| Abstract
| - Nanoporous polymer-based spheres, synthesized by the sequential assembly of various macromolecules (polyelectrolytes, peptides, and proteins) in mesoporous silica (MS) particles followed by removal of the MS templates, can be designed with tailored composition and functionality. This approach affords a versatile and general method to prepare nanoporous particles for potential use in delivery, sensing, and catalysis applications.
- Nanoporous polymer-based spheres were synthesized via sequential assembly of macromolecules (e.g.,polyelectrolytes (PEs), peptides, and proteins) in mesoporous silica (MS) particles, followed by removalof the MS templates. The sequential infiltration of PEs in the mesopores for the model system poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) was demonstrated by various methods,including nitrogen sorption, thermogravimetric analysis, Fourier transform infrared, and confocal laserscanning microscopy (CLSM). The influence of parameters such as layer cross-linking, solution pH,ionic strength, and MS pore size on the synthesis of the PAA/PAH nanoporous polymer spheres (NPS)was investigated. Cross-linking between PAA and PAH was found to add structural integrity to the NPS,while the solution pH and ionic strength govern the conformation of the PEs in solution and the subsequentability of the PEs to infiltrate the mesopores and thereby form intact NPS. Transmission and scanningelectron microscopy data show that the PAA/PAH NPS have pores ranging from about 5−50 nm, whichwas further confirmed by CLSM of protein-loaded NPS. The PAA/PAH NPS exhibited a high capacityfor enzyme loading (ca. 470 mg mL-1 for lysozyme), with stimuli-responsive reversible loading andrelease of the protein triggered by changes in solution pH. The general applicability of the reportedapproach is demonstrated by the preparation of NPS containing peptides, proteins, and low molecularweight molecules. MS fibers were also used as templates to generate PAA/PAH nanoporous fibers, showingthat this process is applicable to templates with different morphologies. These nanoporous materials areenvisaged to find application in biosensing, enzyme catalysis, and controlled drug delivery.
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