Poly Allylamine Hydrochloride Research Articles

Polyoxometalate coupled polymers induced molybdenum phosphide with large surface area for efficient hydrogen evolution

Developing highly active hydrogen evolution reaction (HER) electrocatalysts possesses great significance for the green renewable energy conversion and storage. Here, through the electrostatic attraction between polyoxometalate (PMo12) and ammonium polyphosphate (APP) and the coordination with polyallylamine hydrochloride (PAH), the precursor was constructed, and then nitrogen-doped graphite carbon layer-coated MoP active particles (MoP@NC) were successfully prepared by high temperature carbonization. For HER, the overpotential of η10 for MoP@NC is 119 and 126 mV in acidic and alkaline electrolyte. Furthermore, in alkaline solution, when the current density reaches a certain degree (≥110 mA cm−2), the hydrogen production activity of the catalysts are the same as that of the industrial Pt/C catalysts, or even have a slight advantage. The synergistic interaction of active particles (MoP) and graphitic carbon layers and high specific surface area ensure the excellent activity of HER. N-doped porous carbon layers also protect MoP@NC working for 24 h. Moreover, the catalysts prepared in the same experimental environment with ammonium molybdate as metal source also showed good HER performance in acidic and alkaline environments. This study opens a general way to develop earth-rich Mo-based phosphide electrocatalysts with high activity for hydrolysis applications.

Influence of density and chemical additives on paper mechanical properties

AbstractIn this work we have investigated the effect of surface modification of fibres on the overall mechanical properties of high-density papers. Paper sheets were prepared by a combination of heat-pressing and polyelectrolyte Layer-by-Layer (LbL) modification of different softwood fibres. LbLs of Polyallylamine Hydrochloride (PAH) and Hyaluronic Acid (HA) were adsorbed onto unbleached kraft fibres and bleached Chemo-ThermoMechanical Pulp (CTMP) to improve the strength of the fibre–fibre joints in papers made from these fibres. Additionally, different sheet-making procedures were used to prepare a range of network densities with different degrees of fibre–fibre interaction in the system. The results demonstrate that interfacial adhesion within fibre–fibre joints plays a pivotal role in the network's performance, even at higher paper densities. Hygroexpansion measurements and fracture zone imaging with Scanning Electron Microscopy (SEM) further support the claim that stronger interactions between the fibres allow for a better utilisation of the inherent fibre properties. Surface treatments and network densification significantly improved the paper sheets' mechanical properties. Specifically, LbL-treatments alone increased specific stiffness up to 60% and specific strength by over 100%. This improvement is linked to the build-up of residual stresses during drying. Due to a high interaction between the fibres during water removal the fibres become constrained, leading to increased stretching of fibre segments. Strengthened fibre joints intensify this constraint, further increasing the stretch and, consequently, the paper's strength.

Supramolecular citrate poly allylamine hydrochloride nanoparticles for citrate delivery and calcium oxalate nanocrystal dissolution

HypothesisRenal calculi (kidney stones) are mainly made by calcium oxalate and can cause different complications including malfunction of the kidney. The most important urinary stone inhibitors are citrate molecules. Unfortunately, the amount of citrate reaching the kidney after oral ingestion is low. We hypothesized that nanoparticles of polyallylamine hydrochloride (CIT-PAH) carrying citrate ions could simultaneously deliver citrates while PAH would complex oxalate triggering dissolution and removal of CaOx nanocrystals. ExperimentsWe successfully prepared nanoparticles of citrate ions with polyallylamine hydrochloride (CIT-PAH), PAH with oxalate (OX-PAH) and characterize them by Small Angle X ray Scattering (SAXS), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and NMR. Dissolution of CaOx nanocrystals in presence of CIT-PAH have been followed with Wide Angle Xray Scattering (WAXS), DLS and Confocal Raman Microscopy. Raman spectroscopy was used to study the dissolution of crystals in synthetic urine samples. The release of citrate from CIT-PAH was followed by diffusion NMR. Molecular dynamics (MD) simulations were carried out to study the interaction of CIT and OX ions with PAH. FindingsCIT-PAH nanoparticles dissolves CaOx nanocrystals as shown by NMR, DLS, TEM and WAXS in water and by Raman spectroscopy in artificial human urine. WAXS and Raman show that the crystal structure of CaOx disappears in the presence of CIT-PAH. DLS shows that the time required for CaOX dissolution will depend on the concentration of CIT-PAH NPs. NMR proves that citrate ions are released from the CIT PAH NPs during CaOX dissolution, MD simulations showed that oxalates exhibit a stronger interaction for PAH than citrate, explaining the removal of oxalate ions and replacement of the citrate in the polymer nanoparticles.

Preparation and corrosion resistance study of a pH-responsive plasma electrolytic oxidation coating modified by halloysite nanotubes

In this research work, pH-responsive halloysite nanotubes (HNTs) microcontainers were utilized to load 2-mercaptobenzothiazole (MBT) corrosion inhibitors by adopting the layer-by-layer assembly method (LbL). Additionally, a pH-responsive composite self-healing coating was fabricated utilizing plasma electrolytic oxidation combined with micro/nano-container loadings in organic coating technology. To study the evolution of the structure and repair performance of the composite self-healing layer under various pH values, and understand the release behavior of the corrosion inhibitor, SEM, TEM, DTA, infrared absorption spectroscopy, and electrochemical testing techniques were employed. The results of the study indicated that poly allylamine hydrochloride (PAH) and poly sodium 4-styrenesulfonate (PSS) displayed efficient encapsulation of HNTs, and the release rate revealed an increase in acidic and alkaline solutions, while it showed a decrease in neutral solutions. Furthermore, scratch tests were conducted on the coated samples, demonstrating that the HNTs-loaded corrosion inhibitors significantly improved the corrosion resistance and repair performance of the coating. Besides, the protonation of the polyelectrolyte coating layer enabled the corrosion inhibitor MBT to gradually release and diffuse into the defects, leading to the formation of an adsorption film, thus inhibiting corrosion and achieving a self-healing effect.

Buffer induced ionically crosslinked polyelectrolyte treatment for self-extinguishing polyester

Over 60 million tons of polyethylene terephthalate (PET) fibers are produced annually for clothing, upholstery, linens, and carpeting. Despite its widespread use, the versatility of PET is constrained by its flammability, which poses a particular fire hazard to homes with synthetic furnishings. To mitigate this fire risk, a polyelectrolyte complex (PEC) solution composed of polyallylamine hydrochloride and poly(sodium phosphate) is deposited onto the surface of 100% polyester fabric to render it self-extinguishing and eliminate melt dripping. A buffered solution of acetic acid, citric acid, or formic acid is used to initiate ionic complexation, rendering the PEC water resistant. Buffer identity affects deposition, but does not significantly influence the intumescent mechanism. This rapidly deposited aqueous coating primarily operates by facilitating production of an insulating char layer that limits the heat release and degradation of polyester into volatile byproducts.

Azo dye polyelectrolyte multilayer films reversibly re-soluble with visible light

Polymeric multilayer films were prepared using a layer-by-layer (LBL) technique on glass surfaces, by repeated and sequential dipping into dilute aqueous solutions of various combinations of water-soluble polyanions (polyacrylic acid (PAA)), polycations (polyallylamine hydrochloride (PAH) or chitosan (CS)), with bi-functional water-soluble cationic azo dyes bismark brown R bismarck brown red or bismark brown Y (BBY), or anionic azo dyes allura red (ALR) or amaranth (AMA), as ionic cross-linkers. The electrostatically-assembled ionically-paired films showed good long-term stability to dissolution, with no re-solubility in water. However, upon exposure to low power visible light under running water, the films photo-disassembled back to their water-soluble constituent components, via structural photo-isomerization of the azo ionic crosslinkers. The relative rate of the disassembly (RRD) of the films was established using UV-Vis spectroscopy, demonstrating that these assemblies can in principle represent fully recyclable, environmentally structurally degradable materials triggered by exposure to sunlight, with full recovery of starting components. A density functional theory treatment of the allura red azo dye rationalizes the geometrical isomerization mechanism of the photo-disassembly and provides insight into the energetics of the optically-induced structural changes that trigger the disassembly and recovery.

Polyelectrolyte complex‐based thermochromic hydrogels containing carbonized polymer dots for smart windows with fast response, excellent solar modulation ability, and high durability

AbstractThermochromic smart windows have gained increasing popularity in light modulation and energy management in buildings. However, the fabrication of flexible thermochromic smart windows with high luminous transmittance (Tlum), tailorable critical temperature (τc), strong solar modulation ability (ΔTsol), and long‐term durability remains a huge challenge. In this study, hydrogel‐based thermochromic smart windows are fabricated by sandwiching thermochromic hydrogels of polyallylamine hydrochloride, polyacrylic acid, and carbonized polymer dots (CPDs) complexes between two pieces of transparent substrates. Benefiting from the incorporation of nanosized CPDs, the thermochromic hydrogel has an ultrahigh Tlum of ~98.7%, a desirable τc of ~24.2 °C, a ΔTsol of ~89.3% and a rapid transition time of ~3 s from opaque state to transparent state. Moreover, the thermochromic hydrogel exhibits excellent anti‐freezing ability, tight adhesion toward various substrates, and excellent self‐healing capability. The self‐healing capability enables the fabrication of large‐area smart windows by welding multiple hydrogel pieces. The smart windows retain their original thermochromic properties after being stored under ambient conditions for at least 147 days or undergoing 10,000 uninterrupted heating/cooling cycles. The model houses with smart windows can achieve a temperature reduction of 9.2 °C, demonstrating the excellent indoor temperature modulation performance of the smart windows.

Biosensors Based on Stanniocalcin-1 Protein Antibodies Thin Films for Prostate Cancer Diagnosis.

Prostate cancer is one of the most prevalent tumors in men, accounting for about 7.3% of cancer deaths. Although there are several strategies for diagnosing prostate cancer, these are only accurate when the tumor is already at a very advanced stage, so early diagnosis is essential. Stanniocalcin 1 (STC1) is a secreted glycoprotein, which has been suggested as a tumor marker as its increased expression is associated with the development and/or progression of different types of malignant tumors. In this work, an electronic tongue (ET) prototype, based on a set of four sensors prepared from thin films that included STC1 antibodies for detecting prostate cancer, was developed. In the preparation of the thin films, polyelectrolytes of polyallylamine hydrochloride, polystyrene sulfonate of sodium and polyethyleneimine, and the biomolecules chitosan, protein A, and STC1 antibody were used. These films were deposited on quartz lamellae and on solid supports using layer-on-layer and self-assembly techniques. The deposition of the films was analyzed by ultraviolet-visible spectroscopy, and the detection of STC1 in aqueous solutions of PBS was analyzed by impedance spectroscopy. The impedance data were statistically analyzed using principal component analysis. The ETs formed by the four sensors and the three best sensors could detect the antigen at concentrations in the range from 5 × 10-11 to 5 × 10-4 M. They showed a linear dependence with the logarithm of the antigen concentration and a sensitivity of 5371 ± 820 and 4863 ± 634 per decade of concentration, respectively. Finally, the results allow us to conclude that this prototype can advance to the calibration phase with patient samples.

Acoustofluidics-Assisted Coating of Microparticles.

Microparticles have been applied in many areas, ranging from drug delivery, diagnostics, cosmetics, personal care, and the food industry to chemical and catalytic reactions, sensing, and environmental remediation. Coating further provides additional functionality to the microparticles, such as controlled release, surface modification, bio-fouling resistance, stability, protection, etc. In this study, the conformal coating of microparticles with a positively charged polyelectrolyte (polyallylamine hydrochloride, PAH) by utilizing an acoustofluidic microchip was proposed and demonstrated. The multiple laminar streams, including the PAH solution, were formed inside the microchannel, and, under the traveling surface acoustic wave, the microparticles traversed through the streams, where they were coated with PAH. The results showed that the coating of microparticles can be achieved in a rapid fashion via a microfluidic approach compared to that obtained by the batch method. Moreover, the zeta potentials of the microparticles coated via the microfluidic approach were more uniform. For the unfunctionalized microparticles, the charge reversal occurred after coating, and the zeta potential increased as the width of the microchannel or the concentration of the PAH solution increased. As for the carboxylate-conjugated microparticles, the charge reversal again occurred after coating; however, the magnitudes of the zeta potentials were similar when using the microchannels with different widths or different concentrations of PAH solution.

A spectrophotometric trimethylamine monooxygenase assay.

Trimethylamine monooxygenase (Tmm, EC-1.14.13.148) belongs to the family of flavin-containing monooxygenases that oxidize trimethylamine into trimethylamine-N-oxide (TMAO). Conventional methods for assaying Tmm are accurate over a narrow range of substrate/product concentrations. Here we report a TMAO-specific enzymatic assay for Tmm using polyallylamine hydrochloride (PAHCl)-capped MnO2 nanoparticles (PAHCl@MnO2 ). We achieved TMAO specificity using iodoacetonitrile to remove interfering trimethylamine. The change in the concentration of TMAO is measured by observing the difference in the absorbance of 3,3',5,5'-tetramethylbenzidine (TMB) at 650 nm. The assay is tolerant to several interfering metal ions and other compounds. This method is more accessible and reliable than currently known methods. The limit of detection (LOD) and limit of quantitation (LOQ) are 1 μM and 10 μM, respectively, for direct TMAO measurement.

Synthesis and characterization of novel positively charged gold nanoparticle for the detection of food contaminants

The suggested work emphasizes the benefits of employing positively charged gold nanoparticles to detect negatively charged E.coli cells by electrostatic attraction without the need of any identification elements. As a result, a simple, label-free colorimetric biosensor for detecting E.coli, a well-known food contaminant, was developed. Initially, the Taguchi approach was used to synthesis small, stable, and positively charged Au NPs in orthogonal array L8 by optimizing 5 critical parameters such as pH, capping agents, temperature, Sonication duration, and Au/LE ratio. Based on the Maximum wavelength (λ max) values and ANOVA, Trail 3 (T3) a Polyallyl amine hydrochloride capped Au NPs (PAH-Au NPs) along with D-Mannose was chosen to be employed in detecting E.coli. It functions as a colorimetric sensor in both sol and paper coated forms. Based on the sensing technique, we discovered that the LOD in sol is (1*105CFU/mL), which is significantly higher than the sensor based on paper (1*102 CFU/mL).

The Influence of Ag+/Ti4+ Ratio on Structural, Optical and Photocatalytic Properties of MWCNT–TiO2–Ag Nanocomposites

In this paper, we propose a simple procedure to obtain multi-walled carbon nanotubes (MWCNTs) decorated with TiO2–Ag nanoparticles (MWCNT–TiO2–Ag). The MWCNTs were decorated with TiO2–Ag via combined functionalization with –OH and –COOH groups and a polymer-wrapping technique using poly(allylamine)hydrochloride (PAH). TiO2-modified Ag nanoparticles were synthesized via the Pechini method using a mixture of acetylacetonate-modified titanium (IV) isopropoxide with silver nitrate (with Ag+/Ti4+ atomic ratios of 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%) and L(+)-ascorbic acid as reducing agents. XRD analysis revealed the formation of nanocomposites containing CNT, anatase TiO2, and Ag. The presence of nanoparticles on the MWCNT surfaces was determined using TEM. The morphology of the TiO2–Ag nanoparticles on the MWCNT surfaces was also determined using TEM. UV–Vis investigations revealed that an increase in the ratio between Ag+ and Ti4+ decreased the band gap energy of the samples. The characteristic vibrations of the TiO2, Ag, and C atoms of the graphite were identified using Raman spectroscopy. The photocatalytic activity of the MWCNT–TiO2–Ag nanocomposite was assessed by examining the degradation of Allura Red (E129) aqueous solution under UV irradiation. The dye photodegradation process followed a pseudo-first-order kinetic with respect to the Langmuir–Hinshelwood reaction mechanism. The spin-trapping technique evidenced that •O2− was the main species generated responsible for the Allura Red degradation.

Surface modification of polyester films with polyfunctional amines: Effect on bacterial biofilm formation

The development of materials with antifouling properties is crucial in many areas, including medicine and food packaging. In this study, 2D-matrices made of polylactic acid (PLA), polyhydroxybutyrate (PHB), or polyhydroxybutyrate-co-valerate (PHB-HV) were surface functionalized through aminolysis with three polyfunctional amines, 1,6-hexamethylenediamine (HDA), tetraethylenepentamine (TEPA), and polyallylamine hydrochloride (PAH). The aminolysis procedure was thoroughly studied to ensure a high amount of amine groups while preserving the structural properties of the films. Interestingly, PHB and PHB-HV were found to be more sensitive to aminolysis than PLA, and the highest amino group density was achieved in surfaces etched with PAH. A decrease in the contact angle from ca. 85° to ca. 70° was revealed for polymers functionalized with HDA and TEPA and a drastic reduction in Staphylococcus epidermidis adhesion was observed for PHB-HV functionalized with the polymeric amine PAH. Polymer antimicrobial activity was found to be related to the degree of surface functionalization. The functionalized, cationic polymer surfaces were supposed to act upon contact with bacteria, without releasing any antimicrobial agent. The developed bioactive surfaces may have potential applications as flexible films for food packaging.

Optical fiber pH sensor based on a multimode interference device with polymer overlay.

An optical fiber pH sensor based on a multimode interference structure is presented. The sensitive element is a piece of no-core fiber (NCF) coated with a mixture of polyallylamine hydrochloride and polyacrylic acid by a modified layer-by-layer (LbL) self-assembly method. It is experimentally shown that by reducing the diameter of the NCF by chemical etching, the sensitivity is increased from -0.31n m/p H to -2n m/p H. The sensor exhibits a high linear response of 0.997 over a pH range from 5 to 11.3 with a rapid response time lower than 1s.

Assembly and recognition mechanisms of glycosylated PEGylated polyallylamine phosphate nanoparticles: A fluorescence correlation spectroscopy and small angle X-ray scattering study

HypothesisModification of polyallylamine hydrochloride (PAH) with heterobifunctional low molecular weight polyethylene glycol (PEG) (600 and 1395 Da), and subsequent attachment of mannose, glucose, or lactose sugars to PEG, can lead to formation of polyamine phosphate nanoparticles (PANs) with lectin binding affinity and narrow size distribution. ExperimentsSize, polydispersity, and internal structure of glycosylated PEGylated PANs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). Fluorescence correlation spectroscopy (FCS) was used to study the association of labelled glycol-PEGylated PANs. The number of polymer chains forming the nanoparticles was determined from the changes in amplitude of the cross-correlation function of the polymers after formation of the nanoparticles. SAXS and fluorescence cross-correlation spectroscopy were used to investigate the interaction of PANs with lectins: concanavalin A with mannose modified PANs, and jacalin with lactose modified ones. FindingsGlyco-PEGylated PANs are highly monodispersed, with diameters of a few tens of nanometers and low charge, and a structure corresponding to spheres with Gaussian chains. FCS shows that the PANs are single chain nanoparticles or formed by two polymer chains. Concanavalin A and jacalin show specific interactions for the glyco-PEGylated PANs with higher affinity than bovine serum albumin.

Selective and continuous ion recovery using flow electrode capacitive deionization with polymer multilayers functionalized ion exchange membrane

Flow electrode capacitive deionization (FCDI) is a newly developed salt removal technology that overcomes the limitations of conventional CDI by eliminating the need for a discharging process, thus achieving much higher desalination capacity and a continuous desalination operation. In this study, we aimed to achieve selective and continuous sodium recovery from Na+/Ca2+ mixtures through FCDI by utilizing polymer multilayer functionalized cation-exchange membranes (CEM). A layer-by-layer method was used to deposit polymer multilayers consisting of PAH (poly allylamine hydrochloride) and PSS (poly styrene sulfonate) on the CEM. Changes in the concentration of feed electrolyte, number of coated polymer layers, and type of outermost layer were investigated in terms of their effect on the selective ion separation. The functionalized CEM switches from a divalent ion affinity to a monovalent ion affinity due to their different ion sizes and charge densities. As the number of polymer layers increased, the selectivity of Na+/Ca2+ increased, reaching up to 3.26 from 0.16 for pristine CEM. We believe that our approach can provide insight into the selective recovery of valuable materials including lithium-ion battery recycling, the recovery of noble metals, and the separation of toxic ions using the FCDI system.

PEDOT-Polyamine-Based Organic Electrochemical Transistors for Monitoring Protein Binding.

The fabrication of efficient organic electrochemical transistors (OECTs)-based biosensors requires the design of biocompatible interfaces for the immobilization of biorecognition elements, as well as the development of robust channel materials to enable the transduction of the biochemical event into a reliable electrical signal. In this work, PEDOT-polyamine blends are shown as versatile organic films that can act as both highly conducting channels of the transistors and non-denaturing platforms for the construction of the biomolecular architectures that operate as sensing surfaces. To achieve this goal, we synthesized and characterized films of PEDOT and polyallylamine hydrochloride (PAH) and employed them as conducting channels in the construction of OECTs. Next, we studied the response of the obtained devices to protein adsorption, using glucose oxidase (GOx) as a model system, through two different strategies: The direct electrostatic adsorption of GOx on the PEDOT-PAH film and the specific recognition of the protein by a lectin attached to the surface. Firstly, we used surface plasmon resonance to monitor the adsorption of the proteins and the stability of the assemblies on PEDOT-PAH films. Then, we monitored the same processes with the OECT showing the capability of the device to perform the detection of the protein binding process in real time. In addition, the sensing mechanisms enabling the monitoring of the adsorption process with the OECTs for the two strategies are discussed.

Cationic Polymer Functionalized Copper Nanocluster-Based Fluorescent Probe for the Selective and Sensitive Detection of S2– Ions

The sensitive and selective detection of sulfide (S2–) ions in water is of major interest due to its toxicity and physiological effects on organisms. Herein, we have designed a fluorescent probe, poly(allylamine) hydrochloride (PAH) functionalized copper nanocluster (Cu NC@PAH), for the detection of S2– ions. The synthesis of the probe is based on the electrostatic interaction between negatively charged Cu NCs and the positively charged polymer, PAH. The drastic enhancement of the photoluminescence (PL) intensity of Cu NCs and the quantum yield (QY) enhancement from 0.3 to 6% are evident after functionalizing with a cationic polymer matrix of PAH. The steady-state and time-resolved fluorescence studies support the aggregation-induced emission (AIE) phenomenon for PL QY enhancement. In addition, the Cu NCs@PAH exhibit excellent selectivity toward aqueous S2– ions. The probe displays a reasonable quenching response for S2– ions over a concentration range of 0–20 μM with a detection limit of 2.39 μM. We believe that this facile and economical synthesis methodology of Cu NCs@PAH with interesting AIE properties will extend the scope of previously available techniques for the detection of the S2– ion.

Development of a polyallylamine hydrochloride hydrogel imprinted with xylose for the purification of xylose from sugar mixture

A novel molecularly imprinted hydrogel (X-MIP) was developed with poly (allylamine hydrochloride) as monomer and epichlorohydrin as crosslinker. After optimising preparation conditions including reaction temperature, the amount of NaOH and template xylose, the X-MIP was characterised through Fourier transform infrared spectroscopy, scanning electron microscope and swelling ratio. Xylose and glucose were employed to evaluate the adsorption capacity and selectivity of the X-MIP. Its adsorption to xylose followed pseudo-second-order rate kinetics and the adsorption process was multilayer adsorption based on the matched Freundlich isotherm model. Its adsorption capacity to xylose was up to 398.68 mg g−1. The similar adsorption abilities in five successive runs and the good desorption rate (98.9%) verified its reusability. The selectivity for xylose and glucose could reach 4.70, and their separation factors in simulated xylitol production feedstocks were 591.05 (xylose:glucose, 99:1) and 15.42 (xylose:glucose, 3:1), respectively. Results indicated the prepared X-MIP has good potential in industrial xylose purification.

Self-Assembled Oleic Acid-Modified Polyallylamines for Improved siRNA Transfection Efficiency and Lower Cytotoxicity.

Small interference RNA (siRNA) is a tool for gene modulation, which can silence any gene involved in genetic disorders. The potential of this therapeutic tool is hampered by RNA instability in the blood stream and difficulties to reach the cytosol. Polyamine-based nanoparticles play an important role in gene delivery. Polyallylamine hydrochloride (PAH) is a polycation displaying primary amines that can be easily chemically modified to match the balance between cell viability and siRNA transfection. In this work, PAH has been covalently functionalized with oleic acid at different molar ratios by carbodiimide chemistry. The substituted polymers form polyplexes that keep positive surface charge and fully encapsulate siRNA. Oleic acid substitution improves cell viability in the pulmonary cell line A549. Moreover, 6 and 14% of oleic acid substitution show an improvement in siRNA transfection efficiency. CD47 is a ubiquitous protein which acts as "don't eat me signal." SIRPα protein of macrophages recognizes CD47, leading to tumor cell phagocytosis by macrophages. By knocking down CD47 with siRNA, cancer cells become vulnerable to be eliminated by the immune system. PAH-oleic acid substitutes show high efficacy in silencing the CD47 protein, making them a potential candidate for immunotherapy.