State of the art and future research directions of materials science applied to electrochemical biosensor developments.

Centralized laboratories in which analytical processes are automated to enable the analysis of large numbers of samples at relatively low cost are used for analytical testing throughout the world. However, healthcare is changing, partly due to the general recognition that care needs to be more patient-centered and putting the patient at the center of action. One way to achieve this goal is to consider point-of-care testing (PoC) devices as alternative analytical concepts. This requires miniaturization of current analytical concepts and the use of cost-effective diagnostic tools with appropriate sensitivity and specificity. Electrochemical sensors are ideally adapted as they provide robust, low-cost, and miniaturized solutions for the detection of variable analytes, yet lack the high sensitivity comparable to more classical diagnosis approaches. Advances in nanotechnology have opened up a plethora of different nanomaterials to be applied as electrode and/or sensing materials in electrochemical biosensors. The choice of materials significantly influences the sensor's sensitivity, selectivity, and overall performance. A critical review of the state of the art with respect to the development of the utilized materials (between 2019 and 2023) and where the field is heading to are the focus of this article.

Graphene-based field-effect transistors for biosensing: where is the field heading to?

Two-dimensional (2D) materials hold great promise for future applications, notably their use as biosensing channels in the field-effect transistor (FET) configuration. On the road to implementing one of the most widely used 2D materials, graphene, in FETs for biosensing, key issues such as operation conditions, sensitivity, selectivity, reportability, and economic viability have to be considered and addressed correctly. As the detection of bioreceptor-analyte binding events using a graphene-based FET (gFET) biosensor transducer is due to either graphene doping and/or electrostatic gating effects with resulting modulation of the electrical transistor characteristics, the gFET configuration as well as the surface ligands to be used have an important influence on the sensor performance. While the use of back-gating still grabs attention among the sensor community, top-gated and liquid-gated versions have started to dominate this area. The latest efforts on gFET designs for the sensing of nucleic acids, proteins and virus particles in different biofluids are presented herewith, highlighting the strategies presently engaged around gFET design and choosing the right bioreceptor for relevant biomarkers.

Thermoresponsive and Photocrosslinkable Poly(2-alkyl-2-oxazoline) Toolbox - Customizable Ultralow-Fouling Hydrogel Coatings for Blood Plasma Environments.

This study focuses on developing surface coatings with excellent antifouling properties, crucial for applications in the medical, biological, and technical fields, for materials and devices in direct contact with living tissues and bodily fluids such as blood. This approach combines thermoresponsive poly(2-alkyl-2-oxazoline)s, known for their inherent protein-repellent characteristics, with established antifouling motifs based on betaines. The polymer framework is constructed from various monomer types, including a novel benzophenone-modified 2-oxazoline for photocrosslinking and an azide-functionalized 2-oxazoline, allowing subsequent modification with alkyne-substituted antifouling motifs through copper(I)-catalyzed azide-alkyne cycloaddition. From these polymers surface-attached networks are created on benzophenone-modified gold substrates via photocrosslinking, resulting in hydrogel coatings with several micrometers thickness when swollen with aqueous media. Given that poly(2-alkyl-2-oxazoline)s can exhibit a lower critical solution temperature in water, their temperature-dependent solubility is compared to the swelling behavior of the surface-attached hydrogels upon thermal stimulation. The antifouling performance of these hydrogel coatings in contact with human blood plasma is further evaluated by surface plasmon resonance and optical waveguide spectroscopy. All surfaces demonstrate extremely low retention of blood plasma components, even with undiluted plasma. Notably, hydrogel layers with sulfobetaine moieties allow efficient penetration by plasma components, which can then be easily removed by rinsing with buffer.

Reverse Chemical Ecology Suggests Putative Primate Pheromones.

Pheromonal communication is widespread among living organisms, but in apes and particularly in humans there is currently no strong evidence for such phenomenon. Among primates, lemurs use pheromones to communicate within members of the same species, whereas in some monkeys such capabilities seem to be lost. Chemical communication in humans appears to be impaired by the lack or malfunctioning of biochemical tools and anatomical structures mediating detection of pheromones. Here, we report on a pheromone-carrier protein (SAL) adopting a "reverse chemical ecology" approach to get insights on the structures of potential pheromones in a representative species of lemurs (Microcebus murinus) known to use pheromones, Old-World monkeys (Cercocebus atys) for which chemical communication has been observed, and humans (Homo sapiens), where pheromones and chemical communication are still questioned. We have expressed the SAL orthologous proteins of these primate species, after reconstructing the gene encoding the human SAL, which is disrupted due to a single base mutation preventing its translation into RNA. Ligand-binding experiments with the recombinant SALs revealed macrocyclic ketones and lactones as the best ligands for all three proteins, suggesting cyclopentadecanone, pentadecanolide, and closely related compounds as the best candidates for potential pheromones. Such hypothesis agrees with the presence of a chemical very similar to hexadecanolide in the gland secretions of Mandrillus sphinx, a species closely related to C. atys. Our results indicate that the function of this carrier protein has not changed much during evolution from lemurs to humans, although its physiological role has been certainly impaired in humans.

Preparation of Ultrathin and Degradable Polymeric Films by Electropolymerization of 3-Amino-l-tyrosine.

Bioderived polymers are one of many current research areas that promise a sustainable future. Due to their unique properties, the bioderived polymer polydopamine has been in the spotlight over the last decades. Its ability to adhere to virtually any surface and its stability over a wide pH range as well as in several organic solvents make it a suitable candidate for various applications like coatings and biosensors. However, strong light absorption over a broad range of wavelengths and high quenching efficiency limit its uses. Therefore, new bioderived polymers with similar features to polydopamine but without fluorescence quenching properties are highly desirable. Herein, the electropolymerization of a bioderived analog of dopamine, 3-amino-l-tyrosine, is demonstrated. The resulting polymer, poly(amino-l-tyrosine), exhibits several characteristics complementary to or even exceeding those of polydopamine and its analog, polynorepinephrine, rendering poly(amino-l-tyrosine) attractive for the development of sensors and photoactive devices. Cyclic voltammetry, spectro-electrochemistry, and electrochemical quartz crystal microbalance measurements are applied to study the electrodeposition of this material, and the resulting films are compared to polydopamine and polynorepinephrine. Impedance spectroscopy reveals increased ion permeability of poly(amino-l-tyrosine) compared to polydopamine and polynorepinephrine. Moreover, the reduced fluorescence quenching of poly(amino-l-tyrosine) supports its use as coating for biosensors and organic semiconductors.

The Effect of Amino-Phosphate Interactions on the Biosensing Performance of Enzymatic Graphene Field-Effect Transistors.

The interaction between polyamines and phosphate species is found in a wide range of biological and abiotic systems, yielding crucial consequences that range from the formation of supramolecular colloids to structure determination. In this work, the occurrence of phosphate-amino interactions is evidenced from changes in the electronic response of graphene field effect transistors (gFETs). First, the surface of the transistors is modified with poly(allylamine), and the effect of phosphate binding on the transfer characteristics is interpreted in terms of its impact on the surface charge density. The electronic response of the polyamine-functionalized gFETs is shown to be sensitive to the presence of different phosphate anions, such as orthophosphate, adenosine triphosphate, and tripolyphosphate, and a simple binding model is developed to explain the dependence of the shift of the Dirac point potential on the phosphate species concentration. Afterward, the impact of phosphate-amino interactions on the immobilization of enzymes to polyamine-modified graphene surfaces is investigated, and a decrease in the amount of anchored enzyme as the phosphate concentration increases is found. Finally, multilayer polyamine-urease biosensors are fabricated while increasing the phosphate concentration in the enzyme solution, and the sensing properties of the gFETs toward urea are evaluated. It is found that the presence of simple phosphate anions alters the nanoarchitecture of the polyelectrolyte-urease assemblies, with direct implications on urea sensing.

Electrochemical and electronic detection of biomarkers in serum: a systematic comparison using aptamer-functionalized surfaces.

Sensitive and selective detection of biomarkers in serum in a short time has a significant impact on health. The enormous clinical importance of developing reliable methods and devices for testing serum levels of cardiac troponin I (cTnI), which are directly correlated to acute myocardial infarction (AMI), has spurred an unmatched race among researchers for the development of highly sensitive and cost-effective sensing formats to be able to differentiate patients with early onset of cardiac injury from healthy individuals with a mean cTnI level of 26 pg mL-1. Electronic- and electrochemical-based detection schemes allow for fast and quantitative detection not otherwise possible at the point of care. Such approaches rely largely on voltammetric and field-effect-based readouts. Here, we systematically investigate electric and electrochemical point-of-care sensors for the detection of cTnI in serum samples by using the same surface receptors, cTnI aptamer-functionalized CVD graphene-coated interdigated gold electrodes. The analytical performances of both sensors are comparable with a limit of detection (LoD) of 5.7 ± 0.6 pg mL-1(electrochemical) and 3.3 ± 1.2 pg mL-1 (electric). However, both sensors exhibit different equilibrium dissociation constant (KD) values between the aptamer-linked surface receptor and the cTnI analyte, being 160 pg mL-1 for the electrochemical and about three times lower for the electrical approach with KD = 51.4 pg mL-1. This difference is believed to be related to the use of a redox mediator in the electrochemical sensor for readout. The ability of the redox mediator to diffuse from the solution to the surface via the cTnI/aptamer interface is hindered, correlating to higher KD values. In contrast, the electric readout has the advantage of being label-free with a sensing limitation due to ionic strength effects, which can be limited using poly(ethylene) glycol surface ligands.

Reduced graphene oxide-based field effect transistors for the detection of E7 protein of human papillomavirus in saliva.

Several challenging biological sensing concepts have been realized using electrolyte-gated reduced graphene oxide field effect transistors (rGO-FETs). In this work, we demonstrate the interest of rGO-FET for the sensing of human papillomavirus (HPV), one of the most common sexually transmitted viruses and a necessary factor for cervical carcinogenesis. The highly sensitive and selective detection of the HPV-16 E7 protein relies on the attractive semiconducting characteristics of pyrene-modified rGO functionalized with RNA aptamer Sc5-c3. The aptamer-functionalized rGO-FET allows for monitoring the aptamer-HPV-16 E7 protein binding in real time with a detection limit of about 100 pg mL-1 (1.75 nM) for HPV-16 E7 from five blank noise signals (95% confidence level). The feasibility of this method for clinical application in point-of-care technology is evaluated using HPV-16 E7 protein suspended in saliva and demonstrates the successful fabrication of a promising field effect transistor biosensor for HPV diagnosis.Graphical abstract.

Solid-supported lipid bilayers - A versatile tool for the structural and functional characterization of membrane proteins.

The cellular membrane is central to the development of single-and multicellular life, as it separates the delicate cellular interior from the hostile environment. It exerts tight control over entry and exit of substances, is responsible for signaling with other cells in multicellular organisms and prevents pathogens from entering the cell. In the case of bacteria and viruses, the cellular membrane also hosts the proteins enabling invasion of the host organism. In a very real sense therefore, the cellular membrane is central to all life. The study of the cell membrane and membrane proteins in particular has therefore attracted significant attention. Due to the enormous variety of tasks performed by the membrane, it is a highly complex and challenging structure to study. Ideally, membrane components would be studied in isolation from this environment, but unlike water soluble proteins, the amphiphilic environment provided by the cellular membrane is key to the structure and function of the cell membrane. Therefore, model membranes have been developed to provide an environment in which a membrane protein can be studied. This review presents a set of tools that enable the comprehensive characterization of membrane proteins: electrochemical tools, surface plasmon resonance, neutron scattering, the surface forces apparatus and atomic force microscopy are discussed, with a particular focus on experimental technique and data evaluation.

Responses of the Pheromone-Binding Protein of the Silk Moth Bombyx mori on a Graphene Biosensor Match Binding Constants in Solution.

An electronic biosensor for odors was assembled by immobilizing the silk moth Bombyx mori pheromone binding protein (BmorPBP1) on a reduced graphene oxide surface of a field-effect transistor. At physiological pH, the sensor detects the B. mori pheromones, bombykol and bombykal, with good affinity and specificity. Among the other odorants tested, only eugenol elicited a strong signal, while terpenoids and other odorants (linalool, geraniol, isoamyl acetate, and 2-isobutyl-3-methoxypyrazine) produced only very weak responses. Parallel binding assays were performed with the same protein and the same ligands, using the common fluorescence approach adopted for similar proteins. The results are in good agreement with the sensor's responses: bombykol and bombykal, together with eugenol, proved to be strong ligands, while the other compounds showed only poor affinity. When tested at pH 4, the protein failed to bind bombykol both in solution and when immobilized on the sensor. This result further indicates that the BmorPBP1 retains its full activity when immobilized on a surface, including the conformational change observed in acidic conditions. The good agreement between fluorescence assays and sensor responses suggests that ligand-binding assays in solution can be used to screen mutants of a binding protein when selecting the best form to be immobilized on a biosensor.

The Odorant-Binding Proteins of the Spider Mite Tetranychus urticae.

Spider mites are one of the major agricultural pests, feeding on a large variety of plants. As a contribution to understanding chemical communication in these arthropods, we have characterized a recently discovered class of odorant-binding proteins (OBPs) in Tetranychus urticae. As in other species of Chelicerata, the four OBPs of T. urticae contain six conserved cysteines paired in a pattern (C1-C6, C2-C3, C4-C5) differing from that of insect counterparts (C1-C3, C2-C5, C4-C6). Proteomic analysis uncovered a second family of OBPs, including twelve members that are likely to be unique to T. urticae. A three-dimensional model of TurtOBP1, built on the recent X-ray structure of Varroa destructor OBP1, shows protein folding different from that of insect OBPs, although with some common features. Ligand-binding experiments indicated some affinity to coniferyl aldehyde, but specific ligands may still need to be found among very large molecules, as suggested by the size of the binding pocket.

Dual Monitoring of Surface Reactions in Real Time by Combined Surface-Plasmon Resonance and Field-Effect Transistor Interrogation.

By combining surface plasmon resonance (SPR) and electrolyte gated field-effect transistor (EG-FET) methods in a single analytical device we introduce a novel tool for surface investigations, enabling simultaneous measurements of the surface mass and charge density changes in real time. This is realized using a gold sensor surface that simultaneously serves as a gate electrode of the EG-FET and as the SPR active interface. This novel platform has the potential to provide new insights into (bio)adsorption processes on planar solid surfaces by directly relating complementary measurement principles based on (i) detuning of SPR as a result of the modification of the interfacial refractive index profile by surface adsorption processes and (ii) change of output current as a result of the emanating effective gate voltage modulations. Furthermore, combination of the two complementary sensing concepts allows for the comparison and respective validation of both analytical techniques. A theoretical model is derived describing the mass uptake and evolution of surface charge density during polyelectrolyte multilayer formation. We demonstrate the potential of this combined platform through the observation of layer-by-layer assembly of PDADMAC and PSS. These simultaneous label-free and real-time measurements allow new insights into complex processes at the solid-liquid interface (like non-Fickian ion diffusion), which are beyond the scope of each individual tool.

Isoleucine Residues Determine Chiral Discrimination of Odorant-Binding Protein.

Enzymes, receptors, and carrier proteins discriminate between enantiomers of natural and synthetic chemicals. Whereas the structural details of this phenomenon have been investigated in enzymes and receptors, much less is known for carrier proteins of hydrophobic ligands, particularly concerning the contribution of asymmetric centers in the side chains of amino acids to chirally selective binding. Working with a pig odorant-binding protein, we have found that the replacement of either one or both isoleucine residues in the binding pocket by leucines abolishes discrimination of menthol and carvone enantiomers. The results indicate that isoleucines are crucial for chiral discrimination of hydrophobic ligands, and that asymmetry in the side chain may be as important as the overall asymmetry of the protein. The results provide suggestions and guidelines for improving chiral selectivity of binding proteins and enzymes, with consequent applications in the production of enantiomerically pure drugs.

Probe-dependence of competitive fluorescent ligand binding assays to odorant-binding proteins.

Ligand binding experiments between small chemicals and proteins and the evaluation of dissociation constants of their complexes in competitive binding assays often rely on displacement of reporter probes by the tested ligand. The most widely adopted protocol uses a fluorescent ligand which changes its emission spectrum when bound to a protein. A decrease of fluorescence, caused by the addition of a second ligand to the complex is generally interpreted as displacement of the fluorescent probe by the ligand, and therefore as a measure of the affinity of the ligand for the protein. Working with an odorant-binding protein (OBP), we found drastic differences in the calculated affinities when using 1-aminoanthracene or N-phenyl-1-naphthylamine as the fluorescent reporter. This fact was quite unexpected, as OBPs are small compact proteins with a single binding pocket without allosteric sites. Such observation raises doubts on the reliability of the fluorescent binding assay, perhaps the most widely used approach to evaluate affinities of small organic compounds to OBPs and other binding proteins. We recommend that the results of fluorescent binding experiments with OBPs should be confirmed by using two different probes or alternative methods. The reliability of current protocols for ligand binding assays is rather limited, while we still wait for a label-free approach that could be simple, fast and free from the use of radioactive tracers.

Nanoporous thin films in optical waveguide spectroscopy for chemical analytics.

Spectroscopy with planar optical waveguides is still an active field of research for the quantitative analysis of various supramolecular surface architectures and processes, and for applications in integrated optical chip communication, direct chemical sensing, etc. In this contribution, we summarize some recent development in optical waveguide spectroscopy using nanoporous thin films as the planar substrates that can guide the light just as well as bulk thin films. This is because the nanoporosity is at a spacial length-scale that is far below the wavelength of the guided light; hence, it does not lead to an enhanced scattering or additional losses of the optical guided modes. The pores have mainly two effects: they generate an enormous inner surface (up to a factor of 100 higher than the mere geometric dimensions of the planar substrate) and they allow for the exchange of material and charges between the two sides of the solid thin film. We demonstrate this for several different scenarios including anodized aluminum oxide layers for the ultrasensitive determination of the refractive index of fluids, or the label-free detection of small analytes binding from the pore inner volume to receptors immobilized on the pore surface. Using a thin film of Ti metal for the anodization results in a nanotube array offering an even further enhanced inner surface and the possibility to apply electrical potentials via the resulting TiO2 semiconducting waveguide structure. Nanoporous substrates fabricated from SiNx thin films by colloid lithography, or made from SiO2 by e-beam lithography, will be presented as examples where the porosity is used to allow for the passage of ions in the case of tethered lipid bilayer membranes fused on top of the light-guiding layer, or the transport of protons through membranes used in fuel cell applications. The final example that we present concerns the replication of the nanopore structure by polymers in a process that leads to a nanorod array that is equally well suited to guide the light as the mold; however, it opens a totally new field for integrated optics formats for direct chemical and biomedical sensing with an extension to even molecularly imprinted structures. Graphical abstract.

Reversible Switching of the Dirac Point in Graphene Field-Effect Transistors Functionalized with Responsive Polymer Brushes.

The reversible control of the graphene Dirac point using external chemical stimuli is of major interest in the development of advanced electronic devices such as sensors and smart logic gates. Here, we report the coupling of chemoresponsive polymer brushes to reduced graphene oxide (rGO)-based field-effect transistors to modulate the graphene Dirac point in the presence of specific divalent cations. Poly[2-(methacryloyloxy)ethyl] phosphate (PMEP) brushes were grown on the transistor channel by atom transfer radical polymerization initiated from amine-pyrene linkers noncovalently attached to rGO surfaces. Our results show an increase in the Dirac point voltage due to electrostatic gating effects upon the specific binding of Ca2+ and Mg2+ to the PMEP brushes. We demonstrate that the electrostatic gating is reversibly controlled by the charge density of the polymer brushes, which depends on the divalent cation concentration. Moreover, a theoretical formalism based on the Grahame equation and a Langmuir-type binding isotherm is presented to obtain the PMEP-cation association constant from the experimental data.

Shedding Light on the Dark Corners of Metal-Organic Framework Thin Films: Growth and Structural Stability of ZIF-8 Layers Probed by Optical Waveguide Spectroscopy.

Metal-organic framework (MOF) thin films are promising materials for multiple technological applications, such as chemical sensing. However, one potential limitation for their widespread use in different settings is their stability in aqueous environments. In the case of ZIF-8 (zeolitic imidazolate framework) thin films, their stability in aqueous media is currently a matter of debate. Here, we show that optical waveguide spectroscopy (OWS), in combination with surface plasmon resonance (SPR) spectroscopy, offers a convenient way for answering intriguing questions related to the stability of MOF thin films in aqueous solutions and, eventually provide a tool for assessing changes in MOF layers under different environmental conditions. Our experiments relied on the use of ZIF-8 thin films grown on surface-modified gold substrates, as optical waveguides. We have found a linear thickness increase after each growing cycle and observed that the growing characteristics are strongly influenced by the nature of the primer layer. One of our findings is that substrate surface modification with a 3-mercapto-1-propanesulfonate (MPSA) primer layer is critical to achieve ZIF-8 layers that can effectively act as optical waveguides. We observed that ZIF-8 films are structurally stable upon exposure to pure water and 50 mM NaCl solutions but they exhibit a slight swelling and an increase in porosity probably due to the permeation of the solvent in the intergrain mesoporous cavities. However, OWS revealed that exposure of ZIF-8 thin films to phosphate-buffered saline solutions (pH 8) promotes significant film degradation. This poses an important question as to the prospective use of ZIF-8 materials in biologically relevant applications. In addition, it was demonstrated that postsynthetic polyelectrolyte modification of ZIF-8 films has no detrimental effects on the structural stability of the films.

From radioactive ligands to biosensors: binding methods with olfactory proteins.

In this paper, we critically review the binding protocols currently reported in the literature to measure the affinity of odorants and pheromones to soluble olfactory proteins, such as odorant-binding proteins (OBPs), chemosensory proteins (CSPs) and Niemann-Pick class C2 (NPC2) proteins. The first part contains a brief introduction on the principles of binding and a comparison of the techniques adopted or proposed so far, discussing advantages and problems of each technique, as well as their suitable application to soluble olfactory proteins. In the second part, we focus on the fluorescent binding assay, currently the most widely used approach. We analyse advantages and drawbacks, trying to identify the causes of anomalous behaviours that have been occasionally observed, and suggest how to interpret the experimental data when such events occur. In the last part, we describe the state of the art of biosensors for odorants, using soluble olfactory proteins immobilised on biochips, and discuss the possibility of using such approach as an alternative way to measure binding events and dissociation constants.

Odorant-Binding Proteins as Sensing Elements for Odour Monitoring.

Odour perception has been the object of fast growing research interest in the last three decades. Parallel to the study of the corresponding biological systems, attempts are being made to model the olfactory system with electronic devices. Such projects range from the fabrication of individual sensors, tuned to specific chemicals of interest, to the design of multipurpose smell detectors using arrays of sensors assembled in a sort of artificial nose. Recently, proteins have attracted increasing interest as sensing elements. In particular, soluble olfaction proteins, including odorant-binding proteins (OBPs) of vertebrates and insects, chemosensory proteins (CSPs) and Niemann-Pick type C2 (NPC2) proteins possess interesting characteristics for their use in sensing devices for odours. In fact, thanks to their compact structure, their soluble nature and small size, they are extremely stable to high temperature, refractory to proteolysis and resistant to organic solvents. Moreover, thanks to the availability of many structures solved both as apo-proteins and in complexes with some ligands, it is feasible to design mutants by replacing residues in the binding sites with the aim of synthesising proteins with better selectivity and improved physical properties, as demonstrated in a number of cases.

Understanding How Sterols Regulate Membrane Remodeling in Supported Lipid Bilayers.

The addition of single-chain lipid amphiphiles such as antimicrobial fatty acids and monoglycerides to confined, two-dimensional phospholipid bilayers can trigger the formation of three-dimensional membrane morphologies as a passive means to regulate stress. To date, relevant experimental studies have been conducted using pure phospholipid compositions, and extending such insights to more complex, biologically relevant lipid compositions that include phospholipids and sterols is warranted because sterols are important biological mediators of membrane stress relaxation. Herein, using the quartz crystal microbalance-dissipation (QCM-D) technique, we investigated membrane remodeling behaviors triggered by the addition of sodium dodecyl sulfate (SDS), lauric acid (LA), and glycerol monolaurate (GML) to supported lipid bilayers (SLBs) composed of phospholipid and cholesterol mixtures. The SLB platforms were prepared by the solvent-assisted lipid bilayer method in order to form cholesterol-rich SLBs with tunable cholesterol fractions (0-52 mol %). The addition of SDS or LA to fabricated SLBs induced tubule formation, and the extent of membrane remodeling was greater in SLBs with higher cholesterol fractions. In marked contrast, GML addition led to bud formation, and the extent of membrane remodeling was lower in SLBs with higher cholesterol fractions. To explain these empirical observations, we discuss how cholesterol influences the elastic (stiffness) and viscous (stress relaxation) properties of phospholipid/cholesterol lipid bilayers as well as how the membrane translocation properties of single-chain lipid amphiphiles affect the corresponding membrane morphological responses. Collectively, our findings demonstrate that single-chain lipid amphiphiles induce highly specific membrane morphological responses across both simplified and complex model membranes, and cholesterol can promote or inhibit membrane remodeling by a variety of molecular mechanisms.