A cost-effective approach to surface activation of polypropylene microplates for covalent immobilization of a protein

The conventional surface modification of inert polymers to immobilize biomolecules has been dependent on specialized UV crosslinkers or Stratalinker devices, although the prohibitive cost of these instruments has been a significant limiting factor to laboratories in resource-poor environments. The use of natural sunlight as a free solution has previously been discussed; however, this method has the disadvantage of variable UV intensity and is also weather-dependent and not reproducible. To overcome these drawbacks, the current study assesses the application of a typical laboratory UV cabinet-typically used to sterilize and document gels-as an affordable and feasible alternative to UV-mediated activation of polypropylene micro test plates (PPµTPs). Comparative experiments demonstrated that the greatest immobilization efficiency of PPμTP was achieved with short-wavelength UV exposure (254 nm) in a UV cabinet, yielding a mean saturation of 72.0 ± 1.4% (CV = 1.9%). In contrast, long-wavelength UV (365 nm) produced moderate activation (44.8 ± 1.6%, CV = 3.5%), while direct sunlight gave 60.1 ± 10.2% (CV = 16.9%), reflecting significant variability due to environmental factors. These results indicate that UV cabinets, particularly at 254 nm, offer reproducible, consistent, and cost-effective activation. Moreover, repurposing common laboratory equipment for polymer activation can increase access to high-quality biomolecular assays in low-resource research settings, providing a practical solution for laboratories that lack specialized instrumentation while maintaining reliable experimental outcomes.