- Cart 0
- English
Comparison of Fluorescent Probes for Cellular Functions: Detection Principles, Core Differences and Selection Strategies of Ca²⁺/Na⁺/ROS/NO/H₂S
May 14, 2026
Clicks：73
I. Core Differences Among Five Types of Fluorescent Probes
| Probe Type | Target Analyte | Representative Probes | Kd Value / Detection Range | Spectral Properties (Ex/Em) | Core Mechanism |
|---|---|---|---|---|---|
| Ca²⁺ Probes | Calcium ion (Ca²⁺) | Fluo‑4 AM, Fura‑2 | 100‑400 nM | 506/526 nm (Fluo‑4) | Fluorescence enhancement upon chelation |
| Na⁺ Probes | Sodium ion (Na⁺) | SBFI‑AM, CoroNa | 10‑20 mM | Dual‑excitation at 340/380 nm (SBFI) | Spectral shift upon chelation |
| ROS Probes | Reactive oxygen species (H₂O₂, O₂⁻, etc.) | H₂DCFDA, MitoSOX | ‑ | 488/525 nm (H₂DCFDA) | Fluorescence generation after oxidation |
| NO Probes | Nitric oxide (NO) | DAF‑FM DA | ‑ | 495/515 nm | Fluorescence enhancement after cyclization reaction with NO |
| H₂S Probes | Hydrogen sulfide (H₂S) | WSP‑1, SFP‑1 | ‑ | Visible light range (380‑550 nm) | Fluorophore release after thiolytic reaction |
II. Detailed Introduction and Key Differences of Each Probe Type
Ca²⁺ Probes (Most Well‑Established)
Representatives: Fluo‑4 AM (most commonly used), Fura‑2 (gold‑standard ratiometric probe), Rhod‑2 (red fluorescence)
Mechanism: Based on the BAPTA chelator structure; binding with Ca²⁺ inhibits photoinduced electron transfer (PET), leading to 10‑100‑fold fluorescence enhancement
Advantages: High sensitivity (detects nanomolar‑level changes), fast response (millisecond scale), AM‑ester form enables easy penetration into live cells
Limitations: Fluorescence intensity easily affected by probe concentration and cell thickness (non‑ratiometric probes); high concentration may buffer intracellular Ca²⁺ signals
Applications: Neuronal excitation, myocardial contraction, calcium oscillation studies
Na⁺ Probes (Selectivity Challenges)
Representative: SBFI‑AM (Sodium‑binding benzofuran isophthalate)
Mechanism: Structurally similar to Ca²⁺ probes but with different selectivity. Binding with Na⁺ shifts the excitation spectrum; dual‑excitation ratiometric quantification at 340/380 nm is required
Key Differences:
1) Low selectivity: K⁺ selectivity ratio is only 18:1 (Ca²⁺ probes >10⁶:1), requiring correction for K⁺ interference
2) High Kd value: ~10‑20 mM, matching intracellular Na⁺ concentration (5‑15 mM)
Applications: Renal tubular Na⁺ reabsorption, neuronal Na⁺ influx
ROS Probes (Reaction Specificity Issues)
Representatives: H₂DCFDA (total ROS), MitoSOX Red (mitochondrial superoxide anion O₂⁻‑specific)
Mechanism: H₂DCFDA is non‑fluorescent and oxidized by ROS into fluorescent DCF; MitoSOX targets mitochondria and is specifically oxidized by O₂⁻
Core Limitations: Non‑specificity — H₂DCFDA is oxidized by multiple ROS including H₂O₂, O₂⁻, and •OH; photosensitivity — prone to photo‑oxidation causing false positives; irreversibility — probes cannot be reset after reaction, only suitable for endpoint detection
Applications: Oxidative stress, drug toxicity, aging research
NO Probes (Oxygen‑Dependent Response)
Representative: DAF‑FM DA (4‑Amino‑5‑methylamino‑2',7'‑difluorofluorescein diacetate)
Mechanism: Reacts with NO in the presence of oxygen to form triazole fluorescein, with approximately 100‑fold fluorescence enhancement
Unique Features: Oxygen‑dependent — significantly reduced response under hypoxic conditions; slow response — reaction takes several minutes (millisecond‑scale for Ca²⁺ probes); pH‑sensitive — fluorescence intensity affected by pH
Applications: Vascular function, neural signal transmission, immune response
H₂S Probes (Emerging Probe Type)
Representatives: WSP‑1 (Washington State Probe), SFP‑1
Mechanism: H₂S‑mediated thiolytic reaction cleaves disulfide bonds or azide groups to release fluorophores
Distinctive Features:
1) Highest selectivity: Far higher H₂S selectivity than other thiols (cysteine, glutathione)
2) Late development: First effective probes appeared after 2011, less technically mature than Ca²⁺ probes
3) Variable response speed: WSP‑1 responds within <10 min, while some probes require >30 min
4) Validation required: Potential photostability issues of reaction products
Applications: Cardiovascular protective mechanisms, inflammatory regulation, mitochondrial function research
III. Probe Selection Guidelines
Which signal needs to be detected?
IV. Key Experimental Design Reminders
| Probe Type | Mandatory Controls | Common Pitfalls |
|---|---|---|
| Ca²⁺ | Ionomycin (max fluorescence), EGTA (min fluorescence) | Signal distortion caused by uneven probe loading |
| Na⁺ | Selectivity correction with gradient K⁺ solutions | Artificially high signals due to K⁺ interference |
| ROS | Antioxidant control (NAC) | Light‑induced false positives |
| NO | NO donor positive control (SNAP) | No response under hypoxic conditions |
| H₂S | NaHS positive control | Thiol interference requiring parallel reference controls |
Core Summary:
Ca²⁺ probes are the most technically mature but require distinction between ratiometric and non‑ratiometric types; Na⁺ probes exhibit the poorest selectivity; ROS probes have the lowest specificity; NO probes show the slowest response; H₂S probes are the newest with limited validation data. Positive and negative controls must be selected according to target characteristics and research objectives during experimental design.
Recommended Absin Fluorescent Probes
Ca²⁺ Probes
| Cat. No. | Product Name | λEx(nm)/ λEm (nm) |
|---|---|---|
| abs45153639 | Fluo‑3 AM (Green) | 506/526 |
| abs47014952 | Fluo‑4 AM (Green) | 494/516 |
| abs47045183 | Rhod‑2 AM (Red) | 557/581 |
Na⁺ Probes
| Cat. No. | Product Name | λEx(nm)/ λEm (nm) |
|---|---|---|
| abs42027097 | SBFI‑AM | 389/580 |
ROS Probes
| Cat. No. | Product Name | λEx(nm)/ λEm (nm) |
|---|---|---|
| abs42197174 | DCFH‑DA (Green) | 502/523 |
| abs810256 | DHE (Red) | 530/610 |
| abs42026818 | HPF (Green) | 490/515 |
NO Probes
| Cat. No. | Product Name | λEx(nm)/ λEm (nm) |
|---|---|---|
| abs819299 | DAF‑FM DA (Green) | 495/515 |
H₂S Probes
| Cat. No. | Product Name | λEx(nm)/ λEm (nm) |
|---|---|---|
| abs47044989 | WSP‑1 (Green) | 465/515 |
| abs47045297 | WSP‑5 (Green) | 502/525 |
Contact Absin
Absin provides antibodies, proteins, ELISA kits, cell culture, detection kits, and other research reagents. If you have any product needs, please contact us.
| Absin Bioscience Inc. worldwide@absin.cn |
 Follow us on Facebook: Absin Bio |