ORCID Profile
0000-0001-5300-1275
Current Organisation
Nanyang Technological University
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Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7TA01871A
Abstract: Cu electrodeposition was tuned by phosphate anions and the so-prepared electrodes exhibited outstanding selectivity for CO 2 conversion to HCOOH.
Publisher: American Chemical Society (ACS)
Date: 28-02-2014
DOI: 10.1021/LA403409T
Abstract: Certain conjugated oligoelectrolytes (COEs) modify biological function by improving charge transfer across biological membranes as demonstrated by their ability to boost performance in bioelectrochemical systems. Molecular level understanding of the nature of the COE/membrane interactions is lacking. Thus, we investigated cell membrane perturbation by three COEs differing in the number of aromatic rings and presence of a fluorine substitution. Molecular dynamic simulations showed that membrane deformation by all COEs resulted from membrane thinning as the lipid phosphate heads were drawn toward the center of the bilayer layer by positively charged COE side chains. The four-ringed COE, which most closely resembled the lipid bilayer in length, deformed the membrane the least and was least disruptive, as supported by toxicity testing (minimum inhibitory concentration (MIC) = 64 μmol L(-1)) and atomic force microscopy (AFM). Extensive membrane thinning was observed from three-ringed COEs, reducing membrane thickness to <3.0 nm in regions where the COEs were located. Severe localized membrane pitting was observed when the central aromatic ring was unfluorinated, as evident from AFM and simulations. Fluorinating the central aromatic ring delocalized thinning but induced greater membrane disorder, indicated by changes in deuterium order parameter of the acyl chains. The fluorinated three-ringed compound was less toxic (MIC 4 μmol L(-1)) than the nonfluorinated three-aromatic-ringed COE (MIC 2 μmol L(-1)) thus, hydrophobic polar interactions resulting from fluorine substitution of OPV COEs dissipate membrane perturbations. Correlating specific structural features with cell membrane perturbation is an important step toward designing non-antimicrobial membrane insertion molecules.
Publisher: Springer Science and Business Media LLC
Date: 05-08-2014
DOI: 10.1007/S00253-014-5973-3
Abstract: A stilbene-based membrane spanning conjugated oligoelectrolyte 4,4'-bis(4'-N,N-bis(6"-(N,N,N-trimethyl ammonium) hexyl) amino)-styryl) stilbene tetraiodide (DSSN+) has been reported to be able to interact with bacterial cells and enhance their bioelectricity generation in bioelectrochemical devices, although the mechanism remains elusive. The goal of this study was to elucidate the impacts of DSSN+ on extracellular bioactivity and the underlying mechanism. Specifically, extracellular ferrihydrite reduction by Shewanella oneidensis was used to evaluate the influence of cell-DSSN+ interaction. Our results show that DSSN+ enhanced ferrihydrite reduction by S. oneidensis in a growth-dependent manner. The incorporation of DSSN+ into S. oneidensis cell membrane increased the extracellular concentration of redox shuttles, i.e., flavins, and extracellular enzyme activities without significantly decreasing cell viability. The findings suggested that membrane permeabilization is the dominant mechanism for the enhancement of extracellular bioactivity in S. oneidensis by DSSN+. We further demonstrated that the interaction between DSSN+ and S. oneidensis cells enhanced biofilm formation and stability without compromising the overall biofilm activity. Taken together, our results suggest that membrane spanning conjugated oligoelectrolytes, of which DSSN+ is one of many possible molecular structures, may be applied to enhance extracellular bioactivity in bacteria toward more efficient biofilm-based biocatalysis.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8TB00397A
Abstract: The differentiation of MSCs into musculoskeletal tissues has been demonstrated using an electrospun, bi-layered micro particle mesh scaffold (BMMS), that can simultaneously host and release up to three bioactive agents.
Publisher: Elsevier BV
Date: 10-2015
Publisher: IOP Publishing
Date: 28-12-2017
Publisher: Springer Science and Business Media LLC
Date: 10-06-2015
DOI: 10.1038/SREP11222
Abstract: Mutualistic interactions in planktonic microbial communities have been extensively studied. However, our understanding on mutualistic communities consisting of co-existing planktonic cells and biofilms is limited. Here, we report a planktonic cells-biofilm mutualistic system established by the fermentative bacterium Escherichia coli and the dissimilatory metal-reducing bacterium Shewanella oneidensis in a bioelectrochemical device, where planktonic cells in the anode media interact with the biofilms on the electrode. Our results show that the transfer of formate is the key mechanism in this mutualistic system. More importantly, we demonstrate that the relative distribution of E. coli and S. oneidensis in the liquid media and biofilm is likely driven by their metabolic functions towards an optimum communal metabolism in the bioelectrochemical device. RNA sequencing-based transcriptomic analyses of the interacting organisms in the mutualistic system potentially reveal differential expression of genes involved in extracellular electron transfer pathways in both species in the planktonic cultures and biofilms.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0RA02810J
Abstract: There is a huge demand for food-derived polysaccharides in the field of materials research due to the increasing concerns posed by synthetic biopolymers.
Publisher: American Chemical Society (ACS)
Date: 09-06-2015
Publisher: American Chemical Society (ACS)
Date: 26-06-2015
Abstract: Water-soluble conjugated oligoelectrolyte nanoparticles (COE NPs), consisting of a cage-like polyhedral oligomeric silsesquioxanes (POSS) core equipped at each end with pendant groups (oligo(p-phenylenevinylene) electrolyte, OPVE), have been designed and demonstrated as an efficient strategy in increasing the current generation in Escherichia coli microbial fuel cells (MFCs). The as-prepared COE NPs take advantage of the structure of POSS and the optical properties of the pendant groups, OPVE. Confocal laser scanning microscopy showed strong photoluminescence of the stained cells, indicating spontaneous accumulation of COE NPs within cell membranes. Moreover, the electrochemical performance of the COE NPs is superior to that of an established membrane intercommunicating COE, DSSN+ in increasing current generation, suggesting that these COE NPs thus hold great potential to boost the performance of MFCs.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CC02784A
Abstract: Conjugated oligoelectrolytes integrated in Escherichia coli have been proposed to induce release of electroactive cytosolic components, which contributes to extracellular electron transfer.
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.BIORTECH.2013.12.078
Abstract: Microbial species coexist in natural or engineered settings, where they encounter extensive competition and cooperation. Interactions occurring through metabolite exchange or direct contact might be important in establishment of functional biodegradation consortium. Understanding these interactions can facilitate manipulation of selected communities and exploitation of their capacity for specific industrial applications. Here, a simple dual-species consortium (Pseudomonas putida and Shewanella oneidensis) was established for examining simultaneous Congo red bioremediation in planktonic culture and power generation in anode biofilms. Compared to mono-species cultures, co-cultures generated higher current densities and could concurrently degrade Congo red over 72h. Disabling the large secreted adhesion protein, LapA, of P. putida greatly enhanced S. oneidensis biofilm formation on the anode, which increased power generation in co-cultures. This demonstrates simultaneous control of specific planktonic and biofilm communities could be effective in manipulating microbial communities for targeted applications.
Publisher: Wiley
Date: 04-2015
Abstract: The flexible and low-cost polypyrrole nanotube membrane is demonstrated as a promising anode in microbial fuel cells, which significantly enhances the extracellular electron transfer between Shewanella oneidensis MR-1 and the electrode, owing to the large active surface area and high electrical conductivity.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0NR00105H
Abstract: A novel and environmental friendly method was developed to prepare transparent, uniform, crack-free and visible light activated nitrogen doped (N-doped) titania thin films without the use of organic Ti precursors and organic solvents. The N-doped titania films were prepared from heating aqueous peroxotitanate thin films deposited uniformly on superhydrophilic uncoated glass substrates. The pure glass substrates were superhydrophilic after being heated at 500 degrees C for 1 h. Nitrogen concentrations in the titania films were adjusted by changing the amount of ammonia solution. The optimal photocatalytic activity of the N-doped titania films was about 14 times higher than that of a commercial self-cleaning glass under the same visible light illumination. The current reported preparative technique is generally applicable for the preparation of other thin films.
Publisher: Wiley
Date: 24-10-2014
DOI: 10.1002/JHET.2214
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CP50437A
Abstract: It is important to tailor biotic-abiotic interfaces in order to maximize the utility of bioelectronic devices such as microbial fuel cells (MFCs), electrochemical sensors and bioelectrosynthetic systems. The efficiency of electron-equivalent extraction (or injection) across such biotic-abiotic interfaces is dependent on the choice of the microbe and the conductive electrode material. In this contribution, we show that spontaneous intercalation of a conjugated oligoelectrolyte, namely 4,4'-bis(4'-(N,N-bis(6''-(N,N,N-trimethylammonium)hexyl)amino)-styryl)stilbene tetraiodide (DSSN+), into the membranes of Escherichia coli leads to an increase in current generation in MFCs containing carbon-based electrodes. A combination of scanning electron microscopy (SEM) and confocal microscopy was employed to confirm the incorporation of DSSN+ into the cell membrane and biofilm formation atop carbon felt electrodes. Current collection was enhanced by more than 300% with addition of this conjugated oligoelectrolyte. The effect of DSSN+ concentration on electrical output was also investigated. Higher concentrations, up to 25 μM, lead to an overall increase in the number of charge equivalents transferred to the charge-collecting electrode, providing evidence in support of the central role of the synthetic system in improving device performance.
Publisher: American Chemical Society (ACS)
Date: 10-05-2020
Publisher: American Chemical Society (ACS)
Date: 11-02-2010
DOI: 10.1021/LA904751Q
Abstract: We demonstrate a simple synthetic strategy for the fabrication of single-phase rare earth (RE) doped gadolinium oxide (Gd(2)O(3):RE where RE = terbium (Tb), ytterbium (Yb), and erbium (Er)) nanorods (NRs) as multimodal imaging probes. The NRs are ultranarrow and exhibit both emission and magnetic characteristics. The Tb-doped and Yb/Er-codoped Gd(2)O(3) NRs exhibit down- and up-conversion fluorescence respectively, and also exhibit paramagnetism. Importantly, these codoped NRs possess excellent magnetic characteristics, as shown in their longitudinal relaxation time (T1) -weighted image contrast, which is closer to that of commercial Gadovist for magnetic resonance imaging (MRI) applications. This property opens up new avenues in the development of contrast agents.
Publisher: Wiley
Date: 12-02-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1CC13159A
Abstract: We demonstrate a general strategy to prepare Bi(2)WO(6)/Ag/N-TiO(2) film with double visible-light-active components bridged by Ag nanoparticles as an electron shuttle, which exhibits enhanced photocatalytic activity and photoelectrochemical performance under visible light.
Publisher: Wiley
Date: 09-01-2012
Publisher: Wiley
Date: 17-01-2012
Abstract: A polymeric microcapsule that can house different drug-loaded particles using a simple emulsion packaging technique is presented. Compared to the neat microparticles, microcapsules simultaneously release multiple drugs in a sustained manner. These microcapsules could provide a means of controlling release of multiple drugs.
Publisher: American Chemical Society (ACS)
Date: 23-08-2023
Publisher: MDPI AG
Date: 24-05-2021
DOI: 10.3390/MA14112783
Abstract: In recent years, curcumin has been a major research endeavor in food and biopharmaceutical industries owing to its miscellaneous health benefits. There is an increasing amount of research ongoing in the development of an ideal curcumin delivery system to resolve its limitations and further enhance its solubility, bioavailability and bioactivity. The emergence of food-graded materials and natural polymers has elicited new research interests into enhanced pharmaceutical delivery due to their unique properties as delivery carriers. The current study is to develop a natural and food-graded drug carrier with food-derived MCT oil and a seaweed-extracted polymer called k-carrageenan for oral delivery of curcumin with improved solubility, high gastric resistance, and high encapsulation of curcumin. The application of k-carrageenan as a structuring agent that gelatinizes o/w emulsion is rarely reported and there is so far no MCT-KC system established for the delivery of hydrophobic/lipophilic molecules. This article reports the synthesis and a series of in vitro bio-physicochemical studies to examine the performance of CUR-MCT-KC as an oral delivery system. The solubility of CUR was increased significantly using MCT with a good encapsulation efficiency of 73.98 ± 1.57% and a loading capacity of 1.32 ± 0.03 mg CUR/mL MCT. CUR was successfully loaded in MCT-KC, which was confirmed using FTIR and SEM with good storage and thermal stability. Dissolution study indicated that the solubility of CUR was enhanced two-fold using heated MCT oil as compared to naked or unformulated CUR. In vitro release study revealed that encapsulated CUR was protected from premature burst under simulated gastric environment and released drastically in simulated intestinal condition. The CUR release was active at intestinal pH with the cumulative release of % CUR after 5 h incubation, which is the desired outcome for CUR absorption under human intestinal conditions. A similar release profile was also obtained when CUR was replaced with beta-carotene molecules. Hence, the reported findings demonstrate the potencies of MCT-KC as a promising delivery carrier for hydrophobic candidates such as CUR.
Publisher: American Chemical Society (ACS)
Date: 18-06-2019
Abstract: In this study, we report an interdisciplinary and novel strategy toward biofilm engineering for the development of a biofilm-templated heteroatom-doped catalytic system through bioreduction and biofilm matrix-facilitated immobilization of the in situ-formed catalytic nanoparticles followed by controlled pyrolysis. We showed that (i) even under room temperature and bulk aerobic conditions,
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4RA01049C
Abstract: Four polyaromatic compounds with 11- or 13-fused rings have been synthesized and their physical properties have been studied.
Publisher: American Chemical Society (ACS)
Date: 13-10-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7NH00167C
Abstract: Lipid-polymer hybrid nanoparticle enhances antibiotic efficacy through localised, sustained delivery to bacterial biofilms.
Publisher: Springer Science and Business Media LLC
Date: 06-2012
Publisher: Elsevier BV
Date: 04-2014
Publisher: Elsevier BV
Date: 02-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 24-06-2014
DOI: 10.1039/C4TA02250E
No related grants have been discovered for Joachim Loo.