Site-specific conjugation of metal carbonyl dendrimer to antibody and its use as detection reagent in immunoassay

Synthesis and Biological Studies of Novel Aminophosphonates and Their Metal Carbonyl Complexes (Fe, Ru)

The quest to find new inhibitors of biologically relevant targets is considered an important strategy to introduce new drug candidates for the treatment of neurodegenerative diseases. A series of (aminomethyl)benzylphosphonates 8a–c and their metallocarbonyl iron 9a–c and ruthenium 10a–c complexes were designed, synthesized, and evaluated for their inhibitory potentials against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) by determination of IC₅₀. Metallocarbonyl derivatives, in general, did not show significant inhibition activity against these enzymes, the most potent inhibitor was the (aminomethyl)benzylphosphonate 8a (IC₅₀ = 1.215 µM against AChE). Molecular docking analysis of AChE and (aminomethyl)benzylphosphonates 8a–c showed the strongest interactions of 8a and AChE compared to isomers 8b and 8c. Cytotoxicity studies of synthesized compounds towards the V79 cell line were also performed and discussed.

An infrared IgG immunoassay based on the use of a nanocomposite consisting of silica coated Fe3O4 superparticles

A reliable, rapid and ultrasensitive immunoassay is described for determination of immunoglobulin G (IgG). It is making use of biofunctional magnetite (Fe₃O₄) superparticles coated with SiO₂ and serving as an infrared (IR) probe. The unique IR fingerprint signals originating from the transverse and longitudinal phonon modes, respectively, of the asymmetric stretching of the Si-O-Si bridges display a satisfactory resistance to optical interference from the environment. The adoption of Fe₃O₄ superparticles instead of Fe₃O₄ nanoparticles as the magnetic core warrants a controllable structure and a strong magnetic response. This facilitates the efficient purification of the probes and the alleviation of the interfacial resistance between the liquid-solid interfaces by using a magnet. The gold-coated substrate was used to immobilize goat-anti-human IgG. The analyte (human IgG) was incubated with the IR probes, and then captured by the substrate immobilized antibody with the assistance of an external magnetic field. The integral area of the IR absorption band between 1250 cm^-1 - 900 cm^-1 was chosen for quantitative assay. The limit of detection is 95 fM, which is two orders of magnitude better than that without the magnetic field. The assay time was shortened from 2 h to 1 min. High selectivity, specificity, and long-term stability of the immunoassay were achieved. The performance of the assay when analyzing blood samples confirmed the practicability of the method. Graphical abstract Schematic presentation of the infrared (IR) immunoassay based on Fe₃O₄ superparticle@SiO₂ nanocomposites. The assistance of an external magnetic field reduces the incubation time and improves the detection sensitivity.

Site-selective orientated immobilization of antibodies and conjugates for immunodiagnostics development

Immobilized antibody systems are the key to develop efficient diagnostics and separations tools. In the last decade, developments in the field of biomolecular engineering and crosslinker chemistry have greatly influenced the development of this field. With all these new approaches at our disposal, several new immobilization methods have been created to address the main challenges associated with immobilized antibodies. Few of these challenges that we have discussed in this review are mainly associated to the site-specific immobilization, appropriate orientation, and activity retention. We have discussed the effect of antibody immobilization approaches on the parameters on the performance of an immunoassay.

In Vitro Evaluation of Gd(3+)-Anionic Linear Globular Dendrimer-Monoclonal Antibody: Potential Magnetic Resonance Imaging Contrast Agents for Prostate Cancer Cell Imaging

PURPOSE

Early stage prostate cancer diagnosis is of high global interest. Magnetic resonance imaging (MRI) is a non-invasive modality for early cancer diagnosis, in particular for prostate cancer detection. The research aim is to synthesize a nanodendrimer and its conjugate with C595 monoclonal antibody (mAb C595), against prostate cancer, followed by its chelating with Gd(3+).

PROCEDURES

Anti-MUC-1 mAb C595 was conjugated to an anionic linear globular dendrimer (ALGDG2). The polyethylene glycol core and citric acid shell were synthesized followed by loading with Gd(3+) to make novel contrast agents for functional MRI. The in vitro behavior and MRI parameters of the nanoconjugate were investigated performing several studies such as cell toxicity and TNF-alpha evaluations. The investigation of magnetic resonance imaging parameters indicated how well nanoconjugate performs in (1)H-NMR and (17)O-NMR in vitro.

RESULTS

Results showed a potential specific MRI activity by improving the swelling responses cell binding. The MTT (2-(4,5-dimethyl-2-thiazolyl)-3,5-diphenyl-2H-tetrazolium bromide) assay demonstrated that this contrast agent had significant cytotoxicity on prostate cancer cells.

CONCLUSIONS

These results showed that Gd(3+)-ALGDG2-C595 is a potential prostate molecular imaging agent and could be considered as an ideal functional nanoprobe. Additionally, further investigations by clinical trials are in the pipeline.

Vibrational spectroscopy of metal carbonyls for bio-imaging and -sensing

Transition metal carbonyls exhibit strong CO absorptions in the 2200–1800 cm⁻¹ region, which is free of interference from other functional groups. This feature has led to their applications in bio-imaging and -sensing, in particular through mid-IR, Raman and more recently, surface-enhanced Raman spectroscopy (SERS).

Iron-Carbonyl Aqueous Vesicles (MCsomes) by Hydration of [Fe(CO){CO(CH2)5CH3}(Cp)(PPh3)] (FpC6): Highly Integrated Colloids with Aggregation-Induced Self-Enhanced IR Absorption (AI-SEIRA)

Self-assembly of hydrophobic molecules into aqueous colloids contradicts common chemical intuition, but has been achieved through hydration of [Fe(CO){CO(CH2)5CH3}(Cp)(PPh3)] (FpC6). FpC6 has no surface activity, no NMR signals in D2O and no critical aggregation concentration (CAC) in H2O. The molecule, however, contains both acyl and terminal CO groups that are prone to being hydrated. By adding water to a solution in THF, self-assembly of FpC6 can be initiated through water-carbonyl interactions (WCIs) with the highly polarized acyl CO groups. This aggregation subsequently enhances the hydration of the acyl CO groups and also induces the WCI of otherwise unhydrated terminal CO groups. The resultant metal-carbonyl aggregates have been proved to be bilayer vesicles with iron complexes exposed towards water and alkyl chains forming inner walls (MCsomes). These MCsomes show high structure integration upon dilution due to the hydrophobic nature of the building blocks. The highly polarized CO groups on the surface of the MCsomes result in a negative zeta potential (-65 mV) and create a local electric field, which significantly enhances the IR absorption of CO groups by more than 100-fold. This is the first discovery of aggregation-induced self-enhanced IR absorption (AI-SRIRA) without the assistant of external dielectric substrates. Highly integrated MCsomes are, therefore, promising as a novel group of materials, for example, for IR-based sensing and imaging.