Antibody-capped mesoporous nanoscopic materials: design of a probe for the selective chromo-fluorogenic detection of finasteride

Toward Point-of-Care Diagnostics to Monitor MMP-9 and TNF-α Levels in Inflammatory Bowel Disease

We have investigated the association of matrix metallopeptidase 9 (MMP-9) and tumor necrosis factor α (TNF-α) levels with colitis severity using an established IL10-/- mouse model, which reflects the severity of inflammation in humans with inflammatory bowel disease (IBD). We found that MMP-9 and TNF-α correlated with colitis severity. In parallel, we developed assays to detect fecal MMP-9 and serum TNF-α using "cap and release" mesoporous silica nanoparticles (MSNs). MMP-9 peptide substrates as "caps" were attached to dye-loaded MSNs. The introduction of MMP-9 resulted in substrate cleavage and subsequent dye release, which was rapidly detected using a fluorometer. For TNF-α, an anti-TNF antibody was used as the "cap". The introduction of TNF-α antigen leads to the release of the dyes because the antigen binds more strongly to the antibody cap. The MSN-based assays can detect MMP-9 and TNF-α effectively, although signal amplification is required to meet clinical sensitivity.

Multiplexed Detection of Analytes on Single Test Strips with Antibody-Gated Indicator-Releasing Mesoporous Nanoparticles

Rapid testing methods for the use directly at a point of need are expected to unfold their true potential especially when offering adequate capabilities for the simultaneous measurement of multiple analytes of interest. Considering the unique modularity, high sensitivity, and selectivity of antibody‐gated indicator delivery (gAID) systems, a multiplexed assay for three small‐molecule explosives (TATP, TNT, PETN) was thus developed, allowing to detect the analytes simultaneously with a single test strip at lower ppb concentrations in the liquid phase in <5 min using a fluorescence reader or a smartphone for readout. While the TNT and PETN systems were newly developed here, all the three systems also tolerated harsher matrices than buffered aqueous model solutions. Besides a single‐track strip, the outstanding modularity of the hybrid biosensor materials in combination with strip‐patterning technologies allowed us to obtain a multichannel strip in a straightforward manner, offering comparable analytical performance while allowing to be tailored even more to the user's need.

Silica Nanoparticles-A Versatile Tool for the Treatment of Bacterial Infections

The rapid emergence of drug resistance continues to outpace the development of new antibiotics in the treatment of infectious diseases. Conventional therapy is currently limited by drug access issues such as low intracellular drug accumulations, drug efflux by efflux pumps and/or enzymatic degradation. To improve access, targeted delivery using nanocarriers could provide the quantum leap in intracellular drug transport and retention. Silica nanoparticles (SiNPs) with crucial advantages such as large surface area, ease-of-functionalization, and biocompatibility, are one of the most commonly used nanoparticles in drug delivery applications. A porous variant, called the mesoporous silica nanoparticles (MSN), also confers additional amenities such as tunable pore size and volume, leading to high drug loading capacity. In the context of bacterial infections, SiNPs and its variants can act as a powerful tool for the targeted delivery of antimicrobials, potentially reducing the impact of high drug dosage and its side effects. In this review, we will provide an overview of SiNPs synthesis, its structural proficiency which is critical in loading and conjugation of antimicrobials and its role in different antimicrobial applications with emphasis on intracellular drug targeting in anti-tuberculosis therapy, nitric oxide delivery, and metal nanocomposites. The role of SiNPs in antibiofilm coatings will also be covered in the context of nosocomial infections and surgical implants.

Optimization of analytical assay performance of antibody-gated indicator-releasing mesoporous silica particles

An in-depth study of the chemical tuning modes of antibody-gated indicator delivery (gAID) systems revealed the importance of size matching, localisation of grafting and loading sequence for obtaining high-performance small-molecule sensor materials.

Development of a lateral flow test for rapid pyrethroid detection using antibody-gated indicator-releasing hybrid materials

The employment of type-I pyrethroids for airplane disinfection in recent years underlines the necessity to develop sensing schemes for the rapid detection of these pesticides directly at the point-of-use.

Overview of the Evolution of Silica-Based Chromo-Fluorogenic Nanosensors

This review includes examples of silica-based, chromo-fluorogenic nanosensors with the aim of illustrating the evolution of the discipline in recent decades through relevant research developed in our group. Examples have been grouped according to the sensing strategies. A clear evolution from simply functionalized materials to new protocols involving molecular gates and the use of highly selective biomolecules such as antibodies and oligonucleotides is reported. Some final examples related to the evolution of chromogenic arrays and the possible use of nanoparticles to communicate with other nanoparticles or cells are also included. A total of 64 articles have been summarized, highlighting different sensing mechanisms.

Gated Mesoporous Silica Nanocarriers for a "Two-Step" Targeted System to Colonic Tissue

Colon targeted drug delivery is highly relevant not only to treat colonic local diseases but also for systemic therapies. Mesoporous silica nanoparticles (MSNs) have been demonstrated as useful systems for controlled drug release given their biocompatibility and the possibility of designing gated systems able to release cargo only upon the presence of certain stimuli. We report herein the preparation of three gated MSNs able to deliver their cargo triggered by different stimuli (redox ambient (S1), enzymatic hydrolysis (S2), and a surfactant or being in contact with cell membrane (S3)) and their performance in solution and in vitro with Caco-2 cells. Safranin O dye was used as a model drug to track cargo fate. Studies of cargo permeability in Caco-2 monolayers demonstrated that intracellular safranin O levels were significantly higher in Caco-2 monolayers when using MSNs compared to those of free dye. Internalization assays indicated that S2 nanoparticles were taken up by cells via endocytosis. S2 nanoparticles were selected for in vivo tests in rats. For in vivo assays, capsules were filled with S2 nanoparticles and coated with Eudragit FS 30 D to target colon. The enteric coated capsule containing the MSNs was able to deliver S2 nanoparticles in colon tissue (first step), and then nanoparticles were able to deliver safranin O inside the colonic cells after the enzymatic stimuli (second step). This resulted in high levels of safranin O in colonic tissue combined with low dye levels in plasma and body tissues. The results suggested that this combination of enzyme-responsive gated MSNs and enteric coated capsules may improve the absorption of drugs in colon to treat local diseases with a reduction of systemic effects.

A Pathogen-Specific Cargo Delivery Platform Based on Mesoporous Silica Nanoparticles

We present a synthetic approach to a highly pathogen-selective detection and delivery platform based on the interaction of an antibody nanovalve with a tetrasaccharide from the O-antigen of the lipopolysaccharide (LPS) of Francisella tularensis bacteria, a Tier 1 Select Agent of bioterrorism. Different design considerations are explored, and proof-of-concept for highly pathogen-specific cargo release from mesoporous silica nanoparticles is demonstrated by comparisons of the release of a signal transducer and model drug by LPS from F. tularensis vs Pseudomonas aeruginosa and by F. tularensis live bacteria vs the closely related bacterium Francisella novocida. In addition to the specific response to a biowarfare agent, treatment of infectious diseases in general could benefit tremendously from a delivery platform that releases its antibiotic payload only at the site of infection and only in the presence of the target pathogen, thereby minimizing off-target toxicities.

Oligonucleotide-capped mesoporous silica nanoparticles as DNA-responsive dye delivery systems for genomic DNA detection

New hybrid oligonucleotide-capped mesoporous silica nanoparticles able to detect genomic DNA were designed.

Gated Silica Mesoporous Materials in Sensing Applications

Silica mesoporous supports (SMSs) have a large specific surface area and volume and are particularly exciting vehicles for delivery applications. Such container-like structures can be loaded with numerous different chemical substances, such as drugs and reporters. Gated systems also contain addressable functions at openings of voids, and cargo delivery can be controlled on-command using chemical, biochemical or physical stimuli. Many of these gated SMSs have been applied for drug delivery. However, fewer examples of their use in sensing protocols have been reported. The approach of applying SMSs in sensing uses another concept-that of loading pores with a reporter and designing a capping mechanism that is selectively opened in the presence of a target analyte, which results in the delivery of the reporter. According to this concept, we provide herein a complete compilation of published examples of probes based on the use of capped SMSs for sensing. Examples for the detection of anions, cations, small molecules and biomolecules are provided. The diverse range of gated silica mesoporous materials presented here highlights their usefulness in recognition protocols.

Towards the Development of Smart 3D "gated scaffolds" for on-command delivery

A new approach towards the design of "gated scaffolds" based on the combination of capped mesoporous silica nanoparticles (MSNs) with porous biomaterials is reported. Using this approach, a 3D gelatin-based scaffold able to selectively deliver cargo in the presence of an APase enzyme is prepared and tested. This new design opens up the possibility of developing new smart biomaterials with advanced drug-delivery features.

An aptamer-gated silica mesoporous material for thrombin detection

An aptamer-capped mesoporous material for the selective and sensitive detection of α-thrombin in human plasma and serum has been prepared and characterised.