this study was to examine its effects on decision balance (DB) which consists of the perceived benefits (Pros) and perceived barriers (Cons) of exercise in people with type 2 diabetes mellitus (T2DM). A randomised controlled trial was conducted among people with T2DM at Hospital Universiti Sains Malaysia. The intervention group received Brain Breaks videos for a period of four months. The intervention and control groups completed the validated Malay version of DB questionnaire for five times, at pre-intervention, the first month, the second month, the third month, and post-intervention. Multivariate Repeated Measures Analysis of Variance was performed for data analysis. A total of 70 participants were included (male = 39; female = 31) with a mean age of 57.6 years (SD = 8.5). The intervention group showed a significant change in the Pros and Cons factors of DB scores over time. The intervention group showed significantly higher scores for the Pros (p-value < 0.001) and lower scores for the Cons (p-value = 0.008) factors than the control group. In conclusion, the Brain Breaks video is an effective intervention to improve decisional balance in patients with T2DM to help them in deciding on behaviour change to be more physically active.
  4. Show PL, Ooi CW, Song CP, Chai WS, Lin GT, Liu BL, et al.
    Food Chem, 2021 May 01;343:128543.
    PMID: 33187742 DOI: 10.1016/j.foodchem.2020.128543
    Lysozyme from crude chicken egg white (CEW) feedstock was successfully purified using a stirred fluidized bed adsorption system ion exchange chromatography where STREAMLINE SP and SP-XL high density adsorbents were selected as the adsorption carrier. The thermodynamic and kinetic studies were carried out to understand the characteristics of lysozyme adsorption by adsorbents under various conditions, including adsorption pH, temperature, lysozyme concentration and salt concentrations. Results showed that SP and SP-XL adsorbents achieved optimum lysozyme adsorption at pH 9 with capacity of ~139.77 and ~251.26 mg/mL, respectively. The optimal conditions obtained from batch studies were directly employed to operate in SFBA process. For SP-XL adsorbent, the recovery yield and purification factor of lysozyme were 93.78% and ~40 folds, respectively. For SP adsorbent, lysozyme can be eluted ~100% with purification factor of ~26 folds. These two adsorbents are highly suitable for use in direct recovery of lysozyme from crude CEW.
  5. Cheah WY, Show PL, Ng IS, Lin GY, Chiu CY, Chang YK
    Int J Biol Macromol, 2019 Apr 01;126:569-577.
    PMID: 30584947 DOI: 10.1016/j.ijbiomac.2018.12.193
    The electrospinning PAN nanofiber membrane (P-CN) was hydrolysed to convert carboxylic groups as reaction sites and covalently graft chitosan molecule. The chitosan derivatives with quaternary ammonium groups exerted greater efficiency against bacteria as compared to pure chitosan. Hence, the chitosan modified membrane (P-CS), can be functionalized with quaternary amine (i.e., glycidyl trimethyl ammonium chloride, GTMAC) to form quaternized chitosan nanofiber membrane (designated as P-HTCC) under various conditions (acidic, neutral, and alkaline). N-quaternized derivatives of chitosan modified membrane (N-HTCC) showed 72% and 60% degree of quaternization (DQ) under acidic and neutral conditions, respectively. Under alkaline condition, additional quaternization of N, O-HTCC via its amino and hydroxyl groups, has improved up to 90% DQ of the chitosan. The antibacterial activity of the quaternized chitosan modified membrane prepared from acetic acid medium is stronger than that prepared from water and alkaline media. Also, antibacterial activity of quaternized chitosan is stronger than chitosan modified membrane against E. coli. The microbiological assessments showed that the water-stable P-HTCC nanofiber membrane under modification in acidic medium exerted antibacterial activity up to 99.95% against E. coli. Therefore, the P-HTCC membrane exhibited high potential to be integrated into microfiltration membrane to effectively disinfect E. coli.
  6. Lin TY, Chai WS, Chen SJ, Shih JY, Koyande AK, Liu BL, et al.
    Chemosphere, 2021 May;270:128615.
    PMID: 33077189 DOI: 10.1016/j.chemosphere.2020.128615
    This work studied the potential of using eggshell (ES) (200-300 μm) waste as adsorbent for sequential removal of heavy metals, soluble microbial products, and dye wastes. In this study, among soluble microbial products, chicken egg white (CEW) proteins were selected as simulated contaminants. ES was applied to capture heavy metal ions (e.g., Cu2+ and Zn2+) and the formed eggshell metal (ES-M) complex was use to absorb soluble microbial products (e.g., soluble proteins), followed by subsequent removal of dyes from aqueous solutions using ES-M-CEW adsorbent. The experimental conditions for the adsorption of CEW proteins by ES-M include shaking rate, adsorption pH, isothermal and kinetic studies. The maximum protein adsorption by ES-Zn and ES-Cu were 175.67 and 153.65 mg/g, respectively. Optimal removal efficiencies of the ES-M-CEW particles for Acid Orange (AO7) and Toluidine blue (TBO) dyes were at pH 2 and 12, respectively, achieving performance of 75.38 and 114.18 mg/g, respectively. The removal of TBO dye by ES-M-CEW adsorbent was equilibrated at 5 min. The results showed that low cost and simple preparation of the modified ES particles are feasible for treating various wastewaters.
  7. Pakalapati H, Show PL, Chang JH, Liu BL, Chang YK
    Int J Biol Macromol, 2020 Dec 15;165(Pt B):2494-2507.
    PMID: 33736272 DOI: 10.1016/j.ijbiomac.2020.10.099
    In this research, a protein nanofiber membrane (P-COOH-CEW) was developed to treat the dye waste. Initially, polyacrylonitrile nanofiber membrane (PAN) was prepared by electrospinning, followed by heat treatment, alkaline treatment, and neutralization to obtain weak cation exchange nanofiber membrane (P-COOH). The P-COOH membrane was chemically coated with chicken egg white (CEW) proteins to obtain a 3D structure of complex protein nanofiber membrane (P-COOH-CEW). The composite prepared was characterized with Fourier Transform Infrared analysis (FTIR), Scanning Electron Microscopy (SEM), and thermogravimetric analysis (TGA). Further, the composite was evaluated by investigating the removal of Toluidine Blue O (TBO) from aqueous solutions in batch conditions. Different operating parameters - coupling of CEW, shaking rate, initial pH, contact time, temperature, and dye concentration were studied. From the results, maximum removal capacity and equilibrium association constant was determined to be 546.24 mg/g and 10.18 mg/mg, respectively at pH 10 and 298 K. The experimental data were well fitted to pseudo-second order model. Furthermore, desorption studies revealed that the adsorbed TBO can be completely eluted by using 50% ethanol or 50% glycerol in 1 M NaCl solution. Additionally, the reuse of P-COOH-CEW membrane reported to have 97.32% of removal efficiency after five consecutive adsorption/desorption cycles.
  8. Show PL, Ooi CW, Lee XJ, Yang CL, Liu BL, Chang YK
    Int J Biol Macromol, 2020 Nov 01;162:1711-1724.
    PMID: 32805284 DOI: 10.1016/j.ijbiomac.2020.08.065
    Adsorption of lysozyme on the dye-affinity nanofiber membranes was investigated in batch and dynamic modes. The membrane matrix was made of electrospun polyacrylonitrile nanofibers that were grafted with ethylene diamine (EDA) and/or chitosan (CS) for the coupling of Reactive Blue 49 dye. The physicochemical properties of these dye-immobilized nanofiber membranes (P-EDA-Dye and P-CS-Dye) were characterized microscopically, spectroscopically and thermogravimetrically. The capacities of lysozyme adsorption by the dye-affinity nanofiber membranes were evaluated under various conditions, namely pH, dye immobilized density, and loading flow rate. The adsorption of lysozyme to the dye-affinity nanofiber membranes was well fitted by Langmuir isotherm and pseudo-second kinetic models. P-CS-Dye nanofiber membrane had a better performance in the dynamic adsorption of lysozyme from complex chicken egg white solution. It was observed that after five cycles of adsorption-desorption, the dye-affinity nanofiber membrane did not show a significant loss in its capacity for lysozyme adsorption. The robustness as well as high dynamic adsorption capability of P-CS-Dye nanofiber membrane are promising for the efficient recovery of lysozyme from complex feedstock via nanofiber membrane chromatography.
  9. Song CP, Ooi CW, Tey BT, Lu CX, Liu BL, Chang YK
    Int J Biol Macromol, 2020 Dec 01;164:4455-4465.
    PMID: 32937154 DOI: 10.1016/j.ijbiomac.2020.09.051
    A stirred fluidized bed (SFB) ion exchange chromatography was successfully applied in the direct recovery of recombinant enhanced green fluorescent protein (EGFP) from the unclarified Escherichia coli homogenate. Optimal conditions for both adsorption and elution processes were determined from the packed-bed adsorption systems conducted at a small scale using the clarified cell homogenate. The maximal adsorption capacity and dissociation constant for EGFP-adsorbent complex were found to be 6.3 mg/mL and 1.3 × 10-3 mg/mL, respectively. In an optimal elution of EGFP with 0.2 M of NaCl solution (pH 9) and at 200 cm/h, the recovery percent of the EGFP was approximately 93%. The performances of SFB chromatography for direct recovery of EGFP was also evaluated under different loading volumes (50-200 mL) of crude cell homogenate. The single-step purification of EGFP by SFB recorded in a high yield (95-98%) and a satisfactory purification factor (~3 folds) of EGFP from the cell homogenate at 200 rpm of rotating speed.
  10. Huong DTM, Liu BL, Chai WS, Show PL, Tsai SL, Chang YK
    Int J Biol Macromol, 2020 Dec 15;165(Pt A):1410-1421.
    PMID: 33045299 DOI: 10.1016/j.ijbiomac.2020.10.034
    Electrospinning technology was applied for the preparation of polyacrylonitrile (PAN) nanofiber membrane in this work. After hot pressing, alkaline hydrolysis and neutralization treatment, a weak acid cation exchange membrane (P-COOH) was prepared. By the covalent coupling reaction between the acidic membrane and aminomethane sulfonic acid (AMSA), a strong acidic nanofiber membrane (P-SO3H) was obtained. The surface morphology, chemical structure, and thermal stability of the prepared ion exchange membranes were analyzed via SEM, FTIR and TGA. Analytical results showed that the membranes were prepared successfully and thermally stable. The ion exchange membrane (IEX) was conducted with the newly designed membrane reactor, and different operating conditions affecting the adsorption efficiency of Toluidine Blue dye (TBO) were investigated by dynamic flow process. The results showed that dynamic binding capacity (DBC) of weak and strong IEX membranes for TBO dye was ~170 mg/g in a dynamic flow process. Simultaneously, the ion exchange membranes were also used for purifying lysozyme from chicken egg white (CEW). Results illustrated that the recovery yield and purification factor of lysozyme were 93.43% and 29.23 times (P-COOH); 90.72% and 36.22 times (P-SO3H), respectively. It was revealed that two type ion exchange membranes were very suitable as an adsorber for use in dye waste treatment and lysozyme purification process. P-SO3H strong ion-exchange membrane was more effective either removal of TBO dye or purification of lysozyme. The ion exchange membranes not only effectively purified lysozyme from CEW solution, but also effectively removed dye from wastewater.
  11. Leong HY, Chang YK, Ooi CW, Law CL, Julkifle AL, Show PL
    Front Chem, 2019;7:201.
    PMID: 31001522 DOI: 10.3389/fchem.2019.00201
    Nowadays, downstream bioprocessing industries inclines towards the development of a green and high efficient bioseparation technology. Betacyanins are presently gaining higher interest in the food science as driven by their high tinctorial strength and health promoting functional properties. In this study, a novel green integration process of liquid biphasic electric partitioning system (LBEPS) was proposed for betacyanins extraction from peel and flesh of red-purple pitaya. Initially, the betacyanins extraction using LBEPS with initial settings was compared with that of liquid biphasic partitioning system (LBPS), and the results revealed that both systems demonstrated a comparable betacyanins extraction. This was followed by further optimizing the LBEPS for better betacyanins extraction. Several operating parameters including operation time, voltage applied, and position of graphitic electrodes in the system were investigated. Moreover, comparison between optimized LBEPS and LBPS with optimized conditions of electric system (as post-treatment) as well as color characterization and antioxidant properties assessment were conducted. Overall, the betacyanins extraction employing the optimized LBEPS showed the significant highest values of betacyanins concentration in alcohol-rich top phase (C
    t
    ) and partition coefficient (K) of betacyanins from peel (99.256 ± 0.014% and 133.433 ± 2.566) and flesh (97.189 ± 0.172% and 34.665 ± 2.253) of red-purple pitaya. These results inferred that an optimal betacyanins extraction was successfully achieved by this approach. Also, the LBEPS with the peel and flesh showed phase volume ratio (V
    r
    ) values of 1.667 and 2.167, respectively, and this indicated that they have a clear biphasic separation. In addition, the peel and flesh extract obtained from the optimized LBEPS demonstrated different variations of red color as well as their antioxidant properties were well-retained. This article introduces a new, reliable, and effective bioseparation approach for the extraction of biomolecules, which is definitely worth to explore further as a bioseparation tool in the downstream bioprocessing.
  12. Cheng TH, Sankaran R, Show PL, Ooi CW, Liu BL, Chai WS, et al.
    Int J Biol Macromol, 2021 Aug 31;185:761-772.
    PMID: 34216668 DOI: 10.1016/j.ijbiomac.2021.06.177
    Cylinder-shaped NaY zeolite was used as an adsorbent for eradicating both heavy metal ions (Cu2+, Zn2+, Ni2+, and Co2+) and proteins from the waste streams. As a pseudo-metal ion affinity adsorbent, NaY zeolite was used in the capture of heavy metal ions in the first stage. The amount (molar basis) of metal ions adsorbed onto NaY zeolite decreased in the order of Cu2+ > Zn2+ > Co2+ > Ni2+. Bovine serum albumin (BSA) was utilized as a model of proteins used in the waste adsorption process by NaY zeolite. The adsorption capacities of NaY zeolite and Cu/NaY zeolite for BSA were 14.90 mg BSA/g zeolite and 84.61 mg BSA/g zeolite, respectively. Moreover, Cu/NaY zeolite was highly stable in the solutions made of 2 M NaCl, 500 mM imidazole or 125 mM EDTA solutions. These conditions indicated that the minimal probability of secondary contamination caused by metal ions and soluble proteins in the waste stream. This study demonstrates the potential of Cu/NaY zeolite complex as an efficient pseudo-metal chelate adsorbent that could remove metal ions and water-soluble proteins from wastewater concurrently.
  13. Chang YK, Cheng HI, Ooi CW, Song CP, Liu BL
    Food Chem, 2021 Oct 01;358:129914.
    PMID: 34000689 DOI: 10.1016/j.foodchem.2021.129914
    A high-performance polyacid ion exchange (IEX) nanofiber membrane was used in membrane chromatography for the recovery of lysozyme from chicken egg white (CEW). The polyacid IEX nanofiber membrane (P-BrA) was prepared by the functionalization of polyacrylonitrile (PAN) nanofiber membrane with ethylene diamine (EDA) and bromoacetic acid (BrA). The adsorption performance of P-BrA was evaluated under various operating conditions using Pall filter holder. The results showed that optimal conditions of IEX membrane chromatography for lysozyme adsorption were 10% (w/v) of CEW, pH 9 and 0.1 mL/min. The purification factor and yield of lysozyme were 402 and 91%, respectively. The adsorption process was further scaled up to a larger loading volume, and the purification performance was found to be consistent. Furthermore, the regeneration of IEX nanofiber membrane was achieved under mild conditions. The adsorption process was repeated for five times and the adsorption capacity of adsorber was found to be unaffected.
  14. Xu FX, Ooi CW, Liu BL, Song CP, Chiu CY, Wang CY, et al.
    Int J Biol Macromol, 2021 Jun 30;181:508-520.
    PMID: 33775766 DOI: 10.1016/j.ijbiomac.2021.03.151
    This study aimed to develop a novel electrospun polyacrylonitrile (PAN) nanofiber membrane with the enhanced antibacterial property. The PAN nanofiber membrane was first subjected to alkaline hydrolysis treatment, and the treated membrane was subsequently grafted with chitosan (CS) to obtain a CS-modified nanofiber membrane (P-COOH-CS). The modified membrane was then coupled with different dye molecules to form P-COOH-CS-Dye membranes. Lastly, poly(hexamethylene biguanide) hydrochloride (PHMB) was immobilized on the modified membrane to produce P-COOH-CS-Dye-PHMB. Physical characterization studies were conducted on all the synthesized nanofiber membranes. The antibacterial efficacies of nanofiber membranes prepared under different synthesis conditions were evaluated systematically. Under the optimum synthesis conditions, P-COOH-CS-Dye-PHMB was highly effective in disinfecting a high concentration of Escherichia coli, with an antibacterial efficacy of approximately 100%. Additionally, the P-COOH-CS-Dye-PHMB exhibited an outstanding wash durability as its antibacterial efficacy was only reduced in the range of 5%-7% even after 5 repeated cycles of treatment. Overall, the experimental results of this study suggested that the P-COOH-CS-Dye-PHMB is a promising antibacterial nanofiber membrane that can be adopted in the food, pharmaceutical, and textile industries.
  15. Wu TY, Nien JT, Kuan G, Wu CH, Chang YC, Chen HC, et al.
    Front Psychol, 2021;12:661961.
    PMID: 34248757 DOI: 10.3389/fpsyg.2021.661961
    This study investigated the effects of a mindfulness-based intervention (MBI) called mindfulness-based peak performance (MBPP) on athletic performance and cognitive functions in archers, as well as the role of psychological status and the dose-response relationship of MBPP in archery performance. Twenty-three archers completed a simulated archery competition and the Stroop task prior to and after MBPP training, which consisted of eight sessions over four weeks, while the mindfulness and rumination levels of the archers were assessed at three time points, namely, before, at the mid-point of, and after the MBPP program. The results revealed that the MBPP program significantly improved the shooting performance (p = 0.002, d = 0.27), multiple cognitive functions (ps < 0.001, d = 0.51~0.71), and mindfulness levels of the archers on the post-test, compared to the pre-test (p = 0.032, η p 2 = 0.15 for general; p = 0.004, η p 2 = 0.22 for athletic). Additionally, negative ruminations level was decreased from the pre-test to the middle-test and post-test (ps < 0.001, η p 2 = 0.43). These findings provide preliminary evidence to support the view that MBPP could serve as a promising form of training for fine motor sport performance, cognitive functions, and specific psychological status, such that it warrants further study.
  16. Chang YK, Show PL, Lan JC, Tsai JC, Huang CR
    Bioresour Technol, 2018 Dec;270:320-327.
    PMID: 30241065 DOI: 10.1016/j.biortech.2018.07.138
    An aqueous two-phase system (ATPS) with ionic liquids (ILs) was used for the isolate of C-phycocyanin (CPC) from Spirulina platensis microalga. Various imidazolium ILs and potassium salts were studied. The effect of ILs-ATPS on the extraction efficiency of CPC was also studied. The experimental parameters like pH, loading volume, algae concentration, temperature, and alkyl chain length of IL were well-covered in this report. The experimental results showed that the extraction efficiency, the partition coefficient, and the separation factor for CPC were 99%, 36.6, and 5.8, respectively, for an optimal pH value of 7 and a temperature of 308 K. The order of extraction efficiency for CPC using IL-ATPS was: 1-octyl-3-methylimidazolium bromide (C8MIM-Br) > 1-hexyl-3-methylimidazolium bromide (C6MIM-Br) > 1-butyl-3-methylimidazolium bromide (C4MIM-Br). The isolation process followed the pseudo second-order kinetic model and the thermodynamic results were obviously spontaneous.
  17. Ng IS, Song CP, Ooi CW, Tey BT, Lee YH, Chang YK
    Int J Biol Macromol, 2019 Aug 01;134:458-468.
    PMID: 31078593 DOI: 10.1016/j.ijbiomac.2019.05.054
    Nanofiber membrane chromatography integrates liquid membrane chromatography and nanofiber filtration into a single-step purification process. Nanofiber membrane can be functionalised with affinity ligands for promoting binding specificity of membrane. Dye molecules are a good affinity ligand for nanofiber membrane due to their low cost and high binding affinity. In this study, a dye-affinity nanofiber membrane (P-Chitosan-Dye membrane) was prepared by using polyacrylonitrile nanofiber membrane modified with chitosan molecules and immobilized with dye molecules. Reactive Orange 4, commercially known as Procion Orange MX2R, was found to be the best dye ligand for membrane chromatography. The binding capacity of P-Chitosan-Dye membrane for lysozyme was investigated under different operating conditions in batch mode. Furthermore, desorption of lysozyme using the P-Chitosan-Dye membrane was evaluated systematically. The recovery percentage of lysozyme was found to be ~100%. The optimal conditions obtained from batch-mode study were adopted to develop a purification process to separate lysozyme from chicken egg white. The process was operated continuously using the membrane chromatography and the characteristic of the breakthrough curve was evaluated. At a lower flow rate (i.e., 0.1 mL/min), the total recovery of lysozyme and purification factor of lysozyme were 98.59% and 56.89 folds, respectively.
  18. Ng IS, Tang MSY, Show PL, Chiou ZM, Tsai JC, Chang YK
    Int J Biol Macromol, 2019 Jul 01;132:615-628.
    PMID: 30940588 DOI: 10.1016/j.ijbiomac.2019.03.235
    In this work, a chitosan-modified nanofiber membrane was fabricated and used to examine the permeation characteristics of C-phycocyanin (CPC) obtained from Spirulina platensis. The effects of NaCl concentration (0.1-1.0 M), chitosan coupling pH (6-8), chitosan coupling concentration (0.1-3.0%), algal solution pH (6-8), algal mass concentration (0.1-1.0% dw/v), and membrane flux (4.08 × 10-2-2.04 × 10-1 mL/min·cm2) on the penetration performance of the membrane for CPC were investigated. The results show that the order of binding selectivity of the membrane for these proteins is contaminating proteins (TP) > allophycocyanin (APC) > CPC. TP and APC molecules were more easily adsorbed by the chitosan-modified membrane, and the CPC molecules most easily penetrated the membrane without being adsorbed, enhancing CPC purity. The purification factor and total mass flux were 3.3 fold and 66%, respectively, in a single step.
  19. Ng IS, Ooi CW, Liu BL, Peng CT, Chiu CY, Chang YK
    Int J Biol Macromol, 2020 Jul 01;154:844-854.
    PMID: 32194127 DOI: 10.1016/j.ijbiomac.2020.03.127
    In this study, polyacrylonitrile (PAN) nanofiber membrane was prepared by an electrospinning technique. After alkaline hydrolysis, the ion-exchange nanofiber membrane (P-COOH) was grafted with chitosan molecules to form a chitosan-modified nanofiber membrane (P-COOH-CS). Poly(hexamethylene biguanide) (PHMB) was then covalently immobilized on P-COOH and P-COOH-CS to form P-COOH-PHMB and P-COOH-CS-PHMB, respectively. The nanofiber membranes were subjected to various surface analyses as well as to the evaluations of antibacterial activity against Escherichia coli. The optimal modification conditions for P-COOH-CS-PHMB were attained by water-soluble chitosan at 50 kDa of molecular weight, coupling pH at 7, and 0.05% (w/w) of PHMB. Within 10 min of treatment, the antibacterial rate was close to 100%. Under the similar conditions of antibacterial treatment, the P-COOH-CS-PHMB exhibited a better antibacterial efficacy than the P-COOH-PHMB. When the number of bacterial cells was increased by 2000 folds, both types of nanofiber membranes still maintained the antibacterial rate close to 100%. After five cycles of repeated antibacterial treatment, the antibacterial efficacy of P-COOH-PHMB was 96%, which was higher than that of P-COOH-CS-PHMB (83%). The experimental results revealed that the PHMB-modified nanofiber membranes can be suitably applied in water treatment such as water disinfection and biofouling control.
  20. Liu BL, Ooi CW, Ng IS, Show PL, Lin KJ, Chang YK
    Food Chem, 2020 Oct 15;327:127038.
    PMID: 32447136 DOI: 10.1016/j.foodchem.2020.127038
    Polyacrylonitrile nanofiber membrane functionalized with tris(hydroxymethyl)aminomethane (P-Tris) was used in affinity membrane chromatography for lysozyme adsorption. The effects of pH and protein concentration on lysozyme adsorption were investigated. Based on Langmuir model, the adsorption capacity of P-Tris nanofiber membrane was estimated to be 345.83 mg/g. For the operation of dynamic membrane chromatography with three-layer P-Tris nanofiber membranes, the optimal operating conditions were at pH 9, 1.0 mL/min of feed flow rate, and 2 mg/mL of feed concentration. Chicken egg white (CEW) was applied as the crude feedstock of lysozyme in the optimized dynamic membrane chromatography. The percent recovery and purification factor of lysozyme obtained from the chromatography were 93.28% and 103.98 folds, respectively. Our findings demonstrated the effectiveness of P-Tris affinity nanofiber membrane for the recovery of lysozyme from complex CEW solution.
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