Bilayer dressing based on aerogel/electrospun mats with self-catalytic hydrogen sulfide generation and enhanced antioxidant ability.

Hydrogen sulfide (H2S) releasing wound dressings have attracted much attention for their ability to promote cell proliferation, stimulate angiogenesis, and resist inflammation. Mimicking the skin structure, a bilayer wound dressing based on aerogel/mats with H2S release capability was designed and fabricated. A bio-macromolecular H2S donor based on a keratin-TA conjugate (KTC) was first synthesized through a thiol-disulfide exchange reaction. As an inner layer, KTC was then loaded into a gelatin hydrogel with large pores to absorb the wound exudates and generate H2S self-catalytically. Subsequently, polyurethane was electrospun with glutathione (GSH) to be used as an outer layer with small pores, which provided mechanical support, supplied GSH, and prevented bacterial invasion. The bilayer dressing was capable of generating H2S self-catalytically, achieving a controlled and sustained release. The dressing could also promote cell proliferation and migration. In addition, the dress possessed enhanced antioxidant ability and reactive oxygen species (ROS) scavenging capability. The bilayer dressing on promoting wound healing was investigated in a full-thickness excisional cutaneous wound model in rats. The results demonstrated that it could reduce inflammation, promote vascularization, and facilitate hair follicle regeneration, thereby accelerating wound healing. Overall, the bilayer dressing has great potential applications in the field of the wound dressing.

Immobilization of Collagen on the Surface of a PEEK Implant with Monolayer Nanopores.

Polyetheretherketone (PEEK) is the only polymer material that can replace titanium implants in the field of orthopedics. This is because the mechanical properties of PEEK are similar to those of bone, and PEEK has natural radiolucency, chemical stability, and sterilization resistance. Despite these advantages, PEEK has a disadvantage-that it is bio-inert. Therefore, many studies have attempted to change the bio-inertness of PEEK into bioactivity. Among them, a method of forming pores by acid treatment is attracting attention. In this study, an attempt was made to form pores on the surface of PEEK implant using a mixed acid of sulfuric acid and nitric acid. As a result, it was found that the condition when the PEEK surface is in contact with the acid is very important. That is, it was possible to form single-layered nanopores on the surface by contacting PEEK with a mixed acid under ultrasound. Additionally, by immobilizing type I collagen on the porous PEEK surface through dopamine coating, it was possible to obtain collagen-immobilized porous PEEK (P-PEEK-Col) with high compatibility with osteoblasts. This P-PEEK-Col has high potential for use as a bone substitute that promotes bone formation.

Nitric oxide-releasing poly(ε-caprolactone)/S-nitrosylated keratin biocomposite scaffolds for potential small-diameter vascular grafts.

Rapid endothelialization and regulation of smooth muscle cell proliferation are crucial for small-diameter vascular grafts to address poor compliance, thromboembolism, and intimal hyperplasia, and achieve revascularization. As a gaseous signaling molecule, nitric oxide (NO) regulates cardiovascular homeostasis, inhibits blood clotting and intimal hyperplasia, and promotes the growth of endothelial cells. Due to the instability and burst release of small molecular NO donors, a novel biomacromolecular donor has generated increasing interest. In the study, a low toxic NO donor of S-nitrosated keratin (KSNO) was first synthesized and then coelectrospun with poly(ε-caprolactone) to afford NO-releasing small-diameter vascular graft. PCL/KSNO graft was capable to generate NO under the catalysis of ascorbic acid (Asc), so the graft selectively elevated adhesion and growth of human umbilical vein endothelial cells (HUVECs), while inhibited the proliferation of human aortic smooth muscle cells (HASMCs) in the presence of Asc. In addition, the graft displayed significant antibacterial properties and good blood compatibility. Animal experiments showed that the biocomposite graft could inhibit thrombus formation and preserve normal blood flow via single rabbit carotid artery replacement for 1 month. More importantly, a complete endothelium was observed on the lumen surface. Taken together, PCL/KSNO small-diameter vascular graft has potential applications in vascular tissue engineering with rapid endothelialization and vascular remolding.

Biocompatible Polymers and their Potential Biomedical Applications: A Review.

BACKGROUND: Biocompatible polymers are gaining great interest in the field of biomedical applications. The term biocompatibility refers to the suitability of a polymer to body and body fluids exposure. Biocompatible polymers are both synthetic (man-made) and natural and aid in the close vicinity of a living system or work in intimacy with living cells. These are used to gauge, treat, boost, or substitute any tissue, organ or function of the body. A biocompatible polymer improves body functions without altering its normal functioning and triggering allergies or other side effects. It encompasses advances in tissue culture, tissue scaffolds, implantation, artificial grafts, wound fabrication, controlled drug delivery, bone filler material, etc. OBJECTIVES: This review provides an insight into the remarkable contribution made by some well-known biopolymers such as polylactic-co-glycolic acid, poly(ε-caprolactone) (PCL), polyLactic Acid, poly(3- hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), Chitosan and Cellulose in the therapeutic measure for many biomedical applications. METHODS: Various techniques and methods have made biopolymers more significant in the biomedical fields such as augmentation (replaced petroleum based polymers), film processing, injection modeling, blow molding techniques, controlled / implantable drug delivery devices, biological grafting, nano technology, tissue engineering etc. RESULTS: The fore mentioned techniques and other advanced techniques have resulted in improved biocompatibility, nontoxicity, renewability, mild processing conditions, health condition, reduced immunological reactions and minimized side effects that would occur if synthetic polymers are used in a host cell. CONCLUSION: Biopolymers have brought effective and attainable targets in pharmaceutics and therapeutics. There are huge numbers of biopolymers reported in the literature that has been used effectively and extensively.

Osteoblast behaviours on nanorod hydroxyapatite-grafted glass surfaces.

BACKGROUND: The goal of this study is to obtain basic information to improve the bone adhesion of silica components, which are used as the main ingredient in glass ionomer cement (GIC). To achieve this, nanorod hydroxyapatite (nHA) was grafted to the surface of silica cover glass. Surface analysis confirmed nHA was joined to the glass surface and biocompatibility with osteoblasts was investigated. RESULTS: The grafting of nHA on the surface of slide cover glass (Glass) was confirmed by X-ray photoelectron spectroscopy (XPS) and contact angle (θ) measurement. MC3T3-E1 cells were more stretched out on the nHA-grafted cover glass (Glass-nHA) in comparison to the Glass. In addition, the Glass-nHA was more bioactive in supporting the proliferation of MC3T3-E1 cells in comparison to cells seeded on the Glass. CONCLUSION: The Glass-nHA was to be highly bioactive and this might be useful information for property modification of GIC.

In vitro detection of allergen sensitized basophils by HSA-DNP antigen-anchored liquid crystal microdroplets.

A simple and easy to handle biosensing technique for in vitro detection of HSA-DNP antigen induced allergen reactions in patients has been developed through the detection of sensitized basophils expressed with anti-IgE receptor (FcεRI) by using human serum albumin-dinitrophenol (HSA-DNP) antigen-anchored liquid crystal (LC) microdroplets emulsion. The radial to bipolar transition in nematic 4-cyano-4'-pentyl biphenyl liquid crystal molecules (5CB) confined in HSA-DNP antigen anchored LC microdroplets (8.5 pg HSA-DNP/LC microdroplet) is found to be sensitive in PBS solution in detection of allergen sensitized basophils expressed with a minimum amount of anti HSA-DNP (anti-IgE) receptor (≥4.5 pg/basophil). The detection of allergen sensitized basophils was possible within a contact time of 30 min in presence of control cells and with 10% solution of human blood plasma. The HSA-DNP antigen anchored LC microdroplets in presence of macrophages or non-sensitized basophils did not show radial to bipolar transition in 5CB molecules in PBS or solution with 10 wt% human blood plasma. Thus HSA-DNP antigen anchored LC microdroplets biosensor may be used for in vivo detection of stage I allergen reaction basophils in blood samples.

Hydroxyapatite Nanorod-Modified Sand Blasted Titanium Disk for Endosseous Dental Implant Applications.

BACKGROUND: Sand blasted titanium (Ti) is commonly used in designing endosseous dental implants due to its biocompatibility and ability to form bonds with bone tissues. However, titanium implants do not induce strong interactions with teeth bones. To increase strong interactions between Ti disk implants and teeth bones, the l-glutamic acid grafted hydroxyapatite nanorods (nHA) were immobilized on albumin modified Ti disk implants (Ti-Alb). METHODS: For modification of Ti disk implants by nHA, the l-glutamic acid grafted nHA was synthesized and then immobilized on albumin modified Ti disk implants. Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope; energy dispersive spectroscopy and confocal laser scanning microscopy were used to confirm the modification of Ti disk implants. The bioactivity of nHA-modified Ti disk implants was evaluated by seeding MC3T3-E1 cells on Ti-nHA implants. RESULTS: Characterization techniques have confirmed the successful modification of Ti disk implants by l-glutamic acid grafted nHA. The nHA-modified Ti disk implants have shown enhanced adhesion, proliferation and cytotoxicity of MC3T3-E1 cells in comparison to pristine Ti implants. CONCLUSIONS: The modification of Ti implants by l-glutamic acid grafted nHA has produced highly osteogenic Ti disk plants in comparison to pristine Ti disk implants due to the formation of bioactive surfaces by hydroxyapatite nano rods on Ti disk implants. Ti-nHA disk implants showed enhanced adhesion, proliferation, and MC3T3-E1 cells viability in comparison to pristine Ti disk implants. Thus nHA might be to be useful to enhance the osseointegration of Ti implants with teeth bones.

A novel use of cellulose based filter paper containing silver nanoparticles for its potential application as wound dressing agent.

The frequent use of antibiotics against microbial infections may lead to the emergence of antibiotic resistant microbial strains. To overcome these microbial strains, we need to fabricate alternative materials which can handle them. It is for this reason, we have fabricated cellulose (CE) based filter paper (FP) composite scaffolds comprising of adsorbed chitosan (CS) and sliver (Ag) nanoparticles (NPs). The AgNPs are incorporated in the CS layer of the composite scaffold. Prior to evaluate the efficacy of the scaffolds against gram positive and gram negative bacterial strains, the scaffolds were characterized for the presence of the Ag NPs with field emission scanning electron microscope (FE-SEM), fourier transform infrared (FTIR) spectroscopy and x-ray diffractometer (XRD). These techniques confirmed the presence of Ag NPs in the composite scaffold. The biocompatibility of the scaffolds was assessed by subjecting pristine FP, CS adsorbed FP (CS-FP) and Ag loaded CS-FP (Ag-CS-FP) composite scaffolds to in vitro studies. From the data obtained, it was observed that NIH3T3 fibroblastic cells adhered and proliferated onto all the scaffolds. Furthermore, the scaffolds exhibited good antibacterial activity against both strains of bacteria. It is, therefore, concluded that these scaffolds could find potential application in biomedical field, particularly as a wound dressing agent.

Lamination of microfibrous PLGA fabric by electrospinning a layer of collagen-hydroxyapatite composite nanofibers for bone tissue engineering.

BACKGROUND: To mimic the muscle inspired cells adhesion through proteins secretion, the lamination of collagen-hydroxyapatite nanorod (nHA) composite nanofibers has been carried out successfully on polydopamine (PDA)-coated microfibrous polylactide-co-glycolide (PLGA) fabrics. The lamination of collagen-hydroxyapatite composite nanofibers on polydopamine-coated microfibrous PLGA fabrics was carried through electrospinning the solution of collagen containing L-glutamic acid-grafted hydroxyapatite nanorods (nHA-GA) at a flow rate of 1.5 mL/h and an applied voltage of 15 kV. RESULTS: In comparison to pristine PLGA, dopamine-coated PLGA and collagen-hydroxyapatite composite nanofiber lamination has produced more wettable surfaces and surface wettability is found to higher with dopamine-coated PLGA fabrics then pristine PLGA. The SEM micrographs have clearly indicated that the lamination of polydopamine-coated PLGA fabric with collagen-hydroxyapatite composite nanofibers has shown increased adhesion of MC3T3E1 cells in comparison to pristine PLGA fabrics. CONCLUSION: The results of these studies have clearly demonstrated that collagen-nHA composites fibers may be used to create bioactive 3D scaffolds using PLGA as an architectural support agent.

Broadband pH-Sensing Organic Transistors with Polymeric Sensing Layers Featuring Liquid Crystal Microdomains Encapsulated by Di-Block Copolymer Chains.

We report broadband pH-sensing organic field-effect transistors (OFETs) with the polymer-dispersed liquid crystal (PDLC) sensing layers. The PDLC layers are prepared by spin-coating using ethanol solutions containing 4-cyano-4'-pentyl-biphenyl (5CB) and a diblock copolymer (PAA-b-PCBOA) that consists of LC-philic block [poly(4-cyano-biphenyl-4-oxyundecyl acrylate) (PCBOA)] and acrylic acid block [poly(acrylic acid) (PAA)]. The spin-coated sensing layers feature of 5CB microdomains (<5 µm) encapsulated by the PAA-b-PCBOA polymer chains. The resulting LC-integrated-OFETs (PDLC-i-OFETs) can detect precisely and reproducibly a wide range of pH with only small amounts (10-40 µL) of analyte solutions in both static and dynamic perfusion modes. The positive drain current change is measured for acidic solutions (pH < 7), whereas basic solutions (pH > 7) result in the negative change of drain current. The drain current trend in the present PDLC-i-OFET devices is explained by the shrinking-expanding mechanism of the PAA chains in the diblock copolymer layers.

In vitro detection of human breast cancer cells (SK-BR3) using herceptin-conjugated liquid crystal microdroplets as a sensing platform.

The present study utilizes antibody-protein interactions to develop an LC microdroplet based biosensor for naked eye detection of SK-BR3 human breast cancer cells. The herceptin antibody-conjugated LC microdroplets were fabricated using 4-cyano-4'-pentyl biphenyl (5CB) as the liquid crystalline phase and sodium dodecyl sulfate (SDS) as the surfactant. The poly (styrene-b-acrylic acid) amphiphilic block copolymer (PS-b-PA) played a role as a modifier for the liquid crystalline interfaces. The 5CB molecules in the herceptin antibody-conjugated LC microdroplets have shown an orientation transition from radial to bipolar on selective interactions with targeted SK-BR3 breast cancer cells, which are over expressed by the human epidermal growth factor receptor 2-positive (HER2). The herceptin antibody-conjugated LC microdroplets are found to be highly selective in the detection of SK-BR3 cancer cells in the presence of control cells, such as KB cancer cells and fibroblast (FB), and also in the presence of 10% human blood plasma. The interaction forces of the SK-BR3 cancer cells were only effective in causing orientation transitions in 5CB molecules in the LC microdroplets, which clearly suggested that the herceptin antibody-conjugated LC microdroplets could be used as a selective biosensor for a real-time detection of SK-BR3 cancer cells in biological fluids.

Micro/Nano Multilayered Scaffolds of PLGA and Collagen by Alternately Electrospinning for Bone Tissue Engineering.

The dual extrusion electrospinning technique was used to fabricate multilayered 3D scaffolds by stacking microfibrous meshes of poly(lactic acid-co-glycolic acid) (PLGA) in alternate fashion to micro/nano mixed fibrous meshes of PLGA and collagen. To fabricate the multilayered scaffold, 35 wt% solution of PLGA in THF-DMF binary solvent (3:1) and 5 wt% solution of collagen in hexafluoroisopropanol (HFIP) with and without hydroxyapatite nanorods (nHA) were used. The dual and individual electrospinning of PLGA and collagen were carried out at flow rates of 1.0 and 0.5 mL/h, respectively, at an applied voltage of 20 kV. The density of collagen fibers in multilayered scaffolds has controlled the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. The homogeneous dispersion of glutamic acid-modified hydroxyapatite nanorods (nHA-GA) in collagen solution has improved the osteogenic properties of fabricated multilayered scaffolds. The fabricated multilayered scaffolds were characterized using FT-IR, X-ray photoelectron spectroscopy, and transmission electron microscopy (TEM). The scanning electron microscopy (FE-SEM) was used to evaluate the adhesion and spreads of MC3T3-E1 cells on multilayered scaffolds. The activity of MC3T3-E1 cells on the multilayered scaffolds was evaluated by applying MTT, alkaline phosphatase, Alizarin Red, von Kossa, and cytoskeleton F-actin assaying protocols. The micro/nano fibrous PLGA-Col-HA scaffolds were found to be highly bioactive in comparison to pristine microfibrous PLGA and micro/nano mixed fibrous PLGA and Col scaffolds.

Collagen-grafted porous HDPE/PEAA scaffolds for bone reconstruction.

After tumor resection, bone reconstruction such as skull base reconstruction using interconnected porous structure is absolutely necessary. In this study, porous scaffolds for bone reconstruction were prepared using heat-pressing and salt-leaching methods. High-density polyethylene (HDPE) and poly(ethylene-co-acrylic acid) (PEAA) were chosen as the polymer composites for producing a porous scaffold of high mechanical strength and having high reactivity with biomaterials such as collagen, respectively. The porous structure was observed through surface images, and its intrusion volume and porosity were measured. Owing to the carboxylic acids on PEAA, collagen was successfully grafted onto the porous HDPE/PEAA scaffold, which was confirmed by FT-IR spectroscopy and electron spectroscopy for chemical analysis. Osteoblasts were cultured on the collagen-grafted porous scaffold, and their adhesion, proliferation, and differentiation were investigated. The high viability and growth of the osteoblasts suggest that the collagen-grafted porous HDPE/PEAA is a promising scaffold material for bone generation.

Multifaceted thermoresponsive poly(N-vinylcaprolactam) coupled with carbon dots for biomedical applications.

A fluorescent thermoresponsive polymer consisting of poly(N-vinylcaprolactam) (PVCL) coupled with carbon dots (CDs) (PVCL-CDs) was synthesized by reacting a carboxyl-terminated PVCL derivative with CDs via N-hydroxysuccinimide and N-(3-(dimethylamino)propyl)-N-ethylcarbodiimide hydrochloride coupling. The temperature-dependent fluorescence properties of this material were studied for biomedical applications. Fluorescence quenching in PVCL-CDs was observed above the lower critical solution temperature (LCST) due to thermo-induced aggregation of the PVCL chains. This fluorescent thermoresponsive PVCL-CDs showed good biocompatibility and was demonstrated as a thermometer for sensing intracellular temperatures and also as a marker for bioimaging. In addition, PVCL-CDs showed a significant fluorescence turn-on response to proteins above the LCST, which allows for the utilization of this material in biosensors. Thus, PVCL-CDs, with its tuneable size, low cytotoxicity, good photostability, ease of bioconjugation, and resistance to metabolic degradation, is a novel material for biomedical applications.

Anti-IgG-anchored liquid crystal microdroplets for label free detection of IgG.

The orientational variation of 4-cyano-4'-pentyl biphenyl (5CB) molecules in LC microdroplets in response to IgG antigen (IgG) interactions has been utilized to develop a biosensor for rapid and label-free detection of IgG in biological fluids. In order to prepare a LC microdroplet-based biosensor, the anti-IgG (AIgG) anchored 4-cyano-4'-pentyl biphenyl LC microdroplets were prepared in the presence of sodium dodecylsulfate (SDS) as a mediator and amphiphilic poly(styrene-b-acrylic acid) (PS-b-PA) as a modifier of the LC/water interface. The AIgG-anchored LC microdroplets with a size variation from 20 to 30 µm have been used successfully for the detection of IgG within a concentration range of 20 to 1000 ng mL-1, at a detection limit of as low as 16 ng mL-1, and a response time of 30 min in PBS solution at room temperature. The LC microdroplets anchored with 5 µg mL-1 of AIgG were found to be more sensitive for the detection of IgG in the concentration range from 20 to 800 ng mL-1 in PBS. The AIgG-anchored LC microdroplets have shown a delayed response of 90 minutes for IgG in a solution containing 10% FBS or 10% blood plasma in comparison to PBS solution. The LC microdroplets anchored with 5 µg mL-1 (34 pmol) of AIgG have shown a recovery of 106% of IgG, a coefficient of variance of ±4% and a precision within a limit of 1-6% for a spiked sample of 25 ng mL-1 of IgG. The results indicated that orientational response of LC microdroplets is potentially useful to develop a biosensor for in vivo detection of proteins or pathogens in a biological fluid.

Pamidronic acid-grafted nHA/PLGA hybrid nanofiber scaffolds suppress osteoclastic cell viability and enhance osteoblastic cell activity.

Osteoclasts have the capability to resorb bone. When osteoclastic activity is excessively high, bones generally become weakened and more prone to fracture. In order to treat excessive osteoclastic cell activity, maintain the balance between bone formation and resorption, and enhance osseointegration, pamidronic acid-grafted nanorod hydroxyapatite/poly(lactide-co-glycolide) (P-g-nHA/PLGA) scaffolds were fabricated via an electrospinning technique. Various spectroscopic techniques were used for the structural and morphological characterization of pristine PLGA, nHA/PLGA, and P-g-nHA/PLGA hybrid nanofiber scaffolds. The potential of the P-g-nHA/PLGA hybrid nanofiber scaffold as an implantable material was assessed through in vitro studies. The results showed that the viability of osteoclastic cells on the P-g-nHA/PLGA nanofiber scaffold was significantly suppressed due to the presence of pamidronic acid. Osteoblastic cells adhered and proliferated on all scaffolds tested; however, increased osteoblastic cell proliferation was observed on the P-g-nHA/PLGA hybrid and nHA/PLGA nanofiber scaffolds compared to the pristine PLGA nanofiber scaffolds. Therefore, these types of dual function P-g-nHA/PLGA hybrid nanofiber scaffolds could certainly be used in therapeutic bone implantation.

BMP-2 Grafted nHA/PLGA Hybrid Nanofiber Scaffold Stimulates Osteoblastic Cells Growth.

Biomaterials play a pivotal role in regenerative medicine, which aims to regenerate and replace lost/degenerated tissues or organs. Natural bone is a hierarchical structure, comprised of various cells having specific functions that are regulated by sophisticated mechanisms. However, the regulation of the normal functions in damaged or injured cells is disrupted. In order to address this problem, we attempted to artificially generate a scaffold for mimicking the characteristics of the extracellular matrix at the nanoscale level to trigger osteoblastic cell growth. For this purpose, we have chemically grafted bone morphogenetic protein (BMP-2) onto the surface of L-glutamic acid modified hydroxyapatite incorporated into the PLGA nanofiber matrix. After extensive characterization using various spectroscopic techniques, the BMP-g-nHA/PLGA hybrid nanofiber scaffolds were subjected to various in vitro cytocompatibility tests. The results indicated that BMP-2 on BMP-g-nHA/PLGA hybrid nanofiber scaffolds greatly stimulated osteoblastic cells growth, contrary to the nHA/PLGA and pristine PLGA nanofiber scaffold, which are used as control. These results suggest that BMP-g-nHA/PLGA hybrid nanofiber scaffold can be used as a nanodrug carrier for the controlled and targeted delivery of BMP-2, which will open new possibilities for enhancing bone tissue regeneration and will help in the treatment of various bone-related diseases in the future.

Targeted images of KB cells using folate-conjugated gold nanoparticles.

Mercaptosuccinic acid-coated gold (GM) nanoparticles were prepared and characterized by transmission electron microscopy and dynamic light scattering. Folic acid (F) was then conjugated to the GM to preferentially target oral squamous cancer (KB) cells with folate receptors expressed on their membranes and facilitate the transit of the nanoparticles across the cell membrane. Finally, a fluorescence dye (Atto) was conjugated to the nanoparticles to visualize their internalization into KB cells. After culture of the cells in a medium containing GM and folate-conjugated GM (GF), the interaction of surface-modified gold nanoparticles with KB cells was studied.

Photoinduced development of antibacterial materials derived from isosorbide moiety.

A straightforward method for immobilizing in situ generated silver nanoparticles on the surface of a photoactivable isosorbide-derived monomer is developed with the objective to design a functional material having antibacterial properties. The photoinduced thiol-ene mechanism involved in these syntheses is described by the electron spin resonance/spin trapping technique. The resulting materials with or without silver nanoparticles (Ag NPs) were used as films or as coatings on glass substrate. The surface of the synthesized materials was characterized by X-ray photoelectron spectroscopy and scanning electron microscopy, and their thermal and mechanical properties were evaluated by dynamic-mechanical thermal tests, differential scanning calorimetry, thermogravimetric analyses, along with pencil hardness, nanoindentation, and scratch resistance tests. The photoinduced formation of Ag NPs is also confirmed by UV spectrophotometry. Finally, a primary investigation demonstrates the antibacterial properties of the isosorbide-derived material against Staphylococcus aureus and Escherichia coli, as well as its cytocompatibility toward NIH 3T3 fibroblastic cells.

The role of ligand-receptor interactions in visual detection of HepG2 cells using a liquid crystal microdroplet-based biosensor.

Liquid crystal (LC) microdroplets have been prepared for visual detection of HepG2 cells using 4-cyano-4'-pentyl biphenyl molecules in the presence of sodium dodecyl sulfate as a mediator and ß-galactose-conjugated poly(styrene-b-acrylic acid) block copolymer (PS-b-PA-G) as a modifier of LC-water interfaces. To clarify the effect of ß-galactose-containing ligands on the orientational transitions of LC microdroplets, maltotriose as a ligand simulant was conjugated to poly(styrene-b-acrylic acid) and used as a LC modifier. The interaction of HepG2 cells with the ß-galactose-conjugated block copolymer was effective in causing orientational transitions, from radial to bipolar, in LC microdroplets, whereas interactions of HepG2 cells with maltotriose-conjugated block copolymers were ineffective in inducing orientational transitions in LC microdroplets. To confirm the necessity of the PS segment of the block copolymer for transmitting the ligand-receptor interaction forces from the interface to the core of the LC microdroplets, ß-galactose-conjugated block copolymers (PS-b-PA-G) and homopolymers (PVLA) were synthesized and used to prepare LC microdroplets. The LC microdroplets containing a ß-galactose-conjugated homopolymer did not show orientational transitions upon contact with HepG2 cells. However, LC microdroplets containing a ß-galactose-conjugated block copolymer showed orientational transitions from radial to bipolar, indicating that the polystyrene segment in the amphiphilic block copolymer is essential for the effective transmission of ligand-receptor interactions to the core of LC microdroplets. ß-Galactose anchored LC microdroplets were able to detect 1.0 ± 0.1 HepG2 cells per µm2 of the test cell and had shown significantly high reproducibility (p < 0.05, n = 3). The configurational transition in LC microdroplets that was dependent on ligand-receptor interactions was used to develop a LC microdroplet-based biosensor for the detection of HepG2 cells in biological fluids.