Sari, Anggra Adella Sita (2026) Pemanfaatan Green Synthesis AgNPs Dari Selulosa Eichhornia Crassipes Untuk Aplikasi Biosensor Melalui Efek Localized Surface Plasmon Resonance Dalam Mendeteksi Bakteri Escherichia Coli. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Pencemaran mikrobiologis oleh bakteri Escherichia coli pada perairan, khususnya Kali Mas Surabaya yang tercatat mencapai 50.000 MPN/100 mL, menunjukkan kebutuhan akan metode deteksi yang cepat dan sensitif. Penelitian ini mengembangkan biosensor berbasis Surface Plasmon Resonance (SPR) yang dimodifikasi menggunakan nanopartikel perak (AgNPs) hasil green synthesis berbasis selulosa eceng gondok (Eichhornia crassipes) untuk mendeteksi keberadaan bakteri E. coli. Selulosa diperoleh melalui proses isolasi biomassa eceng gondok menggunakan delignifikasi NaOH 2% dan bleaching H₂O₂ 5%. Karakterisasi XRD menunjukkan bahwa selulosa yang diperoleh mempertahankan struktur kristal tipe I (native cellulose) dengan puncak karakteristik pada 2θ sebesar 22,84°, sedangkan analisis Chesson-Datta menunjukkan kandungan selulosa awal sebesar 52,91%. AgNPs disintesis melalui reaksi suspensi selulosa 1% dengan AgNO₃ 1 mM pada suhu 90°C dan pH 9 selama 4 jam. Hasil karakterisasi menunjukkan terbentuknya AgNPs dengan puncak serapan Vis pada 423,87 nm yang menunjukkan karakteristik Localized Surface Plasmon Resonance (LSPR), ukuran partikel rata-rata D50 sebesar 24,63 nm berdasarkan analisis PSA, serta keberadaan gugus hidroksil (-OH) dan karboksilat (-COO⁻) berdasarkan analisis FTIR yang berperan dalam proses reduksi dan kestabilan nanopartikel. Pengujian sensor dilakukan menggunakan konfigurasi Kretschmann dengan laser He-Ne berpanjang gelombang 632,8 nm terhadap tiga variasi konsentrasi E. coli (10⁵, 10⁶, dan 10⁷ CFU/mL). Hasil pengujian menunjukkan bahwa sensor emas murni menghasilkan pergeseran sudut resonansi (Δθ) sebesar 0,07-0,68° dengan respons yang belum stabil. Setelah modifikasi menggunakan AgNPs, sensor Au/AgNPs menghasilkan pergeseran sudut resonansi yang lebih besar, yaitu 0,12°, 0,26°, dan 2,26° pada konsentrasi E. coli 10⁵, 10⁶, dan 10⁷ CFU/mL. Nilai Figure of Merit (FoM) tertinggi diperoleh pada konsentrasi 10⁷ CFU/mL sebesar 1,4100. Peningkatan performa sensor Au/AgNPs terjadi akibat mekanisme kopling SPR-LSPR yang menghasilkan penguatan medan elektromagnetik lokal sehingga perubahan indeks bias akibat keberadaan bakteri dapat terdeteksi lebih sensitif. Penelitian ini menunjukkan bahwa AgNPs hasil green synthesis berbasis selulosa eceng gondok berpotensi meningkatkan kinerja biosensor SPR untuk deteksi E. coli pada sampel air.
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Microbiological contamination by Escherichia coli in water bodies, particularly the Kali Mas River in Surabaya, which has been reported to reach 50,000 MPN/100 mL, highlights the need for rapid and sensitive detection methods. This study developed a Surface Plasmon Resonance (SPR)-based biosensor modified with silver nanoparticles (AgNPs) synthesized through a green synthesis approach using water hyacinth cellulose (Eichhornia crassipes) for E. coli detection. Cellulose was obtained from water hyacinth biomass through delignification using 2% NaOH and bleaching using 5% H₂O₂. XRD characterization confirmed that the obtained cellulose maintained a type I crystalline structure (native cellulose) with a characteristic diffraction peak at 2θ of 22.84°, while Chesson-Datta analysis showed an initial cellulose content of 52.91%. AgNPs were synthesized by reacting 1% cellulose suspension with 1 mM AgNO₃ at 90°C and pH 9 for 4 hours. The characterization results showed the formation of AgNPs with a UV-Vis absorption peak at 423.87 nm, indicating the characteristic Localized Surface Plasmon Resonance (LSPR) of AgNPs, an average particle size of D50 = 24.63 nm based on Particle Size Analyzer (PSA) analysis, and the presence of hydroxyl (-OH) and carboxylate (-COO⁻) functional groups identified by FTIR analysis, which contributed to the reduction process and nanoparticle stabilization. The sensor performance was evaluated using a Kretschmann configuration with a He-Ne laser at a wavelength of 632.8 nm for three E. coli concentrations (10⁵, 10⁶, and 10⁷ CFU/mL). The results showed that the pure gold sensor produced a resonance angle shift (Δθ) ranging from 0.07° to 0.68° with relatively unstable responses. After modification with AgNPs, the Au/AgNPs sensor produced larger resonance angle shifts of 0.12°, 0.26°, and 2.26° at E. coli concentrations of 10⁵, 10⁶, and 10⁷ CFU/mL, respectively. The highest Figure of Merit (FoM) value was obtained at a concentration of 10⁷ CFU/mL, reaching 1.4100. The enhanced sensor performance of Au/AgNPs was attributed to the SPR-LSPR coupling mechanism, which generates local electromagnetic field enhancement, allowing changes in the refractive index caused by bacterial presence to be detected with higher sensitivity. This study demonstrates that AgNPs synthesized through green synthesis using water hyacinth cellulose have potential to improve the performance of SPR biosensors for E. coli detection in water samples.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Sintesis hijau, LSPR, AgNPs, Eichhornia crassipes, Escherichia coli, green synthesis |
| Subjects: | Q Science > QC Physics > QC451 Spectroscopy Q Science > QC Physics > QC585 Dielectrics Q Science > QD Chemistry > QD117 Absorption Q Science > QD Chemistry > QD117.S64 Spectrophotometry Q Science > QD Chemistry > QD320 Cellulose. Hydrolysis |
| Divisions: | Faculty of Science and Data Analytics (SCIENTICS) > Physics > 45201-(S1) Undergraduate Thesis |
| Depositing User: | Anggra Adella Sita Sari |
| Date Deposited: | 16 Jul 2026 06:52 |
| Last Modified: | 16 Jul 2026 06:52 |
| URI: | http://repository.its.ac.id/id/eprint/135134 |
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