Biomaterials for Interfacing Cell Imaging and Drug Delivery: An Overview

Advances in Injectable Hydrogels Based on Diverse Gelation Methods for Biomedical Imaging

The injectable hydrogels can deliver the loads directly to the predetermined sites and form reservoirs to increase the enrichment and retention of the loads in the target areas. The preparation and injection of injectable hydrogels involve the sol-gel transformation of hydrogels, which is affected by factors such as temperature, ions, enzymes, light, mechanics (self-healing property), and pH. However, tracing the injection, degradation, and drug release from hydrogels based on different ways of gelation is a major concern. To solve this problem, contrast agents are introduced into injectable hydrogels, enabling the hydrogels to be imaged under techniques such as fluorescence imaging, photoacoustic imaging, magnetic resonance imaging, and radionuclide imaging. This review details methods for causing the gelation of imageable hydrogels; discusses the application of injectable hydrogels containing contrast agents in various imaging techniques, and finally explores the potential and challenges of imageable hydrogels based on different modes of gelation.

Boric Acid-Functionalized Carbon Dots as a High-Performance Antibacterial Agent against Escherichia coli

Bacterial infections and antibiotic abuse are a global threat to human health. In recent years, there has been a boom in research on antimicrobial agents with low toxicity and efficient nanomaterials. Boric acid-functionalized carbon dots (B-CDs) with negative surface charge were synthesized by the hydrothermal method. Covalent bonds were formed between the boric acid groups and the cis-diol groups of the polysaccharide in the bacterial cell wall, and numerous B-CDs were trapped on the bacterial surface. In the experiments of antibacterial activity, B-CDs presented strong bactericidal activity against Escherichia coli (E. coli) with a minimum bactericidal concentration of 12.5 μg/mL. The antibacterial mechanism suggested that B-CDs entered the cell interior by diffusion and posed significant damage to the double helix structure of E. coli DNA. Furthermore, B-CDs exhibited low toxicity. The results demonstrated that the novel antimicrobial B-CDs not only fought against E. coli infection and antibiotic misuse but also provided new ideas for safe and effective antimicrobial agents of carbon nanomaterials.

Impact of a Polymer-Based Nanoparticle with Formoterol Drug as Nanocarrier System In Vitro and in an Experimental Asthmatic Model

The implementation of nanotechnology in pulmonary delivery systems might result in better and more specific therapy. Therefore, a nano-sized drug carrier should be toxicologically inert and not induce adverse effects. We aimed to investigate the responses of a polymer nano drug carrier, a lysine poly-hydroxyethyl methacrylate nanoparticle (NP) [Lys-p(HEMA)], loaded with formoterol, both in vitro and in vivo in an ovalbumin (OVA) asthma model. The successfully synthesized nanodrug formulation showed an expectedly steady in vitro release profile. There was no sign of in vitro toxicity, and the 16HBE and THP-1 cell lines remained vital after exposure to the nanocarrier, both loaded and unloaded. In an experimental asthma model (Balb/c mice) of ovalbumin sensitization and challenge, the nanocarrier loaded and unloaded with formoterol was tested in a preventive strategy and compared to treatment with the drug in a normal formulation. The airway hyperresponsiveness (AHR) and pulmonary inflammation in the bronchoalveolar lavage (BAL), both cellular and biochemical, were assessed. The application of formoterol as a regular drug and the unloaded and formoterol-loaded NP in OVA-sensitized mice followed by a saline challenge was not different from the control group. Yet, both the NP formulation and the normal drug application led to a more deteriorated lung function and increased lung inflammation in the OVA-sensitized and -challenged mice, showing that the use of the p(HEMA) nanocarrier loaded with formoterol needs more extensive testing before it can be applied in clinical settings.

Simultaneous Electrophysiology and Imaging Reveal Changes in Lipid Membrane Thickness and Tension upon Uptake of Amphiphilic Gold Nanoparticles

Amphiphilic gold core nanoparticles (AmNPs) striped with hydrophilic 11-mercapto-1-undecanesulfonate (MUS) and hydrophobic 1-octanethiol (OT) ligands are promising candidates for drug carriers that passively and nondisruptively enter cells. Yet, how they interact with cellular membranes is still only partially understood. Herein, we use electrophysiology and imaging to carefully assess changes in droplet interface bilayer lipid membranes (DIBs) incurred by striped AmNPs added via microinjection. We find that AmNPs spontaneously reduce the steady-state specific capacitance and contact angle of phosphatidylcholine DIBs by amounts dependent on the final NP concentration. These reductions, which are greater for NPs with a higher % OT ligands and membranes containing unsaturated lipids but negligible for MUS-only-coated NPs, reveal that AmNPs passively embed in the interior of the bilayer where they increase membrane thickness and lateral tension through disruption of lipid packing. These results demonstrate the enhanced evaluation of nano-bio interactions possible via electrophysiology and imaging of DIBs.

BioMOF-Based Anti-Cancer Drug Delivery Systems

A variety of nanomaterials have been developed specifically for biomedical applications, such as drug delivery in cancer treatment. These materials involve both synthetic and natural nanoparticles and nanofibers of varying dimensions. The efficacy of a drug delivery system (DDS) depends on its biocompatibility, intrinsic high surface area, high interconnected porosity, and chemical functionality. Recent advances in metal-organic framework (MOF) nanostructures have led to the achievement of these desirable features. MOFs consist of metal ions and organic linkers that are assembled in different geometries and can be produced in 0, 1, 2, or 3 dimensions. The defining features of MOFs are their outstanding surface area, interconnected porosity, and variable chemical functionality, which enable an endless range of modalities for loading drugs into their hierarchical structures. MOFs, coupled with biocompatibility requisites, are now regarded as highly successful DDSs for the treatment of diverse diseases. This review aims to present the development and applications of DDSs based on chemically-functionalized MOF nanostructures in the context of cancer treatment. A concise overview of the structure, synthesis, and mode of action of MOF-DDS is provided.

Nanotechnological advancements in the brain tumor therapy: a novel approach

Nanotechnological advancements over the past few years have led to the development of newer treatment strategies in brain cancer therapy which leads to the establishment of nano oncology. Nanostructures with high specificity, are best suitable to penetrate the blood-brain barrier (BBB). Their desired physicochemical properties, such as small sizes, shape, higher surface area to volume ratio, distinctive structural features, and the possibility to attach various substances on their surface transform them into potential transport carriers able to cross various cellular and tissue barriers, including the BBB. The review emphasizes nanotechnology-based treatment strategies for the exploration of brain tumors and highlights the current progress of different nanomaterials for the effective delivery of drugs for brain tumor therapy.

Latest advances in biomimetic nanomaterials for diagnosis and treatment of cardiovascular disease

Cardiovascular disease remains one of the leading causes of death in China, with increasingly serious negative effects on people and society. Despite significant advances in preventing and treating cardiovascular diseases, such as atrial fibrillation/flutter and heart failure over the last few years, much more remains to be done. Therefore, developing innovative methods for identifying and managing cardiovascular disorders is critical. Nanomaterials provide multiple benefits in biomedicine, primarily better catalytic activity, drug loading, targeting, and imaging. Biomimetic materials and nanoparticles are specially combined to synthesize biomimetic nanoparticles that successfully reduce the nanoparticles' toxicity and immunogenicity while enhancing histocompatibility. Additionally, the biological targeting capability of nanoparticles facilitates the diagnosis and therapy of cardiovascular disease. Nowadays, nanomedicine still faces numerous challenges, which necessitates creating nanoparticles that are highly selective, toxic-free, and better clinically applicable. This study reviews the scientific accomplishments in this field over the past few years covering the classification, applications, and prospects of noble metal biomimetic nanozymes and biomimetic nanocarriers.

Fluorescent Multifunctional Organic Nanoparticles for Drug Delivery and Bioimaging: A Tutorial Review

Fluorescent organic nanoparticles (FONs) are a large family of nanostructures constituted by organic components that emit light in different spectral regions upon excitation, due to the presence of organic fluorophores. FONs are of great interest for numerous biological and medical applications, due to their high tunability in terms of composition, morphology, surface functionalization, and optical properties. Multifunctional FONs combine several functionalities in a single nanostructure (emission of light, carriers for drug-delivery, functionalization with targeting ligands, etc.), opening the possibility of using the same nanoparticle for diagnosis and therapy. The preparation, characterization, and application of these multifunctional FONs require a multidisciplinary approach. In this review, we present FONs following a tutorial approach, with the aim of providing a general overview of the different aspects of the design, preparation, and characterization of FONs. The review encompasses the most common FONs developed to date, the description of the most important features of fluorophores that determine the optical properties of FONs, an overview of the preparation methods and of the optical characterization techniques, and the description of the theoretical approaches that are currently adopted for modeling FONs. The last part of the review is devoted to a non-exhaustive selection of some recent biomedical applications of FONs.

Advances and challenges in developing smart, multi-functional microneedles for biomedical applications

Microneedles (MNs) have been developed as minimally invasive tools for diagnostic and therapeutic applications. However, in recent years, there has been an increasing interest in developing smart multi-functional MN devices to provide automated and closed-loop systems for body fluid extraction, biosensing, and drug delivery in a stimuli-responsive manner. Although this technology is still in its infancy and far from being translated into the clinic, preclinical trials have shown some promise for the broad applications of multi-functional MN devices. The main challenge facing the fabrication of smart MN patches is the integration of multiple modules, such as drug carriers, highly sensitive biosensors, and data analyzers in one miniaturized MN device. Researchers have shown the feasibility of creating smart MNs by integrating stimuli-responsive biomaterials and advanced microscale technologies, such as microsensors and microfluidic systems, to precisely control the transportation of biofluids and drugs throughout the system. These multi-functional MN devices can be envisioned in two distinct strategies. The first type includes individual drug delivery and biosensing MN units with a microfluidic system and a digital analyzer responsible for fluid transportation and communication between these two modules. The second type relies on smart biomaterials that can function as drug deliverers and biosensors by releasing drugs in a stimuli-responsive manner. These smart biomaterials can undergo structural changes when exposed to external stimuli, such as pH and ionic changes, mimicking the biological systems. Studies have demonstrated a high potential of hydrogel-based MN devices for a wide variety of biomedical applications, such as drug and cell delivery, as well as interstitial fluid extraction. Biodegradable hydrogels have also been advantageous for fabricating multi-functional MNs due to their high loading capacity and biocompatibility with the drug of choice. Here, we first review a set of MN devices that can be employed either for biosensing or delivery of multiple target molecules and compare them to the conventional and more simple systems, which are mainly designed for single-molecule sensing or delivery. Subsequently, we expand our insight into advanced MN systems with multiple competencies, such as body fluid extraction, biosensing, and drug delivery at the point of care. The improvement of biomaterials knowledge and biofabrication techniques will allow us to efficiently tune the next generation of smart MNs and provide a realistic platform for more effective personalized therapeutics. This article is protected by copyright. All rights reserved.

Carbon Dots in Biomedicine: A Review

Despite the rapid development of science and technology, the effective treatment of cancer still threatens human life and health. However, the success of cancer treatment is closely related to early diagnosis, identification, and effective treatment. In recent years, with the strengthening of the development and research of nanomaterials for cancer diagnosis and treatment, researchers have found that carbon dots (CDs) have the advantages of wide absorption, excellent biocompatibility, diverse imaging characteristics, and photostability and are widely used in various fields, such as sensing, imaging, and drug/gene transportation. Recently, researchers also discovered that CDs could be used as an effective photosensitizer to generate active oxygen or convert light energy into heat under the stimulation of the external lasers, making them have the effects of photothermal and photodynamic therapy for cancer. In this review, we first outline the single-modal and multimodal imaging analysis of CDs in cancer cells. After introducing diversified imaging functions, we focused on the design and the latest research progress of CDs in phototherapy and introduced in detail the strategies of CDs in phototherapy treatment and the challenges faced by clinical applications. We hope that this overview can provide important insights for researchers and accelerate the pace of research on CDs in imaging-guided phototherapy treatment.

Distinctive Adsorption Mechanism and Kinetics of Immunoglobulin G on a Nanoscale Polymer Surface

Elucidation of protein adsorption beyond simple polymer surfaces to those presenting greater chemical complexity and nanoscopic features is critical to developing well-controlled nanobiomaterials and nanobiosensors. In this study, we repeatedly and faithfully track individual proteins on the same nanodomain areas of a block copolymer (BCP) surface and monitor the adsorption and assembly behavior of a model protein, immunoglobulin G (IgG), over time into a tight surface-packed structure. With discrete protein adsorption events unambiguously visualized at the biomolecular level, the detailed assembly and packing states of IgG on the BCP nanodomain surface are subsequently correlated to various regimes of IgG adsorption kinetic plots. Intriguing features, entirely different from those observed from macroscopic homopolymer templates, are identified from the IgG adsorption isotherms on the nanoscale, chemically varying BCP surface. They include the presence of two Langmuir-like adsorption segments and a nonmonotonic regime in the adsorption plot. Via correlation to time-corresponding topographic data, the unique isotherm features are explained with single biomolecule level details of the IgG adsorption pathway on the BCP. This work not only provides much needed, direct experimental evidence for time-resolved, single protein level, adsorption events on nanoscale polymer surfaces but also signifies mutual linking between specific topographic states of protein adsorption and assembly to particular segments of adsorption isotherms. From the fundamental research viewpoint, the correlative ability to examine the nanoscopic surface organizations of individual proteins and their local as well as global adsorption kinetic profiles will be highly valuable for accurately determining protein assembly mechanisms and interpreting protein adsorption kinetics on nanoscale surfaces. Application-wise, such knowledge will also be important for fundamentally guiding the design and development of biomaterials and biomedical devices that exploit nanoscale polymer architectures.

Effect of Electrolytic Medium on the Electrochemical Reduction of Graphene Oxide on Si(111) as Probed by XPS

The wafer-scale integration of graphene is of great importance in view of its numerous applications proposed or underway. A good graphene–silicon interface requires the fine control of several parameters and may turn into a high-cost material, suitable for the most advanced applications. Procedures that can be of great use for a wide range of applications are already available, but others are to be found, in order to modulate the offer of different types of materials, at different levels of sophistication and use. We have been exploring different electrochemical approaches over the last 5 years, starting from graphene oxide and resulting in graphene deposited on silicon-oriented surfaces, with the aim of understanding the reactions leading to the re-establishment of the graphene network. Here, we report how a proper choice of both the chemical environment and electrochemical conditions can lead to a more controlled and tunable graphene–Si(111) interface. This can also lead to a deeper understanding of the electrochemical reactions involved in the evolution of graphene oxide to graphene under electrochemical reduction. Results from XPS, the most suitable tool to follow the presence and fate of functional groups at the graphene surface, are reported, together with electrochemical and Raman findings.

Anisotropic and Amphiphilic Mesoporous Core-Shell Silica Microparticles Provide Chemically Selective Environments for Simultaneous Delivery of Curcumin and Quercetin

Porous silica materials are often used for drug delivery. However, systems for simultaneous delivery of multiple drugs are scarce. Here we show that anisotropic and amphiphilic dumbbell core-shell silica microparticles with chemically selective environments can entrap and release two drugs simultaneously. The dumbbells consist of a large dense lobe and a smaller hollow hemisphere. Electron microscopy images show that the shells of both parts have mesoporous channels. In a simple etching process, the properly adjusted stirring speed and the application of ammonium fluoride as etching agent determine the shape and the surface anisotropy of the particles. The surface of the dense lobe and the small hemisphere differ in their zeta potentials consistent with differences in dye and drug entrapment. Confocal Raman microscopy and spectroscopy show that the two polyphenols curcumin (Cur) and quercetin (QT) accumulate in different compartments of the particles. The overall drug entrapment efficiency of Cur plus QT is high for the amphiphilic particles but differs widely between Cur and QT compared to controls of core-shell silica microspheres and uniformly charged dumbbell microparticles. Furthermore, Cur and QT loaded microparticles show different cancer cell inhibitory activities. The highest activity is detected for the dual drug loaded amphiphilic microparticles in comparison to the controls. In the long term, amphiphilic particles may open up new strategies for drug delivery.

Screening and Quantification of the Encapsulation of Dyes in Supramolecular Particles

The encapsulation of therapeutic agents, such as drugs and vaccines, into colloidal particles offers an attractive strategy to enhance their efficacy. Previously, we reported the development of guanosine-based supramolecular colloidal particles suitable for encapsulating a broad array of guests ranging from small molecule drugs, like doxorubicin, to proteins, like GFP. Many biomedical applications of such particles require a precise determination of the amount of encapsulated therapeutic agents. Despite many studies describing the development of particle-based delivery systems, a general method for the precise and quick quantification of the encapsulated payload is still lacking. Here, we report a method based on flow cytometry measurements for complexes made from guanosine-based particles and a variety of commercially available fluorescent dyes. This method allows us to determine the apparent affinities of such dyes for two variants of these particles, which in turn provides insightful structure-affinity relationships. In contrast to the current methods, such as those that rely on fluorescence microscopy based on measurements of absorption/fluorescence of dissolved particles or on the supernatant of the solution, the reported method is suitable for high-throughput screening and more reproducible results. The protocol described here should be applicable to a wide variety of colloidal particles being developed around the world. Our group is currently expanding the scope to quantify the encapsulation of other molecules of biomedical interest, such as proteins and nucleic acids.

Ionic Liquid-Controlled Shape Transformation of Spherical to Nonspherical Polymersomes via Hierarchical Self-Assembly of a Diblock Copolymer

Here, we report the self-assembly of poly(ethylene glycol) methyl ether-block-poly(ε-caprolactone) (PEG-b-PCL) copolymer in three ionic liquids (ILs) possessing different cations with common bis(trifluoromethylsulfonyl)imide anion. The observed polymeric nanostructures in ILs were directly visualized by room temperature conventional transmission and field emission scanning electron microscopy and were further examined for their size and shape by dynamic light scattering technique. The results show that through changes in the concentration of PEG-b-PCL and/or changing the solvent by using a different IL, we can effectively induce shape transformation of self-assembled PEG-b-PCL nanostructures in order to generate nonspherical polymersomes, such as worm-like aggregates, stomatocytes, nanotubes, large hexagonal and tubular-shaped polymersomes. These findings provide a promising platform for the design of biodegradable soft dynamic systems in the micro-/nano-motor field for cancer-targeted delivery, diagnosis and imaging-guided therapy, and controlled release of therapeutic drugs for treatment of many diseases. Non-spherical polymersome-based vaccines may be taken up more efficiently, especially against viruses for pulmonary drug delivery than the spherical polymersomes-based.

A review on advances of treatment modalities for Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease which is mainly characterized by progressive impairment in cognition, emotion, language and memory in older population. Considering the impact of AD, formulations of pharmaceutical drugs and cholinesterase inhibitors have been widely propagated, receiving endorsement by FDA as a form of AD treatment. However, these medications were gradually discovered to be ineffective in removing the root of AD pathogenesis but merely targeting the symptoms so as to improve a patient's cognitive outcome. Hence, a search for better disease-modifying alternatives is put into motion. Having a clear understanding of the neuroprotective mechanisms and diverse properties undertaken by specific genes, antibodies and nanoparticles is central towards designing novel therapeutic agents. In this review, we provide a brief introduction on the background of Alzheimer's disease, the biology of blood-brain barrier, along with the potentials and drawbacks associated with current therapeutic treatment avenues pertaining to gene therapy, immunotherapy and nanotherapy for better diagnosis and management of Alzheimer's disease.

Aqueous Suspensions of Cellulose Oligomer Nanoribbons for Growth and Natural Filtration-Based Separation of Cancer Spheroids

In vitro growth of cancer spheroids (CSs) and the subsequent separation of CSs from a 2D or 3D cell culture system are important for fundamental cancer studies and cancer drug screening. Although biopolymer-based or synthetic hydrogels are suitable candidates to be used as 3D cell culture scaffolds, alternatives with better processing capabilities are still required to set up cell culture microenvironment. In this study, we show that aqueous suspensions of crystalline nanoribbons composed of cellulose oligomers have a potential for CS growth and separation. The nanoribbon suspensions in serum-containing cell culture media fixed single cancer cells and CSs with large sizes in a 3D space, leading to suspension cultures for CS growth corresponding to culture time. Well-grown CSs were easily separated from the suspensions by natural filtration using a mesh filter with a suitable pore size. Cell viability tests revealed negligible cytotoxicity of the nanoribbons. In addition, physical damages to CSs by the separation procedures were negligible. Stable suspensions of biocompatible nanomaterials will thus provide novel microenvironments for growth and separation of diverse cell aggregates.

Nanomaterials for Diagnosis and Treatment of Brain Cancer: Recent Updates

Brain tumors, especially glioblastoma, remain the most aggressive form of all the cancers because of inefficient diagnosis and profiling. Nanostructures, such as metallic nanostructures, silica nano-vehicles, quantum dots, lipid nanoparticles (NPs) and polymeric NPs, with high specificity have made it possible to permeate the blood–brain barrier (BBB). NPs possess optical, magnetic and photodynamic properties that can be exploited by surface modification, bio composition, contrast agents’ encapsulation and coating by tumor-derived cells. Hence, nanotechnology has brought on a revolution in the field of diagnosis and imaging of brain tumors and cancers. Recently, nanomaterials with biomimetic functions have been introduced to efficiently cross the BBB to be engulfed by deep skin tumors and cancer malignancies for imaging. The review focuses on nanotechnology-based diagnostic and imaging approaches for exploration in brain tumors and cancers. Moreover, the review also summarizes a few strategies to image glioblastoma and cancers by multimodal functional nanocomposites for more precise and accurate clinical diagnosis. Their unique physicochemical attributes, including nanoscale sizes, larger surface area, explicit structural features and ability to encapsulate diverse molecules on their surface, render nanostructured materials as excellent nano-vehicles to cross the blood–brain barrier and convey drug molecules to their target region. This review sheds light on the current progress of various kinds of nanomaterials, such as liposomes, nano-micelles, dendrimers, carbon nanotubes, carbon dots and NPs (gold, silver and zinc oxide NPs), for efficient drug delivery in the treatment and diagnosis of brain cancer.

Fabrication of Poly(ethylene glycol) Capsules via Emulsion Templating Method for Targeted Drug Delivery

To reduce nonspecific interactions and circumvent biological barriers, low-fouling material of poly(ethylene glycol) (PEG) is most used for the modification of drug nanocarriers. Herein, we report the fabrication of PEG capsules via the free-radical polymerization of linear PEG or 8-arm-PEG using an emulsion templating method for targeted drug delivery. Doxorubicin (DOX) could be loaded in capsules via electrostatic interactions. The obtained capsules composed of 8-arm-PEG result in a lower cell association (2.2%) compared to those composed of linear PEG (7.3%) and, therefore, demonstrate the stealth property. The functionalization of cyclic peptides containing Arg-Gly-Asp (cRGD) on PEG capsules induce high cell targeting to U87 MG cells. A cell cytotoxicity assay demonstrates the biocompatibility of PEG capsules and high drug delivery efficacy of the targeted capsules. The reported capsules with the stealth and targeting property provide a potential platform for improved drug delivery.

Targeted therapy in chronic diseases using nanomaterial-based drug delivery vehicles

The application of nanomedicines is increasing rapidly with the promise of targeted and efficient drug delivery. Nanomedicines address the shortcomings of conventional therapy, as evidenced by several preclinical and clinical investigations indicating site-specific drug delivery, reduced side effects, and better treatment outcome. The development of suitable and biocompatible drug delivery vehicles is a prerequisite that has been successfully achieved by using simple and functionalized liposomes, nanoparticles, hydrogels, micelles, dendrimers, and mesoporous particles. A variety of drug delivery vehicles have been established for the targeted and controlled delivery of therapeutic agents in a wide range of chronic diseases, such as diabetes, cancer, atherosclerosis, myocardial ischemia, asthma, pulmonary tuberculosis, Parkinson's disease, and Alzheimer's disease. After successful outcomes in preclinical and clinical trials, many of these drugs have been marketed for human use, such as Abraxane®, Caelyx®, Mepact®, Myocet®, Emend®, and Rapamune®. Apart from drugs/compounds, novel therapeutic agents, such as peptides, nucleic acids (DNA and RNA), and genes have also shown potential to be used as nanomedicines for the treatment of several chronic ailments. However, a large number of extensive clinical trials are still needed to ensure the short-term and long-term effects of nanomedicines in humans. This review discusses the advantages of various drug delivery vehicles for better understanding of their utility in terms of current medical needs. Furthermore, the application of a wide range of nanomedicines is also described in the context of major chronic diseases.