SINTESIS NANOPARTIKEL EMAS TERTUDUNG HISTIDIN UNTUK DETEKSI Hg2+

DEWI EVIANE, Prof. Drs. Sri Juari Santosa, M.Eng, Ph.D; Drs. Dwi Siswanta, M.Eng, Ph.D.

2020 | Disertasi | DOKTOR KIMIA

Dalam penelitian ini telah dikaji sintesis nanopartikel emas (AuNPs) tertudung histidin untuk deteksi kolorimetri Hg2+. Sintesis AuNPs tertudung histidin dilakukan dengan 2 cara yaitu sintesis AuNPs menggunakan agen pereduksi natrium sitrat dan agen penudung histidin (AuNPs(st-his)) dan sintesis AuNPs menggunakan agen pereduksi dan agen penudung histidin (AuNPs(his)). AuNPs disintesis dengan menggunakan metode Turkevich. Hasil penelitian menunjukkan koloid AuNPs memiliki warna merah dengan puncak surface plasmon resonance (SPR) pada panjang gelombang (lamda) 525 nm. Karakterisasi PSA menunjukkan AuNPs(st) yang memiliki ukuran 1-100 nm sebanyak 82,9% dengan rata-rata ukuran 38,6 nm dan nilai potensial zeta -34,8 mV. Karakterisasi PSA menunjukkan penambahan histidin menyebabkan peningkatan jumlah AuNPs(st-his) berukuran 1-100 nm menjadi 97,5% dengan rata-rata ukuran 32,1 nm. Penambahan histidin pada AuNPs(st) menyebabkan perubahan nilai potensial zeta AuNPs dari -34,8 mV menjadi -64,4 mV. Histidin dapat digunakan sebagai agen pereduksi HAuCl4 pada pH histidin 11. Karakterisasi PSA menunjukkan AuNPs(his) memiliki ukuran 1-100 nm sebanyak 100% dengan rata-rata ukuran 17,9 nm dan nilai potensial zeta -22,4 mV. Interaksi AuNPs(st-his) dengan Hg2+ dibuktikan perubahan warna koloid AuNPs dari merah menjadi biru yang disebabkan turunnya puncak SPR pada 525 nm dan terbentuk puncak baru di sekitar 650 nm. Interaksi AuNPs(st-his) dan Hg2+ terjadi pada pH larutan histidin 12 dan selektif terhadap keberadaan 14 jenis kation selain Hg2+ yaitu: K+, Co2+, Na+, Ag+, Cu2+, Mg2+, Zn2+, Mn2+, Al3+, Fe3+, Cr3+, Ni2+, Pb2+, dan Cd2+. Uji kecermatan pengukuran 7 sampel memperlihatkan nilai relative standard deviation (RSD) 1,02%. Batas deteksi (LoD) dan batas kuantifikasi (LoQ) dari AuNPs(st-his) dalam mendeteksi Hg2+ masing-masing adalah 1,77 mikro M = 0,35 ppm dan 5,89 mikro M = 1,18 ppm, nilai perolehan kembali 115% dan 117%. AuNPs(his) interaksinya dengan Hg2+ ditandai dengan adanya perubahan warna AuNPs dari merah menjadi ungu, akibat dari bergesernya puncak SPR pada lamda 525 ke 540 nm. Uji pengaruh penambahan kation terhadap AuNPs(his) dilakukan terhadap 14 jenis kation selain Hg2+ yaitu: K+, Co2+, Na+, Ag+, Cu2+, Mg2+, Zn2+, Mn2+, Al3+, Fe3+, Cr3+, Ni2+, Pb2+, dan Cd2+tidak memberikan gangguan berarti. Pengukuran terhadap 7 sampel berbeda menghasilkan spektra SPR yang berdekatan dengan nilai RSD 0,47%. LoD dan LoQ AuNPs(his) dalam mendeteksi Hg2+ masing-masing adalah 55 mikro M = 0.31 ppm dan 5.17 mikro M = 1.03 ppm. Uji ketepatan menunjukkan nilai perolehan kembali 111% dan 114%.

In this study, the synthesis of histidine-coated gold nanoparticles (AuNPs) for colorimetric detection of Hg2+ has been done. Synthesis of AuNPs using histidine as capping agent has been done in 2 ways: synthesis of AuNPs using sodium citrate as reducing agent and histidine as capping agent (AuNPs(st-his)) and synthesis of AuNPs using histidine as reducing and capping agents (AuNPs(his)). AuNPs(st) were synthesized using the Turkevich method. Results showed that AuNPs(st) colloids had a red color with a surface plasmon resonance (SPR) peak at a wavelength of 525 nm. The PSA characterization results showed 82.9% AuNPs(st) had a size of 1-100 nm, an average size of 38.6 nm, and a zeta potential value of -34.8 mV. The increase in SPR peak intensity indicates that the addition of histidine to AuNPs(st) results in an increase in the efficiency of the formation of AuNPs(st-his). The results of PSA characterization showed that the addition of histidine caused 97.5% AuNPs(st-his) to have a size of 1-100 nm with an average size of 32.1 nm. The addition of histidine to AuNPs(st) caused a change in zeta potential from -34.8 to -64.4 mV. Synthesis of AuNPs(his) was carried out at the pH of histidine solution 11. The results of PSA characterization showed 100% AuNPs(his) have a size of 1-100 nm, the average size of 17.9 nm, and the zeta potential of -22.4 mV. The interaction between AuNPs(st-his) with Hg2+ was known from the colloidal color change from red to blue due to a decrease in the SPR peak at a wavelength of 525 nm and appearance of new peak at around 650 nm. The interaction of AuNPs(st-his) and Hg2+ that occurred at the pH of histidine solution 12 was very selective towards interferences from 14 other types of cations: K+, Co2+, Na+, Ag+, Cu2+, Mg2+, Zn2+, Mn2+, Al3+, Fe3+, Cr3+, Ni2+, Pb2+, and Cd2+. The precision test on the measurement of 7 different samples showed a relative standard deviation (RSD) value of 1.02%. The detection limit (LoD) and the quantification limit (LoQ) of AuNPs(st-his) in detecting Hg2+ were 1.77 mikro M = 0.35 ppm and 5.89 mikro M = 1.18 ppm, respectively with recovery values were 115% and 117%. In the case AuNPs(his), their interaction with Hg2+ could be observed from the color change from colloidal red to purple. This color change was followed by a shift in the SPR peak from 525 to 540 nm. The presence of 14 other types of cations i.e. K+, Co2+, Na+, Ag+, Cu2+, Mg2+, Zn2+, Mn2+, Al3+, Fe3+, Cr3+, Ni2+, Pb2+, and Cd2+ gave no interference. The precision test on the measurement of 7 different samples produces reproducible SPR spectra with RSD value of 0.47%. LOD and LoQ of AuNPs(his) in detecting Hg2+ were 1.55 mikro M = 0.31 ppm and 5.17 mikro M = 1.03 ppm, respectively. The accuracy test shows the recovery values were 111% and 114%.

Kata Kunci : gold nanoparticles, sodium citrate, histidine, Hg2+