Table 1 Summary of processes for cyanobacterial culture, PC extraction, analysis, and sensor Preparation

Cyanobacterial culture

Strain

Neowestiellopsis persica (CCC ALBORZ collection, Iran)

Growth medium

Modified liquid Z8 medium

Light intensity

300 µmol/m²/s

Temperature

28 ± 2 °C

Incubation period

10–15 days (log-phase harvested at 14 days)

Magnetic field (MF) exposure

Intensity

30 mT and 60 mT (ferrite magnets)

Duration

1 h daily; magnets positioned 15 cm above culture vessels

Post-exposure processing

Centrifugation at 4,000 rpm for cell pelleting

PC extraction

Biomass source

500 mL log-phase culture (14 days)

Centrifugation

4,000 rpm (cell pellet), 10,000 rpm (30 min, supernatant clarification)

Buffers

Phosphate buffer (pH 7.2), sodium phosphate buffer (0.1 M, pH 7.2)

Cell disruption

Repeated freeze-thaw cycles (− 20 °C freezing, room tempration thawing; 1 week)

Lyophilization

Supernatant lyophilized; stored at − 20 °C

Spectrophotometric analysis

Instrument

UV-Vis spectrophotometer

Wavelengths

\(\:{\mathbf{A}}_{615},\:{\mathbf{A}}_{620},\:{\mathbf{A}}_{652},\:{\mathbf{A}}_{280}\)

Standardization

Urea (0–10 M)

Antibacterial assays

Test organism

Staphylococcus aureus (1.0×\(\:{10}^{7}\) CFU/mL)

Disc diffusion assay

Inhibition zone measured after 24 h at 37 °C (triplicate)

MIC/MBC determination

Microdilution method; MIC = lowest inhibitory concentration; MBC = 99.9% CFU reduction

Sensor preparation

Coating agents

2% (w/w) (NCT), 2% (w/w) (SA)

Matrix solution

10% (w/w) (PVA) in deionized water (60 °C, 30 min stirring)

Plasticizer

15% (w/w) glycerol

Homogenization

10,000 rpm

Film formation

Casting in Petri dishes; drying at 25 ± 2 °C (48 h) followed by 50 °C (5 h)