Probe and Stain Indicators

Creative Biolabs' Probe and Stain Indicators

The primary goal of Creative Biolabs is to create a new generation of improved probe and stain indicators. We collaborate closely with customers to produce pure, superior goods that enhance research outcomes. For your research needs, we provide a variety of membrane permeable and impermeable ION indicators that target Ca²⁺, Na⁺, K⁺, TI⁺, as well as other fluorescent dyes. Since our indicators have the lowest lot-to-lot variability, you may be sure that your findings are accurate.

Fig.1 Fluorescent probe and stain indicators. (Lai, 2021)

Fluorescent Probe and Stain Indicators

• Calcium Indicators

Three chemical types of Ca²⁺ indicator dyes are available: salts, dextran conjugates, or acetoxymethyl (AM) esters. Although salts are the most basic type of Ca²⁺ indicators, they are membrane impermeable due to their hydrophilic nature. The issue of compartmentalization was especially addressed by the development of dextran conjugates of Ca²⁺ indicator dyes. To provide a more practical way to load hydrophilic dyes into cells, Ca²⁺ indicator dyes containing AM esters were developed.

Fig.2 Calcium indicators. (Barykina, 2016)

• Sodium Indicators

There is almost always a significant differential in sodium concentration between the interior of animal cells and the extracellular environment. This gradient drives electrical impulse transmission, epithelial transport, control of other intracellular ions, and nutritional intake. Na⁺ indicator have great spatial and unmatched temporal resolution, are compatible with cell types, and can be applied to single cells.

• Potassium Indicators

Potassium channels serve a variety of purposes, including controlling the balance of solutes and altering neuronal activity. A K⁺-binding moiety is a component of potassium indicators. The sensor's fluorescence is noticeably reduced in situations where K⁺ is not bound. The quenching is alleviated and the sensor's fluorescence rises sharply when K⁺ is bound.

Improving Indicator Loading and Retention

Although fluorescent indicators in their AM forms easily traverse the plasma membrane, other conditions may have an impact on how well the indicators load into cells. Due to the hydrophobic nature of the AM forms of the indicators, it is usual practice to apply a non-ionic surfactant to increase their solubility in aqueous solution and hence increase their loading into cells. The presence of transport proteins that can carry a variety of ion-sensitive, fluorescent markers can also have an impact on cell loading and intracellular localization. The function of these transporters can cause the compartmentalization of the indicators into intracellular compartments as well as their ejection outside of the cell in a variety of cell types. In some cell types, such as CHO cells, both of these processes can significantly lower the signal-to-background levels, making appropriate loading of fluorescent markers practically impossible. Fortunately, cytoplasmic localization and indication retention can be enhanced by using inhibitors of these transport proteins.

References

1. Lai, Y.; et al. Evaluation of cell viability with a single fluorescent probe based on two kinds of fluorescence signal modes. Analytical Chemistry. 2021, 93(36): 12487-12493.
2. Barykina, N. V.; et al. A new design for a green calcium indicator with a smaller size and a reduced number of calcium-binding sites. Scientific reports. 2016, 6(1): 34447.