Physically cross-linked protein-based materials possess a number of advantages over their chemically cross-linked counterparts, including ease of processing and the ability to avoid the addition or removal of chemical reagents or unreacted intermediates. The investigations reported herein sought to examine the nature of physical cross-links within two-phase elastin−mimetic protein triblock copolymer networks through an analysis of macroscopic viscoelastic properties. Given the capacity of solution processing conditions, including solvent type and temperature to modulate the microstructure of two-phase protein polymer networks, viscoelastic properties were examined under conditions in which interphase block mixing had been either accentuated or diminished during network formation. Protein networks exhibited strikingly different properties in terms of elastic modulus, hysteresis, residual deformability, and viscosity in response to interdomain mixing. Thus, two-phase protein polymer networks exhibit tunable responses that extend the range of application of these materials to a variety of tissue engineering applications.
Electrospinning was employed to fabricate 3-D fiber networks from a recombinant amphiphilic elastin-mimetic tri-block protein polymer and the effects of moderate thermal conditioning (60 degrees C, 4 h) on network mechanical responses investigated. Significantly, while cryo-high resolution scanning electron microscopy (cryo-HRSEM) revealed that the macroscopic and microscopic morphology of the network structure was unchanged, solid-state (1)H-NMR spectroscopy demonstrated enhanced interphase mixing of hydrophobic and hydrophilic blocks. Significantly, thermal annealing triggered permanent changes in network swelling behavior (28.75 +/- 2.80 non-annealed vs. 13.55 +/- 1.39 annealed; P < 0.05) and uniaxial mechanical responses, including Young's modulus (0.170 +/- 0.010 MPa non-annealed vs. 0.366 +/- 0.05 MPa annealed; P < 0.05) and ultimate tensile strength (0.079 +/- 0.008 MPa vs. 0.119 +/- 0.015 MPa; P < 0.05). To our knowledge, these investigations are the first to note that mechanical responses of protein polymers can be permanently altered through a temperature-induced change in microphase mixing.
Objective: This pilot study explores the patient-centered demand for mobile phone-based health (mobile health [m-health]) services in the rural United States by documenting rural patients' access to mobile phones and patients' willingness to receive m-health services. Subjects and Methods: An anonymous institutional review board–approved survey was completed by patients visiting two rural pharmacies in Nebraska from August to October 2011. Patients who volunteered to complete the survey provided their demographic data, disease state information, health status, mobile phone access, and willingness to receive (in terms of using and giving time to) m-health services. Results: The majority of the 24 survey respondents were 19–40 years old (52%), female (88%), married (63%), with excellent to very good health status (63%), with no comorbidities (83%), with ≤$100 monthly medication expenses (80%), with private insurance (78%), living within 5 miles of their pharmacy (71%), and reporting that m-health services are important to them (75%; 12/16). Approximately 95%, 81%, 73%, and 55% of respondents reported access to a mobile phone, voice mails, text messaging, and mobile phone applications, respectively. Of the respondents, 65%, 57%, 52%, and 48% were willing to receive prerecorded messages for appointment reminders from the doctor, disease information, medication use/self-care information, and symptom monitoring information, respectively. In total, 70%, 63%, 61%, 54%, and 50% were willing to receive prerecorded messages from the pharmacist containing contact requests, new/refill prescription reminders, information on medication problems, reviewing/monitoring of medication use, and medication self-management/preventive screenings/immunizations, respectively. Of 44% (7/16) respondents willing to give time for m-health services, 83% were willing to give 15 min, and 17% were willing to give 30 min every month. Conclusions: By demonstrating rural patients' demand for m-health (including pharmacy) services, this is one of the first pilot studies showing rural patients have access to mobile phones and may be willing to use and give time to m-health services. Further research is needed on delivery and coordination of transitions in patient-centered care in the United States with m-health services.
Protein secondary structures may exhibit reversible transitions that occur in an abrupt and controllable manner. In this report, we demonstrate that such transitions may be utilized in the design of a "smart" protein micellar system, in which a stimulus-induced change in protein structure triggers a rapid change in micelle compacticity and size. Specifically, recombinant DNA methods were used to prepare a protein triblock copolymer containing a central hydrophilic block and two hydrophobic end blocks derived from elastin-mimetic peptide sequences. Below the copolymer inverse transition temperature (Tt), dilute solutions of this amphiphilic protein formed monodispersed micelles in a narrow range of RH of ∼100 nm. When the the temperature was raised above Tt, an abrupt increase in micelle internal density was observed with a concomitant reduction in micelle size. This reversible change in micelle compacticity was triggered by helix-to-sheet protein folding transition. Significantly, these protein polymer-based micelles, which are rapidly responsive to environmental stimuli, establish a new mechanism for the design of controlled drug delivery vehicles.
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