Publications by authors named "Akhmad Irhas Robby"

4 Publications

  • Page 1 of 1

NIR-vis-Induced pH-Sensitive TiO Immobilized Carbon Dot for Controllable Membrane-Nuclei Targeting and Photothermal Therapy of Cancer Cells.

ACS Appl Mater Interfaces 2020 Aug 12;12(34):37929-37942. Epub 2020 Aug 12.

Department of Green Bio Engineering, Korea National University of Transportation, Chungju 380-702, Republic of Korea.

This study investigated a selective and sensitive theragnosis system for the specific targeting of the membrane and nuclei based on visible-light and pH-responsive TiO-integrated cross-linked carbon dot (C-CD/TiO) for tumor detection and controllable photothermal therapy. The cross-linking system was formed by boronate ester linkages between the TiO-immobilized Dopa-decyl (D-CD) and zwitterionic-formed CD (Z-CD) for nuclear targeting, which showed fluorescence "off" at physiological pH. The fluorescence recovered to the "on" state in acidic cancer cells owing to cleavages of the boronate ester bonds, resulting in the disruption of the Förster resonance energy transfer that generated different CDs useful for tumor-selective biosensors and therapy. D-CD, which is hydrophobic, can penetrate the hydrophobic sites of the cell membrane; it caused a loss in the hydrophobicity of these sites after visible-light irradiation. This was achieved by the photocatalytic activity of the TiO modulating energy bandgap, whereas the Z-CD targeted the nucleus, as confirmed by merged confocal microscopy images. D-CD augmented by photothermal heat also exhibited selective anticancer activity in the acidic tumor condition but showed only minimal effects at a normal site at pH 7.4. After C-CD/TiO injection to an tumor model, C-CD/TiO efficiently ablated tumors under NIR light irradiation. The C-CD/TiO group showed up-regulation of the pro-apoptotic markers such as and in tumor. This material exhibited its potential as a theragnostic sensor with excellent biocompatibility, high sensitivity, selective imaging, and direct anticancer activity via photothermal therapy.
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http://dx.doi.org/10.1021/acsami.0c11979DOI Listing
August 2020

Construction of [email protected] Carbon Dots Nanoflowers as Binder Free Electrode for Reduction and Oxidation of Water.

Materials (Basel) 2020 Jul 13;13(14). Epub 2020 Jul 13.

Department of Chemical and Biological Engineering, Korea National University of Transportation, Chungju 380-702, Korea.

Electrochemical water splitting is known as a potential approach for sustainable energy conversion; it produces H fuel by utilizing transition metal-based catalysts. We report a facile synthesis of [email protected] dots (CDs) nanoflowers supported on nickel foam through a hydrothermal technique in the absence of organic solvents and an inert environment. The synthesized material with a judicious choice of CDs shows superior performance in hydrogen and oxygen evolution reactions (HER and OER) compared to the FeCoO electrode alone in alkaline media. For HER, the overpotential of 205 mV was able to produce current densities of up to 10 mA cm, whereas an overpotential of 393 mV was needed to obtain a current density of up to 50 mA cm for OER. The synergistic effect between CDs and FeCoO accounts for the excellent electrocatalytic activity, since CDs offer exposed active sites and subsequently promote the electrochemical reaction by enhancing the electron transfer processes. Hence, this procedure offers an effective approach for constructing metal oxide-integrated CDs as a catalytic support system to improve the performance of electrochemical water splitting.
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http://dx.doi.org/10.3390/ma13143119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7411927PMC
July 2020

Recyclable metal nanoparticle-immobilized polymer dot on montmorillonite for alkaline phosphatase-based colorimetric sensor with photothermal ablation of Bacteria.

Anal Chim Acta 2019 Nov 27;1082:152-164. Epub 2019 Jul 27.

Department of IT Convergence, Korea National University of Transportation, Chungju, 380-702, Republic of Korea; Department of Chemical and Biological Engineering, Korea National University of Transportation, Chungju, 380-702, Republic of Korea. Electronic address:

Development of simultaneous bacteria detection and eradication with simple, rapid, and reusable material is important in addressing bacterial contamination issues. In this study, we utilized the expression of alkaline phosphatase (ALP) from bacteria to design fluorescence ON/OFF system for bacteria detection, also using metal oxide nanoparticle for obtaining antibacterial activity and recyclability. The fluorescent-based biosensor with antibacterial activity was prepared by intercalating ALP-sensitive polymer dot (PD) containing β-cyclodextrin (β-CD) onto montmorillonite (MMT) as loading matrix via ionic exchange reaction, followed by immobilization of magnetic iron oxide (FeO) and NIR-responsive cesium tungsten oxide (CsWO). The PD-βCD-MMT/FeO-CsWO nanocomposite exhibited strong fluorescence intensity, which was quenched in the presence of bacterial ALP (0-1000 U/L) due to hydrolysis of p-nitrophenyl phosphate (NPP) into p-nitrophenol (NP) in the hydrophobic site of β-CD. Furthermore, the nanocomposite could detect both gram-negative Escherichia coli and gram-positive Staphylococcus aureus in the range of 10-10 CFU/mL (LOD 5.09 and 4.62 CFU/mL, respectively), and showed high antibacterial activity against bacteria by generating photothermal heat under 5 min NIR irradiation, causing damage to bacterial cells. This material also demonstrated recyclability via magnetic field exposure due to the presence of FeO In addition, the fluorescence can be recovered following pH shock and re-conjugation of β-CD molecules. After 4 cycles, nanocomposite still showed stable photothermal effects and fluorescence-based bacteria detection. Thus, this reusable material offers promising approach for simultaneous bacteria detection and killing, which is simple, rapid, and effective.
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http://dx.doi.org/10.1016/j.aca.2019.07.053DOI Listing
November 2019

Photoluminescence-tunable fluorescent carbon dots-deposited silver nanoparticle for detection and killing of bacteria.

Mater Sci Eng C Mater Biol Appl 2019 Apr 22;97:613-623. Epub 2018 Dec 22.

Department of Chemical and Biological Engineering, Korea National University of Transportation, Chungju 380-702, Republic of Korea; Department of IT Convergence, Korea National University of Transportation, Chungju 380-702, Republic of Korea. Electronic address:

Innovative methods to detect and kill pathogenic bacteria have a pivotal role in the eradication of infectious diseases and the prevention of the growth of antibiotic-resistant bacteria. The combination of fluorescent carbon dots (FCDs) with silver nanoparticles (AgNPs) is an effective material for synergic detection and antimicrobial activity determination. However, the fluorescence quenching of the FCDs owing to an interaction with AgNP is a major limitation. In this study, we designed a system to utilize poly(vinylpyrrolidone) (PVP) and catechol chemistry ([email protected]:FCD) in order to avoid the fluorescence quenching of the FCD-AgNP combination due to Forster Resonance Energy Transfer (FRET). [email protected]:FCD exhibited bright fluorescence, which can be used for bacterial detection, through the promotion of electrostatic binding with the negatively-charged bacterial surface and generation of fluorescence quenching due to aggregation-induced quenching. Furthermore, the presence of silver nanoparticles in [email protected]:FCD produced an excellent bacteria killing efficiency against E. coli and S. aureus, even at low concentrations (0.1 mg/mL). In contaminated river water, the [email protected]:FCD system showed a simple, highly sensitive, and effective performance for both the detection and eradication of bacteria. Therefore, this system offers an auspicious method for the future detection and killing of bacteria.
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http://dx.doi.org/10.1016/j.msec.2018.12.070DOI Listing
April 2019
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