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Preliminary Investigation of pH-Dependent Optical Properties of Curcumin-Derived Carbon Dots Santika, Arum Sinda; Permatasari, Fitri Aulia; Iskandar, Ferry
Progressive Physics Journal Vol. 6 No. 1 (2025): Progressive Physics Journal
Publisher : Program Studi Fisika, Jurusan Fisika, FMIPA, Universitas Mulawarman

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30872/ppj.v6i1.1522

Abstract

Carbon dots (CDs) are photoluminescent nanoparticles smaller than 10 nm with excellent optical properties, including high photostability, UV and visible light absorption, water solubility, low toxicity, and good biocompatibility. These features make them attractive for biomedical, optoelectronic, and catalytic applications. Curcumin, a polyphenol from turmeric, possesses anti-inflammatory, antibacterial, anticancer, and antiviral properties, but its poor water solubility limits its biomedical use. In this study, CDs were synthesized from curcumin and urea via a solvothermal method at 140 °C for 180 minutes to improve curcumin's solubility. The effect of pH on the optical properties of CDs was investigated by adjusting acidity with citric acid and alkalinity with NaOH. UV-Vis and photoluminescence (PL) spectroscopy revealed that the optical properties of CDs are strongly influenced by pH, likely due to the presence of keto-enol tautomerism in curcumin. The pH sensitivity of these curcumin-derived CDs highlights their potential for biomedical applications such as photothermal therapy, bioimaging, drug delivery, and antiviral agents.
Development of a Fluorescence Immunoassay Based on Curcumin Carbon Dots-labeled IgY Antibodies for SARS-CoV-2 Detection Rachmadani, Nisa Amanda; Soetomo, Meilisa Keizia; Taharuddin, Audrey Angelina Putri; Santika, Arum Sinda; Abdillah, Oktaviardi Bityasmawan; Permatasari, Fitri Aulia; Iskandar, Ferry; Rachmawati, Heni; Fibriani, Azzania
HAYATI Journal of Biosciences Vol. 33 No. 1 (2026): January 2026
Publisher : Bogor Agricultural University, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.4308/hjb.33.1.44-57

Abstract

Carbon dots (CDs) are widely utilized in biomedical applications as fluorescent labels for imaging and diagnostics due to their excellent biocompatibility and superior optical properties. These advantages often make CDs a substitute for organic fluorescent dyes, which suffer from low emission intensity and poor photostability when interacting with biomolecules. Moreover, carbon-based materials are eco-friendly and can be synthesized from natural sources, such as curcumin, a chromophore compound abundantly available in Indonesia. Therefore, this study conducted a preliminary investigation on curcumin CDs-labeled IgY antibodies (IgY-cur CDs) for fluorescence immunoassay of SARS-CoV-2 in rapid test applications. The synthesis of the fluorescent label involved a carbodiimide coupling reaction using EDC/NHS agents to conjugate IgY antibodies with curcumin CDs. The IgY-cur CDs conjugate was confirmed to detect antigens through FRET immunosensor mechanisms, showing a significant increase in fluorescence intensity with increasing antigen concentrations (p < 0.05), with a minimum sample concentration of 10 ng. Furthermore, the IgY-CDs cur conjugate was applied as a reporter in a fluorescence-based LFIA using a sandwich assay format. The test strip successfully detected synthetic multiepitope SARS-CoV-2 antigens with an estimated detection limit of 54.28 µg and nasopharyngeal samples from confirmed COVID-19 patients within 35 minutes of operation. The test strip was evaluated to be stable under cold storage at 4°C for up to 3 weeks. In conclusion, curcumin CDs-labeled IgY antibodies demonstrate promising potential for further development as fluorescent labels in rapid diagnostic applications targeting SARS-CoV-2.
Evaluation of Curcumin-derived Carbon-dots' Inhibitory Activity as SARS-CoV-2 Antiviral Candidate Using Chemical Crosslinking Taharuddin, Audrey Angelina Putri; Yamahoki, Nicholas; Stephanie, Rebecca; Agustiyanti, Dian Fitria; Wisnuwardhani, Popi Hadi; Angelina, Marissa; Rubiyana, Yana; Ningrum, Ratih Asmana; Wardiana, Andri; Desriani, Desriani; Hariyatun, Hariyatun; Iskandar, Ferry; Permatasari, Fitri Aulia; Giri-Rachman, Ernawati Arifin; Fibriani, Azzania
HAYATI Journal of Biosciences Vol. 33 No. 1 (2026): January 2026
Publisher : Bogor Agricultural University, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.4308/hjb.33.1.232-239

Abstract

In our previous work, we demonstrated that curcumin-derived carbon dots (Cur-CDs) have potential as antivirals for COVID-19. However, the precise mechanism of action remains unclear. This study investigated the potential of Cur-CDs against SARS-CoV-2 by targeting the dimerization of the C-terminal domain of nucleocapsid protein (N-CTD) using chemical crosslinking. Recombinant SARS-CoV-2 N-CTD was expressed, purified, and subjected to chemical crosslinking. The dimerization inhibition ability of Cur-CDs was assessed with ligand concentrations ranging from 0 to 2,000 μg/mL. Successful inhibition —defined as a noticeable reduction in SARS-CoV-2 N-CTD dimer band intensity on SDS-PAGE—was observed when Cur-CDs were present at 8 to 16 times the protein concentration. We hypothesize that Cur-CDs bind to the dimerization residues, preventing non-covalent interactions between monomers and limiting dimer formation. Our findings suggest that Cur-CDs could be a promising antiviral strategy for SARS-CoV-2, especially targeting the dimerization of the nucleocapsid protein. Additionally, this study also highlights the use of chemical crosslinking as a valuable tool for interaction-based drug screening.