Synthetic Peptide Antibodies as TNF-α Inhibitors: Molecularly Imprinted Polymer Nanogels Neutralize the Inflammatory Activity of TNF-α in THP-1 Derived Macrophages

Tumor Necrosis Factor-α (TNF-α) is a cytokine that is normally produced by immune cells when fighting an infection. But, when too much TNF-α is produced as in autoimmune diseases, this leads to unwanted and persistent inflammation. Anti-TNF-α monoclonal antibodies have revolutionized the therapy of these disorders by blocking TNF-α and preventing its binding to TNF-α receptors, thus suppressing the inflammation. Herein, we propose an alternative in the form of molecularly imprinted polymer nanogels (MIP-NGs). MIP-NGs are synthetic antibodies obtained by nanomoulding the 3-dimensional shape and chemical functionalities of a desired target in a synthetic polymer. Using an in-house developed in silico rational approach, epitope peptides of TNF-α were generated and 'synthetic peptide antibodies' were prepared. The resultant MIP-NGs bind the template peptide and recombinant TNF-α with high affinity and selectivity, and can block the binding of TNF-α to its receptor. Consequently they were applied to neutralize pro-inflammatory TNF-α in the supernatant of human THP-1 macrophages, leading to a downregulation of the secretion of pro-inflammatory cytokines. Our results suggest that MIP-NGs, which are thermally and biochemically more stable and easier to manufacture than antibodies, and cost-effective, are very promising as next generation TNF-α inhibitors for the treatment of inflammatory diseases.

Synthesis and Integration of Hybrid Metal Nanoparticles Covered with a Molecularly Imprinted Polymer Nanolayer by Photopolymerization

Interfacing recognition materials with transducers has consistently presented a challenge in the development of sensitive and specific chemical sensors. In this context, a method based on near-field photopolymerization is proposed to functionalize gold nanoparticles, which are prepared by a very simple process. This method allows in situ preparation of a molecularly imprinted polymer for sensing by surface-enhanced Raman scattering (SERS). In a few seconds, a functional nanoscale layer is deposited by photopolymerization on the nanoparticles. In this study, the dye Rhodamine 6G was chosen as a model target molecule to demonstrate the principle of the method. The detection limit is 500 pM. Due to the nanometric thickness, the response is fast, and the substrates are robust, allowing regeneration and reuse with the same performance level. Finally, this method of manufacturing has been shown to be compatible with integration processes, allowing the future development of sensors integrated in microfluidic circuits and on optical fibers.

Optical Fiber-Based Polymer Microcantilever for Chemical Sensing: A Through-Fiber Fabrication Scheme

Fiber optics offer an emerging platform for chemical and biological sensors when engineered with appropriate materials. However, the large aspect ratio makes the optical fiber a rather challenging substrate for standard microfabrication techniques. In this work, the cleaved end of an optical fiber is used as a fabrication platform for cantilever sensors based on functional polymers. The through-fiber fabrication process is triggered by photo-initiated free-radical polymerization and results in a high-aspect-ratio polymer beam in a single step. The dynamic mode application of these cantilevers is first demonstrated in air. These cantilevers are then tuned for sensing applications, including humidity and chemical sensing based on molecularly imprinted polymers.

Molecularly Imprinted Polymers as Synthetic Antibodies for Protein Recognition: The Next Generation

Molecularly imprinted polymers (MIPs) are chemical antibody mimics obtained by nanomoulding the 3D shape and chemical functionalities of a desired target in a synthetic polymer. Consequently, they possess exquisite molecular recognition cavities for binding the target molecule, often with specificity and affinity similar to those of antigen-antibody interactions. Research on MIPs targeting proteins began in the mid-90s, and this review will evaluate the progress made till now, starting from their synthesis in a monolith bulk format through surface imprinting to biocompatible soluble nanogels prepared by solid-phase synthesis. MIPs in the latter format will be discussed more in detail because of their tremendous potential of replacing antibodies in the biomedical domain like in diagnostics and therapeutics, where the workforce of antibodies is concentrated. Emphasis is also put on the development of epitope imprinting, which consists of imprinting a short surface-exposed fragment of a protein, resulting in MIPs capable of selectively recognizing the whole macromolecule, amidst others in complex biological media, on cells or tissues. Thus selecting the 'best' peptide antigen is crucial and in this context a rational approach, inspired from that used to predict peptide immunogens for peptide antibodies, is described for its unambiguous identification.

A general photoiniferter approach to the surface functionalization of acrylic and methacrylic structures written by two-photon stereolithography

Two-photon stereolithography (TPS) is an established additive fabrication technique allowing the voxel-by-voxel direct writing of even intricate 3D nano/microstructures via the polymerization of a photoresin. An obvious way to tune the chemical functionalities of such nano/microstructures is formulating a photoresin with the desired functional monomer(s). Unfortunately, this makes every photoresin "unique" in terms of viscosity and reactivity, thus requiring a tedious and often time-consuming optimization of its printing parameters. In this work, we describe a general approach for the chemical functionalization of TPS-written structures based on two commercial photoresins. Our strategy entailed the grafting of functional polymer layers via an innovative approach based on photoiniferter coupling to unreacted double bonds and photopolymerization. After writing woodpiles as 3D model structures, we demonstrated the viability of this approach by anchoring a photoiniferter via its photoinduced addition to the residual CC on the structure's surface triggered by green light. This in turn allowed for the blue light-mediated, surface-initiated photopolymerization of functional monomers. Molecularly imprinted polymer films were also easily synthesized by using the same approach on model honeycombs. The imprinted layers resulted in only a minimal increase in size with no effect on the geometrical features of the honeycombs. Overall, this strategy offers a general approach for the surface modification of TPS-written (meth)acrylic structures with a wide variety of functional polymers via photoiniferter polymerization.

Introduction to New era in advanced functional materials emerging from molecular imprinting and related techniques

Professor Karsten Haupt, Professor Toshifumi Takeuchi and Professor Guoping Chen introduce the Journal of Materials Chemistry B themed issue on a New era in advanced functional materials emerging from molecular imprinting and related techniques.

An organic transistor for the selective detection of tropane alkaloids utilizing a molecularly imprinted polymer

This study proposes a chemical sensing approach for the selective detection of tropane alkaloid drugs based on an extended-gate-type organic field-effect transistor (OFET) functionalized with a molecularly imprinted polymer (MIP). From the viewpoint of pharmaceutical chemistry, the development of versatile chemical sensors to determine the enantiomeric purity of over-the-counter (OTC) tropane drugs is important because of their side effects and different pharmacological activities depending on their chirality. To this end, we newly designed an OFET sensor with an MIP (MIP-OFET) as the recognition element for tropane drugs based on a high complementarity among a template (i.e., (S)-hyoscyamine) and functional monomers such as N-isopropylacrylamide and 2,2-dimethyl-4-pentenoic acid. Indeed, the MIP optimized by density functional theory (DFT) has succeeded in the sensitive and selective detection of (S)-hyoscyamine (as low as 1 μM) by the combination of the OFET with highly selective recognition sites in the MIP. The MIP-OFET was further applied to determine the enantiomeric excess (ee) of commercially available (S)-hyoscyamine, and the linearity changes in the threshold voltages of the OFET corresponded to the % ee values of (S)-hyoscyamine. Overall, the validation with tropane alkaloids revealed the potential of the MIP combined with OFET as a chemical sensor chip for OTC drugs in real-world scenarios.

Molecularly imprinted polymer nanogels targeting the HAV motif in cadherins inhibit cell-cell adhesion and migration

Cadherins are cell-surface proteins that mediate cell-cell adhesion. By regulating their grip formation and strength, cadherins play a pivotal role during normal tissue morphogenesis and homeostasis of multicellular organisms. However, their dysfunction is associated with cell migration and proliferation, cancer progression and metastasis. The conserved amino acid sequence His-Ala-Val (HAV) in the extracellular domain of cadherins is implicated in cadherin-mediated adhesion and migration. Antagonists of cadherin adhesion such as monoclonal antibodies and small molecule inhibitors based on HAV peptides, are of high therapeutic value in cancer treatment. However, antibodies are not stable outside their natural environment and are expensive to produce, while peptides have certain limitations as a drug as they are prone to proteolysis. Herein, we propose as alternative, a synthetic antibody based on molecularly imprinted polymer nanogels (MIP-NGs) to target the HAV domain. The MIP-NGs are biocompatible, have high affinity for N-cadherin and inhibit cell adhesion and migration of human cervical adenocarcinoma (HeLa) cells, as demonstrated by cell aggregation and Matrigel invasion assays, respectively. The emergence of MIPs as therapeutics for fighting cancer is still in its infancy and this novel demonstration reinforces the fact that they have a rightful place in cancer treatment.

Overview of Traditional and Environmental Factors Related to Bone Health

Bone mass in adulthood depends on growth and mineralization acquired during childhood and adolescence. It is well known that these stages of life are crucial for bone development, where genetic, nutritional, hormonal, and lifestyle factors play a significant role. Bone loss is normally a natural and slow process that begins years later after the peak bone mass is achieved and continues throughout the lifespan. Lifestyle choices in childhood and adolescence such as minimal physical activity, excessive caffeine or carbonated beverages intake, malnutrition, cigarette use, or high alcohol consumption and other factors like environmental pollutants can also negatively affect bone health and accelerate the bone loss process. The aim of this work is an overview of risk factors associated with inadequate bone health in early life.

Decreased Renal Gluconeogenesis Is a Hallmark of Chronic Kidney Disease

INTRODUCTION

CKD is associated with alterations of tubular function. Renal gluconeogenesis is responsible for 40% of systemic gluconeogenesis during fasting, but how and why CKD affects this process and the repercussions of such regulation are unknown.

METHODS

We used data on the renal gluconeogenic pathway from more than 200 renal biopsies performed on CKD patients and from 43 kidney allograft patients, and studied three mouse models, of proteinuric CKD (POD-ATTAC), of ischemic CKD, and of unilateral urinary tract obstruction. We analyzed a cohort of patients who benefitted from renal catheterization and a retrospective cohort of patients hospitalized in the intensive care unit.

RESULTS

Renal biopsies of CKD and kidney allograft patients revealed a stage-dependent decrease in the renal gluconeogenic pathway. Two animal models of CKD and one model of kidney fibrosis confirm gluconeogenic downregulation in injured proximal tubule cells. This shift resulted in an alteration of renal glucose production and lactate clearance during an exogenous lactate load. The isolated perfused kidney technique in animal models and renal venous catheterization in CKD patients confirmed decreased renal glucose production and lactate clearance. In CKD patients hospitalized in the intensive care unit, systemic alterations of glucose and lactate levels were more prevalent and associated with increased mortality and a worse renal prognosis at follow-up. Decreased expression of the gluconeogenesis pathway and its regulators predicted faster histologic progression of kidney disease in kidney allograft biopsies.

CONCLUSION

Renal gluconeogenic function is impaired in CKD. Altered renal gluconeogenesis leads to systemic metabolic changes with a decrease in glucose and increase in lactate level, and is associated with a worse renal prognosis.

Molecularly Imprinted Polymer Hydrogel Nanoparticles: Synthetic Antibodies for Cancer Diagnosis and Therapy

Cancer is a leading cause of death worldwide and according to the World Health Organization (WHO) accounted for 10 million deaths in 2020. Promising theranostic (therapy and diagnostic) agents in the treatment of cancer are nanomaterials, which have come to the forefront because of their small size approaching those of protein complexes in the human body, and of their easy functionalization giving access to nanocomposite materials with diverse functions (fluorescence, magnetic, stimuli-responsiveness, etc.), and improved biocompatibility. Among them, affinity nanoparticles, often decorated with highly specific targeting ligands such as antibodies, aptamers, lectins and peptides, have enabled enhanced binding and exquisite recognition of biomarkers overexpressed in cancer cells. In this review, we describe an emerging class of targeting ligands, molecularly imprinted polymer hydrogel nanoparticles for their application in the early detection of disease, with the aim to improve diagnosis and treatment.

Fighting Antibiotic-Resistant Bacteria : Promising Strategies Orchestrated by Molecularly Imprinted Polymers

Infections caused by antibiotic-resistant bacteria are difficult and sometimes impossible to treat, making them one of the major public health problems of our time. We highlight how one unique material , molecularly imprinted polymers (MIPs), can orchestrate several strategies to fight this major societal issue. MIPs are tailor-made biomimetic supramolecular receptors that recognize and bind target molecules with a high affinity and selectivity, comparable to those of antibodies. While research on MIPs for combatting cancer has been constantly flourishing, comprehensive work on their involvement in combatting resistant superbugs has been rather scarce. This review aims at filling this gap. We will describe what are the causes of bacterial resistance and at which level MIPs can deploy their weapons. MIPs' targets can be biofilm constituents, quorum sensing messengers, bacterial surface proteins and antibiotic-deactivating enzymes, among others. We will conclude on the current challenges and future developments in this field.

Evolution of Molecularly Imprinted Enzyme Inhibitors: From Simple Activity Inhibition to Pathological Cell Regulation

Molecular imprinting represents one of the most promising strategies to design artificial enzyme inhibitors. However, the study of molecularly imprinted enzyme inhibitors (MIEIs) remains at a primary stage. Advanced applications of MIEIs for cell regulation have rarely been explored. Using a solid-phase oriented imprinting strategy so as to leave the active site of the enzymes accessible, we synthesized two MIEIs that exhibit high specificity and potent inhibitory effects (inhibition constant at low nM range) towards trypsin and angiogenin. The trypsin MIEI inhibits trypsin activity, tryptic digestion-induced extracellular matrix lysis and cell membrane destruction, indicating its utility in the treatment of active trypsin-dependent cell injury. The angiogenin MIEI blocks cancer cell proliferation by suppressing the ribonuclease activity of angiogenin and decreasing the angiogenin level inside and outside HeLa cells. Our work demonstrates the versatility of MIEIs for both enzyme inhibition and cell fate manipulation, showing their great potential as therapeutic drugs in biomedicine.

Molecularly Imprinted Polymer Nanogels for Protein Recognition: Direct Proof of Specific Binding Sites by Solution STD and WaterLOGSY NMR Spectroscopies

Molecularly imprinted polymers (MIPs) are tailor-made synthetic antibodies possessing specific binding cavities designed for a target molecule. Currently, MIPs for protein targets are synthesized by imprinting a short surface-exposed fragment of the protein, called epitope or antigenic determinant. However, finding the epitope par excellence that will yield a peptide "synthetic antibody" cross-reacting exclusively with the protein from which it is derived, is not easy. We propose a computer-based rational approach to unambiguously identify the "best" epitope candidate. Then, using Saturation Transfer Difference (STD) and WaterLOGSY NMR spectroscopies, we prove the existence of specific binding sites created by the imprinting of this peptide epitope in the MIP nanogel. The optimized MIP nanogel could bind the epitope and cognate protein with a high affinity and selectivity. The study was performed on Hepatitis A Virus Cell Receptor-1 protein, also known as KIM-1 and TIM-1, for its ubiquitous implication in numerous pathologies.

Molecularly Imprinted Polymers: Antibody Mimics for Bioimaging and Therapy

Molecularly imprinted polymers (MIPs) are tailor-made chemical receptors that recognize and bind target molecules with a high affinity and selectivity. MIPs came into the spotlight in 1993 when they were dubbed "antibody mimics," and ever since, they have been widely studied for the extraction or trapping of chemical pollutants, in immunoassays, and for the design of sensors. Owing to novel synthesis strategies resulting in more biocompatible MIPs in the form of soluble nanogels, these synthetic antibodies have found favor in the biomedical domain since 2010, when for the first time, they were shown to capture and eliminate a toxin in live mice. This review, covering the years 2015-2020, will first describe the rationale behind these antibody mimics, and the different synthesis methods that have been employed for the preparation of MIPs destined for in vitro and in vivo targeting and bioimaging of cancer biomarkers, an emerging and fast-growing area of MIP applications. MIPs have been synthesized for targeting and visualizing glycans and protein-based cell receptors overexpressed in certain diseases, which are well-known biomarkers for example for tumors. When loaded with drugs, the MIPs could locally kill the tumor cells, making them efficient therapeutic agents. We will end the review by reporting how MIPs themselves can act as therapeutics by inhibiting cancer growth. These works mark a new opening in the use of MIPs for antibody therapy and even immunotherapy, as materials of the future in nanomedicine.

Polydopamine-based molecularly imprinted thin films for electro-chemical sensing of nitro-explosives in aqueous solutions

A sensitive electrochemical sensor was developed for the detection of nitro-explosives in aqueous solutions based on thin molecularly imprinted polydopamine films. Dopamine was identified in silico, based on DFT (density functional theory) calculations with the ωB97X-D/6-31G* basis set, as the best functional monomer and electropolymerized via cyclic voltammetry (CV) in the presence of carboxylic acid-based structural analogues ('dummy' templates) for two model nitro-explosives: TNT (2,4,6-trinitrotoluene) and RDX (Research Department eXplosive, 1,3,5-trinitroperhydro-1,3,5-triazine). This approach afforded a homogenous coverage of gold electrodes with imprinted films of tunable thickness. The electropolymerized molecularly imprinted polydopamine films allowed for a 10⁵-fold sensitivity improvement over a bare gold electrode based on tracking the redox peaks of the targets by CV. This improved sensitivity is ascribed to the ability of the MIP to concentrate its target in proximity to the transduction element. The MIP films showed reproducible binding in phosphate buffer (10 mM, pH 7.4), with a dynamic range from 0.1 nM to 10 nM for both TNT and RDX and an increased selectivity over closely related structural analogues.

Reduction-responsive molecularly imprinted nanogels for drug delivery applications

Degradable molecularly imprinted polymers (MIPs) with affinity for S-propranolol were prepared by the copolymerization of methacrylic acid as functional monomer and a disulfide-containing cross-linker, bis(2-methacryloyloxyethyl)disulfide (DSDMA), using bulk polymerization or high dilution polymerization for nanogels synthesis. The specificity and the selectivity of DSDMA-based molecularly imprinted polymers toward S-propranolol were studied in batch binding experiments, and their binding properties were compared to a traditional ethylene glycol dimethacrylate (EDMA)-based MIP. Nanosized MIPs prepared with DSDMA as crosslinker could be degraded into lower molecular weight linear polymers by cleaving the disulfide bonds and thus reversing cross-linking using different reducing agents (NaBH4, DTT, GSH). Turbidity, viscosity, polymer size and IR-spectra were measured to study the polymer degradation. The loss of specific recognition and binding capacity of S-propranolol was also observed after MIP degradation. This phenomenon was applied to modulate the release properties of the MIP. In presence of GSH at its intracellular concentration, the S-propranolol release was higher, showing that these materials could potentially be applied as intracellular controlled drug delivery system.

RAFT coupling chemistry: a general approach for post-functionalizing molecularly imprinted polymers synthesized by radical polymerization

Herein we describe a straightforward protocol for the surface functionalization of free-radically synthesized imprinted nanoparticles via polymer grafting.

Molecularly Imprinted Polymer Nanoparticles as Potential Synthetic Antibodies for Immunoprotection against HIV

We describe the preparation and characterization of synthetic antibodies based on molecularly imprinted polymer nanoparticles (MIP-NPs) for the recognition and binding of the highly conserved and specific peptide motif SWSNKS (3S), an epitope of the envelope glycoprotein 41 (gp41) of human immunodeficiency virus type 1 (HIV-1). This motif is implicated in the decline of CD4⁺ T cells and leads to the deterioration of the immune system during HIV infection. Therefore, the development of MIP-NPs that can target and block the 3S peptide to prevent subsequent cascade interactions directed toward the killing of CD4⁺ T cells is of prime importance. Because most antibodies recognize their protein antigen via a conformational or structured epitope (as opposed to a linear epitope commonly used for molecular imprinting), we employed protein molecular modeling to design our template epitope so that it mimics the three-dimensional structure fold of 3S in gp41. The resulting template peptide corresponds to a cyclic structure composed of CGSWSNKSC, with the 3S motif well orientated for imprinting. MIP-NPs with a size of 65 nm were obtained by solid-phase synthesis and were water-soluble. They were prepared by a judicious combination of multiple functional monomers affording hydrogen bonding, ionic, π-π, and hydrophobic interactions, conferring high affinity and selectivity toward both the cyclic peptide and the whole gp41 protein. These results suggest that our MIPs could potentially be used for blocking the function of the 3S motif on the virus.

Molecularly imprinted polymers by thiol–yne chemistry: making imprinting even easier

Molecularly imprinted polymers (MIPs) are synthetic, bio-mimetic materials with recognition properties on a par with those of antibodies, which feature superior physical and chemical stability.

In Vitro Removal of Human Igg by Pseudobiospecific Affinity Membrane Filtration on a Large Scale. A Preliminary Report

We have developed a pseudobiospecific affinity membrane device for selective removal of human IgG from plasma or serum in vitro for clinical apheresis application. The pseudobiospecific affinity ligand L-histidine was immobilized through an ether linkage onto poly(ethylenevinyl alcohol) hollow fiber cartridge. The obtained affinity membranes showed high selectivity for IgG adsorption from untreated human serum. These membranes are able to adsorb lgG1, lgG2, lgG3 if Mops buffer is used, and more selectively lgG1 and lgG3 in Tris-HCl buffer. With respect to the binding capacity, the pseudobiospecific affinity membrane used showed a higher capacity as compared to protein A-membranes described in the literature. Due to the high capacity, specificity and stability of the histidine affinity membranes, in addition to their lower cost, the approach proposed in this paper may offer a useful alternative to protein A based devices in the treatment of immune-related diseases.

Tracking Hyaluronan: Molecularly Imprinted Polymer Coated Carbon Dots for Cancer Cell Targeting and Imaging

War against cancer constantly requires new affinity tools to selectively detect, localize, and quantify biomarkers for diagnosis or prognosis. Herein, carbon nanodots (CDs), an emerging class of fluorescent nanomaterials, coupled with molecularly imprinted polymers (MIPs), are employed as a biocompatible optical imaging tool for probing cancer biomarkers. First, N-doped CDs were prepared by hydrothermal synthesis using starch as carbon source and l-tryptophan as nitrogen atom provider to achieve a high quantum yield of 25.1 ± 2%. The CDs have a typical size of ∼3.2 nm and produce an intense fluorescence at 450 nm upon excitation with UV light. A MIP shell for specific recognition of glucuronic acid (GlcA) was then synthesized around the CDs, using the emission of the CDs as an internal light source for photopolymerization. GlcA is a substructure (epitope) of hyaluronan, a biomarker for certain cancers. The biotargeting and bioimaging of hyaluronan on fixated human cervical cancer cells using CD core-MIP shell nanocomposites is demonstrated. Human keratinocytes were used as noncancerous reference cells and indeed, less staining was observed by the CD-MIP.

Competitive fluorescent pseudo-immunoassay exploiting molecularly imprinted polymers for the detection of biogenic amines in fish matrix

We developed a competitive fluorescent molecularly imprinted polymer (MIP) assay to detect biogenic amines in fish samples. MIPs synthesized by precipitation polymerization using histamine as template were used in a batch binding assay analogous to competitive fluoroimmunoassays. Introducing a complex sample matrix, such as fish extract, into the assay changes the environment and the binding conditions, therefore the importance of the sample preparation is extensively discussed. Several extraction and purification methods for fish were comprehensively studied, and an optimal clean-up procedure for fish samples using liquid-liquid extraction was developed. The feasibility of the competitive MIP assay was shown in the purified fish extract over a broad histamine range (1 - 430µM). The MIP had the highest affinity towards histamine, but recognized also the structurally similar biogenic amines tyramine and tryptamine, as well as spermine and spermidine, providing simultaneous analysis and assessment of the total amount of biogenic amines.

Core-Shell Molecularly Imprinted Polymer Nanoparticles as Synthetic Antibodies in a Sandwich Fluoroimmunoassay for Trypsin Determination in Human Serum

We describe the application of a fluorescently labeled water-soluble core-shell molecularly imprinted polymer (MIP) for fluorescence immunoassay (FIA) to detect trypsin. p-Aminobenzamidine (PAB), a competitive inhibitor of trypsin, was immobilized in the wells of a microtiter plate enabling the capture of trypsin in an oriented position, thus maintaining its native conformation. Fluorescent MIP nanoparticles, which bound selectively to trypsin, were used for quantification. The MIP was prepared by a multistep solid-phase synthesis approach on glass beads functionalized with PAB, orientating all trypsin molecules in the same way. The core-MIP was first synthesized, using a thermoresponsive polymer based on N-isopropylacrylamide, so as to enable its facile liberation from the immobilized template by a simple temperature change. The shell, mainly composed of allylamine to introduce primary amino groups for postconjugation of fluorescein isothiocyanate (FITC), was grafted in situ on the core-MIP, whose binding cavities were still bound and protected by the immobilized trypsin. The resulting core-shell MIP was endowed with a homogeneous population of high-affinity binding sites, all having the same orientation. The MIP has no or little cross-reactivity with other serine proteases and unrelated proteins. Our MIP-based FIA system was successfully applied to detect low trypsin concentrations spiked into nondiluted human serum with a low limit of quantification of 50 pM, which indicates the significant potential of this assay for analytical and biomedical diagnosis applications.

Guide to the Preparation of Molecularly Imprinted Polymer Nanoparticles for Protein Recognition by Solid-Phase Synthesis

Molecularly imprinted polymers (MIPs) are synthetic antibody mimics possessing specific cavities designed for a target molecule. Nowadays, molecular imprinting of proteins still remains a challenge as the generation of selective imprinted cavities is extremely difficult, due to their flexible structure and the presence of a multitude of functional sites. To overcome this difficulty, we propose a solid-phase synthesis strategy to prepare MIPs specific for any protein that can be immobilized in an oriented way on a solid support. Trypsin and kallikrein were used as model proteins. The solid-phase support consists of glass beads functionalized with two affinity ligands of the enzymes, the competitive inhibitor p-aminobenzamidine to orient the enzymes via their active site, or a Cu²⁺chelate to orient via the surface histidine residues of the enzyme. Thermoresponsive molecularly imprinted polymer nanoparticles (MIP-NPs) are then synthesized around the immobilized enzyme. The MIP-NPs are released by a simple temperature change, resulting in protein-free polymers endowed with improved binding site homogeneity since all binding sites have the same orientation. The MIP-NPs exhibit apparent dissociation constants between 0.02 and 2nM toward their target proteins, which is comparable to those of natural antibodies. Moreover, these water-compatible polymers, targeting different domains of the enzyme, can also function as protective agents (armor), hence preventing the target proteins from denaturation by heat or pH.

Synthesis of molecularly imprinted polymers by photo-iniferter polymerization under visible light

A new prospect for the synthesis of molecularly imprinted polymers: photo-iniferter polymerization under visible light.

Cell and Tissue Imaging with Molecularly Imprinted Polymers

Advanced tools for cell imaging are of particular interest as they can detect, localize and quantify molecular targets like abnormal glycosylation sites that are biomarkers of cancer and infection. Targeting these biomarkers is often challenging due to a lack of receptor materials. Molecularly imprinted polymers (MIPs) are promising artificial receptors; they can be tailored to bind targets specifically, be labeled easily, and are physically and chemically stable. Herein, we demonstrate the application of MIPs as artificial antibodies for selective labeling and imaging of cellular targets, on the example of hyaluronan and sialylation moieties on fixated human skin cells and tissues. Thus, fluorescently labeled MIP nanoparticles templated with glucuronic acid (MIPGlcA) and N-acetylneuraminic acid (MIPNANA) are respectively applied. Two different fluorescent probes are used: (1) MIPGlcA particles, ~400 nm in size are labeled with the dye rhodamine that target the extracellular hyaluronan on cells and tissue specimens and (2) MIP-coated InP/ZnS quantum dots (QDs) of two different colors, ~125 nm in size that target the extracellular and intracellular hyaluronan and sialylation sites. Green and red emitting QDs are functionalized with MIPGlcA and MIPNANA respectively, enabling multiplexed cell imaging. This is a general approach that can also be adapted to other target molecules on and in cells.

Rapid Prototyping of Chemical Microsensors Based on Molecularly Imprinted Polymers Synthesized by Two-Photon Stereolithography

Two-photon stereolithography is used for rapid prototyping of submicrometre molecularly imprinted polymer-based 3D structures. The structures are evaluated as chemical sensing elements and their specific recognition properties for target molecules are confirmed. The 3D design capability is exploited and highlighted through the fabrication of an all-organic molecularly imprinted polymeric microelectromechanical sensor.

Programmable bioelectronics in a stimuli-encoded 3D graphene interface

The ability to program and mimic the dynamic microenvironment of living organisms is a crucial step towards the engineering of advanced bioelectronics. Here, we report for the first time a design for programmable bioelectronics, with 'built-in' switchable and tunable bio-catalytic performance that responds simultaneously to appropriate stimuli. The designed bio-electrodes comprise light and temperature responsive compartments, which allow the building of Boolean logic gates (i.e."OR" and "AND") based on enzymatic communications to deliver logic operations.