Models of Chemical Communication for Micro/Nanoparticles.

Engineering chemical communication between micro/nanosystems (via the exchange of chemical messengers) is receiving increasing attention from the scientific community. Although a number of micro- and nanodevices (e.g., drug carriers, sensors, and artificial cells) have been developed in the last decades, engineering communication at the micro/nanoscale is a recent emergent topic. In fact, most of the studies in this research area have been published within the last 10 years. Inspired by nature─where information is exchanged by means of molecules─the development of chemical communication strategies holds wide implications as it may provide breakthroughs in many areas including nanotechnology, artificial cell research, biomedicine, biotechnology, and ICT. Published examples rely on nanotechnology and synthetic biology for the creation of micro- and nanodevices that can communicate. Communication enables the construction of new complex systems capable of performing advanced coordinated tasks that go beyond those carried out by individual entities. In addition, the possibility to communicate between synthetic and living systems can further advance our understanding of biochemical processes and provide completely new tailored therapeutic and diagnostic strategies, ways to tune cellular behavior, and new biotechnological tools. In this Account, we summarize advances by our laboratories (and others) in the engineering of chemical communication of micro- and nanoparticles. This Account is structured to provide researchers from different fields with general strategies and common ground for the rational design of future communication networks at the micro/nanoscale. First, we cover the basis of and describe enabling technologies to engineer particles with communication capabilities. Next, we rationalize general models of chemical communication. These models vary from simple linear communication (transmission of information between two points) to more complex pathways such as interactive communication and multicomponent communication (involving several entities). Using illustrative experimental designs, we demonstrate the realization of these models which involve communication not only between engineered micro/nanoparticles but also between particles and living systems. Finally, we discuss the current state of the topic and the future challenges to be addressed.

Future Nanotechnology-Based Strategies for Improved Management of Helicobacter pylori Infection.

Helicobacter pylori (H. pylori) is a recalcitrant pathogen, which can cause gastric disorders. During the past decades, polypharmacy-based regimens, such as triple and quadruple therapies have been widely used against H. pylori. However, polyantibiotic therapies can disturb the host gastric/gut microbiota and lead to antibiotic resistance. Thus, simpler but more effective approaches should be developed. Here, some recent advances in nanostructured drug delivery systems to treat H. pylori infection are summarized. Also, for the first time, a drug release paradigm is proposed to prevent H. pylori antibiotic resistance along with an IVIVC model in order to connect the drug release profile with a reduction in bacterial colony counts. Then, local delivery systems including mucoadhesive, mucopenetrating, and cytoadhesive nanobiomaterials are discussed in the battle against H. pylori infection. Afterward, engineered delivery platforms including polymer-coated nanoemulsions and polymer-coated nanoliposomes are poposed. These bioinspired platforms can contain an antimicrobial agent enclosed within smart multifunctional nanoformulations. These bioplatforms can prevent the development of antibiotic resistance, as well as specifically killing H. pylori with no or only slight negative effects on the host gastrointestinal microbiota. Finally, the essential checkpoints that should be passed to confirm the potential effectiveness of anti-H. pylori nanosystems are discussed.

Nanoprogrammed Cross-Kingdom Communication Between Living Microorganisms.

The engineering of chemical communication at the micro/nanoscale is a key emergent topic in micro/nanotechnology, synthetic biology, and related areas. However, the field is still in its infancy; previous advances, although scarce, have mainly focused on communication between abiotic micro/nanosystems or between microvesicles and living cells. Here, we have implemented a nanoprogrammed cross-kingdom communication involving two different microorganisms and tailor-made nanodevices acting as "nanotranslators". Information flows from the sender cells (bacteria) to the nanodevice and from the nanodevice to receiver cells (yeasts) in a hierarchical way, allowing communication between two microorganisms that otherwise would not interact.

Confined Motion: Motility of Active Microparticles in Cell-Sized Lipid Vesicles.

Active materials can transduce external energy into kinetic energy at the nano and micron length scales. This unique feature has sparked much research, which ranges from achieving fundamental understanding of their motility to the assessment of potential applications. Traditionally, motility is studied as a function of internal features such as particle topology, while external parameters such as energy source are assessed mainly in bulk. However, in real-life applications, confinement plays a crucial role in determining the type of motion active particles can adapt. This feature has been however surprisingly underexplored experimentally. Here, we showcase a tunable experimental platform to gain an insight into the dynamics of active particles in environments with restricted 3D topology. Particularly, we examined the autonomous motion of coacervate micromotors confined in giant unilamellar vesicles (GUVs) spanning 10-50 µm in diameter and varied parameters including fuel and micromotor concentration. We observed anomalous diffusion upon confinement, leading to decreased motility, which was more pronounced in smaller compartments. The results indicate that the theoretically predicted hydrodynamic effect dominates the motion mechanism within this platform. Our study provides a versatile approach to understand the behavior of active matter under controlled, compartmentalized conditions.

Engineering chemical communication between micro/nanosystems.

Chemical communication, based on the exchange of molecules as messengers, allows different entities to share information, cooperate and orchestrate collective behaviors. In recent years, the development of strategies of chemical communication between micro/nanosystems is becoming a key emergent topic in micro/nanotechnology, biomimicry and related areas. In this tutorial review, we provide a general perspective of the concepts used on the topic of chemical communication, and the advances made using different approaches that include nanomaterials, synthetic biology and information-processing tools. Although studies in this direction are very recent, they can be divided in two main categories: (i) communication between abiotic systems and (ii) communication between living and abiotic systems. Using illustrative examples, we give an overview of the ongoing progress, potential applications in different areas and current challenges. The engineering of chemical communication between micro/nanosystems represents a paradigm shift and may open a myriad of new concepts, applications and new technological possibilities in the near future in a number of research fields.

Hybrid Biodegradable Nanomotors through Compartmentalized Synthesis.

Designer particles that are embued with nanomachinery for autonomous motion have great potential for biomedical applications; however, their development is highly demanding with respect to biodegradability/compatibility. Previously, biodegradable propulsive machinery based on enzymes has been presented. However, enzymes are highly susceptible to proteolysis and deactivation in biological milieu. Biodegradable hybrid nanomotors powered by catalytic inorganic nanoparticles provide a proteolytically stable alternative to those based upon enzymes. Herein we describe the assembly of hybrid biodegradable nanomotors capable of transducing chemical energy into motion. Such nanomotors are constructed through a process of compartmentalized synthesis of inorganic MnO2 nanoparticles (MnPs) within the cavity of organic stomatocytes. We show that the nanomotors remain active in cellular environments and do not compromise cell viability. Effective tumor penetration of hybrid nanomotors is also demonstrated in proof-of-principle experiments. Overall, this work represents a new prospect for engineering of nanomotors that can retain their functionality within biological contexts.

A Versatile New Paradigm for the Design of Optical Nanosensors Based on Enzyme-Mediated Detachment of Labeled Reporters: The Example of Urea Detection.

Here, a new bio-inspired nanoarchitectonics approach for the design of optical probes is presented. It is based on nanodevices that combine 1) an enzymatic receptor subunit, 2) a signaling subunit (consisting of a labeled reporter attached to a silica surface), and 3) a mechanism of communication between the two sites based on the production of chemical messengers by the enzymatic subunit, which induces the detachment of the reporter molecules from the silica surface. As a proof of concept, a urea nanosensor based on the release of Alexa-Fluor-647-labeled oligonucleotide from enzyme-functionalized Janus gold-mesoporous-silica nanoparticles (Au-MSNPs) was developed. The Janus particles were functionalized on the silica face with amino groups to which the labeled oligonucleotides were attached by electrostatic interactions, whereas the gold face was used for grafting urease enzymes. The nanodevice was able to release the fluorescent oligonucleotide through the enzyme-mediated hydrolysis of urea to ammonia and the subsequent deprotonation of amino groups on the silica face. This simple nanodevice was applied for the fluorometric detection of urea in real human blood samples and for the identification of adulterated milk. Given the large variety of enzymes and reporter species that could be combined, this is a general new paradigm that could be applied to the design of a number of optical probes for the detection of target analytes.

Janus Gold Nanostars-Mesoporous Silica Nanoparticles for NIR-Light-Triggered Drug Delivery.

Janus gold nanostar-mesoporous silica nanoparticle (AuNSt-MSNP) nanodevices able to release an entrapped payload upon irradiation with near infrared (NIR) light were prepared and characterized. The AuNSt surface was functionalized with a thiolated photolabile molecule (5), whereas the mesoporous silica face was loaded with a model drug (doxorubicin) and capped with proton-responsive benzimidazole-ß-cyclodextrin supramolecular gatekeepers (N 1). Upon irradiation with NIR-light, the photolabile compound 5 photodissociated, resulting in the formation of succinic acid, which induced the opening of the gatekeeper and cargo delivery. In the overall mechanism, the gold surface acts as a photochemical transducer capable of transforming the NIR-light input into a chemical messenger (succinic acid) that opens the supramolecular nanovalve. The prepared hybrid nanoparticles were non-cytotoxic to HeLa cells, until they were irradiated with a NIR laser, which led to intracellular doxorubicin release and hyperthermia. This induced a remarkable reduction in HeLa cells viability.

An Interactive Model of Communication between Abiotic Nanodevices and Microorganisms.

The construction of communication models at the micro-/nanoscale involving abiotic nanodevices and living organisms has the potential to open a wide range of applications in biomedical and communication technologies. However, this area remains almost unexplored. Herein, we report, as a proof of concept, a stimuli-responsive interactive paradigm of communication between yeasts (as a model microorganism) and enzyme-controlled Janus Au-mesoporous silica nanoparticles. In the presence of the stimulus, the information flows from the microorganism to the nanodevice, and then returns from the nanodevice to the microorganism as a feedback.

Enzyme-Controlled Nanodevice for Acetylcholine-Triggered Cargo Delivery Based on Janus Au-Mesoporous Silica Nanoparticles.

This work reports a new gated nanodevice for acetylcholine-triggered cargo delivery. We prepared and characterized Janus Au-mesoporous silica nanoparticles functionalized with acetylcholinesterase on the Au face and with supramolecular ß-cyclodextrin:benzimidazole inclusion complexes as caps on the mesoporous silica face. The nanodevice is able to selectively deliver the cargo in the presence of acetylcholine via enzyme-mediated acetylcholine hydrolysis, locally lowering the pH and opening the supramolecular gate. Given the key role played by ACh and its relation with Parkinson's disease and other nervous system diseases, we believe that these findings could help design new therapeutic strategies.

Artificial cells with viscoadaptive behavior based on hydrogel-loaded giant unilamellar vesicles.

Viscoadaptation is an essential process in natural cells, where supramolecular interactions between cytosolic components drive adaptation of the cellular mechanical features to regulate metabolic function. This important relationship between mechanical properties and function has until now been underexplored in artificial cell research. Here, we have created an artificial cell platform that exploits internal supramolecular interactions to display viscoadaptive behavior. As supramolecular material to mimic the cytosolic component of these artificial cells, we employed a pH-switchable hydrogelator based on poly(ethylene glycol) coupled to ureido-pyrimidinone units. The hydrogelator was membranized in its sol state in giant unilamellar lipid vesicles to include a cell-membrane mimetic component. The resulting hydrogelator-loaded giant unilamellar vesicles (designated as HL-GUVs) displayed reversible pH-switchable sol-gel behavior through multiple cycles. Furthermore, incorporation of the regulatory enzyme urease enabled us to increase the cytosolic pH upon conversion of its substrate urea. The system was able to switch between a high viscosity (at neutral pH) and a low viscosity (at basic pH) state upon addition of substrate. Finally, viscoadaptation was achieved via the incorporation of a second enzyme of which the activity was governed by the viscosity of the artificial cell. This work represents a new approach to install functional self-regulation in artificial cells, and opens new possibilities for the creation of complex artificial cells that mimic the structural and functional interplay found in biological systems.

Toward Interdisciplinary Synergies in Molecular Communications: Perspectives from Synthetic Biology, Nanotechnology, Communications Engineering and Philosophy of Science.

Within many chemical and biological systems, both synthetic and natural, communication via chemical messengers is widely viewed as a key feature. Often known as molecular communication, such communication has been a concern in the fields of synthetic biologists, nanotechnologists, communications engineers, and philosophers of science. However, interactions between these fields are currently limited. Nevertheless, the fact that the same basic phenomenon is studied by all of these fields raises the question of whether there are unexploited interdisciplinary synergies. In this paper, we summarize the perspectives of each field on molecular communications, highlight potential synergies, discuss ongoing challenges to exploit these synergies, and present future perspectives for interdisciplinary efforts in this area.

Quorum sensing communication between lipid-based artificial cells.

Population behavior based on quorum sensing communication is a key property of living microorganisms. Here, we show quorum sensing behavior in an artificial cell population consisting of giant lipid vesicles loaded with sender-receiver machinery (enzymes and responsive biomolecules). Our system allows the examination of the collective output based on cell density, fuel concentration and proximity, which are important factors controlling natural quorum sensing behavior.

Growth, crystal structure, Hirshfeld surface analysis, DFT studies, physicochemical characterization, and cytotoxicity assays of novel organic triphosphate.

A novel organic-inorganic hybrid compound, named (1-phenylpiperazinium) trihydrogen triphosphate, with the formula (C10H15N2)2H3P3O10 has been obtained by low speed of evaporation of a mixture of an alcoholic solution of 1-phenylpiperazine and triphosphoric acid H5P3O10 at room temperature after using the ion exchange chemical procedure. To carry out a detailed crystallographic structure analysis, single-crystal X-ray diffraction has been reported. In the molecular arrangement, the different entities are held together through N-H…O, O-H…O, and C-H…O hydrogen bonds, building up a three-dimensional packing. Powder X-ray diffraction analysis is acquired to confirm the purity of the product. The nature and the proportion of intermolecular interactions were investigated by Hirshfeld surface analysis. In order to support the experimental results, a density functional theory (DFT) calculation was performed, using the Becke-3-parameter-Lee-Yang-Parr (B3LYP) function with LANL2DZ basis set, and the data indicate much agreement between the experimental and the theoretical results. Thus, the physicochemical properties were studied employing a variety of techniques (FTIR, NMR, UV-visible, and photoluminescence). To get an insight of the possible employment of the present material in biology, cell viability assays were performed.

Horseradish Peroxidase-Functionalized Gold Nanoconjugates for Breast Cancer Treatment Based on Enzyme Prodrug Therapy.

INTRODUCTION: Breast cancer has the highest mortality rate among cancers in women. Patients suffering from certain breast cancers, such as triple-negative breast cancer (TNBC), lack effective treatments. This represents a clinical concern due to the associated poor prognosis and high mortality. As an approach to succeed over conventional therapy limitations, we present herein the design and evaluation of a novel nanodevice based on enzyme-functionalized gold nanoparticles to efficiently perform enzyme prodrug therapy (EPT) in breast cancer cells. RESULTS: In particular, the enzyme horseradish peroxidase (HRP) - which oxidizes the prodrug indole-3-acetic acid (IAA) to release toxic oxidative species - is incorporated on gold nanoconjugates (HRP-AuNCs), obtaining an efficient nanoplatform for EPT. The nanodevice is biocompatible and effectively internalized by breast cancer cell lines. Remarkably, co-treatment with HRP-AuNCs and IAA (HRP-AuNCs/IAA) reduces the viability of breast cancer cells below 5%. Interestingly, 3D tumor models (multicellular tumor spheroid-like cultures) co-treated with HRP-AuNCs/IAA exhibit a 74% reduction of cell viability, whereas the free formulated components (HRP, IAA) have no effect. CONCLUSION: Altogether, our results demonstrate that the designed HRP-AuNCs nanoformulation shows a remarkable therapeutic performance. These findings might help to bypass the clinical limitations of current tumor enzyme therapies and advance towards the use of nanoformulations for EPT in breast cancer.

The Potential Use of Antibiotics Against Helicobacter pylori Infection: Biopharmaceutical Implications.

Helicobacter pylori (H. pylori) is a notorious, recalcitrant and silent germ, which can cause a variety of debilitating stomach diseases, including gastric and duodenal ulcers and gastric cancer. This microbe predominantly colonizes the mucosal layer of the human stomach and survives in the inhospitable gastric microenvironment, by adapting to this hostile milieu. In this review, we first discuss H. pylori colonization and invasion. Thereafter, we provide a survey of current curative options based on polypharmacy, looking at pharmacokinetics, pharmacodynamics and pharmaceutical microbiology concepts, in the battle against H. pylori infection.

Ultrafast Directional Janus Pt-Mesoporous Silica Nanomotors for Smart Drug Delivery.

Development of bioinspired nanomachines with an efficient propulsion and cargo-towing has attracted much attention in the last years due to their potential biosensing, diagnostics, and therapeutics applications. In this context, self-propelled synthetic nanomotors are promising carriers for intelligent and controlled release of therapeutic payloads. However, the implementation of this technology in real biomedical applications is still facing several challenges. Herein, we report the design, synthesis, and characterization of innovative multifunctional gated platinum-mesoporous silica nanomotors constituted of a propelling element (platinum nanodendrite face), a drug-loaded nanocontainer (mesoporous silica nanoparticle face), and a disulfide-containing oligo(ethylene glycol) chain (S-S-PEG) as a gating system. These Janus-type nanomotors present an ultrafast self-propelled motion due to the catalytic decomposition of low concentrations of hydrogen peroxide. Likewise, nanomotors exhibit a directional movement, which drives the engines toward biological targets, THP-1 cancer cells, as demonstrated using a microchip device that mimics penetration from capillary to postcapillary vessels. This fast and directional displacement facilitates the rapid cellular internalization and the on-demand specific release of a cytotoxic drug into the cytosol, due to the reduction of the disulfide bonds of the capping ensemble by intracellular glutathione levels. In the microchip device and in the absence of fuel, nanomotors are neither able to move directionally nor reach cancer cells and deliver their cargo, revealing that the fuel is required to get into inaccessible areas and to enhance nanoparticle internalization and drug release. Our proposed nanosystem shows many of the suitable characteristics for ideal biomedical destined nanomotors, such as rapid autonomous motion, versatility, and stimuli-responsive controlled drug release.

Dynamic spatial and structural organization in artificial cells regulates signal processing by protein scaffolding.

Structural and spatial organization are fundamental properties of biological systems that allow cells to regulate a wide range of biochemical processes. This organization is often transient and governed by external cues that initiate dynamic self-assembly processes. The construction of synthetic cell-like materials with similar properties requires the hierarchical and reversible organization of selected functional components on molecular scaffolds to dynamically regulate signaling pathways. The realization of such transient molecular programs in synthetic cells, however, remains underexplored due to the associated complexity of such hierarchical platforms. In this contribution, we effectuate dynamic spatial organization of effector protein subunits in a synthetic biomimetic compartment, a giant unilamellar vesicle (GUV), by associating in a reversible manner two fragments of a split luciferase to the membrane. This induces their structural dimerization, which consequently leads to the activation of enzymatic signaling. Importantly, such organization and activation are dynamic processes, and can be autonomously regulated - thus opening up avenues toward continuous spatiotemporal control over supramolecular organization and signaling in an artificial cell.

A 1-to-2 demultiplexer hybrid nanocarrier for cargo delivery and activation.

A biocomputing strategy implemented in hybrid nanocarriers for controlled cargo delivery is described. The nanodevice consists of enzyme-functionalized Janus Au-mesoporous silica nanoparticles, which behave as an electronic demultiplexer (DEMUX). The nanocarrier is capable of reading molecular information from the environment (lactose) and selecting one of two possible outputs (galactose production or 4-methylumbellilferone release and activation) depending on the presence of an addressing input (NAD+).

A chemical circular communication network at the nanoscale.

In nature, coordinated communication between different entities enables a group to accomplish sophisticated functionalities that go beyond those carried out by individual agents. The possibility of programming and developing coordinated communication networks at the nanoscale-based on the exchange of chemical messengers-may open new approaches in biomedical and communication areas. Here, a stimulus-responsive circular model of communication between three nanodevices based on enzyme-functionalized Janus Au-mesoporous silica capped nanoparticles is presented. The output in the community of nanoparticles is only observed after a hierarchically programmed flow of chemical information between the members.