**4.1 Bio-engineered microalgae: systematic approach**

Microalgae are produced naturally but not in so much abundance that they could help in research, medical, and other fields [66]. Therefore, it is cultured and grown artificially to meet the requirements. To protect environmental and

**Figure 1.** *Illustration depicting hallmarks of cancer.*

ethical issues, the consumption of this nature's gift is kept to a minimum [81]. Now on the take for medical fields, the compound cannot be directly taken or consumed intravenously, there is a proper procedure to use up [66]. The bioactive compound, which shows potential as an anti-cancer agent, needs to be fully accepted by the body to get maximum benefits [82]. Here comes the role of genetic engineering, which further modifies and makes microalgae and other special compounds hostile to the human body [82]. The complete transformation is a required process for the nucleus and chloroplast. However, the studies point out the biological synthesis of lipids, carotenoids, and photosynthesis. *Chlamydomonas reinhardtii* is the supreme class for modification and engineering processes [83]. The lipids and carotenoids have the utmost qualities, which were discussed with several examples in previous sections [84]. The latest update regarding this is the use of the CRISPR gene editing tool, but it might not work on all microalgae as it also has some of its limitations like delivery by the large size of proteins, activity of nuclease activity, etc. In this section, the study of RBCM-Algae is taken [85]. The microalgae are isolated from *Chlorella vulgaris*, which is engineered with red blood cells from human [86]. The purpose is to get a layer of blood on the membrane to serve some respectful purposes [87]. This engineered element promotes oxygen content and tumor tissues because the tumor grows better in hypoxia conditions and increasing the levels would make it sensitive [88]. Then it is subjected to irradiation, which many times is successful to remove the tumor completely [89]. But this is not always the case. It is effective against breast cancer [90].

## **4.2 Effectiveness over other therapies**

The traditional protocol to treat tumor lines is radiation and chemotherapy [9]. This set does not usually affect the patient's condition in various aspects but numerous other factors in the body of the patient either benefit worsen day by day [11]. The survivor must be able to fight the tumor, but he won't be able to fight the opportunist diseases which might take over [14]. These aspects only regress the condition of the body, which then many times leads to a relapse of the malignant tumor and then the person falls into cancer syndromes like cachexia [91]. The delay in detection of the tumor, carelessness, cost of the treatment, the ability of the cells to divide uncontrollably, metastasize to a secondary site, etc. point out the severity of the disease [91]. Research on the new drugs and different drug delivery systems is being done to provide maximum comfort and relief to the patient. The major side effect observed in the patient is that immunity is chiefly affected [9]. It is seen that the condition takes a toll toll on health [1]. The already in-market drugs, which are known as anti-malignant drugs, inhibit or cease the escalation of the outgrowth. It stimulates the action of the immune system and, along with it, triggers the killer cell activity naturally and initiates the defense mechanism of the host [9]. As it is known cancer multiplies in the hypoxia condition [3]. Cancer cells are immune to oxygen species which are reactive or scavenging capacity of the fundamental unit of cell stirs programmed cell death called apoptosis [92]. The standard chemotherapy eliminates tumor tissues, liver, nephron, nausea, anorexia, and mucous membrane inflammation [91]. The sector of nutraceuticals composed of antioxidant supplements is supposed to cover up for the side effects [9]. These are generally plant-based herbal medications, and the antioxidants polyphenols, carotenoids, etc. [25]. The chemicals produced by plants, which are called phytochemicals, work as antioxidants to perform defense against chemotherapy in normal cells by exerting pressure on radiation or other forms of treatment via oxidative stress [9].
