Abdul Rahim Ferhan

• PhD
• Research Fellow at Nanyang Technological University

Multivalent ligand-receptor interactions between receptor-presenting lipid membranes and ligand-modified biological and biomimetic nanoparticles influence cellular entry and fusion processes. Environmental pH changes can drive these membrane-related interactions by affecting membrane nanomechanical properties. Quantitatively, however, the correspon...

While noncovalent forces typically drive lipid vesicle adsorption and rupture to form supported lipid bilayer (SLB) coatings on inorganic surfaces for various material science applications, this strategy only works on a few materials with suitable energetics such as SiO2. The use of coordination chemistry between inverse phosphocholine (PC) lipid h...

Owing to high surface sensitivity, gold nanorods (AuNRs) are widely used to construct surface-based nanoplasmonic biosensing platforms for label-free molecular diagnostic applications. A key fabrication step involves controlling AuNR deposition onto the target surface, which requires maximizing surface density while minimizing inter-particle aggreg...

Lipid‐based nanoparticles have emerged as a clinically viable platform technology to deliver nucleic acids for a wide range of healthcare applications. Within this scope, one of the most exciting areas of recent progress and future innovation potential lies in the material science of lipid‐based nanoparticles, both to refine existing nanoparticle s...

While noncovalent forces typically drive lipid vesicle adsorption and rupture to form supported lipid bilayer (SLB) coatings on inorganic surfaces, this strategy only works on a few materials with suitable energetics such as SiO2. The use of coordination chemistry between inverse-phosphocholine (PC) lipid headgroups and surfaces has emerged as a pr...

Plasmonic chips comprising gold nanoisland structures that are fabricated by solution-phase seeding, have demonstrated excellent promise as high-sensitivity substrates for molecular detection and medical diagnostic applications. Even so, there still remains an outstanding need to examine the potential utility of these plasmonic chips for label-free...

The ongoing coronavirus disease 2019 (COVID-19) pandemic has accelerated efforts to develop high-performance antiviral surface coatings while highlighting the need to build a strong mechanistic understanding of the chemical design principles that underpin antiviral surface coatings. Herein, we critically summarize the latest efforts to develop anti...

The biosensing performance of plasmonic nanostructures critically depends on detecting changes in the local refractive index near the sensor surface, which is referred to as surface sensitivity. For biosensing applications at solid-liquid interfaces, recent efforts to boost surface sensitivity have narrowly focused on laterally isotropic nanostruct...

There is broad interest in functionalizing solid surfaces with lysozyme, which is a widely studied antimicrobial protein. To date, most efforts have focused on developing more effective immobilization schemes to promote lysozyme attachment in fully aqueous conditions, while there remains an outstanding need to understand how tuning the solution-pha...

Human hair keratins have proven to be a viable biomaterial for diverse regenerative applications. However, the most significant characteristic of this material, the ability to self-assemble into nanoscale intermediate filaments, has not been exploited. Herein, we successfully demonstrated the induction of hair-extracted keratin self-assembly in vit...

The ongoing coronavirus disease 2019 (COVID‐19) pandemic highlights the importance of developing effective virus targeting strategies to treat and prevent viral infections. Since virus particles are nanoscale entities, nanomaterial design strategies are ideally suited to create advanced materials that can interact with and mimic virus particles. In...

Polymer-nanoparticle composites find relevance in various fields ranging from optoelectronics to the biomedical sciences. Various efforts have been made to devise fabrication strategies that are simple, robust,and reproducible. Herein, we demonstrate a universal strategy to fabricate plasmon-active polymer-nanoparticle composites, exemplified by th...

The development of nanostructured material interfaces is critical to various application areas spanning diverse fields such as medicine, energy, and sensing. One of the most promising areas involves nanomedicine and drug delivery and involves the formation of noncovalently adsorbed protein coatings on nanostructured surfaces such as inorganic nanop...

Silica-coated nanoparticles are widely used in biomedical applications such as theragnostics, imaging, and drug delivery. While silica-coated nanoparticles are biocompatible, experimental evidence shows that they can trigger innate immune reactions and a broader understanding of what types of reactions are caused and how to mitigate them is needed....

Natural proteins such as bovine serum albumin (BSA) are readily extracted from biological fluids and widely used in various applications such as drug delivery and surface coatings. It is standard practice to dope BSA proteins with an amphipathic stabilizer, most commonly fatty acids, during purification steps in order to maintain BSA conformational...

Bovine serum albumin (BSA) protein is widely used to fabricate antifouling coatings for nanobiotechnology applications. Numerous BSA protein options are commercially available and obtained through different purification methods, however, there is no guidance on which ones are preferable for antifouling coatings. Herein, we investigate the real-time...

Understanding biointerfacial processes is crucial in various fields across fundamental and applied biology, but performing quantitative studies via conventional characterization techniques remains challenging due to instrumentation as well as analytical complexities and limitations. In order to accelerate translational research and address current...

Serum albumins are evolutionary conserved proteins that are found in many animal species, and purified forms are widely used in biotechnology applications, such as components within surface passivation coatings and drug delivery systems. As such, there has long been interest in studying how serum albumins adsorb onto solid supports, although existi...

Plasmonic nanostructures have applications in a wide range of fields, including chemical and biological sensing. However, the development of techniques to fabricate sub-micron plasmonic structures over large scales remains challenging. We demonstrate a high-throughput, cost-effective approach to fabricate Au nanoribbons via chemical lift-off lithog...

Bovine serum albumin (BSA) is one of the most widely used protein reagents in the scientific community, especially for surface passivation ("blocking") applications in various bioassays. Numerous BSA protein options are commercially available, however, there is scarce information about which ones are preferable for blocking applications. Herein, we...

Tethered bilayer lipid membranes (tBLMs) represent a promising model membrane system that can host transmembrane proteins to serve as biosensors with exceptional detection performance. Herein, using the quartz crystal microbalance-dissipation (QCM-D) technique, we systematically investigated the influence of tether density on tBLM-peptide interacti...

Understanding the properties of cell membranes is important in the fields of fundamental and applied biology. While the characterization of simplified biological membrane mimics comprising liquid phase lipids has been routinely performed due to the ease of fabrication, the characterization of more realistic membrane mimics comprising multi-phase li...

The design and application of surface-based nanoplasmonic sensors has spurred broad interest from the chemical science community, touching upon diverse topics such as plasmonics, nanoscience, surface chemistry, measurement analysis, and interfacial science. One of the most exciting areas involves taking advantage of the simple instrumental requirem...

The supported lipid bilayer (SLB) platform is a popular cell membrane mimic that is utilized in the chemical, biological, materials science, and medical fields. To date, SLB preparation has proven challenging because of the need for specialized fabrication equipment, domain-specific knowledge about topics relevant to lipid self-assembly, and extens...

Human serum albumin (HSA) is one of the most abundant proteins in the human body and also used as a biomaterial coating. While there is significant interest in modifying the properties of solid supports to control HSA adsorption, there is an outstanding need to investigate whether modulating the conformational properties of HSA proteins can influen...

Zika virus is a mosquito-borne virus that is associated with neurodegenerative diseases, including Guillain–Barré syndrome¹ and congenital Zika syndrome². As Zika virus targets the nervous system, there is an urgent need to develop therapeutic strategies that inhibit Zika virus infection in the brain. Here, we have engineered a brain-penetrating pe...

Unraveling the details of how supported lipid bilayers (SLBs) are coupled to oxide surfaces is experimentally challenging, and there is an outstanding need to develop highly surface-sensitive measurement strategies to determine SLB separation distances. Indeed, subtle variations in separation distance can be associated with significant differences...

Bovine serum albumin (BSA) is the most widely used protein for surface passivation applications, although it has relatively weak, non-sticky interactions with hydrophilic surfaces such as silica-based materials. Herein, we report a simple and versatile method to increase the stickiness of BSA protein molecules adsorbing onto silica surfaces, result...

Nanoplasmonic sensors have emerged as a promising measurement approach to track biomacromolecular interactions involving lipid membrane interfaces. By taking advantage of nanoscale fabrication capabilities, it is possible to design sensing platforms with various architectural configurations. Such capabilities open the door to fabricating lipid memb...

Nanoplasmonic sensors are a popular, surface-sensitive measurement tool to investigate biomacromolecular interactions at solid-liquid interfaces, opening the door to a wide range of applications. In addition to high surface sensitivity, nanoplasmonic sensors have versatile surface chemistry options as plasmonic metal nanoparticles can be coated wit...

The detection of cancer biomarkers represents an important aspect of cancer diagnosis and prognosis. Recently, the concept of liquid biopsy has been introduced whereby diagnosis and prognosis are performed by means of analyzing biological fluids obtained from patients to detect and quantify circulating cancer biomarkers. Unlike conventional biopsy...

We present a simple method for obtaining high-density two- and threedimensional assemblies of gold nanorods (AuNRs) on polymer brush, referred to as “surface-floating super-aggregates”, with uniform distribution spanning macroscopic distances. This was achieved via the single-step immersion of a poly(oligo ethylene glycol methacrylate) brush-contai...

The integration of supported lipid membranes with surface-based nanoplasmonic arrays provides a powerful sensing approach to investigate biointerfacial phenomena at membrane interfaces. While a growing number of lipid vesicles, protein, and nucleic acid systems have been explored with nanoplasmonic sensors, there has been only very limited investig...

In recent years, nanoplasmonic sensors have become widely used for the label-free detection of biomolecules across medical, biotechnology, and environmental science applications. To date, many nanoplasmonic sensing strategies have been developed with outstanding measurement capabilities, enabling detection down to the single-molecule level. One of...

Understanding the physicochemical factors that influence protein adsorption onto solid supports holds wide relevance for fundamental insights into protein structure and function as well as for applications such as surface passivation. Ionic strength is a key parameter that influences protein adsorption, although how its modulation might be utilized...

On account of high surface sensitivity, localized surface plasmon resonance (LSPR) sensors have proven widely useful for studying lipid membrane configurations at solid-liquid interfaces. Key measurement capabilities include distinguishing adsorbed vesicles from supported lipid bilayers (SLBs) as well as profiling the extent of deformation among ad...

Characterizing the shape of sub-100 nm, biological soft-matter particulates (e.g., liposomes and exosomes) adsorbed at a solid-liquid interface remains a challenging task. Here, we introduce a localized surface plasmon resonance (LSPR) sensing approach to quantitatively profile the deformation of nanoscale, fluid-phase 1,2-dioleoyl-sn-glycero-3-pho...

With mounting evidence that nanomaterials can trigger adverse innate immune responses such as complement activation, there is increasing attention to the development of strategies that mask the complement-activating properties of nanomaterials. The current gold standard to reduce complement activation of nanomaterials is the covalent attachment of...

The range of scanning probe microscopy (SPM) applications for atomic force microscopy (AFM) is expanding in the biological sciences field, reflecting an increasing demand for tools that can improve our fundamental understanding of the physics behind biological systems. However, the complexity associated with applying SPM techniques in biomedical re...

Nanoparticle polymer composites have wide-ranging applications in fields such as catalysis, optoelectronics, drug delivery and biochemical sensing. In recent years, the use of noble metal nanoparticle polymer composites for plasmonic sensing has attracted much attention. Because several fabrication methodologies for such nanocomposites have already...

Understanding the adsorption behavior of lipid vesicles at solid-liquid interfaces is important for obtaining fundamental insights into soft matter adsorbates as well as for practical applications such as supported lipid bilayer (SLB) fabrication. While the process of SLB formation has been highly scrutinized, less understood are the details of ves...

We present a new approach for the synthesis of gold (Au)-palladium (Pd) bimetallic supra-nanoparticles in which densely packed anisotropic Pd nanostructures surround a central Au nanoparticle (rod, sphere, cubic shape). They were obtained by means of Pd crystal growth on Au nanoparticle surfaces which are modified with a mixture of cetyltrimethylam...

We introduce a convenient single-step approach for controlled synthesis of unique two- and three-dimensional hierarchical assemblies of silver nanoparticles by utilizing binary and ternary mixtures of capping agents. The binary mixtures comprise of trisodium citrate mixed with either cysteamine or mercaptopropionic acid while the ternary mixtures f...

The control of polymer brush morphology is important in determining its performance for various applications such as for anti-fouling coatings or as a host for polymer brush-nanoparticle nanocomposites. Herein we introduce a novel method to vary the surface roughness of polymer brushes by sequential growth in different solvent qualities. Poly(oligo...

One-dimensional (1D) micro- and nanostructures have become increasingly popular due to their tremendous prospect in various applications. While the design and fabrication of these structures from a single component in two-dimensional (2D) arrays is common, the attainment of hierarchical three-dimensional (3D) architectures made up of multicomponent...

A novel permeability gate-based electrochemiluminescent (ECL) aptasensor has been constructed by utilizing target-responsive polyelectrolyte-aptamer film deposited on the solid-state ECL electrode to control the rate of diffusion of a coreactant that triggers the ECL.

We report the synthesis of uniform triangular gold nanoplates by a modified seeded growth method. The concentration of cetyltrimethylammonium bromide (CTAB) in the growth solution and the time interval between multiple steps of growth were important factors which determine the formation of uniform triangular Au nanoplates. In addition, by further i...

We report a method to modify a silica capillary with poly(oligo(ethylene glycol)methacrylate) (POEGMA) and its performance for protein separation. We optimized the grafting density and thickness of the POEGMA film and investigated the effect of running buffer pH, ionic strength, separation voltage, and sample injection time. The POEGMA-coated capil...

The common drawbacks of current colorimetric sensors using gold nanoparticle aggregation is its relatively low sensitivity and narrow dynamic range, which restrict their application in real sample analysis when competing with other analytical techniques such as fluorescence and chemiluminescence. In this article, we demonstrate a novel strategy to...

By controlling the thickness of the silver shell, Au-Ag core-shell nanorods with quadruple plasmonic peaks corresponding to red, green, violet and deep violet regions have been prepared. Additionally, under polarized light, we achieved tunability of scattered colors from a single nanoparticle over an exceptionally wide wavelength range. The observe...

The physical immobilization of antibodies via spot-drying on polymer brush, poly(oligo(ethylene glycol) methacrylate) (POEGMA), was investigated by employing immunoglobulin G (IgG). Fluorescence measurements across a wide range of brush thicknesses from 6 to 102 nm interestingly revealed that the protein loading capacity of the brush did not linear...

We report a novel, simple strategy to efficiently enhance the fluorescence of metal-coated up-conversion nanoparticles (UCNPs), NaYF4:Yb,Er/Tm. The UCNPs are functionalized with a polyamidoamine generation 1 (PAMAM G1) dendrimer, followed by a continuous growth of gold (Au) or silver (Ag) nanoshells to selectively enhance the up-converted green, vi...

We introduce gold nanorods (GNRs) decoration on NaYF4:Yb/Tm upconversion nanocrystals (UCNCs) by functionalizing the UCNCs with polyamidoamine generation 1 (PAMAM G1) dendrimer, followed by a single-step seed-mediated growth of long-range GNRs to enhance "biological window" upconversion emission. The up-conversion emission of GNR-decorated UCNCs ca...

We introduce a novel solid-phase colorimetric sensor facilely fabricated by loading unmodified gold nanoparticles into poly(oligo (ethylene glycol) methacrylate) (POEGMA) brushes grown on glass. Our work reports the first synergistic combination of metallic nanoparticles acting as a colorimetric sensing module with a non-fouling polymer matrix acti...

The first reconfigurable colorimetric DNA switches based on target DNA binding are reported. This DNA binding actuates a change in the interparticle distance between gold nanoparticle dimers. A significant spectral shift of 68 nm is achievable from on-off switching. The reconfigurability is possible owing to thiol and EDC-imidazole coupling which a...

The picture shows an approach to real-time monitoring of single molecular binding events by the construction of a reconfigurable colorimetric DNA switch, described on page 234. A significant spectral shift of over 60 nm is achievable from on-off switching. The switching is based on changing the interparticle distance between gold nanoparticles in d...

We introduce a facile strategy to obtain dense 3-dimensional assembly of non-functionalized gold nanoparticles into unmodified, end-tethered poly(oligo(ethylene glycol) methacrylate) bottle brushes of high grafting densities. Referred to as 'in-stacking', we present its mechanism based on evidence from UV-vis absorbance, AFM and FESEM.

The surface of neural electrodes was modified with rnultilayered, polypyrrole (PPy)-coated, multiwalled carbon nanotubes (MWCNTs) via the layer-by-layer fabrication method. The modified electrode with PPy-coated MWCNTs exhibited a significant improvement over conventional Au electrodes and PPy-coated electrodes with respect to the electrical proper...

Here, we present a mean to expand the use of individual metallic nanoparticles to two-dimensional plasmonic nanoarrays. An optical detection platform to track down localized surface plasmon resonance (LSPR) signals of individual nanoparticles on substrates was built for the application of plasmonic nanoarrays. A pseudoimage of nanoparticles on a su...

The effect of ionic strength as well as surfactant concentration on the surface assembly of cetyltrimethylammonium bromide (CTAB)-capped gold nanorods (GNRs) has been studied. Glass substrates were modified to yield a net negative charge through electrostatic coating of polystyrenesulfonate (PSS) over a self-assembled monolayer (SAM) of positively...

An ultrasensitive electrical detection method of nucleic acids has been developed on a nanogapped biosensor. In this study, peptide nucleic acid (PNA) probes were immobilized in the gaps of a pair of finger microelectrodes first and were then hybridized with their complementary target DNA. After that, pectin molecules were introduced into the DNA s...