Ethanol, 2-[2-[2-[2-[4-(2-benzothiazolyl)phenoxy]ethoxy]ethoxy]ethoxy]-

2-(2-(2-(2-(4-(Benzo[D]thiazol-2-yl)phenoxy)ethoxy)ethoxy)ethoxy)ethanol (CAS: 2274723-90-7) is a highly valuable multifunctional linker and fluorescent building block widely used in bioconjugation, drug delivery, and advanced materials development. Featuring a bright benzothiazole fluorophore conjugated to a hydrophilic tetra(ethylene glycol) (PEG4) spacer with a terminal hydroxyl group, it offers excellent water solubility, stable fluorescence emission, and a versatile handle for further derivatization, making it an important reagent in modern chemical biology and nanomedicine. Its primary applications are outlined below:

1. Bioconjugation & Drug Delivery

Key Spacer for Antibody‑Drug Conjugates (ADCs)
The PEG4 chain provides optimal hydrophilicity and flexibility to reduce aggregation and improve pharmacokinetic properties. This compound serves as a cleavable or non‑cleavable linker precursor for attaching cytotoxic payloads to monoclonal antibodies, supporting the development of targeted cancer therapies.

Targeted Drug Delivery Systems
The terminal hydroxyl group can be activated (e.g., as a carbonate, succinimidyl ester, or alkyne) for conjugation with targeting ligands such as folate, peptides, or saccharides. The benzothiazole moiety allows for real‑time fluorescence tracking of nanocarriers, liposomes, or polymer‑drug conjugates in cellular and in vivo studies.

2. Fluorescent Probes & Bioimaging

Versatile Fluorophore for Live‑Cell Imaging
Benzothiazole derivatives are known for their high quantum yield, large Stokes shift, and environmental sensitivity. This compound can be directly used as a membrane‑permeable fluorescent tracer, or further modified with reactive groups (e.g., NHS ester, maleimide) to label proteins, antibodies, or nucleic acids for fluorescence microscopy and flow cytometry.

Development of Ratiometric and Turn‑On Sensors
The PEGylated benzothiazole scaffold can be conjugated with recognition moieties (e.g., boronic acids for sugars, crown ethers for metal ions) to construct smart sensors. Its excellent water solubility enables assays in physiological buffers without organic co‑solvents, making it suitable for detecting biomarkers, enzyme activities, or reactive oxygen species.

3. Materials Science & Polymer Chemistry

Functional Monomer for Smart Hydrogels
The terminal hydroxyl group allows polymerization or post‑functionalization with acrylates, methacrylates, or epoxides. Incorporating this benzothiazole‑PEG4 unit into hydrogels or dendritic polymers imparts fluorescent tracking capability and improved biocompatibility for tissue engineering and drug release monitoring.

Surface Modification & Biosensor Interfaces
The PEG4 chain acts as an anti‑fouling spacer when immobilized on gold, glass, or silica surfaces. The benzothiazole fluorophore provides a stable optical readout for microarray chips, lateral flow assays, and fiber‑optic sensors, enhancing signal‑to‑noise ratios in complex biological matrices.

4. Research & Development Applications

High‑Throughput Screening (HTS) Probe Development
Researchers employ this compound to synthesize fluorescently labeled small‑molecule libraries or peptide arrays. Its defined structure and stable photophysics support hit identification in target‑based and phenotypic screens for drug discovery.

Process Development & Scale‑Up
The crystalline or waxy solid form, combined with straightforward PEGylation chemistry, makes this compound suitable for laboratory‑scale synthesis, gram‑to‑kilogram production, and GMP‑compliant linker manufacturing for preclinical and clinical ADC programs.

Handling & Storage

Storage Conditions
Store in tightly sealed, light‑protected containers under an inert atmosphere (e.g., argon) at –20°C for long‑term stability, or at 2–8°C for short‑term use. The PEG chain is hygroscopic; minimize exposure to ambient air. Avoid strong oxidizing agents and prolonged heating.

Intended Use
This compound is intended for research, development, and intermediate manufacturing applications only. It is not for direct human or veterinary use, nor for diagnostic or therapeutic purposes without appropriate regulatory approval.

Summary

The value of 2-(2-(2-(2-(4-(benzo[D]thiazol-2-yl)phenoxy)ethoxy)ethoxy)ethoxy)ethanol lies in its unique combination of a bright, stable benzothiazole fluorophore and a hydrophilic, bioinert PEG4 spacer with a reactive terminal hydroxyl group. This structure enables the construction of targeted drug conjugates, fluorescent probes, and smart biomaterials with excellent water solubility and traceability. Its well‑defined chemistry and reliable performance make it an indispensable building block for modern bioconjugation, imaging, and nanomedicine research.

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