Immunoassays have shown great advances in the fields of biomedical diagnosis. However, successful immunoassays in blood plasma or whole blood based on the designed biointerfaces are still rare. Here, a newly cell-inspired biointerface for immunoassays in blood is demonstrated. Inspired by the high resistance to protein and cell adhesion and extraordinary biological recognition of stem cells, the biointerfaces are constructed by patterning smart hydrogels (PNIPAAm-co-PNaAc) on hydrophilic layers (PEG), followed by immobilization of antibodies on the patterned hydrogels. The hierarchical biointerfaces are hydrophilic to resist blood plasma and blood cell adhesion, but exhibit high affinity to the target antigens. As a result, successful immunoassays in blood are achieved. In addition, the detection signal is further enhanced by the manipulation of the phase transition of the smart hydrogels with temperature, and the sensitivity is higher than that of the widely-used poly(acrylic acid)/(polyacrylate) platform. The biointerface is versatile and effective in antibody–antigen recognition, which offers a potential new approach for developing highly sensitive immunoassays in blood.

A simple approach for preparing bicomponent polymer patterns was developed by coating polydopamine (PDA) on superhydrophilic poly(2-acryl-amido-2-methylpropane sulfonic acid) (PAMPS) brushes. Well-defined and versatile arrays of proteins and cells were achieved without harm to proteins and cells.

A newly glycopolymer-patterned surface for capturing red blood cells (RBCs) is demonstrated. Our strategy is based on the surface-initiated photopolymerization of 2-acryl-amido-2-methylpropane sulfonic acid (AMPS) on a thermoplastic elastomer, the patterning of poly(D-gluconamidoethyl methacrylate) (PGAMA, glycopolymer) micro-domains on the PAMPS layer with photomask-assisted photolithography, followed by the generation of a phytohemagglutinin (PHA) array on the patterned surface through lectin–carbohydrate recognition. We demonstrate that the bi-component polymer-patterned surface with high lateral resolution is successfully fabricated; the PAMPS layer with patterned glycopolymer domains remains hydrophilic to resist non-specific plasma protein adsorption and cell adhesion; the PHA array on the patterned PGAMA domains induces nearly no platelet adhesion on the patterned surface, but shows high capability for capturing RBCs in the blood, and in addition, the captured RBCs maintain cellular integrity and function. Our work presented herein not only paves a new way for capturing RBCs from the blood, but also establishes a basic principle to capture non-adherent cells in the blood or biological fluid without damage.

The hemolysis of erythrocytes is a big obstacle to the development of new non-plasticizer polymer containers for erythrocyte preservation. To construct a long-term anti-hemolytic surface of a plasticizer-free polymer, we coaxially electrospin core–shell structured D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS)/poly(ethylene oxide) nanofibers on the surface of a styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) elastomer that is covered with grafted poly(ethylene glycol) (PEG) chains. Our strategy is based on the fact that the grafted layers of PEG reduce mechanical damage to red blood cells (RBCs) while the TPGS released from the nanofibers on a blood-contacting surface can act as an antioxidant to protect RBCs from oxidative damage. We demonstrate that TPGS/PEO core–shell structured nanofibers have been well prepared on the surface of PEG modified SEBS; the controlled release of TPGS in distilled water is obtained and the release can last for almost 4 days at 4 °C; during RBC preservation, TPGS acts as the antioxidant to decrease the membrane oxidation and hemolysis of RBCs. Our work paves a new way for the development of non-plasticizer polymers for RBC preservation, which may be helpful for the fabrication of long-term anti-hemolytic biomaterials in vivo.

A novel hydrophilic PAMPS–PAAm brush pattern is fabricated to selectively capture blood cells from whole blood. PAMPS brushes provide antifouling surfaces to resist protein and cell adhesion while PAAm brushes effectively entrap targeted proteins for site-specific and cell-type dependent capture of blood cells.

•The blood-contacting surface was constructed by coaxial electrospinnig of (ascorbic acid and lecithin)/PEO core–shell nanofibers onto the surface of PEG-grafted SEBS.•Ascorbic acid and lecithin could release from the nanofibers and interact with erythrocyte to reduce oxidation and lipid loss of the stored erythrocyte, resulting in low mechanical fragility and hemolysis of stored erythrocyte.•Our work paved new way to fabricate biomaterials with the capability of long-term anti-hemolysis.There is an urgent need to develop blood-contacting biomaterials with long-term anti-hemolytic capability. To obtain such biomaterials, we coaxially electrospin [ascorbic acid (AA) and lecithin]/poly (ethylene oxide) (PEO) core–shell nanofibers onto the surface of styrene-b-(ethylene-co-butylene)-b-styrene elastomer (SEBS) that has been grafted with poly (ethylene glycol) (PEG) chains. Our strategy is based on that the grafted layers of PEG render the surface hydrophilic to reduce the mechanical injure to red blood cells (RBCs) while the AA and lecithin released from nanofibers on blood-contacting surface can actively interact with RBCs to decrease the oxidative damage to RBCs. We demonstrate that (AA and lecithin)/PEO core–shell structured nanofibers have been fabricated on the PEG grafted surface. The binary release of AA and lecithin in the distilled water is in a controlled manner and lasts for almost 5 days; during RBCs preservation, AA acts as an antioxidant and lecithin as a lipid supplier to the membrane of erythrocytes, resulting in low mechanical fragility and hemolysis of RBCs, as well as high deformability of stored RBCs. Our work thus makes a new approach to fabricate blood-contacting biomaterials with the capability of long-term anti-hemolysis.

The construction of biocompatible and antibacterial surfaces is becoming increasingly important. However, most of the existing techniques require multi-step procedures, stringent conditions and specific substrates. We present here a facile method to create a biocompatible and antibacterial surface on virtually any substrate under ambient conditions. The strategy is based on casting a highly adherent elastomer, styrene-b-(ethylene-co-butylene)-b-styrene, from a solvent mixture of xylene and decanol, in which decanol acts as both a polymer precipitator to induce phase separation and a liquid template to stabilize the superhydrophobic structure. The stable and durable superhydrophobic surface shows good biocompatibility and antibacterial properties.

Contrary to a prevailing concept on protein adsorption and cell adhesion, novel micropatterned polyacrylamide (PAAm) brushes that can resist cell adhesion but promote protein retention are created through patterning of ATRP initiators and surface-initiated ATRP on a polymer substrate.

Hemolysis of red blood cells (RBCs) caused by implant devices in vivo and nonpolyvinyl chloride containers for RBC preservation in vitro has recently gained much attention. To develop blood-contacting biomaterials with long-term antihemolysis capability, we present a facile method to construct a hydrophilic, 3D hierarchical architecture on the surface of styrene-b-(ethylene-co-butylene)-b-styrene elastomer (SEBS) with poly(ethylene oxide) (PEO)/lecithin nano/microfibers. The strategy is based on electrospinning of PEO/lecithin fibers onto the surface of poly [poly(ethylene glycol) methyl ether methacrylate] [P(PEGMEMA)]-modified SEBS, which renders SEBS suitable for RBC storage in vitro. We demonstrate that the constructed 3D architecture is composed of hydrophilic micro- and nanofibers, which transforms to hydrogel networks immediately in blood; the controlled release of lecithin is achieved by gradual dissolution of PEO/lecithin hydrogels, and the interaction of lecithin with RBCs maintains the membrane flexibility and normal RBC shape. Thus, the blood-contacting surface reduces both mechanical and oxidative damage to RBC membranes, resulting in low hemolysis of preserved RBCs. This work not only paves new way to fabricate high hemocompatible biomaterials for RBC storage in vitro, but provides basic principles to design and develop antihemolysis biomaterials for implantation in vivo.Keywords: blood-contacting surface; controlled release; electrospinning; hemolysis; lecithin;

Detection of dysfunctional and apoptotic cells plays an important role in clinical diagnosis and therapy. To develop a portable and user-friendly platform for dysfunctional and aging cell detection, we present a facile method to construct 3D patterns on the surface of styrene-b-(ethylene-co-butylene)-b-styrene elastomer (SEBS) with poly(ethylene glycol) brushes. Normal red blood cells (RBCs) and lysed RBCs (dysfunctional cells) are used as model cells. The strategy is based on the fact that poly(ethylene glycol) brushes tend to interact with phosphatidylserine, which is in the inner leaflet of normal cell membranes but becomes exposed in abnormal or apoptotic cell membranes. We demonstrate that varied patterned surfaces can be obtained by selectively patterning atom transfer radical polymerization (ATRP) initiators on the SEBS surface via an aqueous-based method and growing PEG brushes through surface-initiated atom transfer radical polymerization. The relatively high initiator density and polymerization temperature facilitate formation of PEG brushes in high density, which gives brushes worm-like morphology and superhydrophilic property; the tendency of dysfunctional cells adhered on the patterned surfaces is completely different from well-defined arrays of normal cells on the patterned surfaces, providing a facile method to detect dysfunctional cells effectively. The PEG-patterned surfaces are also applicable to detect apoptotic HeLa cells. The simplicity and easy handling of the described technique shows the potential application in microdiagnostic devices.Keywords: 3D patterned surface; dysfunctional cell detection; phosphatidylserine; poly(ethylene glycol) brushes; superhydrophilicity

Platelets have exhibited capabilities beyond clotting in recent years. Most of their functions are related to the nature of platelet adhesion. Establishing a facile method to understand the platelet adhesion and assess the platelet function through the mechanism and mechanics of adhesion is highly desired. Here, we report a generally applicable UV lithography technique with a photomask, which performs selective surface functionalization on large substrate areas, for creating stable, physical adhesive sites in the range of 12 μm to 3 μm. Our study demonstrated that the patterned surface facilitated probing of single platelet adhesion in a quantitative manner, and rendered platelets sensitive to adhesive proteins even at a low protein concentration. In addition, the platelet function in the presence of antiplatelet (anticancer) agents on platelets could be accurately estimated based on single platelet adhesion (SPA). This work paves a new way to understand and assess the blood platelet function. The SPA assay methodology has the potential to enable a rapid, accurate point-of-care platform suitable for evaluation of platelet function, detection of dysfunctional platelets, and assay of drug effects on platelets in cancer patients.

Despite the importance of adhesion between electrospun meshes and substrates, the knowledge on adhesion mechanism and the method to improve the adhesion remain limited. Here, we precisely design the model system based on electrospun poly(ethylene oxide) (PEO) meshes and the substrate of styrene-b-(ethylene-co-butylene)-b-styrene elastomer (SEBS), and quantitatively measure the adhesion with a weight method. The surfaces of SEBS with different roughness are obtained by casting SEBS solution on the smooth and rough glass slides, respectively. Then, the surfaces of casted SEBS are respectively grafted with PEG oligomers and long PEG chains much larger than the entanglement molecular weight by surface-initiated atom transfer radical polymerization (SI-ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA). The detached surfaces of SEBS and electrospun fibers after adhesion measurements are analyzed by scanning electron microscopy (SEM). The adhesive force and adhesion energy are found to lie in the range from 68 to 220 mN and from 12 to 46 mJ/m2, respectively, which are slightly affected by surface roughness of substrate but mainly determined by surface interactions. Just as the chemical cross-linking induces the strong adhesion, the chain entanglements on the interface lead to the higher adhesion than those generated by hydrophilic–hydrophobic interactions and hydrophilic interactions. The long grafted chains and the enhanced temperature facilitate the chain entanglements, resulting in the strong adhesive force. This work sheds new light on the adhesion mechanism at molecular level, which may be helpful to improve the adhesion between the electrospun fibers and substrates in an environmentally friendly manner.

Contrary to a prevailing concept on protein adsorption and cell adhesion, novel micropatterned polyacrylamide (PAAm) brushes that can resist cell adhesion but promote protein retention are created through patterning of ATRP initiators and surface-initiated ATRP on a polymer substrate.

The construction of biocompatible and antibacterial surfaces is becoming increasingly important. However, most of the existing techniques require multi-step procedures, stringent conditions and specific substrates. We present here a facile method to create a biocompatible and antibacterial surface on virtually any substrate under ambient conditions. The strategy is based on casting a highly adherent elastomer, styrene-b-(ethylene-co-butylene)-b-styrene, from a solvent mixture of xylene and decanol, in which decanol acts as both a polymer precipitator to induce phase separation and a liquid template to stabilize the superhydrophobic structure. The stable and durable superhydrophobic surface shows good biocompatibility and antibacterial properties.

The hemolysis of erythrocytes is a big obstacle to the development of new non-plasticizer polymer containers for erythrocyte preservation. To construct a long-term anti-hemolytic surface of a plasticizer-free polymer, we coaxially electrospin core–shell structured D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS)/poly(ethylene oxide) nanofibers on the surface of a styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) elastomer that is covered with grafted poly(ethylene glycol) (PEG) chains. Our strategy is based on the fact that the grafted layers of PEG reduce mechanical damage to red blood cells (RBCs) while the TPGS released from the nanofibers on a blood-contacting surface can act as an antioxidant to protect RBCs from oxidative damage. We demonstrate that TPGS/PEO core–shell structured nanofibers have been well prepared on the surface of PEG modified SEBS; the controlled release of TPGS in distilled water is obtained and the release can last for almost 4 days at 4 °C; during RBC preservation, TPGS acts as the antioxidant to decrease the membrane oxidation and hemolysis of RBCs. Our work paves a new way for the development of non-plasticizer polymers for RBC preservation, which may be helpful for the fabrication of long-term anti-hemolytic biomaterials in vivo.

A newly glycopolymer-patterned surface for capturing red blood cells (RBCs) is demonstrated. Our strategy is based on the surface-initiated photopolymerization of 2-acryl-amido-2-methylpropane sulfonic acid (AMPS) on a thermoplastic elastomer, the patterning of poly(D-gluconamidoethyl methacrylate) (PGAMA, glycopolymer) micro-domains on the PAMPS layer with photomask-assisted photolithography, followed by the generation of a phytohemagglutinin (PHA) array on the patterned surface through lectin–carbohydrate recognition. We demonstrate that the bi-component polymer-patterned surface with high lateral resolution is successfully fabricated; the PAMPS layer with patterned glycopolymer domains remains hydrophilic to resist non-specific plasma protein adsorption and cell adhesion; the PHA array on the patterned PGAMA domains induces nearly no platelet adhesion on the patterned surface, but shows high capability for capturing RBCs in the blood, and in addition, the captured RBCs maintain cellular integrity and function. Our work presented herein not only paves a new way for capturing RBCs from the blood, but also establishes a basic principle to capture non-adherent cells in the blood or biological fluid without damage.

A novel hydrophilic PAMPS–PAAm brush pattern is fabricated to selectively capture blood cells from whole blood. PAMPS brushes provide antifouling surfaces to resist protein and cell adhesion while PAAm brushes effectively entrap targeted proteins for site-specific and cell-type dependent capture of blood cells.

Platelets have exhibited capabilities beyond clotting in recent years. Most of their functions are related to the nature of platelet adhesion. Establishing a facile method to understand the platelet adhesion and assess the platelet function through the mechanism and mechanics of adhesion is highly desired. Here, we report a generally applicable UV lithography technique with a photomask, which performs selective surface functionalization on large substrate areas, for creating stable, physical adhesive sites in the range of 12 μm to 3 μm. Our study demonstrated that the patterned surface facilitated probing of single platelet adhesion in a quantitative manner, and rendered platelets sensitive to adhesive proteins even at a low protein concentration. In addition, the platelet function in the presence of antiplatelet (anticancer) agents on platelets could be accurately estimated based on single platelet adhesion (SPA). This work paves a new way to understand and assess the blood platelet function. The SPA assay methodology has the potential to enable a rapid, accurate point-of-care platform suitable for evaluation of platelet function, detection of dysfunctional platelets, and assay of drug effects on platelets in cancer patients.

A simple approach for preparing bicomponent polymer patterns was developed by coating polydopamine (PDA) on superhydrophilic poly(2-acryl-amido-2-methylpropane sulfonic acid) (PAMPS) brushes. Well-defined and versatile arrays of proteins and cells were achieved without harm to proteins and cells.

Immunoassays have shown great advances in the fields of biomedical diagnosis. However, successful immunoassays in blood plasma or whole blood based on the designed biointerfaces are still rare. Here, a newly cell-inspired biointerface for immunoassays in blood is demonstrated. Inspired by the high resistance to protein and cell adhesion and extraordinary biological recognition of stem cells, the biointerfaces are constructed by patterning smart hydrogels (PNIPAAm-co-PNaAc) on hydrophilic layers (PEG), followed by immobilization of antibodies on the patterned hydrogels. The hierarchical biointerfaces are hydrophilic to resist blood plasma and blood cell adhesion, but exhibit high affinity to the target antigens. As a result, successful immunoassays in blood are achieved. In addition, the detection signal is further enhanced by the manipulation of the phase transition of the smart hydrogels with temperature, and the sensitivity is higher than that of the widely-used poly(acrylic acid)/(polyacrylate) platform. The biointerface is versatile and effective in antibody–antigen recognition, which offers a potential new approach for developing highly sensitive immunoassays in blood.