Molecularly imprinted polymers synthesized on a rigid substrate as a solid phase coupled with sers for detection of prostate cancer biomarker.
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Date
2025
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Publisher
Universidad de ConcepciĆ³n
Abstract
Prostate cancer (PCa) remains the most common malignancy in men worldwide, yet conventional prostate-specific antigen (PSA) testing faces significant limitations, including high false positives and unnecessary biopsies. To address these diagnostic challenges, the integration of molecularly imprinted polymers (MIPs) with surface-enhanced Raman spectroscopy (SERS) offers a promising alternative, providing enhanced sensitivity, specificity, and reproducibility compared to traditional antibody-based methods. This research aimed to develop a novel MIPs-SERS biosensing platform for highly sensitive and specific PSA detection, leveraging the molecular recognition capabilities of nanoMIPs and the signal enhancement properties of plasmonic gold nanostructures (NSs). The study focused on three main objectives: (1) optimizing seedless synthesis of gold nanoparticles (NPs) and nanorods (NRs) for SERS substrate fabrication, (2) developing free-radical solid-phase synthesis protocols for PSA-imprinted nanoMIPs using glass slides, and (3) constructing and evaluating integrated MIPs-SERS sensors for quantitative PSA detection. The research employed a systematic three-phase experimental approach. Gold NSs (NPs and NRs) were synthesized using modified Turkevich and seedless methods, correspondingly, with systematic optimization of key parameters (AgNO3, NaBH4, H2O2, and NaOH concentrations) to achieve longitudinal surface plasmon resonance (SPR) matching 630 nm laser excitation. Finitedifference time-domain (FDTD) simulations validated experimental observations and demonstrated electromagnetic field enhancements of 103-104 at NR tips. Solid-phase synthesis of nanoMIPs utilized sequential glass slide functionalization through piranha cleaning, silanization with APTES, and glutaraldehyde (GA) activation to create reactive surfaces for template immobilization. Free-radical polymerization employed optimized monomer compositions (NIPAm, TBAm, BIS, APMA, AAc) with APS/TEMED initiator systems, followed by temperature-dependent extraction protocols exploiting thermoresponsive polymer properties. Lysozyme (Lyz) was initially employed as a model protein to optimize synthesis conditions, yielding nanoMIPs with sizes ranging from 40-200 nm and narrow size distributions (PDI 0.1-0.3). The optimal formulation (S1: 5 mM total monomer concentration) demonstrated exceptional sensitivity with a limit of detection of 1.95 pM for Lyz and excellent linearity (R2= 0.9962). Subsequent PSA-imprinted nanoMIPs achieved remarkable analytical performance with detection limits reaching 0.02 pg/mL (attomolar range), representing a 5,000-fold improvement over conventional ELISA methods. Cross-reactivity studies confirmed high specificity, with the sensor effectively distinguishing PSA from interfering biomolecules including BSA and Lysozyme. The developed MIPs-SERS platform offers substantial improvements over current diagnostic methods. This research successfully demonstrates the feasibility of integrating solid-phase synthesized nanoMIPs with optimized plasmonic NSs for ultrasensitive PSA detection. The developed platform overcomes fundamental limitations of current PSA screening by providing enhanced sensitivity, specificity, and operational simplicity while maintaining cost-effectiveness. Future clinical translation through multicenter validation studies and expansion to additional cancer biomarkers represents the next critical phase in advancing precision oncology diagnostics.
Description
Tesis presentada para optar al grado de Doctor/a en Ciencias e IngenierĆa de Materiales.
Keywords
Imprinted polymers, Prostate Cancer, Solid-phase synthesis