金纳米颗粒（AuNPs）在各种生物医学领域的应用备受关注。传统的非生物合成方法存在着产生有毒副产物、耗能大等缺点，而绿色合成，尤其是蓝藻合成可解决上述问题。然而，蓝藻合成金纳米颗粒的机制尚未明确。有研究表明蓝藻合成金纳米颗粒后自发荧光减弱，藻胆蛋白含量下降，推测金纳米颗粒合成可能与藻胆蛋白有关。藻胆蛋白（PBP）是一类水溶性胞内蛋白，在蓝藻中可占细胞总蛋白质的50%以上，具有很强的抗氧化性。因此，本研究用鱼腥藻7120的藻胆蛋白粗提物与三价金离子反应，来探索蓝藻合成金纳米颗粒的机制。结果表明：（1）鱼腥藻7120提取的藻胆蛋白浓度很高，达318.61 mg/L，占总可溶性蛋白的95.19%。提出的藻胆蛋白放置2周内，紫外吸收光谱扫描显示藻胆蛋白主要的特征峰重合，表明藻胆蛋白稳定。藻胆蛋白平均总抗氧化能力为0.3945 μg Trolox/mg prot；（2）在藻胆蛋白浓度（mg/L）与金离子浓度（ppm）的比值Q为7.0802 ≥ Q ≥ 2.7700时产生液态金纳米颗粒，颜色为紫色，在540 nm处有SPR特征峰；Q为2.7306 ≥ Q ≥ 0.9693时产生固态金纳米颗粒，颜色为紫色；经研磨后，在540 nm处有SPR特征峰；（3）藻胆蛋白还原三价金离子为金纳米颗粒的转化率最高可达89.9%；（4）TEM电镜显示，藻胆蛋白合成金纳米颗粒的大小在20-30 nm之间，分散性好，形状近似；（5）鱼腥藻7120细胞合成金纳米颗粒主要分布在类囊体膜上。上述结果证明鱼腥藻藻胆蛋白可合成金纳米颗粒，且蓝藻细胞合成的金纳米颗粒主要定位在类囊体膜上，其上有以藻胆蛋白组装的藻胆体，因此得出结论：藻胆蛋白在鱼腥藻7120合成金纳米颗粒过程中起关键作用。本研究不仅解释了蓝藻合成金纳米颗粒的机制，又增加了藻胆蛋白的新功能。

Gold nanoparticles (AuNPs) have received considerable attention for their applications in various biomedical fields. Traditional non-biological synthesis methods have drawbacks such as producing toxic by-products and high energy consumption, while green synthesis, especially cyanobacterial synthesis, can address these issues. However, the mechanism of cyanobacterial synthesis of AuNPs is not yet clear. Some studies suggest that the spontaneous fluorescence of cyanobacteria decreases and the phycobiliprotein (PBP) content decreases after synthesizing AuNPs, indicating that the synthesis of AuNPs may be related to PBP. PBP is a type of water-soluble intracellular protein that accounts for more than 50% of total protein in cyanobacteria and has strong antioxidant properties. Therefore, this study explored the mechanism of cyanobacterial synthesis of AuNPs by reacting crude PBP extract from Anabaena 7120 with trivalent gold ions. The results showed that: (1) The concentration of PBP extracted from Anabaena 7120 was high, reaching 318.61 mg/L, accounting for 95.19% of the total soluble protein. The UV absorption spectra of the proposed PBP between two weeks showed that the main characteristic peaks of PBP overlapped, indicating that PBP was stable. The average total antioxidant capacity of PBP was 0.3945 μg Trolox/mg prot; (2) Liquid AuNPs with a purple color and a SPR characteristic peak at 540 nm were produced when the ratio of PBP concentration (mg/L) to gold ion concentration (ppm) Q was 7.0802 ≥ Q ≥ 2.7700. Solid AuNPs with a purple color and a SPR characteristic peak at 540 nm were produced when Q was 2.7306 ≥ Q ≥ 0.9693. After grinding, a SPR characteristic peak was observed at 540 nm; (3) The conversion rate of PBP to reduce trivalent gold ions to AuNPs was up to 89.9%; (4) TEM microscopy showed that the size of AuNPs synthesized by PBP was between 20-30 nm with good dispersion and similar shapes; (5) the cyanobacteria synthesized AuNPs mainly distributed on the thylakoid membrane. The above results demonstrate that PBP from Anabaena 7120 can synthesize AuNPs, and the gold nanoparticles synthesized by cyanobacteria are mainly located on the thylakoid membrane, where phycobilisomes are assembled by PBP. Therefore, it is concluded that PBP plays a critical role in the synthesis of AuNPs in Anabaena 7120. This study not only explains the mechanism of cyanobacterial synthesis of AuNPs but also adds a new function to PBP.