1. Introduction
As part of the human diet, FACHB-314 is one of the long-used
cyanobacteria, and it is also the first batch of algae bacteria to be
industrialized using modern biotechnology (Almomani, 2020; Ambati et
al., 2019). FACHB-314 belongs to blue-green prokaryotic
microalgae with photosynthesis, filamentous, spiral, and multicellular
blue-green microalgae, larger than other types of microalgae (Nematian
et al., 2020; Shi et al., 2020). Due to the lack of cellulose in the
cell membrane (Ribeiro et al., 2021; Rosenau et al., 2021) is easily
digested and absorbed by the human body (Karthikeyan et al., 2020). And
it has many benefits to human health, including anti-cancer (Patel et
al., 2021), antioxidant (Mustafa et al., 2021), anti-viral (Lupatini
Menegotto et al., 2021; Mona et al., 2021) and anti-inflammatory
(Basavarajappa et al., 2020; Grossmann et al., 2020; Hazeem et al.,
2020). Therefore, it can be used to produce health foods (Keller et al.,
2021), cosmetics (Hong et al., 2021b), food additives (Hong et al.,
2021a) and medicines (Almomani, 2020). In addition, due to the high
content of nutrients in its cells (Guo et al., 2021), it can produce
more substances, such as pigments, fatty acids, vitamins, minerals, etc.
(Sathasivam et al., 2019; Wang et al., 2019; Yucetepe et al., 2019),
especially for the production of phycocyanin (Akter et al., 2021), which
content can reach 10-20% (Rosa et al., 2019).
Phycocyanin is composed of apolipoprotein (Fu et al., 2021) and
phycocyanin (Liu et al., 2019). Apolipoprotein binds to phycocyanin
through ether-sulfur bonds (Li et al., 2019). The protein part is
composed of the α subunit and β subunit (Karakas et al., 2019; Kashyap
et al., 2019). Due to the presence of open-chain tetrapyrrole, it is an
auxiliary photosynthetic pigment, and its color is dark blue (Alagawany
et al., 2021; He et al., 2019). It is a non-toxic pigment protein with
good water solubility (Ferreira-Santos et al., 2021), antioxidant,
anti-inflammatory, neuroprotective, and liver protective effects (Ambati
et al., 2019; Buchmann et al., 2019; Dalu et al., 2019). It’s the
research object of many scholars. In the food industry, phycocyanin is
mainly used as a natural dye to replace artificial dyes that are harmful
to human health (Ye et al., 2018; Zhang et al., 2018). In the medical
field, the absorption and emission wavelengths are high, the
fluorescence quantum yield and light stability are good, the extinction
coefficient is large, and the solubility in water is high (Thirumdas et
al., 2018; Wang & Lan, 2018). Therefore, based on the properties of
phycocyanin, can also be used as a fluorescent label (Sengupta et al.,
2018).
However, as a phycocyanin extracted from biological algae, its
application has certain limitations, such as low yield and difficulty in
large-scale production (Rizwan et al., 2018; Rodrigues et al., 2018).
Therefore, the main method to overcome such limitations is to increase
biomass (because of its higher value) and increase the content of
valuable products produced by cell metabolism (Ozkaleli & Erdem, 2018;
Raji et al., 2018). In recent years, the importance of nanomaterials has
greatly increased (Wang et al., 2017). Based on previous studies,
titanium dioxide (TiO2) nanoparticles (NPs) are
currently one of the most widely used nanomaterials (Nguyen et al.,
2018; Ozkaleli & Erdem, 2018). However, in such studies, we found that
TiO2 has a certain inhibitory and toxic effect on the
growth of algae cells due to its relatively poor biocompatibility and
strong cytotoxicity (Zhou et al., 2021; Zhu et al., 2021). For this, we
creatively upgrade materials, Synthesized rGO-TiO2composite nanomaterials for the co-cultivation of Spirulina.
This work fabricated highly biocompatible rGO-TiO2nanoparticles to be used in the cultivation process of FACHB-314 .
Aims to improve the absorption and utilization of light by algae, and
promote the growth of algae cells and the accumulation of
photosynthesis, thereby increasing the production of phycocyanin. In the
process of microalgae cultivation, increasing the production of own
cells can also increase the output of phycocyanin. Developing a
technology that can effectively synthesize phycocyanin inFACHB-314 and explore the feasibility of the corresponding
technology.