Adsorption Of Chloramphenicol Research Articles

Adsorption of chloramphenicol onto cobalt-based zeolitic-imidazolate framework (Co-ZIF-67)

Adsorption of chloramphenicol onto cobalt-based zeolitic-imidazolate framework (Co-ZIF-67)

Highly enhanced chloramphenicol adsorption performance of MIL-53-NH2(Al)-derived porous carbons modified with tannic acid

The worldwide demand for antibiotics has experienced a notable surge, propelled by the repercussions of the COVID-19 pandemic and advancements in the global healthcare sector. A prominent challenge confronting humanity is the unregulated release of antibiotic-laden wastewater into the environment, posing significant threats to public health. The adoption of affordable carbon-based adsorbents emerges as a promising strategy for mitigating the contamination of antibiotic wastewater. Here, we report the synthesis of novel porous carbons (MPC) through a direct pyrolysis of MIL-53-NH2(Al) and tannic acid (TANA) under N2 atmosphere at 800 °C for 4 h. The effect of TANA amount ratios (0%–20%, wt wt−1) on porous carbon structure and adsorption performance was investigated. Results showed that TANA modification resulted in decreased surface area (1,600 m2 g−1–949 m2 g−1) and pore volume (2.3 cm3 g−1–1.7 cm3 g−1), but supplied hydroxyl functional groups. Adsorption kinetic, intraparticle diffusion, and isotherm were examined, indicating the best fit of Elovich and Langmuir models. 10%-TANA-MPC obtained an ultrahigh adsorption capacity of 564.4 mg g−1, which was approximately 2.1 times higher than that of unmodified porous carbon. 10%-TANA-MPC could be easily recycled up to 5 times, and after reuse, this adsorbent still remained highly stable in morphology and surface area. The contribution of H bonding, pore-filling, electrostatic and π–π interactions to chloramphenicol adsorption was clarified. It is recommended that TANA-modified MIL-53-NH2(Al)-derived porous carbons act as a potential adsorbent for removal of pollutants effectively.

Effect of pyrolysis temperature on characteristics and chloramphenicol adsorption performance of NH2-MIL-53(Al)-derived amine-functionalized porous carbons

Several activities such as aquaculture, human and feedstock therapies can directly release antibiotics into water. Due to high stability, low hydrolysis and non-biodegradation, they can accumulate in the aqueous environment and transport to aquatic species. Here, we synthesized amine-functionalized porous carbons (ANC) by a direct-pyrolysis process of NH2-MIL-53(Al) as a sacrificial template at between 600 and 900 °C and utilized them to eliminate chloramphenicol antibiotic from water. The NH2-MIL-53(Al)-derived porous carbons obtained high surface areas (304.7–1600 m2 g−1) and chloramphenicol adsorption capacities (148.3–261.5 mg g−1). Several factors such as hydrogen bonding, Yoshida hydrogen bonding, and π–π interaction, hydrophobic interaction possibly controlled adsorption mechanisms. The ANC800 could be reused four cycles along with high stability in structure. As a result, NH2-MIL-53(Al)-derived porous carbons are recommended as recyclable and efficient adsorbents to the treatment of antibiotics in water.

Dense pyridine nitrogen as surface decoration of interwoven Cu-MOFs for chloramphenicol-specific electrochemical sensor

The detection of chloramphenicol (CAP), a strictly prohibited antibiotic in veterinary drugs, remains challenging owing to its specific-sensing requirements. However, achieving a specific sensing strategy is crucial and requires the design of high-performance materials. In this study, a stable, double-interpenetrated dual-wall cage-in-cage metal–organic framework (MOF), SXNU-3-Cu ({[Cu2(INA)2(TATB)]·H2O}n), was designed using a mixed-linker strategy that incorporated the ligands of 4,4,4,-s-triazine-2,4,6-triyltribenzonic acid (H3TATB) and isonicotinic acid (HINA). Owing to their high connectivity and double-interpenetrated structure, the SXNU-3-Cu MOFs exhibited excellent thermal stability, as well as resistance to water and pH changes. The SXNU-3-Cu/ACET/GCE electrochemical sensor demonstrated a wide linearity range from 0.03 to 0.1 μM and 0.3–70 μM, with an impressive CAP detection limit of 9.51 nM. In particular, the interaction between –NO2 in CAP and dense pyridine nitrogen of HINA ligand enhanced the adsorption of CAP on the surface of the cage via Van der Waals forces. Subsequently, targeted oxidation–reduction catalytic reactions occurred inside accessible copper sites against nitro groups in the CAP molecules, resulting in high sensitivity and specific sensing towards CAP. Furthermore, we conducted comprehensive experimental and theoretical investigations to verify the sensing mechanism between the SXNU-3-Cu MOFs and CAP molecules. We determined that Cu-based MOFs have significant potential for drug monitoring and biochemical analyses.

Self-Assembled Aminated and TEMPO Cellulose Nanofibers (Am/TEMPO-CNF) Aerogel for Adsorptive Removal of Oxytetracycline and Chloramphenicol Antibiotics from Water.

Antibiotics are used for the well-being of human beings and other animals. Detectable levels of antibiotics can be found in pharmaceutical, municipal, and animal effluents. Therefore, the treatment of antibiotic contaminated water is of great concern. In this study, we fabricated a sustainable aminated/TEMPO cellulose nanofiber (Am/TEMPO-CNF) aerogel to remove oxytetracycline (OTC) and chloramphenicol (CAP) from synthetic wastewater. The prepared aerogel was characterized using different analytical techniques such as elemental analysis, FTIR, TGA, SEM-EDS, and N2 adsorption-desorption isotherms. The characterization techniques confirmed the presence and interaction of quaternary amine -[NR3]+ and -COOH groups on Am/TEMPO-CNF with OTC and CAP, which validates the successful modification of Am/TEMPO-CNF. The adsorption process of the pollutants was examined as a function of solution pH, concentrations, reaction time, and temperatures. The maximum adsorption capacity was 153.13 and 150.15 mg/g for OTC and CAP, respectively. The pseudo-second order (PSO-2) was well fitted to both OTC and CAP, confirming the removal is via chemisorption. Hydrogen bonding and electrostatic attraction have been postulated as key factors in facilitating OTC and CAP adsorption according to spectroscopic studies. Energetically, the adsorption was spontaneous and endothermic for both pollutants. In conclusion, the efficient removal rate and excellent reusability of Am/TEMPO-CNF indicate the strong potential of the adsorbent for antibiotics' removal.

Adsorption behavior and interaction mechanism of microplastics with typical hydrophilic pharmaceuticals and personal care products

Microplastics (MPs) and pharmaceuticals and personal care products (PPCPs) are two types of emerging contaminants widely present in the global aquatic ecosystem. The ecological risks associated with the coexistence of these two contaminants have garnered increasing attention from researchers. In this study, we selected 15 typical hydrophilic PPCPs, including Sulfacetamide (SA), Thiamphenicol, Florfenicol, Chloramphenicol (CHL), Ampicillin, Cephalexin, Ofloxacin, Fluorouracil, Phenytoin, Theophylline, Cimetidine, Methylparaben, Diethyltoluamide, Benzophenone-2 (BP-2), and Benzophenone-4, as adsorbates. We evaluated the adsorption potential of five traditional plastics (TPs), namely Polyamide 6 (PA6), Polystyrene (PS), Polyethylene terephthalate (PET), Polyvinyl chloride (PVC), and Polyurethane (TPU), as well as three biodegradable plastics (BDPs), including Polylactic acid (PLA), Polybutylene succinate (PBS), and Poly (ε-caprolactone) (PCL), for these adsorbates. Out of the 120 combinations of MPs and PPCPs tested, only 24 exhibited significant adsorption behavior. Notably, the adsorption performance of the three BDPs was stronger than that of the three typical TPs (PS, PET, and PVC). Based on their adsorption potential, PA6, BDPs, phenytoin, and BP-2 were identified as potential sources of high ecological risk. To further explore the adsorption mechanism, we investigated the adsorption behaviors of SA, BP-2, and CHL on PA6. The conclusions were as follows: SA, BP-2, and CHL all reached adsorption equilibrium within 24 h, with the partition coefficient (Kd) following this order: BP-2 (8.051) ≫ SA (0.052) > CHL (0.018). The primary forces of adsorption were electrostatic interactions, intermolecular hydrogen bonding, and hydrophobic interaction, respectively. Additionally, weak electrostatic effects were observed in the adsorption of CHL and BP-2. The effects of pH, ionic strength, and fulvic acid on adsorption capacity varied. These results highlight a complex adsorption mechanism between MPs and hydrophilic contaminants in the aquatic environment. This study provides a basis for further evaluating the ecological risks of MPs and PPCPs combined pollution.

A free elution immunoassay for chloramphenicol in chicken and egg after magnetic ZIF-8 adsorption separation

The excellent adsorption and rapid separation capabilities of magnetic MOFs make them desirable pretreatment materials for solid substrates. In this study, magnetic ZIF-8 (mZIF-8) was synthesized in situ by a one-step method in the aqueous solution of magnetic beads. Isothermal adsorption verified that the maximum adsorption capacity of (011) crystal-exposed rhombic dodecahedral ZIF-8 for chloramphenicol was up to 128.31 mg/g (mZIF-8 = 67.18 mg/g). Kinetic adsorption revealed that the type of ZIF-8/mZIF-8 adsorption on chloramphenicol belongs to the pseudo-secondary adsorption kinetics of chemical monomolecular layers. Characterization by FTIR, XPS, and XRD revealed that mZIF-8 interacts with chloramphenicol mainly by π-π electron stacking, electrostatic attraction, and hydrogen bonding interaction. ELISA confirmed that chloramphenicol remained antigenically active after adsorption by mZIF-8. The adsorption and separation of chloramphenicol residues in chicken and egg were completed by mZIF-8 within 20 min. mZIF-8 can be used directly for elution-free ELISA after the adsorption of chloramphenicol. The limits of detection (IC10) of the mZIF-8 + ELISA in chicken and eggs were 1.18 ng/mL and 0.64 ng/mL, respectively. mZIF-8 is expected to be used as a magnetic solid-phase extraction material for the rapid pretreatment of antibiotic residues in other complex solid matrices.

Optimization of Paracetamol and Chloramphenicol Removal by Novel Activated Carbon Derived from Sawdust Using Response Surface Methodology

Paracetamol (PCT) and chloramphenicol (CPL) can have unfavorable impacts on human health, as well as on natural ecosystems. These substances contribute to the aquatic environment’s contamination and disturb the performance of municipal wastewater treatment systems, causing ecosystem disruption and microbial resistance. In this study, activated carbon produced from sawdust (ACs) was synthesized utilizing the chemical activation process for the removal of both PCT and CPL compounds from an aqueous solution. ACs has a primarily microporous structure with a significant specific surface area of 303–1298 m2/g, total pore volume of 0.462 cm3/g and bimodal distribution of pores of 0.73–1.7 nm. The removal efficiencies for PCT and CPL with the low-cost activated carbon, determined at the optimum dose (750 mg/L for PCT and 450 mg/L for CPL), were significantly high at 85% and 98%, respectively. The adsorption kinetics for both pharmaceuticals exhibited a quick initial decline. For PCT and CPL adsorption, the equilibrium was attained after just 20 and 90 min, respectively. The Langmuir isotherm model and the pseudo-second-order kinetics model offered the best fits for the adsorption of both compounds. Additionally, the central composite design (CCD) and Box–Behnken design (BBD) were used to optimize the experimental adsorption conditions using a response surface methodology (RSM). On the basis of the findings, it is evident that activated carbon made from sawdust may be used as a new, effective alternative adsorbent for removing PCT and CPL in aqueous environments.

One-dimensional benzo[1,2-b:4,5-b′]dithiophene-based graphdiyne for electrochemical adsorption of chloramphenicol

One-dimensional benzo[1,2-b:4,5-b′]dithiophene-based graphdiyne (1D-BDT-GDY) shows enhanced electrochemical adsorption ability for chloramphenicol (CAP).

Methodological approach to the chloramphenicol adsorption by acid-leached halloysites: Preparation, characterization, performance and mechanism

Adsorptive removal was found to be an environmentally friendly and effective approach to treat emerging contaminants such as chloramphenicol (CAP), an antibiotic widely used to care for human and animal diseases, which after using is discharged into the environment, disrupting thus ecosystems and inducing microbial resistance. In this study, we systematically investigated the effect of sulfuric acid treatment on the physico-chemical and adsorptive properties of halloysite with the objective of combining the results of acid-leached halloysite characterization, CAP adsorption and spectroscopic investigation to propose a coherent mechanism of the CAP−acid-leached halloysite interaction. After preparation, the acid-leached samples were characterized by X-ray diffraction analysis (XRD), X-ray fluorescence (XRF), N2 adsorption–desorption, Transmission electron microscopy (TEM), zetametry, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), and used in CAP adsorption. The specific surface area increased significantly from 63 for H to a maximum of 240 m2 g−1 for the H2SO4-leached sample with 10 M concentration (H-10M). An amount of CAP adsorbed by the best adsorbent, H-10M, of 197.2 was found compared to 92.5 mg g−1 for H. The experimental isotherms were suitably fitted by the Langmuir-Freundlich equation. Thermodynamic parameters suggested physical, spontaneous, and endothermic adsorption. H-10M was easily desorbed by methanol whose involvement was explained by FTIR, and maintained its adsorption capacity for three cycles. By combining the results of the characterization, adsorption parameters such as the influence of pH, affinity, and thermodynamic data, and the FTIR and XPS (X-ray photoelectron spectroscopy) investigations between CAP and H-10M, a mechanism has been proposed which involves two interactions: a hydrophobic interaction taking place between −Si–O–Si− species and CAP aromatic ring and hydrogen bonding which occurs between the oxygen of the carbonyl group and the hydrogen of silanols (SiO–H). This integrated methodological approach has significant implications for the effective understanding and prediction of the environmental fate of these emergent contaminants in wastewater.

Adsorption of chloramphenicol from water using Carex meyeriana Kunth-derived hierarchical porous carbon with open channel arrays.

A carbon material with both open macrochannel arrays and abundant micro/mesopores was prepared, characterized, and applied for removing chloramphenicol (CAP) from water. In the preparation process, Carex meyeriana Kunth (CM) with natural channel arrays was used as the precursor for producing the biochar, and NaOH was used for removing silicon and formatting micro- and mesopores of the porous carbon. The product (PCCM) exhibited the highest specific surface area (2700.24 m2g-1) among the reported CM-derived porous carbons. The adsorption performances of PCCM were evaluated through batch adsorption experiments. The maximum adsorption capacity of PCCM toward CAP was 1659.43mgg-1. The adsorption mechanism was investigated with the aid of theoretical calculations. Moreover, PCCM exhibited better performance than other porous carbon adsorbents in fixed-bed experiments, which may be due to its structural advantages.

A dual purpose aluminum-based metal organic framework for the removal of chloramphenicol from wastewater

The presence of antibiotics in the aquatic environment can cause significant environmental and human health problems even at trace concentrations. Conventional treatment systems alone are ineffective in removing these resistant antibiotics. To address this problem, oxidation and adsorption techniques were used to explore the removal of recalcitrant antibiotic chloramphenicol (CAP). An aluminum-based metal-organic framework (Al-MIL) with high surface area and extended porosity, was prepared and used both as adsorbent and catalyst for the oxidation of CAP. Characterization of the Al-MIL revealed a large surface area of 1137 m2 g−1, a homogeneous microporous structure, good crystallinity, and particle size in the range of 200–400 nm. Adsorption of CAP on Al-MIL achieved equilibrium after 1 h, reaching a maximum adsorption capacity of 96.1 mg g−1 at the optimum pH value of 5.3. The combination of adsorption and oxidation did not improve the % TOC reduction considerably, indicating an antagonistic rather than synergistic effect between the two processes. Oxidation alone in the presence of persulfate, achieved a % TOC reduction of 71% after 2 h, compared to 56% achieved by adsorption alone at the same duration. The optimum persulfate concentration was determined as 2.5 mM. The Al-MIL structure did not demonstrate any substantial deterioriation after six repeated runs, according to the reusability experiments.

Preparation of in-situ nitrogen-doped lignin-based porous carbon and its efficient adsorption of chloramphenicol in water.

Porous carbon is an excellent absorbent for pollutants in water. Here, we report a breakthrough in performance of porous carbon based on lignin prepared using sodium lignosulfonate (SLS), potassium carbonate and melamine as precursor, activator and nitrogen source, respectively. A series of characterization tests confirmed that in-situ nitrogen doping greatly enhanced porous structure, resulting in a specific surface area of 2567.9 m2g-1 and total pore volume of 1.499 cm3g-1, which is nearly twice that of non-nitrogen-doped porous carbon. Moreover, adsorption experiments revealed that at 303K, the saturated adsorption capacity of chloramphenicol was as high as 713.7mgg-1, corresponding to an improvement of 33.7%. Further, the prepared porous carbon exhibited a strong anti-interference against metal ions and humic acid. The adsorption process was confirmed to be an endothermic reaction dominated by physical adsorption, indicating that an increase in temperature is conducive to adsorption. The results of this study show that nitrogen-doped lignin-based porous carbon prepared by in-situ doping is a promising material to significantly alleviate water pollution owing to its low cost, excellent pore structure and good adsorption properties.

High Selectivity and Reusability of Biomass-Based Adsorbent for Chloramphenicol Removal.

Recently, biomass-based materials have attracted increasing attention because of their advantages of low cost, environment-friendly and nonpollution. Herein, the feasibility of using corn stalk biomass fiber (CF) and Fe3O4 embedded chitosan (CS) as a novel biomass-based adsorbent (CFS) to remove chloramphenicol (CAPC) from aqueous solution. Structure of CFS was characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and zeta potential techniques. The effects of solution pH, adsorption time and ion strength on the adsorption capacity were examined. Adsorption isotherms obtained from batch experiments were better fitted by Langmuir model compared with Freundlich model, Dubinin–Radushkevich model and Temkin model. Adsorption kinetic data matched well to the pseudo-second order kinetic model. CAPC adsorption was endothermic, spontaneous, and entropy-increasing nature on CFS. In addition, the CFS could be separated by an external magnetic field, recycled, and reused without any significant loss in the adsorption capacity of CAPC. Based on these excellent performances, there is potential that CFS can be considered as a proficient and economically suitable material for the CAPC removal from the water environment.

PCN-222 MOF decorated conductive PEDOT films for sensitive electrochemical determination of chloramphenicol

PCN-222, a kind of zirconium-based porphyrinic metal-organic frameworks, was decorated on poly 3,4-ethylenedioxythiophene (PEDOT) films modified ITO electrode to fabricate a sensitive chloramphenicol (CAP) sensor. The designed PCN-222-CHIT/PEDOT/ITO sensor combined the CAP adsorption of PCN-222 and the good conductivity of PEDOT films. Cyclic voltammetry and differential pulse voltammetry techniques was examined to investigate the electrochemical performances of this sensor. Under the optimized experimental condition, the proposed sensor exhibited an ultralow detection limit of 0.0018 μM (S/N = 3). Good anti-interference ability and reproducibility were also displayed. Furthermore, the designed sensor realized the accurate detection of CAP in the real sample. • PCN-222-CHIT/PEDOT/ITO displayed the synergistic effect between the CAP adsorption of PCN-222 and the conductive PEDOT films. • The sensing performance of PCN-222-CHIT/PEDOT/ITO sensor was optimized systematacially. • An ultralow detection limit of PCN-222-CHIT/PEDOT/ITO sensor was obtained.

Mesoporous Silica MCM-48 as Chloramphenicol Adsorbent

This study is aimed to determine the potential use of MCM-48 to adsorb chloramphenicol pollution. Chloramphenicol adsorption was conducted at various times contact and concentration. Adsorption isotherm was studied by comparing Langmuir and Freundlich adsorption isotherm. The results showed that chloramphenicol adsorption was suited to Freundlich isotherm with an optimum contact time of 80 minutes

Desorption of chloramphenicol from ordered mesoporous carbon-alginate beads: Effects of operating parameters, and isotherm, kinetics, and regeneration studies

This study has investigated the desorption of an emerging contaminant, known as chloramphenicol (CPC), from ordered mesoporous carbon (OMC)-alginate beads. The effects of initial concentration, operating temperature, and a selection of eluents (water, ethanol, and sodium chloride (NaCl)) on the whole desorption process were analysed. The desorption efficiency was found to decrease with increasing temperature, an indication for a favourable desorption process at a lower temperature range. NaCl was the most effective eluent for the CPC desorption process, followed by ethanol and water. The use of 1 M NaCl has resulted in the highest desorption efficiency of 84.7%. Redlich-Peterson and Freundlich isotherm models fitted well to the CPC desorption experimental data. The desorption kinetic data for ethanol and NaCl as eluents fitted well to the pseudo-second order kinetic model. Meanwhile, distilled water as an eluent was best fitted to the pseudo-first order kinetic model. The CPC adsorption efficiency began to notably decrease from 78.9% to 48.5% after five consecutive adsorption/desorption cycles. Similarly, the desorption efficiency began to decrease from 76.0% in the first cycle down to 35.2% in the fifth cycle. These findings demonstrated that the OMC-alginate beads are a very promising adsorbent with excellent desorption and reusability characteristics towards the targeted antibiotic, CPC.

Novel chloramphenicol sensor based on aggregation-induced electrochemiluminescence and nanozyme amplification

Combining electrochemiluminescence (ECL) with nanozyme amplification provides unique advantages for the detection of antibiotic residues. Herein, a molecularly imprinted chloramphenicol (CAP) sensor was established based on aggregation-induced (AI)-ECL and nanozyme amplification. Covalent organic framework materials with AI-ECL groups (COF-AI-ECL) and nanozyme Co3O4 were synthesised as the signal element and the amplification element, respectively. Subsequently, using CAP as a template molecule, a molecularly imprinted polymer (MIP) was fabricated on the electrode surface modified with COF-AI-ECL and Co3O4. The ECL signal of COF-AI-ECL was catalytically amplified by Co3O4, whereas CAP effectively quenched this signal. Consequently, the ECL signal was controlled by the elution and adsorption of CAP by the MIP, thus establishing a new method for CAP detection. Unlike traditional ECL reagent, COF-AI-ECL exhibited a stable and strong ECL signal. Therefore, COF-AI-ECL in combination with the MIP provided greater sensitivity and enhanced selectivity. The linear range of the developed CAP sensor was 5 × 10−13 to 4 × 10−10 mol/L, with a detection limit of 1.18 × 10−13 mol/L. Moreover, the recoveries range of 85.0%–106.2% were obtained for the detection of CAP in real honey, milk, and chicken samples, indicating the potential of this sensor design for the detection of trace antibiotic residues in food safety applications.

Adsorption of Heavy Metal ions and Antibiotics from Aqueous Solution on Activated Carbons Prepared from Agricultural Waste

The contamination of water by heavy metal ions and antibiotics is presently a serious environmental challenge of the world. This work intends to use activated carbons made out of agricultural waste to alleviate the problem of water pollution. Commercialized coconut shell activated carbon was used for the experiment. Cadmium ions and chloramphenicol were selected as the model compounds for heavy metal and antibiotics in water solution. TOC analyzer and the atomic absorption spectrophotometry were used to determine the concentration of antibiotics and metal ions in solution, respectively. The coconut shell activated carbon turned out to be efficient in the adsorption of metal ions (removal efficiency up to 90% when concentration is 1mg/L) and chloramphenicol (removal efficiency up to 40% when concentration is 1ml/L). The rates of adsorption of both cadmium ions and chloramphenicol were high at first but declined as the contact time increases. The competitive adsorption was investigated in this study by using a mixed solution of cadmium nitrate and chloramphenicol. It was found that the adsorption capacity of chloramphenicol of activated carbon remains the same while the adsorption capacity of metal ions sharply dropped by 44%, indicating that Cadmium ions have no obvious effect on the adsorption of chloramphenicol, whereas chloramphenicol hinders the adsorption of cadmium ions.

Detection of chloramphenicol with anaptamer-based colorimetric assay: critical evaluation of specific and unspecific binding of analyte molecules.

A chloramphenicol (CAP)-binding aptamer of 80nucleotides (nt) was reported in 2011. In 2014, it was truncated to 40nt and has since been used by most researchers, although a careful binding study is still lacking. In this work, binding assays using isothermal titration calorimetry and various DNA-staining dyeswere performed. By comparing the truncated aptamer with three control sequences, no specific binding of CAP was observed in each case. Thesecondary structures of the original and truncated aptamerswere analyzed, and it was shown thatthe likelihood of the truncated aptamer to retain the same binding mechanism as the original sequence is low. We further examined gold nanoparticle (AuNP)-based label-free colorimetric assays. By quantifying the extinction ratio at 620nm over that at 520nm, a similar color response was observed regardless of the sequence of DNA, suggesting the color change mainly reflectedother events such as the adsorption of CAP by the AuNPs, instead of aptamer binding to CAP. Salt-induced aggregation experiments suggested direct adsorption of CAP on AuNPs. CAP only weakly inhibited DNA adsorption by AuNPs but did not displace pre-adsorbed DNA. Therefore, CAP adsorption by AuNPs needs to be considered when designing related sensors, for example, by using non-aptamer sequences as controls. This work calls for careful confirmation of aptamer binding and control experiments for designing aptamer and AuNP-based biosensors.