A Glucose Biosensor Based on Phosphorescence Lifetime Sensing and a Thermoresponsive Membrane.

The adoption of existing continuous glucose monitors (CGMs) is limited by user burden. Herein, a design for a glucose biosensor with the potential for subcutaneous implantation, without the need for a transcutaneous probe or affixed transmitter, is presented. The design is based on the combination of an enzyme-driven phosphorescence lifetime-based glucose-sensing assay and a thermoresponsive membrane anticipated to reduce biofouling. The metalloporphyrin, Pd meso-tetra(sulfophenyl)-tetrabenzoporphyrin ([PdPh4 (SO3 Na)4 TBP]3 , HULK) as well as glucose oxidase (GOx) are successfully incorporated into the UV-cured double network (DN) membranes by leveraging electrostatic interactions and covalent conjugation, respectively. The oxygen-sensitive metalloporphyrin is incorporated at different levels within the DN membranes. These HULK-containing membranes retain the desired thermosensitivity, as well as glucose diffusivity and primary optical properties of the metalloporphyrin. After subsequently modifying the membranes with GOx, glucose-sensing experiments reveal that membranes prepared with the lowest GOx level exhibit the expected increase in phosphorescent lifetime for glucose concentrations up to 200 mg dL-1 . For membranes prepared with relatively higher GOx, oxygen-limited behavior is considered the source of diminished sensitivity at higher glucose levels. This proof-of-concept study demonstrates the promising potential of a biosensor design integrating a specific optical biosensing chemistry into a thermoresponsive hydrogel membrane.

Amphiphilic, thixotropic additives for extrusion-based 3D printing of silica-reinforced silicone.

The ability to utilize extrusion-based, direct ink write (DIW) 3D printing to create silica-reinforced silicones with complex structures could expand their utility in industrial and biomedical applications. Sylgard 184, a common Pt-cure silicone, lacks the thixotropic behavior necessary for effective printing and its hydrophobicity renders cured structures susceptible to biofouling. Herein, we evaluated the efficacy of various PEO-silane amphiphiles (PEO-SAs) as thixotropic and surface modifying additives in Sylgard 184. Eight amphiphilic PEO-SAs of varying architecture (e.g. linear, star, and graft), crosslinkability, and PEO content were evaluated. Modified formulations were also prepared with additional amounts of silica filler, both hexamethyldisilazane (HMDS)-treated and dimethyldichlorosilane (DiMeDi)-treated types. Numerous PEO-SA modified silicone formulations demonstrated effective water-driven surface hydrophilicity that was generally diminished with the addition of HMDS-treated silica filler. While increased yield stress was observed for PEO-SA modified silicones with added HMDS-treated filler, none achieved the initial target for 3D printing (>1000 Pa). Only the formulations containing the DiMeDi-treated filler (17.3 wt%) were able to surpass this value. These formulations were then tested for their thixotropic properties and all surpassed the targets for recovered storage modulus (G') (>1000 Pa) and loss factor (<0.8). In particular, the triblock linear PEO-SA produced exceptionally high recovered G', low loss factor, and substantial water-driven restructuring to form a hydrophilic surface. Combined, these results demonstrate the potential of silicones modified with PEO-SA surface-modifying additives (SMAs) for extrusion-based, DIW 3D printing applications.

Suitability of EtO Sterilization for Polydopamine-coated, Self-fitting Bone Scaffolds.

Irregularly shaped craniomaxillofacial (CMF) defects may be advantageously treated by "self-fitting" shape memory polymer (SMP) scaffolds, namely those prepared from poly(ε-caprolactone)diacrylate (PCL-DA) networks and PCL-DA/poly(L-lactic acid) (PLLA) (75:25 wt%) semi-interpenetrating polymer networks (semi-IPNs). In addition to achieving good scaffold-tissue contact, a polydopamine (PD) coating can be leveraged to enhance bioactivity for improved osseointegration. Sterilization with ethylene oxide (EtO) represents a logical choice due to its low operating temperature and humidity. Herein, for the first time, the impact of EtO sterilization on the material properties of PD-coated SMP scaffolds was systematically assessed. Morphological features (i.e., pore size and pore interconnectivity), and in vitro bioactivity were preserved as were PCL crystallinity, PLLA crystallinity, and crosslinking. These latter features led to sustained shape memory properties, and compressive modulus. EtO-sterilized, PD-coated scaffolds displayed similar in vitro degradation behaviors versus analogous non-sterilized scaffolds. This included maintenance of compression modulus following 28 days of exposure to non-accelerated degradation conditions.

PCL-Based Shape Memory Polymer Semi-IPNs: The Role of Miscibility in Tuning the Degradation Rate.

The utility of poly(ε-caprolactone) (PCL) as a shape memory polymer (SMP) may be improved by accelerating its degradation. Recently, we have reported novel semi-interpenetrating networks (semi-IPNs) composed of cross-linked PCL diacrylate (PCL-DA) and thermoplastic poly(l-lactic acid) (PLLA) that exhibited SMP behavior, accelerated degradation, and enhanced moduli versus the PCL-DA control. Herein, we systematically varied the thermoplastic component of the PCL-based semi-IPNs, incorporating homo- and copolymers based on lactic acid of different Mn, hydrophilicity, and crystallinity. Specifically, semicrystalline PLLAs of different Mns (7.5, 15, 30, and 120 kDa) were explored as the thermoplastics in the semi-IPNs. Additionally, to probe crystallinity and hydrophilicity, amorphous (or nearly amorphous) thermoplastics of different hydrophilicities (PDLLA and PLGAs 85:15, 70:30, and 50:50, l-lactide:glycolide mole % ratio) were employed. For all semi-IPNs, the wt % ratio of the cross-linked PCL-DA to thermoplastic was 75:25. The nature of the thermoplastics was linked to semi-IPN miscibility and the trends in accelerated degradation rates.

Enhanced Osteogenic Potential of Phosphonated-Siloxane Hydrogel Scaffolds.

In a material-guided approach, instructive scaffolds that leverage potent chemistries may efficiently promote bone regeneration. A siloxane macromer has been previously shown to impart osteoinductivity and bioactivity when included in poly(ethylene glycol) diacrylate (PEG-DA) hydrogel scaffolds. Herein, phosphonated-siloxane macromers were evaluated for enhancing the osteogenic potential of siloxane-containing PEG-DA scaffolds. Two macromers were prepared with different phosphonate pendant group concentrations, poly(diethyl(2-(propylthio)ethyl)phosphonate methylsiloxane) diacrylate (PPMS-DA) and 25%-phosphonated analogue (PPMS-DA 25%). Macroporous, templated scaffolds were prepared by cross-linking these macromers with PEG-DA at varying mol % (15:85, 30:70, and 45:55 PPMS-DA to PEG-DA; 30:70 PPMS-DA 25% to PEG-DA). Other scaffolds were also prepared by combining PEG-DA with PDMS-MA (i.e., no phosphonate) or with vinyl phosphonate (i.e., no siloxane). Scaffold material properties were thoroughly assessed, including pore morphology, hydrophobicity, swelling, modulus, and bioactivity. Scaffolds were cultured with human bone marrow-derived mesenchymal stem cells (normal media) and calcium deposition and protein expression were assessed at 14 and 28 days.

Double Network Hydrogels that Mimic the Modulus, Strength, and Lubricity of Cartilage.

The development of a hydrogel-based synthetic cartilage has the potential to overcome many limitations of current chondral defect treatments. Many attempts have been made to replicate the unique characteristics of cartilage in hydrogels, but none have simultaneously achieved high modulus, strength, and toughness while maintaining the necessary hydration required for lubricity. Herein, double network (DN) hydrogels, composed of a poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) first network and a poly( N-isopropylacrylamide- co-acrylamide) [P(NIPAAm- co-AAm)] second network, are evaluated as a potential off-the-shelf material for cartilage replacement. While predominantly used for its thermosensitivity, PNIPAAm is employed to achieve superior mechanical properties with its thermal transition temperature tuned above the physiological range. These PNIPAAm-based DNs demonstrate a 50-fold increase in compressive strength (∼25 MPa, similar to cartilage) compared to traditional single network hydrogels while also achieving cartilage-like modulus (∼1 MPa) and hydration (∼80%). In direct comparison to healthy cartilage (porcine), these hydrogels were confirmed to not only parallel the strength, modulus, and hydration of native articular cartilage but also exhibit a 50% lower coefficient of friction (COF). The exceptional cartilage-like properties of the PAMPS/P(NIPAAm- co-AAm) DN hydrogels makes them candidates for synthetic cartilage grafts for chondral defect repair, even in load-bearing regions of the body.

A self-cleaning, mechanically robust membrane for minimizing the foreign body reaction: towards extending the lifetime of sub-Q glucose biosensors.

Long-term, subcutaneously implanted continuous glucose biosensors have the potential to improve diabetes management and reduce associated complications. However, the innate foreign body reaction (FBR) both alters the local glucose concentrations in the surrounding tissues and compromises glucose diffusion to the biosensor due to the recruitment of high-metabolizing inflammatory cells and the formation of a dense, collagenous fibrous capsule. Minimizing the FBR has mainly focused on "passively antifouling" materials that reduce initial cellular attachment, including poly(ethylene glycol) (PEG). Instead, the membrane reported herein utilizes an "actively antifouling" or "self-cleaning" mechanism to inhibit cellular attachment through continuous, cyclic deswelling/reswelling in response to normal temperature fluctuations of the subcutaneous tissue. This thermoresponsive double network (DN) membrane is based on N-isopropylacrylamide (NIPAAm) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) (75:25 and 100:0 NIPAAm:AMPS in the 1st and 2nd networks, respectively; "DN-25%"). The extent of the FBR reaction of a subcutaneously implanted DN-25% cylindrical membrane was evaluated in rodents in parallel with a PEG-diacrylate (PEG-DA) hydrogel as an established benchmark biocompatible control. Notably, the DN-25% implants were more than 25× stronger and tougher than the PEG-DA implants while maintaining a modulus near that of subcutaneous tissue. From examining the FBR at 7, 30 and 90 days after implantation, the thermoresponsive DN-25% implants demonstrated a rapid healing response and a minimal fibrous capsule (~20-25 µm), similar to the PEG-DA implants. Thus, the dynamic self-cleaning mechanism of the DN-25% membranes represents a new approach to limit the FBR while achieving the durability necessary for long-term implantable glucose biosensors.

Antifouling amphiphilic silicone coatings for dairy fouling mitigation on stainless steel.

Pasteurization of dairy products is plagued by fouling, which induces significant economic, environmental and microbiological safety concerns. Herein, an amphiphilic silicone coating was evaluated for its efficacy against fouling by a model dairy fluid in a pilot pasteurizer and against foodborne bacterial adhesion. The coating was formed by modifying an RTV silicone with a PEO-silane amphiphile comprised of a PEO segment and flexible siloxane tether ([(EtO)3Si-(CH2)2-oligodimethylsiloxanem-block-(OCH2CH2)n-OCH3]). Contact angle analysis of the coating revealed that the PEO segments were able to migrate to the aqueous interface. The PEO-modified silicone coating applied to pretreated stainless steel was exceptionally resistant to fouling. After five cycles of pasteurization, these coated substrata were subjected to a standard clean-in-place process and exhibited a minor reduction in fouling resistance in subsequent tests. However, the lack of fouling prior to cleaning indicates that harsh cleaning is not necessary. PEO-modified silicone coatings also showed exceptional resistance to adhesion by foodborne pathogenic bacteria.

Porous Poly(ε-caprolactone)-Poly(l-lactic acid) Semi-Interpenetrating Networks as Superior, Defect-Specific Scaffolds with Potential for Cranial Bone Defect Repair.

The treatment of irregular cranial bone defects is currently limited due to the graft resorption that can occur when an ill-fitting interface exists between an autograft and the surrounding tissue. A tissue engineering scaffold able to achieve defect-specific geometries could improve healing. This work reports a macroporous, shape memory polymer (SMP) scaffold composed of a semi-interpenetrating network (semi-IPN) of thermoplastic poly(l-lactic acid) (PLLA) within cross-linked poly(ε-caprolactone) diacrylate (PCL-DA) that is capable of conformal fit within a defect. The macroporous scaffolds were fabricated using a fused salt template and were also found to have superior, highly controlled properties needed for regeneration. Specifically, the scaffolds displayed interconnected pores, improved rigidity, and controlled, accelerated degradation. Although slow degradation rates of scaffolds can limit healing, the unique degradation behavior observed could prove promising. Thus, the described SMP semi-IPN scaffolds overcome two of the largest limitations in bone tissue engineering: defect "fit" and tailored degradation.

Thermoresponsive Double Network Hydrogels with Exceptional Compressive Mechanical Properties.

The utility of thermoresponsive hydrogels, such as those based on poly(N-isopropylacrylamide) (PNIPAAm), is severely limited by their deficient mechanical properties. In particular, the simultaneous achievement of high strength and stiffness remains unreported. In this work, a thermoresponsive hydrogel is prepared having the unique combination of ultrahigh compressive strength (≈23 MPa) and excellent compressive modulus (≈1.5 MPa). This is accomplished by employing a double network (DN) design comprised of a tightly crosslinked, highly negatively charged 1st network based on poly(2-acrylamido-2-methylpropane sulfonic acid (PAMPS) and a loosely crosslinked, zwitterionic 2nd network based on a copolymer of thermoresponsive NIPAAm and zwitterionic 2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (MEDSAH). Comparison to other DN designs reveals that this PAMPS/P(NIPAAm-co-MEDSAH) DN hydrogel's remarkable properties stem from the intra- and internetwork ionic interactions of the two networks. Finally, this mechanically robust hydrogel retains the desirable thermosensitivity of PNIPAAm hydrogels, exhibiting a volume phase transition temperature of ≈35 °C.

PCL-PLLA Semi-IPN Shape Memory Polymers (SMPs): Degradation and Mechanical Properties.

Thermoresponsive shape memory polymers (SMPs) based on poly(ε-caprolactone) (PCL) whose shape may be actuated by a transition temperature (T trans ) have shown utility for a variety of biomedical applications. Important to their utility is the ability to modulate mechanical and degradation properties. Thus, in this work, SMPs are formed as semi-interpenetrating networks (semi-IPNs) comprised of a cross-linked PCL diacrylate (PCL-DA) network and thermoplastic poly(l-lactic acid) (PLLA). The semi-IPN uniquely allows for requisite crystallization of both PCL and PLLA. The influence of PLLA (PCL:PLLA wt% ratio) and PCL-DA molecular weight (n) on film properties are investigated. PCL-PLLA semi-IPNs are able to achieve enhanced mechanical properties and accelerated rates of degradation.

Bacteria and diatom resistance of silicones modified with PEO-silane amphiphiles.

Silicone coatings with enhanced antifouling behavior towards bacteria, diatoms, and a diatom dominated slime were prepared by incorporating PEO-silane amphiphiles with varied siloxane tether lengths (a-c): α-(EtO)3Si(CH2)2-oligodimethylsiloxanen-block-poly(ethylene oxide)8-OCH3 [n = 0 (a), 4 (b), and 13 (c)]. Three modified silicone coatings (A-C) were prepared by the acid-catalyzed sol-gel cross-linking of a-c, respectively, each with a stoichiometric 2:3 M ratio of α, ω-bis(Si-OH)polydimethylsiloxane (Mn = 3,000 g mol(-1)). The coatings were exposed to the marine bacterium Bacillus sp.416 and the diatom (microalga) Cylindrotheca closterium, as well as a mixed community of Bacillus sp. and C. closterium. In addition, in situ microfouling was assessed by maintaining the coatings in the Atlantic Ocean. Under all test conditions, biofouling was reduced to the highest extent on coating C which was prepared with the PEO-silane amphiphile having the longest siloxane tether length (c).

Trends in bioactivity: inducing and detecting mineralization of regenerative polymeric scaffolds.

Due to limitations of biological and alloplastic grafts, regenerative engineering has emerged as a promising alternative to treat bone defects. Bioactive polymeric scaffolds are an integral part of such an approach. Bioactivity importantly induces hydroxyapatite mineralization that promotes osteoinductivity and osseointegration with surrounding bone tissue. Strategies to confer bioactivity to polymeric scaffolds utilize bioceramic fillers, coatings and surface treatments, and additives. These approaches can also favorably impact mechanical and degradation properties. A variety of fabrication methods are utilized to prepare scaffolds with requisite morphological features. The bioactivity of scaffolds may be evaluated with a broad set of techniques, including in vitro (acellular and cellular) and in vivo methods. Herein, we highlight contemporary and emerging approaches to prepare and assess scaffold bioactivity, as well as existing challenges.

Star-PCL shape memory polymer (SMP) scaffolds with tunable transition temperatures for enhanced utility.

Thermoresponsive shape memory polymers (SMPs) prepared from UV-curable poly(ε-caprolactone) (PCL) macromers have the potential to create self-fitting bone scaffolds, self-expanding vaginal stents, and other shape-shifting devices. To ensure tissue safety during deployment, the shape actuation temperature (i.e., the melt transition temperature or Tm of PCL) must be reduced from ∼55 °C that is observed for scaffolds prepared from linear-PCL-DA (Mn ∼ 10 kg mol-1). Moreover, increasing the rate of biodegradation would be advantageous, facilitating bone tissue healing and potentially eliminating the need for stent retrieval. Herein, a series of six UV-curable PCL macromers were prepared with linear or 4-arm star architectures and with Mns of 10, 7.5, and 5 kg mol-1, and subsequently fabricated into six porous scaffold compositions (10k, 7.5k, 5k, 10k★, 7.5k★, and 5k★) via solvent casting particulate leaching (SCPL). Scaffolds produced from star-PCL-tetraacrylate (star-PCL-TA) macromers produced pronounced reductions in Tm with decreased Mnversus those formed with the corresponding linear-PCL-diacrylate (linear-PCL-DA) macromers. Scaffolds were produced with the desired reduced Tm profiles: 37 °C < Tm < 55 °C (self-fitting bone scaffold), and Tm ≤ 37 °C (self-expanding stent). As macromer Mn decreased, crosslink density increased while % crystallinity decreased, particularly for scaffolds prepared from star-PCL-TA macromers. While shape memory behavior was retained and radial expansion pressure increased, this imparted a reduction in modulus but with an increase in the rate of degradation.

Ultra-strong thermoresponsive double network hydrogels.

Thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels are widely studied smart materials, particularly for biomedical applications, but are limited by their mechanical strength. In this study, double network (DN) hydrogels were prepared with an asymmetric crosslink design and inclusion of an electrostatic co-monomer, 2-acrylamido-2-methylpropane sulfonic acid (AMPS). These P(NIPAAm-co-AMPS)/PNIPAAm DN hydrogels were sequentially formed with a tightly crosslinked 1st network comprised of variable levels of AMPS (100 : 0 to 25 : 75 wt% ratio of NIPAAm:AMPS) and a loosely crosslinked 2nd network comprised of PNIPAAm. The impact of AMPS content in the 1st network on the volume phase transition temperature (VPTT), morphology, deswelling-reswelling kinetics and mechanical properties was evaluated. Without substantially altering the VPTT of conventional PNIPAAm hydrogels but with improving thermosensitivity, the DN hydrogel formed with 25 : 75 wt% of NIPAAm:AMPS achieved exceptional strength, high modulus and high %strain at break.

Biomedical Silicones: Leveraging Additive Strategies to Propel Modern Utility.

Silicones have a long history of use in biomedical devices, with unique properties stemming from the siloxane (Si-O-Si) backbone that feature a high degree of flexibility and chemical stability. However, surface, rheological, mechanical, and electrical properties of silicones can limit their utility. Successful modification of silicones to address these limitations could lead to superior and new biomedical devices. Toward improving such properties, recent additive strategies have been leveraged to modify biomedical silicones and are highlighted herein.

Adhesive Hydrogel Building Blocks to Reconstruct Complex Cartilage Tissues.

Cartilage has an intrinsically low healing capacity, thereby requiring surgical intervention. However, limitations of biological grafting and existing synthetic replacements have prompted the need to produce cartilage-mimetic substitutes. Cartilage tissues perform critical functions that include load bearing and weight distribution, as well as articulation. These are characterized by a range of high moduli (≥1 MPa) as well as high hydration (60-80%). Additionally, cartilage tissues display spatial heterogeneity, resulting in regional differences in stiffness that are paramount to biomechanical performance. Thus, cartilage substitutes would ideally recapitulate both local and regional properties. Toward this goal, triple network (TN) hydrogels were prepared with cartilage-like hydration and moduli as well as adhesivity to one another. TNs were formed with either an anionic or cationic 3rd network, resulting in adhesion upon contact due to electrostatic attractive forces. With the increased concentration of the 3rd network, robust adhesivity was achieved as characterized by shear strengths of ∼80 kPa. The utility of TN hydrogels to form cartilage-like constructs was exemplified in the case of an intervertebral disc (IVD) having two discrete but connected zones. Overall, these adhesive TN hydrogels represent a potential strategy to prepare cartilage substitutes with native-like regional properties.

Amphiphilic silicones for the facile dispersion of carbon nanotubes and formation of soft skin electrodes.

Flexible, dry skin electrodes represent a potentially superior alternative to standard Ag/AgCl metal electrodes for wearable devices used in long-term monitoring. Herein, such electrodes were formed using a facile method for dispersing carbon nanotubes (CNTs) in a silicone matrix using custom amphiphilic dispersive additives (DSPAs). Using only brief mixing and without the use of solvents or surface modification of CNTs, twelve poly(ethylene oxide)-silanes (PEO-SAs) of varying crosslinkability, architecture, siloxane tether length, and molar ratio of siloxane:PEO were combined with an addition cure silicone and CNTs. Nearly all PEO-SA modified silicone-CNT composites demonstrated improved conductivity compared to the unmodified composite. Best conductivities correlated to composites prepared with PEO-SAs that formed micelles of particular sizes (d ~ 200 - 300 nm) and coincided to PEO-SAs with a siloxane:PEO molar ratio of ~ 0.75 - 3.00. Superior dispersion of CNT by such PEO-SAs was exemplified by scanning electron microscopy (SEM). Advantageously, modified composites retained their moduli, rather than becoming more rigid. Resultant electrodes fabricated with modified composites showed skin-electrode impedance comparable to that of Ag/AgCl electrodes. Combined, these results demonstrate the potential of silicone-CNT composites prepared with PEO-SA DSPAs as flexible, dry electrodes as a superior alternative to traditional electrodes.

High-Throughput Screening of Thiol-ene Click Chemistries for Bone Adhesive Polymers.

Metal surgical pins and screws are employed in millions of orthopedic surgical procedures every year worldwide, but their usability is limited in the case of complex, comminuted fractures or in surgeries on smaller bones. Therefore, replacing such implants with a bone adhesive material has long been considered an attractive option. However, synthesizing a biocompatible bone adhesive with a high bond strength that is simple to apply presents many challenges. To rapidly identify candidate polymers for a biocompatible bone adhesive, we employed a high-throughput screening strategy to assess human mesenchymal stromal cell (hMSC) adhesion toward a library of polymers synthesized via thiol-ene click chemistry. We chose thiol-ene click chemistry because multifunctional monomers can be rapidly cured via ultraviolet (UV) light while minimizing residual monomer, and it provides a scalable manufacturing process for candidate polymers identified from a high-throughput screen. This screening methodology identified a copolymer (1-S2-FT01) composed of the monomers 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TATATO) and pentaerythritol tetrakis (3-mercaptopropionate) (PETMP), which supported highest hMSC adhesion across a library of 90 polymers. The identified copolymer (1-S2-FT01) exhibited favorable compressive and tensile properties compared to existing commercial bone adhesives and adhered to bone with adhesion strengths similar to commercially available bone glues such as Histoacryl. Furthermore, this cytocompatible polymer supported osteogenic differentiation of hMSCs and could adhere 3D porous polymer scaffolds to the bone tissue, making this polymer an ideal candidate as an alternative bone adhesive with broad utility in orthopedic surgery.

Porous inorganic-organic shape memory polymers.

Thermoresponsive shape memory polymers (SMPs) are a type of stimuli-sensitive materials that switch from a temporary shape back to their permanent shape upon exposure to heat. While the majority of SMPs have been fabricated in the solid form, porous SMP foams exhibit distinct properties and are better suited for certain applications, including some in the biomedical field. Like solid SMPs, SMP foams have been restricted to a limited group of organic polymer systems. In this study, we prepared inorganic-organic SMP foams based on the photochemical cure of a macromer comprised of inorganic polydimethylsiloxane (PDMS) segments and organic poly(ε-caprolactone) (PCL) segments, diacrylated PCL(40)-block-PDMS(37)-block-PCL(40). To achieve tunable pore size with high interconnectivity, the SMP foams were prepared via a refined solvent-casting/particulate-leaching (SCPL) method. By varying design parameters such as degree of salt fusion, macromer concentration in the solvent and salt particle size, the SMP foams with excellent shape memory behavior and tunable pore size, pore morphology, and modulus were obtained.