Chemical recognition in cell-imprinted polymers

Surface-Imprinted Polysiloxane with Recognition Ability Based on an ITO Layer for Rapid Detection of Fusarium oxysporum f. sp. cubense by the Naked Eye

Direct observation by the naked eye of fluorescence-stained microbes adsorbed on surface imprinted polymers (SIPs) is highly challenging and limited by speed, accuracy and the semiquantitative nature of the method. In this study, we tested for the presence of spores of Fusarium oxysporum f. sp. cubense race 4 (Foc4), which cause severe banana Fusarium wilt disease and reduces the area of banana plants. This kind of spore can become dormant in soil, which means that the detection of secreted molecules (molecular imprinting) in soil may be inaccurate; detection methods such as polymerase chain reaction (PCR) and Raman spectroscopy are more accurate but time-consuming and inconvenient. Therefore, a semiquantitative and rapid SIP detection method for Foc4 was proposed. Based on the ITO conductive layer, a reusable and naked-eye-detectable Foc4-PDMS SIP film was prepared with a site density of approximately 9000 mm-2. Adsorption experiments showed that when the Foc4 spore concentration was between 104 to 107 CFU/mL, the number of Foc4 spores adsorbed and the fluorescence intensity were strongly correlated with the concentration and could be fully distinguished by the naked eye after fluorescence staining. Adsorption tests on other microbes showed that the SIP film completely recognized only the Foc series. All the results were highly consistent with the naked-eye observations after fluorescence staining, and the results of the Foc4-infected soil experiment were also close to the ideal situation. Taken together, these results showed that Foc4-PDMS SIPs have the ability to rapidly and semiquantitatively detect the concentration of Foc in soil, which can provide good support for banana cultivation. This method also has potential applications in the detection of other fungal diseases.

Macrophage cell morphology-imprinted substrates can modulate mesenchymal stem cell behaviors and macrophage M1/M2 polarization for wound healing applications

Mesenchymal stem cells and macrophages (MQ) are two very important cells involved in the normal wound healing process. It is well understood that topological cues and mechanical factors can lead to different responses in stem cells and MQ by influencing their shape, cytoskeleton proliferation, migration, and differentiation, which play an essential role in the success or failure of biomaterial implantation and more importantly wound healing. On the other hand, the polarization of MQ from proinflammatory (M1) to prohealing (M2) phenotypes has a critical role in the acceleration of wound healing. In this study, the morphology of different MQ subtypes (M0, M1, and M2) was imprinted on a silicon surface (polydimethylsiloxane [PDMS]) to prepare a nano-topography cell-imprinted substrate with the ability to induce anti-inflammatory effects on the mouse adipose-derived stem cells (ADSCs) and RAW264.7 monocyte cell line (MO). The gene expression profiles and flow cytometry of MQ revealed that the cell shape microstructure promoted the MQ phenotypes according to the specific shape of each pattern. The ELISA results were in agreement with the gene expression profiles. The ADSCs on the patterned PDMS exhibited remarkably different shapes from no-patterned PDMS. The MOs grown on M2 morphological patterns showed a significant increase in expression and section of anti-inflammatory cytokine compared with M0 and M1 patterns. The ADSCs homing in niches heavily deformed the cytoskeletal, which is probably why the gene expression and phenotype unexpectedly changed. In conclusion, wound dressings with M2 cell morphology-induced surfaces are suggested as excellent anti-inflammatory and antiscarring dressings.

Molecularly imprinted polymer-based optical immunosensors

Molecularly imprinted polymers (MIPs) are artificial antibodies for a target molecule. The review focuses mainly on mechanistic steps involved in forming MIPs and the role of co-monomers and porogen. In addition, the electronic transition between different energy levels is explained with the help of the Jablonski diagram. Diverse receptor and target molecules for anchoring artificial MIPs are discussed, accentuating the synergetic effects obtained. The binding efficiency, selectivity, and sensitivity of various optical sensors are discussed intensively. In addition to this, we focused on synthesis, physical forms, characterization techniques, and microorganism detection of imprinted polymers. A brief investigation on the use of MIPs in cancer diagnosis is also included, and attention is extended to the important challenges faced in using imprinted polymers.

Colloidal antibiotic mimics: selective capture and killing of microorganisms by shape-anisotropic colloids

The development of targeted and efficient antimicrobials for the selective killing of pathogenic bacteria is of great importance, yet remains challenging. Here, we propose a targeted approach to selectively capture and kill microorganisms with colloidal antibiotic mimics that are readily prepared by common chemical syntheses. The mimics are shape-anisotropic colloids, which can selectively capture shape-matching microorganisms due to lock-key depletion attractions. Furthermore, after being modified with gold nanoparticles (AuNPs) and irradiated with near-infrared light, the colloidal mimics can kill the selectively captured microorganisms due to the localized photothermal effect of the AuNPs. The work demonstrates the important ability of anisotropic colloids to selectively capture and precisely kill microorganisms, which holds considerable promise for safe and adaptive antibacterial therapies without the risk of antibiotic resistance.

Rational In Silico Design of Molecularly Imprinted Polymers: Current Challenges and Future Potential

The rational design of molecularly imprinted polymers has evolved along with state-of-the-art experimental imprinting strategies taking advantage of sophisticated computational tools. In silico methods enable the screening and simulation of innovative polymerization components and conditions superseding conventional formulations. The combined use of quantum mechanics, molecular mechanics, and molecular dynamics strategies allows for macromolecular modelling to study the systematic translation from the pre- to the post-polymerization stage. However, predictive design and high-performance computing to advance MIP development are neither fully explored nor practiced comprehensively on a routine basis to date. In this review, we focus on different steps along the molecular imprinting process and discuss appropriate computational methods that may assist in optimizing the associated experimental strategies. We discuss the potential, challenges, and limitations of computational approaches including ML/AI and present perspectives that may guide next-generation rational MIP design for accelerating the discovery of innovative molecularly templated materials.

Improving performance of cell imprinted PDMS by integrating boronate affinity and local post-imprinting modification for selective capture of circulating tumor cells from cancer patients

Efficient capture of circulating tumor cells (CTCs) from cancer patients is an important technique that may promote early diagnosis and prognosis monitoring of cancer. However, the existing systems have certain disadvantages, such as poor selectivity, low capture efficiency, consumption of antibodies, and difficulty in release of CTCs for downstream analysis. Herein, we fabricated an innovative PEGylated boronate affinity cell imprinted polydimethylsiloxane (PBACIP) for highly efficient capture of CTCs from cancer patients. The antibody-free PBACIP possessed hierarchical structure of imprinted cavities, which were inlaid with boronic acid modified SiO₂ nanoparticles (SiO₂@BA), so it could specifically capture target CTCs from biological samples due to the synergistic effect of boronate affinity and cell imprinting. Furthermore, PEGylation was accurately completed in the non-imprinted region by the template cells occupying the imprinted cavity, which not only retained the microstructure of original imprinted cavities, but also endowed PBACIP with hydrophilicity. The artificial PBACIP could efficiently capture human breast-cancer cells from biological sample. When 5 to 500 SKBR3 cells were spiked in 1 mL mice lysed blood, the capture efficiency reached 86.7 ± 11.5% to 96.2 ± 2.3%. Most importantly, the PBACIP was successfully used to capture CTCs from blood of breast cancer patients, and the captured CTCs were released for subsequent gene mutation analysis. The PBACIP can efficiently capture and release CTCs for downstream analysis, which provides a universal strategy toward individualized anti-tumor comprehensive treatments and has great potential in the future cell-based clinical applications.

Imprinted Polydimethylsiloxane-Graphene Oxide Composite Receptor for the Biomimetic Thermal Sensing of Escherichia coli

This work presents an imprinted polymer-based thermal biomimetic sensor for the detection of Escherichia coli. A novel and facile bacteria imprinting protocol for polydimethylsiloxane (PDMS) films was investigated, and these receptor layers were functionalized with graphene oxide (GO) in order to improve the overall sensitivity of the sensor. Upon the recognition and binding of the target to the densely imprinted polymers, a concentration-dependent measurable change in temperature was observed. The limit of detection attained for the sensor employing PDMS-GO imprints was 80 ± 10 CFU/mL, a full order lower than neat PDMS imprints (670 ± 140 CFU/mL), illustrating the beneficial effect of the dopant on the thermo-dynamical properties of the interfacial layer. A parallel benchmarking of the thermal sensor with a commercial impedance analyzer was performed in order to prove the possibility of using the developed PDMS-GO receptors with multiple readout platforms. Moreover, S. aureus, C. sakazakii and an additional E. coli strain were employed as analogue species for the assessment of the selectivity of the device. Finally, because of the potential that this biomimetic platform possesses as a low-cost, rapid, and on-site tool for monitoring E. coli contamination in food safety applications, spiked fruit juice was analyzed as a real sample. Reproducible and sensitive results fulfill the limit requirements of the applicable European microbiological regulation.

Investigations on sub-structures within cavities of surface imprinted polymers using AFM and PF-QNM

Investigations on lithographically formed cavities of surface-imprinted polymers (SIP) can help to gain deeper understanding on cell recognition with SIPs: it is known that surface topography and biomolecules transferred during surface imprinting contribute to cell adhesion. In this work, SIPs synthesized via two different imprinting techniques, namely stamp imprinting and polymerization of Pickering emulsions, were investigated and compared to each other, using atomic force microscopy (AFM) and Peak Force Quantitative Nano Mechanics (PF-QNM). We focused on SIPs based on poly(styrene-co-divinylbenzene) as model polymer and E. coli as model template for cell imprinting. Both imprinting approaches led to cavities that revealed nanostructures within the imprints. Stamp imprinting cavities feature low surface roughness and channel structures that resemble the negative pattern of the bacteria on the stamp and their filaments, while SIPs synthesized via polymerization of Pickering emulsions reveal globular nanostructures accumulating in the imprints. AFM phase imaging and adhesion mapping using PF-QNM show that these globular structures are remainders of the imprinted E. coli cells, most likely lipopolysaccarides, which is not observable in imprints resulting from stamp imprinting.

Raman and Scanning Probe Microsocopy for differentiating surface imprints of E.coli and B.cereus

Molecularly imprinted polymers (MIPs) are artificial recognition materials mimicking biological recognition entities such as antibodies. The general model of imprinting assumes that functional monomers interact with functional groups present on...

Reusable and universal impedimetric sensing platform for the rapid and sensitive detection of pathogenic bacteria based on bacteria-imprinted polythiophene film

A bacteria-imprinted polythiophene film (BIF)-based impedimetric sensor was proposed for the rapid and sensitive detection of S. aureus. A significant improvement is the reduced time for both BIF fabrication (15 min) and bacterial capturing (10 min).

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.

Biomarker imprinted magnetic core-shell nanoparticles for rapid, culture free detection of pathogenic bacteria

Rapid and selective detection of microorganisms in complex biological systems draws huge attention to address the rising issue of antimicrobial resistance. Diagnostics based on the identification of whole microorganisms are laborious, time-consuming and costly, thus alternative strategies for early clinical diagnosis include biomarker based microbial detection. This paper describes a low-cost, easy-to-use method for the detection of Pseudomonas aeruginosa infections by specifically identifying a biomarker pyocyanin, using surface-molecularly imprinted nanoparticles or "plastibodies". The selective nanopockets are created by templating pyocyanin onto 20 nm allyl-functionalized magnetic nanoparticles coated with a thin layer of the acrylamide-based polymer. This functional material with an impressive imprinting factor (IF) of 5 and a binding capacity of ∼2.5 mg g-1 of polymers can be directly applied for the detection of bacteria in complex biological samples based on the presence of pyocyanin. These MIPs are highly selective and sensitive to pyocyanin and can consistently bind with pyocyanin in repeated use. Finally, the facile and efficient capture of pyocyanin has versatile applications ranging from biomarker based culture free detection of P. aeruginosa to monitoring of the therapeutic regime, in addition to developing a new class of antibiotics.

Hosseini I, Raeissi K, Karimzadeh F, Jalali M, Kharaziha M, Sheibani S, Shariati L, Presley JF, Vali H, Mahshid S. Gold Nano/Micro-Islands Overcome the Molecularly Imprinted Polymer Limitations to Achieve Ultrasensitive Protein Detection

Here, we report on an electrochemical biosensor based on core-shell structure of gold nano/micro-islands (NMIs) and electropolymerized imprinted ortho-phenylenediamine (o-PD) for detection of heart-fatty acid binding protein (H-FABP). The shape and distribution of NMIs (the core) were tuned by controlled electrodeposition of gold on a thin layer of electrochemically reduced graphene oxide (ERGO). NMIs feature a large active surface area to achieve a low detection limit (2.29 fg mL^-1, a sensitivity of 1.34 × 10¹³ μA mM^-1) and a wide linear range of detection (1 fg mL^-1 to 100 ng mL^-1) in PBS. Facile template H-FABP removal from the layer (the shell) in less than 1 min, high specificity against interference from myoglobin and troponin T, great stability at ambient temperature, and rapidity in detection of H-FABP (approximately 30 s) are other advantages of this biomimetic biosensor. The electrochemical measurements in human serum, human plasma, and bovine serum showed acceptable recovery (between 91.1 ± 1.7 and 112.9 ± 2.1%) in comparison with the ELISA method. Moreover, the performance of the biosensor in clinical serum showed lower detection time and limit of detection against lateral flow assay (LFA) rapid test kits, as a reference method. Ultimately, the proposed biosensor based on the core-shell structure of gold NMIs and MIP opens interesting avenues in the detection of proteins with low cost, high sensitivity and significantstability for clinical applications.

Molecular Imprinting Strategies for Tissue Engineering Applications: A Review

Tissue Engineering (TE) represents a promising solution to fabricate engineered constructs able to restore tissue damage after implantation. In the classic TE approach, biomaterials are used alongside growth factors to create a scaffolding structure that supports cells during the construct maturation. A current challenge in TE is the creation of engineered constructs able to mimic the complex microenvironment found in the natural tissue, so as to promote and guide cell migration, proliferation, and differentiation. In this context, the introduction inside the scaffold of molecularly imprinted polymers (MIPs)—synthetic receptors able to reversibly bind to biomolecules—holds great promise to enhance the scaffold-cell interaction. In this review, we analyze the main strategies that have been used for MIP design and fabrication with a particular focus on biomedical research. Furthermore, to highlight the potential of MIPs for scaffold-based TE, we present recent examples on how MIPs have been used in TE to introduce biophysical cues as well as for drug delivery and sequestering.

Visual detection of hepatocellular carcinoma cells with cell imprinted substrate and pH-sensitive allochroic-graphene oxide

Herein, we integrate cell-imprinted substrate (CIS) and allochroic-graphene oxide (AGO) for specific visualization sorting of hepatocellular carcinoma cells. The state-of-the-art-of detection method relies on the enzyme linked immunosorbent assay (ELISA)-like sandwich strategy with hierarchical recognition. The target tumor cells are first selectively captured by the CIS based on cell imprinted recognition, and then specifically labeled with AGO by boronate affinity recognition between boronic acid on AGO and cis-diols on the surface of target cells. The selectively recognition of CIS for target template cells is verified by cell function experiments. It is also worth mentioning that the AGO can specifically recognize target tumor cells under physiological pH, and then perform signal amplification and output through pH-triggered allochroism. The CIS linked AGO for cell assay (CIS-AGO-CA) is successfully used for visualization detection of human hepatocarcinoma HLE cells from hepatocyte suspension. When the hepatocyte suspension is spiked with 1.0 × 10⁵ cells, the recoveries of CIS-AGO-CA are 80.67 ± 4.33% for target HLE cells, and only 12.00 ± 1.00% for non-target Hep3B cells. It is worth emphasizing that the CIS-AGO-CA process is antibody-free. Therefore, this novel ELISA-like sandwich strategy is high specificity, cost-efficient and easy-to-use, and exhibits great prospect in the visualization sorting of tumor subpopulation.

Molecular imprinting technology for sensing foodborne pathogenic bacteria

Foodborne diseases caused by bacterial pathogens pose a widespread and growing threat to public health in the world. Rapid detection of pathogenic bacteria is of great importance to prevent foodborne diseases and ensure food safety. However, traditional detection methods are time-consuming, labour intensive and expensive. In recent years, many attempts have been made to develop alternative methods for bacterial detection. Biosensors integrated with molecular imprinted polymers (MIPs) and various transducer platforms are among the most promising candidates for the detection of pathogenic bacteria in a highly sensitive, selective and ultra-rapid manner. In this review, we summarize the most recent advances in molecular imprinting for bacterial detection, introduce the underlying recognition mechanisms and highlight the applications of MIP-based biosensors. In addition, the challenges and future perspectives are discussed with the aim of accelerating the development of MIP-based biosensors and extending their applications.

Rapid, sensitive and label-free detection of pathogenic bacteria using a bacteria-imprinted conducting polymer film-based electrochemical sensor

The rapid and sensitive detection of pathogenic bacteria is very important for timely prevention and treatment of foodborne disease. Here, a bacteria-imprinted conductive poly(3-thiopheneacetic acid) (BICP) film-based impedimetric sensor was developed for the rapid, sensitive and label-free detection of staphylococcus aureus (S. aureus). The BICP film preparation was very convenient and eco-friendly, which was in situ deposited on gold electrode surface without the use of toxic organic solvents and cross-linkers. The process of imprinting and recognition were characterized by electrochemical technique and scanning electron microscope. The BICP had a novel structure without cocci-shaped cavities formed in the poly(3-thiopheneacetic acid) (PTAA) matrices. To obtain the optimal sensing performance, a set of factors affecting the imprinting and recognition were investigated. Under the optimized conditions, an extremely rapid recognition within 10 min, a very low limit of detection (LOD) of 2 CFU/mL, and wide linear range from 10 to 10⁸ CFU/mL were achieved by the BICP film-based impedimetric sensor. The sensor also demonstrated high selectivity, and good universality and repeatability. Furthermore, the feasibility of its application has also been demonstrated in the analysis of real milk samples. This sensor offered a simple and universal method for rapid, sensitive, and selective detection of pathogenic bacteria, which could hold great potentials in fields like food safety.

Capture and Kill: Selective Eradication of Target Bacteria by a Flexible Bacteria-Imprinted Chip

This paper reports an antibacterial chip that can selectively capture bacteria and kill them using low-voltage DC electricity. We prepared a bacteria-imprinted, flexible PDMS chip that can separate target bacteria from suspensions with high selectivity. The chip contained integrated electrodes that can kill the captured bacteria within 10 min by applying a low DC voltage. The used chip could be easily regenerated by solution immersion. Meanwhile, the PDMS chip showed good biocompatibility and inhibited adhesion of human blood cells. Our work points to a new strategy to address pathogenic bacterial contamination and infection.

Transparent PDMS Bioreactors for the Fabrication and Analysis of Multi-Layer Pre-vascularized Hydrogels Under Continuous Perfusion

Tissue engineering in combination with stem cell technology has the potential to revolutionize human healthcare. It aims at the generation of artificial tissues that can mimic the original with complex functions for medical applications. However, even the best current designs are limited in size, if the transport of nutrients and oxygen to the cells and the removal of cellular metabolites waste is mainly dependent on passive diffusion. Incorporation of functional biomimetic vasculature within tissue engineered constructs can overcome this shortcoming. Here, we developed a novel strategy using 3D printing and injection molding technology to customize multilayer hydrogel constructs with pre-vascularized structures in transparent Polydimethysiloxane (PDMS) bioreactors. These bioreactors can be directly connected to continuous perfusion systems without complicated construct assembling. Mimicking natural layer-structures of vascular walls, multilayer vessel constructs were fabricated with cell-laden fibrin and collagen gels, respectively. The multilayer design allows functional organization of multiple cell types, i.e., mesenchymal stem cells (MSCs) in outer layer, human umbilical vein endothelial cells (HUVECs) the inner layer and smooth muscle cells in between MSCs and HUVECs layers. Multiplex layers with different cell types showed clear boundaries and growth along the hydrogel layers. This work demonstrates a rapid, cost-effective, and practical method to fabricate customized 3D-multilayer vascular models. It allows precise design of parameters like length, thickness, diameter of lumens and the whole vessel constructs resembling the natural tissue in detail without the need of sophisticated skills or equipment. The ready-to-use bioreactor with hydrogel constructs could be used for biomedical applications including pre-vascularization for transplantable engineered tissue or studies of vascular biology.

Bioimprint Mediated Label-Free Isolation of Pancreatic Tumor Cells from a Healthy Peripheral Blood Cell Population

New techniques are required for earlier diagnosis and response to treatment of pancreatic cancer. Here, a label-free approach is reported in which circulating pancreatic tumor cells are isolated from healthy peripheral blood cells via cell bioimprinting technology. The method involves pre-fabrication of pancreatic cell layers and sequential casting of cell surfaces with a series of custom-made resins to produce negative cell imprints. The imprint is functionalized with a combination of polymers to engineer weak attraction to the cells which is further amplified by the increased area of contact with the matching cells. A flow-through bioimprint chip is designed and tested for selectivity toward two pancreatic tumor cell lines, ASPC-1 and Mia-PaCa-2. Healthy human peripheral blood mononuclear cells (PBMCs) are spiked with pancreatic tumor cells at various concentrations. Bioimprints are designed for preferential retention of the matching pancreatic tumor cells and with respect to PBMCs. Tumor bioimprints are capable of capturing and concentrating pancreatic tumor cells from a mixed cell population with increased retention observed with the number of seedings. ASPC-1 bioimprints preferentially retain both types of pancreatic tumor cells. This technology could be relevant for the collection and interrogation of liquid biopsies, early detection, and relapse monitoring of pancreatic cancer patients.

Bacterial Sensing and Biofilm Monitoring for Infection Diagnostics

Recent insights into the rapidly emerging field of bacterial sensing and biofilm monitoring for infection diagnostics are discussed as well as recent key developments and emerging technologies in the field. Electrochemical sensing of bacteria and bacterial biofilm via synthetic, natural, and engineered recognition, as well as direct redox-sensing approaches via algorithm-based optical sensing, and tailor-made optotracing technology are discussed. These technologies are highlighted to answer the very critical question: "how can fast and accurate bacterial sensing and biofilm monitoring be achieved? Following on from that: "how can these different sensing concepts be translated for use in infection diagnostics? A central obstacle to this transformation is the absence of direct and fast analysis methods that provide high-throughput results and bio-interfaces that can control and regulate the means of communication between biological and electronic systems. Here, the overall progress made to date in building such translational efforts at the level of an individual bacterial cell to a bacterial community is discussed.

Molecularly Imprinted Polymers and Surface Imprinted Polymers Based Electrochemical Biosensor for Infectious Diseases

Owing to their merits of simple, fast, sensitive, and low cost, electrochemical biosensors have been widely used for the diagnosis of infectious diseases. As a critical element, the receptor determines the selectivity, stability, and accuracy of the electrochemical biosensors. Molecularly imprinted polymers (MIPs) and surface imprinted polymers (SIPs) have great potential to be robust artificial receptors. Therefore, extensive studies have been reported to develop MIPs/SIPs for the detection of infectious diseases with high selectivity and reliability. In this review, we discuss mechanisms of recognition events between imprinted polymers with different biomarkers, such as signaling molecules, microbial toxins, viruses, and bacterial and fungal cells. Then, various preparation methods of MIPs/SIPs for electrochemical biosensors are summarized. Especially, the methods of electropolymerization and micro-contact imprinting are emphasized. Furthermore, applications of MIPs/SIPs based electrochemical biosensors for infectious disease detection are highlighted. At last, challenges and perspectives are discussed.

Epitope Imprinting Technology: Progress, Applications, and Perspectives toward Artificial Antibodies

Epitope imprinting is a promising tool to generate antibody-like specific recognition sites. Recently, because of the ease of obtaining templates, the flexibility in selecting monomers, their resistance to harsh environments, and the high specificity toward targets, epitope-imprinted materials have attracted much attention in various fields, such as bioanalysis, clinical therapy, and pharmacy. Here, the discussion is focused on the current representative epitope imprinting technologies, including epitope bulk imprinting and epitope surface imprinting. Moreover, the application of epitope-imprinted materials to the recognition of peptides, proteins, and cells is reviewed. Finally, the remaining challenges arising from the intrinsic properties of epitope imprinting are discussed, and future development in the field is prospected.

Molecularly Imprinted Polymer-Based Microfluidic Systems for Point-of-Care Applications

Fast progress has been witnessed in the field of microfluidic systems and allowed outstanding approaches to portable, disposable, low-cost, and easy-to-operate platforms especially for monitoring health status and point-of-care applications. For this purpose, molecularly imprinted polymer (MIP)-based microfluidics systems can be synthesized using desired templates to create specific and selective cavities for interaction. This technique guarantees a wide range of versatility to imprint diverse sets of biomolecules with different structures, sizes, and physical and chemical features. Owing to their physical and chemical robustness, cost-friendliness, high stability, and reusability, MIP-based microfluidics systems have become very attractive modalities. This review is structured according to the principles of MIPs and microfluidic systems, the integration of MIPs with microfluidic systems, the latest strategies and uses for point-of-care applications and, finally, conclusions and future perspectives.

Direct cell imprint lithography in superconductive carbon black polymer composites: process optimization, characterization and in vitro toxicity analysis

Cell imprint lithography (CIL) or cell replication plays a vital role in fields like biomimetic smart culture substrates, bone tissue engineering, cell guiding, cell adhesion, tissue engineering, cell microenvironments, tissue microenvironments, cell research, drug delivery, diagnostics, therapeutics and many other applications. Herein we report a new formulation of superconductive carbon black photopolymer composite and its characterization towards a CIL process technique. In this article, we demonstrated an approach of using a carbon nanoparticle-polymer composite (CPC) for patterning cells. It is observed that a 0.3 wt % load of carbon nanoparticles (CNPs) in a carbon polymer mixture (CPM) was optimal for cell-imprint replica fabrication. The electrical resistance of the 3-CPC (0.3 wt %) was reduced by 68% when compared to N-CPC (0 wt %). This method successfully replicated the single cell with sub-organelle scale. The shape of microvesicles, grooves, pores, blebs or microvilli on the cellular surface was patterned clearly. This technique delivers a free-standing cell feature substrate. In vitro evaluation of the polymer demonstrated it as an ideal candidate for biomimetic biomaterial applications. This approach also finds its application in study based on morphology, especially for drug delivery applications and for investigations based on molecular pathways.

Molecularly Imprinted Polymers for Cell Recognition

Since their conception 50 years ago, molecularly imprinted polymers (MIPs) have seen extensive development both in terms of synthetic routes and applications. Cells are perhaps the most challenging target for molecular imprinting. Although early work was based almost entirely around microprinting methods, recent developments have shifted towards epitope imprinting to generate MIP nanoparticles (NPs). Simultaneously, the development of techniques such as solid phase MIP synthesis has solved many historic issues of MIP production. This review briefly describes various approaches used in cell imprinting with a focus on applications of the created materials in imaging, drug delivery, diagnostics, and tissue engineering.

Zwitterionic Molecularly Imprinted Cross-Linked Micelles for Alkaloid Recognition in Water

Molecular imprinting within surface/core doubly cross-linked micelles afforded water-soluble nanoparticle receptors for their template molecules. Extremely strong imprinting effects were consistently observed, with the imprinting factor >100:1 in comparison to nonimprinted nanoparticles prepared without the templates. The ionic nature of the cross-linkable surfactant strongly impacted the imprinting and binding process. Imprinted receptors prepared with a zwitterionic cross-linkable surfactant (4) outperformed a similar cationic one (1) when the template was zwitterionic or cationic and preferred their templates over structural analogues regardless of their ionic characteristics. Electrostatic interactions, however, dominated the receptors made with the cationic surfactant. The same micellar imprinting applied to simple as well as complex alkaloids. Imprinted receptors from 4 were also shown to categorize their alkaloid guests according to their structural similarity.

Effects of nano-confinement and conformational mobility on molecular imprinting of cross-linked micelles

Molecular imprinting is a facile method to create guest-complementary binding sites in a cross-linked polymeric network. When performed within cross-linked micelles, the resulting molecularly imprinted nanoparticles (MINPs) exhibited an extraordinary ability to distinguish subtle structural changes in the guest, including the shift of a hydrophilic or hydrophobic group by 1 carbon and addition of a single methylene/methyl group. A high surface-cross-linking density prior to core-cross-linking was key to the high-fidelity imprinting, enhancing both the binding affinity of the imprinted micelle for the template and selectivity among structural analogues. Whereas the imprinted site closely complemented the hydrophilic surface anchoring group and rigid hydrophobic aromatic core, it was expanded significantly for a conformationally mobile small group (i.e., methoxy).

Molecular Imprinting with Functional DNA

Molecular imprinting refers to templated polymerization with rationally designed monomers, and this is a general method to prepare stable and cost-effective ligands. This attractive concept however suffers from low affinity, low specificity, and limited signaling mechanisms for binding. Acrydite-modified DNA oligonucleotides can be readily copolymerized into acrylic polymers. With molecular recognition and catalytic functions, such functional DNAs are recently shown to enhance the performance of molecularly imprinted polymers (MIPs) in a few ways. First, DNA aptamers are used as macromonomers to enhance binding affinity and specificity of MIPs. Second, DNA can help produce optical signals to follow binding events. Third, imprinting can also improve the performance of catalytic DNA by enhancing its activity and specificity toward the template substrate. Finally, MIP is shown to help aptamer selection. Bulk imprinting, nanoparticle imprinting, and surface imprinting are all demonstrated with DNA. Since both DNA and synthetic polymers are cost effective and stable, their hybrid materials still possess such properties while enhancing the function of each component. This review covers recent developments on the abovementioned aspects of DNA-containing MIPs, a field just emerged in the last five years, and future research directions are discussed toward the end.

Cell-Imprint Surface Modification by Contact Photolithography-Based Approaches: Direct-Cell Photolithography and Optical Soft Lithography Using PDMS Cell Imprints

New cell-imprint surface modification techniques based on direct-cell photolithography and optical soft lithography using poly(dimethylsiloxane) (PDMS) cell imprints are presented for enhanced cell-based studies. The core concept of engineering materials for cell-based studies is the material's ability to redesign the physicochemical characteristics of the cellular niche. There is a growing interest in direct molding from cells (cell imprinting). These negative copies of cell surface topographies have been shown to affect cell shape and direct mesenchymal stem cells' differentiation. Analyzing the results is however challenging as cells seeded on these substrates do not always end up in a cell pattern, which leads to decreased effectiveness and biased quantification. To gain control over cell seeding into the patterns and avoid unwanted cell population outside of the patterns, the cell-imprinted surface needs to be modified. From this perspective, the standard optical contact lithography process was modified and cells were introduced to the cleanroom. Direct-cell photolithography was used for a single-step PDMS cell-imprint (chondrocytes as the molding template) surface modification down to single-cell (approximately 5 μm in diameter) resolution. As cells come in a variety of shapes, sizes, and optical profiles, a complementary optical soft lithography-based photomask fabrication technique is also reported. The simplicity of the fabrication process makes this cell-imprint surface modification technique compatible with any adherent cell type and leads to efficient cell-based studies.

A rapid and specific bacterial detection method based on cell-imprinted microplates

Bacterial detection has attracted substantial interest in recent years owing to its importance in biology, medical care, drug discovery, and public health. For such applications, bacterial cell-imprinting technologies are regarded as potential methods, as they can fabricate artificial tailor-made receptors for cellular recognition. In comparison to conventional methods, which generally require a few days for bacterial determination, cell-imprinted polymers can save a substantial amount of time. Here, we report a high-throughput bacterial detection method based on a cell-imprinted 96-well microplate. The fabrication of the bacterial cell-imprinted polypyrrole and nafion complex was accomplished on a gold nanoparticle-coated microplate. The cell-imprinted polymer complex on the microplate can spontaneously rebind and specifically detect target cells with high selectivity in a short time frame (within 30 min). Furthermore, the microplates could discriminate particular target Escherichia coli O157:H7 cells from bacterial mixtures. This simple method may be used for a variety of applications such as clinical testing, food safety, and continuous environmental monitoring.

Cell-imprinted biomimetic interface for intelligent recognition and efficient capture of CTCs

Synergistically contributing to plastic and natural antibodies, a cell-imprinted biomimetic interface exhibited high sensitivity and efficiency in CTC capture, providing novel insight into cell–biointerface interactions.

Molecularly imprinted nanoparticles based plasmonic sensors for real-time Enterococcus faecalis detection

Human fecal contamination poses a crucial environmental and health threat in recent years, resulting in the difficulties of access to clean water. According to the World Health Organization, several fecal bacteria, particularly Enterococci species, are present in human intestinal flora. Enterococcus faecalis (E. faecalis) is one of the indicator bacteria that have been utilized as a pollution indicator in water. However, existing technologies and detection strategies face multiple challenges in terms of low affinity for detection and labelling requirements that limit their access to large scale applications. Here, we present a label-free molecular fingerprinting strategy on a plasmonic sensor to detect E. fecalis from aqueous and seawater samples. The kinetic performance of platform was comprehensively evaluated and the platform provided four orders of magnitude detection range with a low limit of detection (down to ~100 bacteria/mL) and a high correlation coefficient value (> 0.99) in the range of 2 × 10⁴-1 × 10⁸ cfu/mL. The platform also denoted a selectivity and specificity while other bacteria (E. coli, B. subtilis, and S. aureus) samples were applied. Multiple time use and relatively long shelf-life are superior to the existing modality. The presented method is one of the fascinating surface modification technique that utilizes biotarget as a recognition element itself, providing a broad range of versatility to replica other biotargets with different molecular structure, size, and physicochemical properties. Such a reliable and versatile platform would hold potential applications from microbiome characterization to forensics by revitalizing obsolescent detection strategies.

A molecularly imprinted electrochemiluminescence sensor for ultrasensitive HIV-1 gene detection using EuS nanocrystals as luminophore

Development of simple, sensitive and specific method for human immunodeficiency virus (HIV) assays are urgently demand. In this study, we developed a novel molecularly imprinted polymer (MIP) electrochemiluminescence (MIP-ECL) sensor for the highly sensitive and selective HIV-1 gene detection using Europium sulfide nanocrystals (EsNCs) as signal producing compound. Here, the HIV aptamer as the template and o-phenylenediamine as the functional monomer, were electropolymerized directly on the surface of ITO electrode. With the hybridization reaction between the assemblies of EuS NCs functionalized 5-amino-labeled oligonucleotides as capture probes and oligonucleotides as detection target (HIV gene), the ECL signal significantly increased using K₂S₂O₈ as coreactant. Taking advantage of both MIP-ECL assays and the strong electrochemiluminescence emission of EuS NCs, the sensitive and selective HIV gene detection has been achieved in a linear range 3.0 fM to 0.3 nM with a detection limit of 0.3 fM. The present MIP-ECL biosensor showed good specificity for HIV DNA detection compared to non-complementary and two bases mismatched sequences. The proposed ECL biosensor was applied to detect of HIV DNA in real human serum samples and satisfactory results were obtained. Due to high sensitivity and selectivity, excellent reproducibility and stability of the proposed assay, EuS NCs can be used as novel luminophore for development of MIP-ECL sensors for detection of other DNA biomarkers.

Pathogen-Imprinted Organosiloxane Polymers as Selective Biosensors for the Detection of Targeted E. coli

Early detection of pathogens requires methods that are fast, selective, sensitive and affordable. We report the development of a biosensor with high sensitivity and selectivity based on the low-cost preparation of organosiloxane (OSX) polymers imprinted with E. coli-GFP (green fluorescent protein). OSX polymers with high optical transparency, no cracking, and no shrinkage were prepared by varying several parameters of the sol-gel reaction. The unique shape and chemical fingerprint of the targeted inactivated E. coli-GFP were imprinted into bulk polymers by replication imprinting where the polymer solution was dropcast onto a bacteria template that produced a replica of the bacterial shape and chemistry on the polymer surface upon removal of the template. Capture performances were studied under non-laminar flow conditions with samples containing inactivated E. coli-GFP and compared to inactivated S. typhimurium-GFP. Capture selectivity ratios are dependent on the type of alkoxysilanes used, the H2O:silane molar ratio, and the polymerization temperature. The bacteria concentration in suspension ranged from ~6 × 105 to 1.6 × 109 cells/mL. E. coli-imprinted OSX polymers with polyethylene glycol (PEG) differentiated between the targeted bacterium E. coli, and non-targeted bacteria S. typhimurium and native E. coli-GFP, achieving selectivity ratios up to 4.5 times higher than polydimethylsiloxane (PDMS) and OSX polymers without PEG.

Debugging Nano-Bio Interfaces: Systematic Strategies to Accelerate Clinical Translation of Nanotechnologies

Despite considerable efforts in the field of nanomedicine that have been made by researchers, funding agencies, entrepreneurs, and the media, fewer nanoparticle (NP) technologies than expected have made it to clinical trials. The wide gap between the efforts and effective clinical translation is, at least in part, due to multiple overlooked factors in both in vitro and in vivo environments, a poor understanding of the nano-bio interface, and misinterpretation of the data collected in vitro, all of which reduce the accuracy of predictions regarding the NPs' fate and safety in humans. To minimize this bench-to-clinic gap, which may accelerate successful clinical translation of NPs, this opinion paper aims to introduce strategies for systematic debugging of nano-bio interfaces in the current literature.

Molecularly imprinted polymers as receptor mimics for selective cell recognition

Molecularly imprinted polymers are now approaching the perfection of natural receptors, e.g., the ability to interact with or recognize cells.

Optimal multivalent targeting of membranes with many distinct receptors

Cells can often be recognized by the concentrations of receptors expressed on their surface. For better (targeted drug treatment) or worse (targeted infection by pathogens), it is clearly important to be able to target cells selectively. A good targeting strategy would result in strong binding to cells with the desired receptor profile and barely binding to other cells. Using a simple model, we formulate optimal design rules for multivalent particles that allow them to distinguish target cells based on their receptor profile. We find the following: (i) It is not a good idea to aim for very strong binding between the individual ligands on the guest (delivery vehicle) and the receptors on the host (cell). Rather, one should exploit multivalency: High sensitivity to the receptor density on the host can be achieved by coating the guest with many ligands that bind only weakly to the receptors on the cell surface. (ii) The concentration profile of the ligands on the guest should closely match the composition of the cognate membrane receptors on the target surface. And (iii) irrespective of all details, the effective strength of the ligand-receptor interaction should be of the order of the thermal energy [Formula: see text], where [Formula: see text] is the absolute temperature and [Formula: see text] is Boltzmann's constant. We present simulations that support the theoretical predictions. We speculate that, using the above design rules, it should be possible to achieve targeted drug delivery with a greatly reduced incidence of side effects.

Molecular Imprinting of Macromolecules for Sensor Applications

Molecular recognition has an important role in numerous living systems. One of the most important molecular recognition methods is molecular imprinting, which allows host compounds to recognize and detect several molecules rapidly, sensitively and selectively. Compared to natural systems, molecular imprinting methods have some important features such as low cost, robustness, high recognition ability and long term durability which allows molecularly imprinted polymers to be used in various biotechnological applications, such as chromatography, drug delivery, nanotechnology, and sensor technology. Sensors are important tools because of their ability to figure out a potentially large number of analytical difficulties in various areas with different macromolecular targets. Proteins, enzymes, nucleic acids, antibodies, viruses and cells are defined as macromolecules that have wide range of functions are very important. Thus, macromolecules detection has gained great attention in concerning the improvement in most of the studies. The applications of macromolecule imprinted sensors will have a spacious exploration according to the low cost, high specificity and stability. In this review, macromolecules for molecularly imprinted sensor applications are structured according to the definition of molecular imprinting methods, developments in macromolecular imprinting methods, macromolecular imprinted sensors, and conclusions and future perspectives. This chapter follows the latter strategies and focuses on the applications of macromolecular imprinted sensors. This allows discussion on how sensor strategy is brought to solve the macromolecules imprinting.

Efficient Capture of Cancer Cells by Their Replicated Surfaces Reveals Multiscale Topographic Interactions Coupled with Molecular Recognition

Cell-surface topographic interactions can direct the design of biointerfaces, which have been widely used in isolation of circulating tumor cells or fundamental cell biological research. By using three kinds of cancer cell-replicated surfaces with differentiated structures, we uncover that multiscale-cooperative topographic interactions (at both nanoscale and microscale) coupled with molecular recognition enable efficient and specific isolation of cancer cells. The cell replicas precisely inherit the structural features from the original cancer cells, providing not only preferable structures for matching with cancer cells but also a unique platform to interrogate whether certain cancer cells can optimally match with their own replicated surfaces. The results reveal that cancer cells do not show preferential recognitions to their respective replicas, while the capture agent-modified surfaces with hierarchical structures exhibit improved cancer cell capture efficiencies. Two levels of topographic interactions between cancer cells and cell replica surfaces exist. Nanoscale filopodia on cancer cells can topographically interact with different nanostructures on replica surfaces. In addition, microscale concave/convex on surfaces provide suitable sites for trapping cancer cells. This study may promote smart design of multiscale biofunctional materials that can specifically recognize cancer cells.

Vision for Functionally Decorated and Molecularly Imprinted Polymers in Regenerative Engineering

The emerging field of regenerative engineering offers a great challenge and an even greater opportunity for materials scientists and engineers. How can we develop materials that are highly porous to permit cellular infiltration, yet possess sufficient mechanical integrity to mimic native tissues? How can we retain and deliver bioactive molecules to drive cell organization, proliferation, and differentiation in a predictable manner? In the following perspective, we highlight recent studies that have demonstrated the vital importance of each of these questions, as well as many others pertaining to scaffold development. We posit hybrid materials synthesized by molecular decoration and molecular imprinting as intelligent biomaterials for regenerative engineering applications. These materials have potential to present cell adhesion molecules and soluble growth factors with fine-tuned spatial and temporal control, in response to both cell-driven and external triggers. Future studies in this area will address a pertinent clinical need, expand the existing repertoire of medical materials, and improve the field's understanding of how cells and materials respond to one another.

Electrochemiluminescence Detection of Escherichia coli O157:H7 Based on a Novel Polydopamine Surface Imprinted Polymer Biosensor

In this paper, a facilely prepared electrochemiluminescence (ECL) biosensor was developed for Escherichia coli O157:H7 quantitative detection based on a polydopamine (PDA) surface imprinted polymer (SIP) and nitrogen-doped graphene quantum dots (N-GQDs). N-GQDs with a high quantum yield of 43.2% were synthesized. The uniform PDA SIP film for E. coli O157:H7 was established successfully with a facile route. The dopamine and target bacteria were electropolymerized directly on the electrode. After removal of the E. coli O157:H7 template, the established PDA SIP can selectively recognize E. coli O157:H7. Accordingly, E. coli O157:H7 polyclonal antibody (pAb) was labeled with N-GQDs. The bioconjugation of SIP-E. coli O157:H7/pAb-N-GQDs can generate intensive ECL irradiation with K₂S₂O₈. As a result, E. coli O157:H7 was detected with the ECL sensing system. Under optimal conditions, the linear relationships between the ECL intensity and E. coli O157:H7 concentration were obtained from 10¹ colony-forming units (CFU) mL^-1 to 10⁷ CFU mL^-1 with a limit of detection of 8 CFU mL^-1. The biosensor based on this SIP film was applied in water sample detection successfully. The N-GQD-based ECL analytical method for E. coli O157:H7 was reported for the first time. The sensing system had high selectivity to the target analyte, provided new opportunities for use, and increased the rate of disease diagnosis and treatment and the prevention of pathogens.