Residual Detection Kits

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Biological products include immune agents or bioactive agents made from biotechnology such as genetic engineering, cell engineering or fermentation engineering. They can be used to diagnose, prevent and treat disease.
Unlike small molecule drugs, biologics are made from bioactive materials such as cells and body fluids from microbial, animal or human tissues. Due to the complex sources of various materials used in the production process, the production process is complex and susceptible to multiple factors, exogenous factors or toxic chemical materials may be introduced. In addition, the composition of the preparation is complex and terminal sterilization is generally not possible. Therefore, it is difficult to ensure the safety and effectiveness of the preparation only by the intermediate control, the verification quality control of the stock solution and the finished product. Therefore, strict safety and quality control of raw materials and auxiliary materials used in the production of biological products is a necessary measure to reduce the risk of pollution by exogenous factors or toxic impurities and ensure the safety and effectiveness of biological products.

For the safety control of raw and auxiliary materials of biological products in the production and application, domestic and foreign pharmacopoeia and regulations clearly require the factory control process of raw and auxiliary materials, including supplier management, raw and auxiliary materials life cycle management, evaluation of impurity introduction and quality control of single-use system. Through the above control process, the risk of biological contamination introduced by the materials and processes is reduced, the safety of the production of biological products is ensured, and the closed-loop monitoring of raw and auxiliary materials of biological products is realized in the production application.


Importances of Detection
For biological products using materials of human or animal origin, a comprehensive analysis of exogenous factors and metabolites is required, including in vitro kit testing and in vivo inoculation tests. For some cell products, focus on the detection of cell-derived virus and microbial pollution sources, including bacteria, fungi, mycoplasma and other items.

At the same time, a series of testing methods and standards can be referred to, including preparation general rules, spectrophotometry, chromatography, electrophoresis, physical inspection and microbial inspection, etc., to ensure the quality of biological products. In addition, the residual detection process needs to comply with international standards and regulations to ensure the quality and safety of biological products worldwide.


According to the needs of quality control of biological products, the types of residue detection derived from the current market are mainly nucleic acid residue detection, toxic metabolite detection, microbial detection, virus detection and other target protein detection. The residue detection kit for biological products can be classified and summarized as follows according to the different detection targets:

Host cell residual DNA detection kits: This type of kits is used to detect the DNA residue of host cells (such as Vero cells, HEK293 cells, etc.) in biological products. Because host cell DNA can be infectious, immunogenic, or carcinogenic, the amount of residual DNA needs to be strictly controlled.
Protein A residue detection ELISA kits: In the purification process of monoclonal antibodies, protein A is a commonly used affinity filler, but it is easy to leach, so it needs to be detected by ELISA method.
Host cell protein (HCPs) residue detection kits: This type of kits is used to detect host cell protein residues produced in biopharmaceutical processes such as recombinant protein drugs and monoclonal antibodies. The accumulation of HCPs may cause immune reactions or other adverse reactions, so detection and control are needed.
DNase/RNase activity detection kits: RNase enzymes are categorized into two groups: exoribonucleases and endoribonucleases. RNases are ubiquitous in the environment, and in some biological materials, they are present in relatively high concentrations. Since even only minute amounts of RNase contamination would ruin the experiment, it is necessary to evaluate the presence of RNase. DNases are ubiquitous in both the environment and many biological materials. Many molecular biology experiments rely on the use of plastics, chemicals, and solutions that are free from detectable DNase activity, once these materials are contaminated with DNases, the experiments will be affected because of the DNases can degrade DNA. Since even only minute amounts of DNase contamination would ruin the experiment, it is necessary to evaluate the presence of DNase with a reasonable method.


Cell viability detection kits: In cell biological products, the most important thing is to ensure the viability and safety of cells. These kits are commonly used to assess the toxic effects of compounds on cells by measuring the activity of enzymes such as lactate dehydrogenase (LDH) or glutamate-6-phosphate dehydrogenase (G6PD) released into the medium to assess cell damage.
Toxicology detection kits: This type of kits can be used to detect the effects of cytotoxins in biological systems, including quantitative detection of various soluble biomarkers for toxicology research and drug development, and these substances to be tested include antibiotics, endotoxins, lysosomal enzymes, heavy metal ions, etc.
Microbial detection kits: including mycoplasma, bacteria, fungi, etc., can be the object of detection. Mycoplasma is a class of bacteria without cell walls that often contaminate cell cultures but are not easily detected by traditional methods. In particular, it is necessary to pay attention to whether there is microbial contamination in cell biological products.
Virus detection kits: They are used to detect virus contamination in samples. These kits may be based on different viral markers, such as nucleic acids, antigens, or antibodies. Although specific virus detection kits are not explicitly listed in the documentation provided, they are an important part of the safety assessment of biologics and cell therapy products.

Case Study

Case Study 1: Ammonia Colorimetric Assay Kit (Kit-0085)

Hepatic encephalopathy (HE) is a neuropsychiatric complication of liver cirrhosis. HE is associated with poor survival and detrimental effects on quality of life (QOL). This study aimed at evaluating the safety and efficacy of nitazoxanide (NTZ) as compared to rifaximin (RFX) in preventing the recurrence of HE and assessing its impact on QOL.
This prospective, randomized, double-blind controlled study included 60 patients who were randomly assigned to receive either rifaximin 550 mg twice daily (group 1; n = 30) or nitazoxanide 500 mg twice daily (group 2; n = 30) for 24 weeks. The serum levels of HE triggers (ammonia, TNF-α, and octopamine) were assessed. The patients' health-related quality of life was also evaluated. Six months after treatment, patients on NTZ therapy showed a statistically significant improvement in CHESS score and mental status.  Additionally, NTZ showed a statistically significant decrease in serum ammonia, TNF-α, and octopamine levels as compared to rifaximin. Regarding QOL, NTZ group showed an improvement in total Chronic Liver Disease Questionnaire (CLDQ) score.

Fig1. Hepatic encephalopathy related parameters (partial).

Fig1. Hepatic encephalopathy related parameters (partial). (Khadija A M Glal, 2021)

Case Study 2: Cathepsin B Activity Fluorometric Assay Kit (Kit-0181)

Proteasome and lysosome are responsible for the homeostasis of proteins, lipids and carbohydrates in cells. Numerous reports indicate the proteolytic pathways have altered functions during neurodegeneration and aging. Dementia with Lewy bodies (DLB) is one of the leading forms of dementia, and the proteolytic alteration in DLB has not yet been fully investigated. This study shows that the components of proteasome and lysosome had selectively altered gene expression and enzymatic functions. Specifically, PSMB8, an inducible proteasomal β subunit, had elevated mRNA level and protein level in DLB brain compared with age-matched controls. The proteasomal caspase-like peptidase showed significant decreased activity in DLB brains and the trypsin-like/chemotrypsin-like activities did not reach statistical significance. Lysosomal cathepsin B and D had elevated mRNA levels while only cathepsin B showed elevated enzymatic activity in DLB brains.

Fig2. Cell lysate was isolated from the SMTG tissue of each subject and the activity of each enzyme
        was analyzed.

Fig2. Cell lysate was isolated from the SMTG tissue of each subject and the activity of each enzyme was analyzed. (Qunxing Ding, 2018)

Case Study 3: Sandwich ELISA kit

Cystic fibrosis (CF) lung disease is characterised by chronic Pseudomonas aeruginosa infection and leukocyte infiltration. Chemokines recruit leukocytes to sites of infection. Gene expression analysis identified the chemokine CCL18 as upregulated in CF leukocytes. We quantified CCL18 protein levels in the serum and airway fluids of CF patients and healthy controls, and studied CCL18 protein production by airway cells ex vivo. These studies demonstrated that CCL18 levels were increased in the serum and airway fluids from CF patients compared with healthy controls. Within CF patients, CCL18 levels were increased in P. aeruginosa-infected CF patients. CCL18 levels in the airways, but not in serum, correlated with severity of pulmonary obstruction in CF. Airway cells isolated from P. aeruginosa-infected CF patients produced significantly higher amounts of CCL18 protein compared with airway cells from CF patients without P. aeruginosa infection or healthy controls.

Fig3. Ex vivo CCL18 production.

Fig3. Ex vivo CCL18 production. (Andreas Hector, 2014)

The quality control and safety guarantee in the research and development process of biological products have been paid more and more attention. Some small pollution or the introduction of other pollutants will lead to the unuse of biological products. Creative BioMart is now offering a series of kits for residue detection that follow international standards to robustly detect various impurities in your therapeutic antibody, cell therapies, vaccines, or any other biologics! If you have any other customized needs, please feel free to contact us!



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