What Would Be The Optimal Surface Roughness And Topography Of A Poly(lactic-co-glycolic Acid) (PLGA) Substrate To Enhance The Adhesion And Proliferation Of Human Mesenchymal Stem Cells (hMSCs) On A Micro-electromechanical Systems (MEMS)-based Cell Sorting Device, Considering The Effects Of Plasma Treatment And Chemical Surface Modification On The Substrate's Hydrophilicity And Protein Adsorption?

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To optimize a PLGA substrate for enhancing hMSC adhesion and proliferation in a MEMS-based cell sorting device, consider the following structured approach:

  1. Surface Roughness and Topography:

    • Nano-scale Roughness: Opt for nano-scale roughness (Ra: 10-100 nm) to mimic the extracellular matrix, promoting better cell interaction.
    • Hierarchical Structures: Incorporate a combination of nano and micro features to provide mechanical cues and increase surface area for cell attachment.

  2. Plasma Treatment:

    • Use oxygen plasma treatment to enhance hydrophilicity, improving cell adhesion. Optimize treatment duration to avoid damaging the PLGA surface.

  3. Chemical Surface Modifications:

    • Immobilize bioactive molecules like RGD peptides to promote cell adhesion. Consider grafting polymers to tune hydrophilicity and protein adsorption.

  4. Protein Adsorption:

    • Ensure a balance in surface hydrophilicity to facilitate beneficial protein adsorption without denaturation, aiding cell adhesion.

  5. MEMS Compatibility:

    • Design topography to avoid interfering with device operation, ensuring features do not clog microchannels or affect sensors.

  6. Testing and Validation:

    • Assess hydrophilicity via contact angle measurements, roughness with AFM/SEM, and protein adsorption using ELISA or mass spectrometry.
    • Conduct in vitro tests to evaluate hMSC adhesion, proliferation, and differentiation, examining focal adhesions and cytoskeleton organization.

  7. Optimization:

    • Balance modifications to avoid over-treatment, ensuring the surface is conducive to cell interaction without adverse effects.

In conclusion, the optimal PLGA substrate would feature nano-scale roughness with hierarchical structures, oxygen plasma treatment for hydrophilicity, and RGD peptide modification for enhanced cell adhesion. Experimental validation is essential to refine parameters and ensure MEMS compatibility.