Nucleic acid extraction kits have a wide range of applications in multiple fields, as described below:

I. Medical Diagnosis

1. Infectious Disease Diagnosis
   • Virus Detection
     During the COVID – 19 pandemic, nucleic acid extraction kits played a crucial role in detecting the RNA of the novel coronavirus (SARS – CoV – 2). Nucleic acids of the virus are extracted from samples such as nasopharyngeal swabs, sputum, or blood of patients, and then techniques like polymerase chain reaction (PCR) are used for amplification and detection to determine whether the patient is infected. Besides the novel coronavirus, nucleic acid extraction kits are also essential for detecting many other viruses, including influenza virus, human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), etc. This provides a basis for the early diagnosis, isolation, and treatment of infectious diseases.
   • Bacteria Detection
     It is used to extract the DNA or RNA of bacteria. For example, in the diagnosis of tuberculosis, the nucleic acid of Mycobacterium tuberculosis is detected. In the diagnosis of infections caused by drug – resistant bacteria, by extracting the nucleic acid of bacteria and analyzing their drug – resistant genes, doctors can accurately select effective antibiotics, which is crucial for controlling the spread of drug – resistant bacteria and treating infections.
   • Parasite Detection
     In the diagnosis of parasitic diseases such as malaria and schistosomiasis, nucleic acid extraction kits can extract the nucleic acid of parasites from samples like blood and feces to assist in disease diagnosis. For instance, in malaria diagnosis, extracting the nucleic acid of Plasmodium and using nucleic acid detection methods can improve the sensitivity and specificity of diagnosis, especially for patients with low parasitemia.
2. Genetic Disease Diagnosis
   DNA can be extracted from samples such as blood, amniotic fluid, and chorionic villi of patients for detecting chromosomal abnormalities and single – gene genetic diseases. For example, in the prenatal diagnosis of Down syndrome (trisomy 21), fetal cells are obtained through amniocentesis or chorionic villus sampling. The DNA is then extracted using a nucleic acid extraction kit, followed by chromosomal karyotype analysis or genetic testing to determine whether the fetus has Down syndrome. For single – gene genetic diseases like thalassemia and cystic fibrosis, after extracting the patient’s DNA, techniques such as gene sequencing are used to search for mutation sites of disease – causing genes, providing important evidence for the diagnosis, genetic counseling, and prenatal diagnosis of genetic diseases.
3. Tumor Diagnosis and Monitoring
   • Early Diagnosis
     Tumor – related nucleic acid markers such as circulating tumor DNA (ctDNA) and microRNA (miRNA) can be found in the blood, tissues, or body fluids of tumor patients. Nucleic acid extraction kits can extract nucleic acids from these samples to detect abnormal changes in tumor – related genes, such as mutations and methylation, assisting in the early screening and diagnosis of tumors. For example, in the early diagnosis of lung cancer, detecting mutations in ctDNA in the blood can identify early – stage lung cancer patients.
   • Treatment Monitoring
     During the treatment of tumors, nucleic acids are regularly extracted and related markers are detected to monitor the treatment effect. For example, after chemotherapy or targeted therapy, the changes in nucleic acid markers of tumor cells are observed. If the content of these markers decreases, it indicates that the treatment is effective; conversely, if the marker content increases or new mutations occur, it may suggest tumor recurrence or drug resistance, and the treatment plan needs to be adjusted.

II. Forensic Identification

1. Individual Identification
   At crime scenes, forensic scientists can extract DNA from biological samples such as bloodstains, hairs, saliva, and semen. After extracting high – quality nucleic acids using nucleic acid extraction kits, DNA typing techniques (such as short tandem repeat (STR) analysis) are employed to compare the extracted DNA with the known samples of suspects or victims to determine their identities. This method plays a key role in solving criminal cases and identifying the victims of disasters.
2. Paternity Testing
   DNA is extracted from samples such as oral swabs and blood of parents and children. Then, genetic typing and comparison are carried out, and the paternity index is calculated to determine the parent – child relationship. Nucleic acid extraction kits can ensure the quality of the extracted DNA, guaranteeing the accuracy of paternity test results.

III. Food Safety Testing

1. Genetically Modified Food Detection
   It is used to extract the nucleic acids in genetically modified foods. By detecting specific genetically modified elements (such as promoters, terminators, and target genes), it can be determined whether the food is genetically modified and the content of its genetically modified components. This helps protect consumers’ right to know and ensure food safety.
2. Food – borne Pathogen Detection
   Nucleic acids of pathogens such as bacteria, viruses, and parasites are extracted from food or food processing environment samples (such as meat, vegetables, and the surface of processing workshops) to detect the presence of pathogenic microorganisms, such as Salmonella, Escherichia coli O157:H7, and norovirus, preventing the spread of food – borne diseases.

IV. Environmental Monitoring

1. Microbial Monitoring
   In environmental microbiology research, nucleic acid extraction kits can extract the nucleic acids of microorganisms from environmental samples such as soil, water, and air, for analyzing the diversity, community structure, and functional genes of microorganisms. For example, in water environment monitoring, by extracting the nucleic acids of microorganisms in water, the types and quantity changes of microorganisms in water can be understood, the water quality can be evaluated, and water pollution can be monitored.
2. Bioremediation Monitoring
   During the bioremediation of some polluted sites, the nucleic acids of microorganisms involved in the remediation process are extracted to monitor their gene expression and metabolic activity, and to evaluate the effect of bioremediation. For example, in the bioremediation of oil – contaminated soil, the nucleic acid changes of microorganisms that degrade oil are monitored to determine whether the bioremediation is proceeding effectively.