Dendrimers have attracted immense interest in science and technology due to their unique chemical structure that offers a myriad of opportunities for researchers. Dendritic design allows us to present peptides in a branched three-dimensional fashion that eventually leads to a globular shape, thus mimicking globular proteins. Peptide dendrimers, unlike other classes of dendrimers, have immense applications in biomedical research due to their biological origin. The diversity of potential building blocks and innumerable possibilities for design, along with the fact that the area is relatively underexplored, make peptide dendrimers sought-after candidates for various applications. This review summarizes the stepwise evolution of peptidic dendrimers along with their multifaceted applications in various fields. Further, the introduction of biomacromolecules such as proteins to a dendritic scaffold, resulting in complex macromolecules with discrete molecular weights, is an altogether new addition to the area of organic chemistry. The synthesis of highly complex and fully folded biomacromolecules on a dendritic scaffold requires expertise in synthetic organic chemistry and biology. Presently, there are only a handful of examples of protein dendrimers; we believe that these limited examples will fuel further research in this area.

Gene silencing by RNA interference is a powerful technology with broad applications. However, this technology has been hampered by the instability of small interfering RNA (siRNA) molecules in physiological conditions and their inefficient delivery into the cytoplasm of target cells. Porous silicon nanoparticles have emerged as a potential delivery vehicle to overcome these limitationsbeing able to encapsulate RNA molecules within the porous matrix and protect them from degradation. Here, key variables were investigated that influence siRNA loading into porous silicon nanoparticles. The effect of modifying the surface of porous silicon nanoparticles with various amino-functional molecules as well as the effects of salt and chaotropic agents in facilitating siRNA loading was examined. Maximum siRNA loading of 413 μg/(mg of porous silicon nanoparticles) was found when the nanoparticles were modified by a fourth generation polyamidoamine dendrimer. Low concentrations of urea or salt increased loading capacity: an increase in RNA loading by 19% at a concentration of 0.05 M NaCl or 21% at a concentration of 0.25 M urea was observed when compared to loading in water. Lastly, it was demonstrated that dendrimer-functionalized nanocarriers are able to deliver siRNA against ELOVL5, a target for the treatment of advanced prostate cancer.

Novel peptidylated surfaces were designed to minimise interferences when electrochemically detecting cardiac troponin I in complex biological samples. Disulfide-cored peptide dendrons featuring carbomethoxy groups were self-assembled on gold electrodes. The carbomethoxy groups were deprotected to obtain carboxylic groups used to immobilise antibodies for cardiac troponin I marker. The chemisorption of two types of peptides, one containing triazole and the other with native peptide bonds, on a gold substrate was studied by quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and X-ray photoelectron spectroscopy (XPS). Peptides formed ordered self-assembled monolayers, contributing to a more efficient display of the subsequently immobilised antibodies towards their binding to the antigen. As a result, electrochemical immunosensors prepared by self-assembly of peptides afforded higher sensitivities for cardiac troponin I than those prepared by the chemisorption of alkane thiolated compounds. Triazolic peptide-modified immunosensors showed extraordinary sensitivity towards cardiac troponin I [1.7µA/(ng/mL) in phosphate buffer], but suffered from surface fouling in 10% serum. Modification with non-triazolic peptides gave rise to anti-fouling properties and still enabled the detection of cardiac troponin I at pg/mL concentrations in 10% serum without significant matrix effects.

The spherical assemblies named “reverse micellar vesicles” from self-assembling psuedopeptidic bottlebrush polymers are reported. These assemblies exhibited the combined features of both micelles and vesicles viz. molecular arrangement of classical...

We, herein, report the fabrication of light-scattering switches from polymer microsphere-filled liquid crystals (PFLCs) using pseudopeptidic bottlebrush polymers. A simple method of precipitation of a polymer using the 4-cyano-4′-pentylbiphenyl (5CB) nonsolvent is employed for the preparation of PFLC devices. For this, a series of phenylalanine (Phe)-based bottlebrush polymers having different chain lengths are synthesized by ring-opening metathesis polymerization (ROMP) using the Grubbs second-generation ruthenium catalyst and used in a nematic liquid crystal (LC) matrix. The developed PFLC devices are well-characterized using various ultramicroscopic techniques such as field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and polarizing optical microscopy (POM). For the first time, the effect of the molecular weight of a polymer on electro-optic (E-O) properties of PFLC is investigated. PFLCs show significant differences in microsphere size, required operating voltage, transmittance, contrast ratio (CR ratio), memory effect, and switching speed upon subtle variation of the dopant polymer units. Overall, we demonstrated that the chain length of a polymer plays a crucial role in controlling the performance of PFLC devices. The presented methodology offers promising possibilities for the fabrication of PFLC-based switchable scattering devices with improved performance for optoelectronic applications.