Microscope slides are thin pieces of glass that researchers use to observe various substances by putting them under microscopes. The primary demand for these slides is in laboratories for research or testing purposes. These slides have different types, one of the most popular being adhesive slides.
Adhesive slides, also known as charged slides, are widely known by many working in laboratories. These slides are prepared to work under microscopes. Such microscope slides stick to the substance placed on them due to combining the glass molecules with the molecules of that substance. They often help to bond a tissue with the slide chemically.
Furthermore, scientists have categorized these slides into different types according to their properties. For example, scientists can divide them first into poly-lysine coated slides and silanized slides according to the treated reagents. Second, considering the surface, they can divide them into hydrophilic slides and hydrophobic slides.
Thirdly, as per the scope of use, they can be divided into three type: slides for routine H&E staining, slides for Immunohistochemistry, and slides for liquid-based cytology.
Hence, this proves that there are a lot of types of adhesive slides. Thus, many people face the same problem when purchase adhesive slides as there is a wide variety available. Therefore, it makes it difficult to decide to pick the right one out of these types. Thus, this small piece of writing can help you tremendously in epic ways while shopping for such slides.
These slides create an adhesion among the tissues and the slides. Silicate glass surface originally has negatively charged groups. But, the applying of aminopropyltriethoxysilane (APES) or polymer turns it into a positively charged surface. Polymer and APES help coat these slides, which are a bit better than proteins and amino acids, which help coat the poly-lysine slides. This type of adhesive slide allows the saline bonds to remain in the glass due to its acidic media.
Silanized slides are coated with quite strong adhesives, so suitable for manual IHC staining, automatic IHC staining with the Leica and Dako automated IHC Stainers and routine H&E staining of detachable tissue sections
However, in alkaline media, there is less adhesion of the tissue. Therefore, no birefringence and autofluorescence will appear on these modified surfaces.
Notably, they are good for difficult tissues combined with long incubations, procedures that need complex produced and extended antigen retrieval. Therefore, these silanized slides are a good choice for pathology labs when it comes to dealing with demanding procedures and challenging tissues.
Uses of Silanized adhesive slides
- Immunofluorescence microscopy.
- To determine hybridization stringency.
POLY-LYSINE COATED SLIDES
These slides coated with lysine and polymerized amino acid play the role of a coating substrate for cultural dishes and slides. In anti-peeling slides, they act as a sticky reagent. Throughout this process, it keeps the specimen bind to the slide. These slides (prefabricate) are good for reproducibility and consistency. These are non-toxic, ready-to-use slides and are economical slides. We can store them for 18 months at room temperature if protected from direct sunlight.
Advantages of using Poly-lysine coated slides:
- It is not affected by any chemicals.
- For immunocytochemical hybridization assays on tissue sections.
- Can be used immediately, as it is precleaned.
- Pure and corrosion-resistant adhesion slides.
Uses of Poly-lysine slides
- To prepare coelomocytes smear which was further subjected to antibody staining.
- To determine alpha serine/threonine-protein kinase expression by immunohistochemistry.
- In immunofluorescence imaging
These slides repel liquids. In these slides, the droplet is spherical to keep the contact angle high. And the adhesiveness is good with less wettability and dissolvability. In these slides, tissue-damaging and wrinkling may occur because the tissue can’t refloat. It can stay in place and has fewer chances of getting damaged because it is a solid substance.
But, they are not ideal for liquid substances because the free energy is low as it has low water-soluble molecules.
Therefore, they are also known as water-repulsive slides due to their property of having low water-soluble molecules. But, they are exceptionally suitable for decalcified bone tissues. In addition, they have the most significant contact angle among all the different types of adhesive slides.
Advantages of using Hydrophobic slides
- These slides can be used in immunohistochemical (IHC) techniques.
- They are also used in immunofluorescence(IFA) and immunolabeling with cellular cultures and histological sections.
- Hydrophobic slides resist enzymatic treatment and microwaves.
In hydrophilic slides, the drop has a tiny contact angle which encourages reagent dispersal. The adhesiveness is up to the mark with high wettability. The solid surface energy is high in these slides.
Furthermore, these types of slides are ideal for bio-medical purposes in immunohistochemistry. Because of their tissue retention, which is as high as 90-100% with an IHC score of 3-4+. So recommended to automatic IHC staining with the Roche Ventana automated IHC Stainer.
Not only this, but they are also preferable for many other purposes due to their high adhesion and no charge, which leads to zero repulsion of liquids.
Advantages of Hydrophilic slides
It carries approximately three times more positive charges as compared to other available positively charged slides.
It carries more tissue retaining capability than other positive charged slides.
SLIDES FOR ROUTING H&E STAINING
H&E staining of tissues is done to analyze the morphological structures at the cellular level. It has two primary coloring agents that stain the cells (also organelles), such as cytoplasm in pink-red and nuclei in blue color.
Uses of slides for H&E staining:
- identifying the morphology of tissues
- Helps in cell differentiation and variability
- It helps to find out the type of tissue and cell type
- It helps to detect pathological alterations.
Notably, these slides are used for frozen and complex tissues. H&E staining slides are usually stored for indexing formalin-fixed paraffin-embedded sample tissue blocks. These FFPE blocks can clinically annotate human tumor samples, which helps researchers in their studies.
SLIDES FOR IMMUNOHISTOCHEMISTRY(IHC)
Immunohistochemistry is a laboratory technique by which it is easy to detect tissue structures, location, and distribution of Ag-based and Ag Ab-based complexes. Immunohistochemistry slides are used in laboratory techniques that utilize specific antibodies to visualize the quantity, distribution, and cellular location of immunogenic epitopes in histological tissue sections.
Immunohistochemistry Adhesive slides are used in four ways,
- Direct method
- ABC method
- Indirect method
- PAP method
Applications of immunohistochemistry and In-situ Adhesive slides
- Prognostic markers in cancer.
- Infectious and neurodegenerative diseases.
- In genetics.
- In surgical pathology.
- Research application.
SLIDES FOR LIQUID-BASED CYTOLOGY (LBC)
These slides are prepared to improve the diagnostic reliability of pap smears. For using these slides, we have to collect a sample using a spatula and brush. Then, we have to transfer it into a microscope cyto bottle of preservative liquid. These slides help in examining a layer of cells from the body under a microscope. It includes making a suspension of cells out of the sample, which makes a thin layer of cells on a slide. In 2014, liquid-based cytology slides replaced conventional cytology with HPV triage. It is also a new technique to detect cervical cancer and has served as one of the significant advances in cervical cancer screening.
LBC slides have also produced satisfactory results in the pathology lab in a prospective study in Sydney, Australia. From various research-related articles, it is evident that LBC slide technique reduces the chances of false-negative test results. Not only this, but they are also very cost-effective. Their test is a technique to detect nucleotide sequences in tissues, sections, and cells.
It consists of complementary binding of the nucleotide probe with a specific sequence of DNA or RNA. Hence, ISH or IHC slides study helps provide information about proteins, DNA and RNA. It is also helpful when it comes to accessing chromosomal integrity in medical diagnostics.
Uses of Liquid-based cytology Adhesive slides:
- Non-gynecological preparations.
- Thyroid cyst fluid examination.
- Oral pathology.
- Body fluids like urine, pleural effusion.
- Brushing samples like the gastrointestinal tract, lungs.
- Fine needle aspiration.
There are many types of adhesives slides in the market. All you need is to know your requirements and purchase them accordingly. They are usually classified based on treated reagent, surface, and scope of use. Some most widely used adhesive slides are Poly-lysine, silanized, coated, hydrophobic, and hydrophilic adhesive slides. Particular slides with high efficiency and adhesive strength are used for immunohistochemistry, In-situ hybridization, and liquid-based cytology.
In order to get the best performance of slides and proper outcomes, it is suggested to use them within a year of purchasing them. Keeping in mind appropriate storage conditions for increasing the duration of slide performance is also very important. You need to store them at an optimum temperature and in a place where humidity is controlled. Also, avoid storing them on the floor. Keeping them in appropriate boxes and air-tight packaging will also help them stay longer.
So, don’t forget to consider all these types of adhesive slides while choosing the right one for you!