Extreme homeopathic dilutions retain starting materials- A nanoparticulate perspective

Extreme homeopathic dilutions retain starting materials- A nanoparticulate perspective Extreme homeopathic dilutions retain starting materials: A nanoparticulate perspective Prashant Satish Chikramane1, Akkihebbal K Suresh1,2, Jayesh Ramesh Bellare1,2,* and Shantaram Govind Kane1,* 1Department of Chemical Engineering, Indian Institute of Technology (IIT), Bombay, Adi Shankaracharya Marg, Powai, Mumbai 400 076, Maharashtra, India 2Department of Biosciences and Bioengineering, Indian Institute of Technology (IIT), Bombay, Adi Shankaracharya Marg, Powai, Mumbai 400 076, Maharashtra, India Homeopathy is controversial because medicines in high potencies such as 30c and 200c involve huge dilution factors (1060 and 10400 respectively) which are many orders of magnitude greater than Avogadro’s number, so that theoretically there should be no measurable remnants of the starting materials. No hypothesis which predicts the retention of properties of starting materials has been proposed nor has any physical entity been shown to exist in these high potency medicines. Using market samples of metal- derived medicines from reputable manufacturers, we have demonstrated for the first time by Transmission Electron Microscopy (TEM), electron diffraction and chemical analysis by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), the presence of physical entities in these extreme dilutions, in the form of nanoparticles of the starting metals and their aggregates. Homeopathy (2010) 99, 231e242. Keywords: Homeopathy; Nanoparticles; Nanocrystalline materials; Transmission Electron Microscopy Introduction Homeopathy, a mode of therapy, was established in the late 18th century by German physician, Samuel Hahne- mann. Hahnemann, during his experiments, prepared medi- cines from a wide variety of natural products. He discerned that the infinite dilutions of these substances carried out in steps and accompanied by vigorous shaking ‘succussion’ (together known as potentization) at each dilution step, elicited some kind of a potent activity to these solutions.1,2 In spite of the various controversies and frequent challenges by the scientific community regarding its efficacy, this mode of treatment has stood the test of time, and is still being used in many countries for treatment of various chronic conditions, with medicines being prepared from a variety of herbal, animal, metal and other mineral sources. *Correspondence: Jayesh Ramesh Bellare and Shantaram Go- vind Kane, Department of Chemical Engineering, Indian Institute of Technology (IIT), Bombay, Adi Shankaracharya Marg, Powai, Mumbai 400 076, Maharashtra, India. E-mail: jb@iitb.ac.in, sgkane@gmail.com Received 6 November 2009; revised 22 April 2010; accepted 22 May 2010 However, a major lacuna has been the lack of evidence of physical existence of the starting material. The main dif- ficulty in arriving at a rational explanation stems from the fact that homeopathic medicines are used in extreme dilu- tions, including dilution factors exceeding Avogadro’s number by several orders of magnitude, in which one would not expect any measurable remnant of the starting material to be present. In clinical practice, homeopathic potencies of 30c and 200c having dilution factors of 1060 and 10400 respectively, far beyond Avogadro’s number of 6.023 1023 molecules in one mole, are routinely used. Many hypotheses have been postulated to justify and elu- cidate their mechanisms of action. While some hypotheses such as the theory of water memory,3e5 formation of clathrates,6 and epitaxy7 are conjectural in nature, others such as those based on the quantum physical aspects of the solutions8,9 have not been sufficiently tested, either due to complexity in validating the hypothesis or due to non-reproducible results. The ‘silica hypothesis’10 is the only model that proposes the presence of physical entities such as siloxanes or silicates resulting from leaching from the glass containers. Following a dearth of credible and test- able hypotheses to identify any physical entity responsible for medicinal activity, most modern scientists continue to believe that homeopathy at best provides a placebo effect. Homeopathy (2010) 99, 231e242 ! 2010 The Faculty of Homeopathy doi:10.1016/j.homp.2010.05.006, available online at http://www.sciencedirect.com ORIGINAL PAPER  232 Nanoparticles of starting materials in homeopathic medicines PS Chikramane et al Despite the extreme dilutions in 30c and 200c potencies, our approach has been to test for the presence of the starting materials in the form of nanoparticles.. Medicines selected were metal-based, and were so chosen that the metals would not arise either as impurities or as contaminants. The six metals and their respective homeopathic medicines were gold (Aurum metallicum or Aurum met), copper (Cuprum metallicum or Cuprum met), tin (Stannum metallicum or Stannum met), zinc (Zincum metallicum or Zincum met), silver (Argentum metallicum or Argentum met) and platinum (Platinum metallicum or Platinum met). Three potencies: 6c, 30c, and 200c were selected. The dilution factor for 6c is 1012 which is less than Avogadro’s number, whereas the dilution factors for 30c and 200c are well above. Market samples of these medicines in 90%v/v ethanol were obtained from two reputable manufacturers: SBL, India, and Dr. Willmar Schwabe India (WSI) Private Limited. We examined the following physico-chemical aspects: a. The presence of the physical entities in nanoparticle form and their size by Transmission Electron Microscopy (TEM) by bright-field and dark-field imaging. b.Their identification by matching the Selected Area Electron Diffraction (SAED) patterns against literature standards for the corresponding known crystals. c. Estimation of the levels of starting metals by a 500-fold concentration of medicines, followed by chemical analysis using Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). Materials and methods Materials The homeopathic medications used for the purpose of re- search were obtained commercially from authorized distrib- utors of a leading homeopathic drug manufacturer in India (SBL) and an Indian subsidiary of a multi-national homeo- pathic company viz. Dr. Willmar Schwabe India Pvt. Ltd. Random batch number samples were purchased from the market and no special effort was made to get samples from the company. Since we purchased these medicines from the market, only in certain cases were we able to obtain them from a single manufacturing batch. Also no special ef- forts were made to obtain the drugs from a batch. The High- performance liquid chromatography (HPLC) grade ethanol used for the purpose of ICP-AES analyses was procured from Commercial Alcohols Inc., Canada. The TEM grids obtained from Pacific Grid-Tech (USA) were 200 mesh cop- per grids coated with carboneformvar. Methods then allowed to dry completely after which another drop was added. The usual drying time for each drop was ap- proximately 30e60 min in air at room temperature. This procedure was repeated 5 times. After air-drying the sam- ple for further 30e60 min, the grid was kept under an IR lamp for approximately 20 min to ensure complete drying of the sample and thereby preventing the possibility of solvent molecules from adhering to the particles on the grid. The SAED patterns of the particles were taken and the d-spacings were calculated using the camera length (calibrated daily using a standard gold colloid). The dark-field images were also taken by selecting three spots from two inner rings on the SAED pattern. The d-spacing values from SAED patterns and the crystallite sizes from the dark-field images were calculated using the Image-J software. Elemental composition by ICP-AES: The determination of the starting elements in ultra-trace concentrations was performed on Ultima 2, (Jobin Yvon Horiba, Japan). The operating parameters for the ICP-AES instrument were as follows: plasma gas flow rate (Argon gas): 12 l/min; auxil- iary gas flow rate: 0.2 l/min; sample uptake: 2.5 ml/min; integration time: 5.0 s, Spray Chamber: cyclonic chamber. The limit of detection of the instrument was 10 ppb. For the purpose of ICP-AES analyses, the samples were pre- pared by pre-concentrating the solutions (6c, 30c, and 200c potencies) 500-fold in a vacuum rotary evaporator, Roteva Model #8706R (Equitron, India) at 45C and 100 rpm speed. The homeopathic medicines that we purchased were in ei- ther 100 ml or 500 ml capacity bottles. Most of the SBL homeopathic medicine bottles were of 500 ml capacity with a few of 100 ml capacity, while those obtained from Willmar Schwabe India (WSI) Pvt. Ltd. were all 100 ml bot- tles. In the case of medicines obtained as 500 ml bottles, so- lutions from 4 bottles of the same medicine and potency were pooled together for concentration, whereas for medi- cines which were marketed as 100 ml bottles, solutions from 20 bottles of each medicine at the same potency were pooled. The concentration was carried out in a 50 ml clean round bottom flask on a rotary vacuum evaporator. The flask was filled with the solution (approximately 30e35 ml at a time) and the solvent was evaporated. Upon complete evaporation of the solvent, the flask was re- filled with fresh homeopathic solution and the process was repeated till the entire volume of 2000 ml was evaporated. Only one bottle was opened at a time to maintain the integ- rity of the purchased medicines. To prevent contamination, under no circumstances was the solution in the bottle kept exposed. The residues of Cuprum met, Stannum met, and Zincum met were acidified to solubilize the particles of their respective starting metals by addition of concentrated nitric acid. Similarly, aqua regia (concentrated nitric acid and con- centrated hydrochloric acid in the ratio 1:3) was added to residues of Aurum met, Argentum met, and Platinum met. A 1:1 ratio of water: acid was maintained for all the concen- trated samples. The amount of acid and water was adjusted so that the final volume was 4 ml, thus, amounting to a con- centration by a factor of 500. The samples were filtered Nanoparticle characterization by TEM/SAED: analyses were performed on Tecnai G2 120 kV Cryo-TEM (FEI, Hillsboro, USA). All samples were viewed at 120 kV. The TEM analyses were performed for the medicines by placing a drop of the original solution (without pre-concen- tration) on the carboneformvar coated copper TEM grids in a clean environment. The drop of the solution was The TEM Homeopathy through Whatman 40 filter paper to remove the residual mat- ter prior to analysis. The SBL samples were analyzed in trip- licate and samples from WSI were analyzed in duplicate. As a negative control, 90%v/v ethanol samples were also pre- pared using HPLC grade ethanol and Milli-Q water. These ethanolic solutions were also concentrated in the manner similar to that employed for the medicines. The emission lines selected for measuring the concentra- tion of the metals are as follows: Gold: 242.795 nm, Copper: 324.754 nm, Tin: 283.999 nm, Zinc: 213.856 nm, Silver: 328.068 nm, Platinum: 265.945 nm. The instrument re- sponse was calibrated using standards prior to analyses of the samples. Results and discussion Determination of size and morphology by TEM Zincum met, Aurum met, Stannum met and Cuprum met 30c and 200c were analyzed by TEM. The results are given as photomicrographs (Figure 1(a)e(p)), which clearly dem- onstrate the presence of nanoparticles and their aggregates. Due to extreme dilution often only a single nanoparticle or a large aggregate is seen. Hereafter, the term ‘particles’ col- lectively refers to the nanoparticles and their aggregates. We noted a high polydispersity of the particles in the so- lutions with respect to their shapes and sizes for various medicines and potencies. A scrupulous examination of the entire manufacturing process of these medicines sug- gested that two key processes played a vital role in impart- ing the high polydispersity. They are: 1. The dilution steps in the solid phase (till 6 potency) in- volved trituration of the raw materials with lactose. Such a comminution process is expected to generate particles of varied shapes and sizes. The physical characteristics of these particles are dependent on the type of raw mate- rial and the shearing force applied. 2. During liquid dilutions, the succussion process at each potentization step played a vital role. The succussions given to the liquid mass are expected to produce particles of varied shapes and sizes due to three factors including shearing forces generated during the pounding of the liq- uid container against an elastic stop, the properties of the raw materials involved, and variations during pounding of the container, between individuals. The permutations and combinations of the above-men- tioned factors and the possible subtle differences in the manufacturing processes employed by various manufac- turers can explain the findings regarding polydispersity between different medicines and manufacturers. We also made another prominent observation regarding the presence of surface asperities on the particles which were clearly evident from the differences in contrast on sur- faces of these particles along with a substantial difference in their size between different starting metals. Thus, larger aggregates were found in Zincum met (Figure 1(a)e(d)) and Stannum met (Figure 1(i)e(l)) as compared to those Nanoparticles of starting materials in homeopathic medicines PS Chikramane et al observed in Aurum met (Figure 1(e)e(h)) and Cuprum met (Figure 1(m)e(p)) at the same potencies. The mechanism of cavitation or generation of vapor bub- bles caused by ultra-sound irradiation (acoustic cavitation) in the entire liquid mass during manufacturing may explain the observations noted above. We suggest that the process of succussion is the cause of cavitation. As set out in a later section, the extant theories of cavitation11e14 can, in principle, provide an explanation of our findings. The aggregation behavior of the particles seems to be de- pendent on the physical property of the starting metal, spe- cifically its melting point. We observed that the aggregates of zinc in Zincum met and tin in Stannum met were rela- tively larger as compared to the smaller aggregates of gold and copper found in Aurum met and Cuprum met re- spectively. The bulk melting points of tin and zinc are w505 K and w692 K respectively as compared to the higher melting points of gold and copper (w1337 K and w1357 K respectively). A decrease in melting points of metallic and semiconductor particles with decreasing size has also been well characterized.15 A combination of ex- tremely high surface temperatures along with a decrease in the melting point of these particles could facilitate the formation of aggregates that we found. It is probable that during the succussion process, the col- lisions of the particles induce surface temperatures well above the melting points of tin and zinc, thereby facilitat- ing their aggregation. However, the melting points of gold and copper being much higher, the occurrence of melting and fusion of these particles would be relatively less frequent than for tin and zinc. Overall, our data for bright-field TEM do not indicate a major difference in the size or nature of the particles in a particular medicine as we increase potency from 30c to 200c. Therefore, the individual crystallite sizes were deter- mined by dark-field TEM (as shown for Zincum met for both manufacturers in Figure 2(a)e(d)). We observed that the aggregates of all the metals tested had maximum crystal- lites (w40e50%) in the size range of 5e10 nm, and that 70e95% of all the crystallites were below 15 nm (Figure S1 e Supplementary information). Thus, in the case of dark-field TEM also, there was no major potency- dependent difference in size distribution of crystallites. Confirmation of elemental composition of particles by SAED The nanoparticles and aggregates identified in TEM were analyzed by SAED for confirmation of the elemental compo- sition. We took multiple SAED patterns of the same particle at varying intensities so as to focus on the inner and outer rings for calculation of the d-spacings of the respective ele- ments. The SAED patterns of the nanoparticles and their ag- gregates found in the metal-based homeopathic medicines are represented in Figure 3(a)e(p). SAED analyses of all samples showed patterns consis- tent with the starting materials. In particular, Aurum met and Cuprum met from both suppliers (SBL and WSI) in- dexed to gold and copper respectively. Table 1 shows the values of the d-spacings calculated from the diameters of 233 Homeopathy 234 Nanoparticles of starting materials in homeopathic medicines PS Chikramane et al Figure 1 Bright-field TEM images of nanoparticles and aggregates. Zincum met: (a) 30c (SBL), (b) 200c (SBL), (c) 30c (WSI), (d) 200c (WSI). Aurum met: (e) 30c (SBL), (f) 200c (SBL), (g) 30c (WSI), (h) 200c (WSI). Stannum met: (i) 30c (SBL), (j) 200c (SBL), (k) 30c (WSI), (l) 200c (WSI). Cuprum met: (m) 30c (SBL), (n) 200c (SBL), (o) 30c (WSI), (p) 200c (WSI). the ring patterns of particles observed in Aurum met sam- ples. Similarly, in the case of Stannum met from SBL, the observed pattern indexed to a-Sn whereas that from WSI to b-Sn. In the case of Zincum met samples from both sup- pliers, we did not observe pure metallic zinc, but the SAED patterns indexed to zinc hydroxide which is an expected compound derived from zinc (d-spacing data for zinc, tin and copper have been given as Supplementary information e Tables S2eS5). The confirmed presence of these crystalline species of starting materials or those derived from them (as evident from the SAED patterns) despite the ultra-high dilutions Homeopathy such as 30c and 200c was astounding, proving that the starting materials were retained even with extremely high dilutions. The d-spacing values for the particular elements con- formed well to the Joint Committee on Powder Diffraction Standards (JCPDS) data in literature in the range of `2%. However, for some d-spacings corresponding to a few planes in the crystal, the values differed by approximately `4%. The differences in some of the d-spacing values for each metal can be explained on the basis of induction of mi- nor plastic deformations in the crystals. The initial tritura- tion process involving high shearing forces, together with the succussion process involving high-velocity collisions of nanoparticles resulting in the generation of shock waves caused by the imploding cavitations, may have induced minor plastic deformations in the metal crystals. In a few of the SAED patterns for the metals analyzed, the particles also showed presence of diffused ring Figure 1 (continued). Nanoparticles of starting materials in homeopathic medicines PS Chikramane et al 235 Homeopathy 236 Nanoparticles of starting materials in homeopathic medicines PS Chikramane et al Figure 2 Bright-field and corresponding dark-field TEM images of nanoparticles and aggregates observed in Zincum met: (a) 30c (SBL), (b) 200c (SBL), (c) 30c (WSI), (d) 200c (WSI). Inset e SAED patterns of the corresponding nanoparticle/aggregate. patterns similar to that of an amorphous material. The probable reason for presence of amorphous phases on the surface of the nanoparticles and aggregates is de- scribed later in this paper. On the whole, the SAED data indicated that the particles of the starting materials were present in the homeopathic medicines even in po- tencies such as 30c and 200c. In order to quantify the ex- act amounts of these starting metals in ultra-high potencies, we conducted the ICP-AES analyses of these medicines. Estimation of concentration of the starting materials by ICP-AES ICP-AES is an established technique for the estimation of metals and other elements. Our equipment had a mini- mum detectable limit of 10 ppb, thereby necessitating Homeopathy Nanoparticles of starting materials in homeopathic medicines PS Chikramane et al Figure 3 SAED patterns of corresponding nanoparticles and aggregates (shown in Figure 1(a)e(p)). Zincum met: (a) 30c (SBL), (b) 200c (SBL), (c) 30c (WSI), (d) 200c (WSI). Aurum met: (e) 30c (SBL), (f) 200c (SBL), (g) 30c (WSI), (h) 200c (WSI). Stannum met: (i) 30c (SBL), (j) 200c (SBL), (k) 30c (WSI), (l) 200c (WSI). Cuprum met: (m) 30c (SBL), (n) 200c (SBL), (o) 30c (WSI), (p) 200c (WSI). 237 Homeopathy Nanoparticles of starting materials in homeopathic medicines PS Chikramane et al 238 Figure 3 (continued). Homeopathy PS Chikramane et al Table 1 Electron diffraction pattern e comparison of d-spacing for Aurum met 30c and 200c potencies 239 Nanoparticles of starting materials in homeopathic medicines hkl values Relative intensity 111 100 200 52 220 32 311 36 222 12 400 6 331 23 420 22 422 23 333 e 440 e 531 e 442 e 620 e 533 e 622 e 444 e d-spacing Gold [#A] 2.3550 2.0390 1.4420 1.2300 1.1774 1.0196 0.9358 0.9120 0.8325 0.7850 0.7210 0.6890 0.6800 0.6450 0.6220 0.6150 0.5890 Aurum met 30C SBL e Figure 3(e) 2.0300 1.2000 1.0700 0.7600 0.6600 Aurum met 200C SBL e Figure 3(f) 2.0393 1.4389 1.2598 1.1809 1.0072 0.9120 0.7843 0.7179 0.6939 Aurum met 30C WSI e Figure 3(g) 2.3515 2.0213 1.4454 1.1732 1.0152 0.9079 0.8286 0.7196 Aurum met 200C WSI e Figure 3(h) 2.3312 2.0224 1.4418 1.2514 1.1695 1.0211 0.9530 All d-spacing values are in #A units. d-spacing data in ‘bold’ e from JCPDS#04-0784, remaining d-spacing data from Edington.16 concentration of the homeopathic solutions using a tech- nique in which there is absolutely no possibility of adding inadvertently the metal to be detected. The analyses of the metal-based medicines, performed after the concentration of the solutions gave startling re- sults. The starting metals were detected for all potencies (6c, 30c, and 200c) at concentrations of the order of picogram/ml (pg/ml). The measured concentrations are presented in Table 2. The data presented in the table are back-calculated concentrations of the metals in the origi- nal homeopathic medicines. The analyses of the negative control of 90%v/v ethanol did not indicate the presence of either the noble metals or tin, and for metals such as cop- per and zinc, indicated far lower concentrations than those in the medicines. We analyzed several samples of Aurum met, Argentum met, and Platinum met for the presence of their respective starting metals. In the case of Aurum met (SBL), some of the samples tested, including higher potencies such as 30c and 200c indi- cated presence of approximately 60e100 pg/ml of gold; the levels being much higher than the sensitivity of the instrument whereas in the ethanolewater negative controls there was no signal for the presence of gold. However, a few Aurum met (SBL) samples did not show presence of gold. Our results point towards a considerable batch-to-batch variation in the concentrations of the starting material. This is certainly not surprising, considering that the method of preparation in- volved manual processes along with an absence of any at- tempt to estimate the concentrations of the starting materials at the end of the manufacturing process of a partic- ular batch. The Aurum met (WSI) samples did not show gold in detectable quantities. Analogous results were obtained for the Argentum met (SBL) samples wherein silver was detected in one 30c and one 200c sample (30.6 pg/ml and 116 pg/ml respec- tively). The concentrations in the other samples were below the detection limit. Likewise, we discerned detect- able concentration of platinum (w40e220 pg/ml) in the Platinum met (SBL) samples for all potencies. The concentrations of non-noble metals such as copper, tin and zinc in their respective homeopathic medicines viz. Cuprum met, Stannum met, and Zincum met were higher (2e30 times that of noble metals) and easily detectable. In the Cuprum met samples (SBL), we detected w500e2500 pg/ml of copper in the solutions. Similarly, 6c potency of WSI indicated high concentration of copper (w370 and w900 pg/ml respectively in the two samples). However, the concentrations of copper in the higher poten- cies viz. 30c and 200c were very low (w10e40 pg/ml) in some and below detectable limits in the others. Likewise for Stannum met samples (SBL) we detected tin; albeit with very high variations from w70 to 1000 pg/ml. In the WSI homeopathic solutions of Stannum met however, lower concentrations of tin were detected in the range of w20e180 pg/ml. As compared to the other samples of non-noble metals noted above, the concentration of zinc in the Zincum met samples was much higher. In the Zincum met samples we detected presence of zinc with a very high variation in the concentrations between manufacturers from w200 to 2700 pg/ml and w1400 to 4000 pg/ml for SBL and WSI respectively. It was reassuring that there was good reproducibility in terms of the estimated concentrations of the starting mate- rials in the pair of samples of the same medicine, potency, and the manufacturing batch. We observed a variation up to 40% in the samples prepared from the same manufacturing batch as compared to a variation up to 1550% in samples from different batches. These results clearly highlighted the following: 1. Validation of the accuracy of our method involving pre- concentration of the medicines prior to analyses as exemplified by the moderate variation in intra-batch samples (refer data sets for Cuprum met, Stannum met, and Zincum met marked in bold in Table 2). 2. High inter-batch variation in the concentration of the starting materials for a given manufacturer and potency, and between manufacturers. Homeopathy 240 PS Chikramane et al Table 2 Estimated concentration of starting metals in various potencies by ICP-AES (pg/ml) Homeopathic dilution SBL (pg/ml) WSI (pg/ml) 12312 Nanoparticles of starting materials in homeopathic medicines 90%v/v Ethanol ND Aurum met 6c 81.4 Aurum met 30c 64.8* Aurum met 200c ND 90%v/v Ethanol 153.4 Cuprum met 6c 1199.0 Cuprum met 30c 730.2 Cuprum met 200c 485.4 90%v/v Ethanol ND Stannum met 6c 569.4 Stannum met 30c 901.6 Stannum met 200c 877.8 90%v/v Ethanol 208.2 Zincum met 6c 380.0 Zincum met 30c 655.2 Zincum met 200c 357.8 90%v/v Ethanol ND Argentum met 6c ND Argentum met 30c ND Argentum met 200c ND 90%v/v Ethanol ND Platinum met 6c 220.6* Platinum met 30c 41.0* Platinum met 200c 213.6 ND 76.4 ND 104.6 245.0 995.2 703.2 432.2 ND 409.2 889.6 1055.8 210.2 366.0 165.4 191.2* ND ND 116.0 ND ND ND 58.2 ND 149.0 1355.6* 1383.4* 2680.2* ND 195.8* 145.6 63.8* 199.0 1002.8 1224.0 2743.6 ND 30.6 ND ND Samples not obtained ND ND Samples not obtained ND ND ND ND 245.0 149.0 893.4 370.8 38.6* ND ND ND ND ND 180.8 153.0 93.8 76.4 20.8 73.0 208.2 210.2 1432.6* 3989.6 3068.6* 1377.6 2230.2* 2322.8 Samples not obtained Samples not obtained ‘Bold’ against a pair of samples in Limit of Detection (LOD) of the instrument was 10 ng/ml corresponding to 20 pg/ml in the original solutions. All concentrations below this value have been reported as ‘Not Detected’ or ‘ND’. * Data indicate that the bottles used to make up the required quantity (2000 ml) were from the same manufacturing batch. Thus, for each metal-based medicine of a particular po- tency, the estimated values appeared to be within a band of 2 orders of magnitude. These variations could be attributed to the processes employed for manufacturing. A visit to a reputed manufacturer revealed that the initial lactose trit- urations were performed on an automated machine using a mortar and pestle. Apart from the control of particle sizes of the metal powders at 1 potency (wherein 80% of the particles of the starting material should be below 10 mm and none above 50 mm),17 there are no further checks for the distribution of the metals in the triturated 6 mixture, which is the starting material for proceeding to the liquid based succussion steps. This is believed to be the cause of these large variations. The liquid dilutions and the potentization steps (includ- ing succussion) were done manually during manufactur- ing, wherein the entire mass of the liquid in the glass container was pounded against a rubber stop 10 times, with inevitable variation in the force of impact and the ex- tent of cavitation generated during these human powered succussions. Apart from the initial trituration with lactose, succussion per se could also be an important method of generation of nanoparticles of the starting materials, due to intense shearing of these nanoparticles against the walls of the glass containers, by the fluid shear and possibly by particle collision due to the implosion of the cavitations created by the ultra-sound waves generated. Therefore, a difference in the shearing force imparted during succus- sion could result in a large difference in the formation of the nanoparticle fraction of the starting materials, thereby reflecting as inter-batch variation. Once the succussion process was completed, the entire mass of liquid was allowed to settle, prior to transfer of 1% of this dilution to 99 parts fresh 90%v/v ethanol. How- ever, the settling time for the dilutions was not fixed. Also, the removal of one part of the previous dilution for the pur- pose of transferring into a fresh solvent was carried out ran- domly from the container and was a manual process. All the above-mentioned factors combined are expected to im- part a lot of disparity in the concentrations of the starting materials in the final medicines which we observed in our studies. During our analyses we also noted the plateauing effect of the concentrations of the starting metals per se in a partic- ular concentration range in potencies 6c, 30c and 200c, in spite of 30c and 200c potencies being 1048 and 10388 respec- tively more dilute than 6c. It is interesting to note that the plateau for non-noble metals showed a higher metal content than for noble metals. Our ICP-AES results suggested that the asymptote effect commences around 6c potency (Figure 4). Our findings appear to be an extension of the trends noted at lower potencies by Ro ̈der et al.,18 who analyzed the concentrations of a few metals in decimal dilutions from 6 to 8 (corresponding to centesimal potencies of 3c to 4c). Part ‘A’ in Figure 4 explicitly depicts de- crease in the concentrations of starting materials with di- lutions. Only in the case of Au3+ in AuCl3 solutions, the a row for given manufacturer and potency indicates their preparation from same manufacturing batch. The Homeopathy Nanoparticles of starting materials in homeopathic medicines PS Chikramane et al Figure 4 Estimated concentrations of starting elements in homeopathic potencies. Part ‘A’ e estimated by Ro ̈ der et al.18 e solid symbols: expected concentrations, open: estimated concentrations, circles: Au3+, star: Fe3+, left triangle: Hg2+, right triangle: Zn2+. Part ‘B’ e estimated by ICP-AES in our work e squares: zinc concentrations, open: Zincum met (SBL), solid: Zincum met (WSI), open triangles: gold concentrations in Aurum met (SBL) samples. The dotted line at 20 pg/ml indicates the LOD of the instrument. 241 actual concentrations determined were lesser than the expected concentrations (circles, solid: expected; open: estimated concentrations). On the contrary, the concentra- tions of Fe3+ though slightly lower than expected at the 6 potency, did not decrease as expected, and were in fact slightly higher at 7 and 8 potencies (stars, solid: expected; open: determined concentrations). Likewise, the concentrations of Hg2+ and Zn2+ were almost 200% higher than expected at 8 potency. A scrupulous, concurrent analysis of these results suggested the com- mencement of an asymptote formation in the vicinity of the 8 (i.e. 4c) potency. When the data from Part ‘A’ of the graph are compared with our data (Part ‘B’), there appears to be a plateauing effect, reached at 6c potency. While a plateau is reached for each metal, the concentra- tion range varied from one metal to another and between manufacturers. The plateau of Zincum met (WSI) (solid squares) was appreciably higher (between 1300 and 4000pg/ml) than that for Zincum met (SBL) (open squares), albeit with the inherent variation mentioned ear- lier. Similar trends were also observed for all the other metals that were analyzed. Possible key mechanisms at large dilutions Acoustic cavitation, a well studied phenomenon11e14 may explain our TEM findings regarding surface asperities and particle aggregation. Researchers have observed that the vapor bubbles generated due to the high-energy sound waves had temperatures exceeding a few thousand degrees (w5000 K) along with intense pressures (w1000 atm). The bubbles so formed had very short lives before imploding, creating intense shock waves which propel particles in the solution at extremely high velocities resulting in collisions which induced the following morphological changes on the particle surfaces: 1. When the particles collided head-on, localized melting occurred on their surfaces at the point of contact, with the temperatures being w3000 K. With the surrounding liquid at ambient temperature, the melted surfaces instantly cooled at extremely high rates (>1010 K/s), thereby solidifying the melted area instantaneously and fusing the particles at the point of contact to form aggregates. 2. The extremely high rate of cooling, while not allowing for re-crystallization at the point of contact, led to an amorphous phase on the particle surface as evident from the diffused rings obtained in the electron diffraction (ED) patterns. 3. Collision of particles at a glancing angle led to fragmen- tation of the particle surface which may have given rise to surface asperities. The above theories support our observations regarding the presence of the surface asperities we see in TEM, since the forceful pounding of the glass containers during the succus- sion process may have been instrumental in generating the ultra-sound waves, resulting in their formation. Homeopathy 242 Nanoparticles of starting materials in homeopathic medicines PS Chikramane et al Another question that arises from our observations is how in spite of such huge dilutions the particles of the start- ing materials are retained even at 200c potency? The an- swer to this question could lie in the manufacturing process itself. We perceive that during the succussion pro- cess, the pounding of solutions against a rubber stop gener- ates numerous nanobubbles19 as a result of entrapment of air and cavitation due to generation of ultra-sound waves. The particles of the starting material instantaneously get adsorbed on the surface of these bubbles and cavitations. This phenomenon could be similar to the mechanism of formation of Pickering emulsions,20e22 wherein the emulsified phase viz. air bubbles or liquid droplets are stabilized by a layer of particles. This nanoparticleenanobubble complex rises to the sur- face and can be within a monolayer once the total metal concentrations are well below 1ppm (Table S6 e Supplementary information). It is this 1% of the top layer of the solution which is collected and added to the next vessel, into 99 parts of fresh solvent and the succussion process is repeated. This transfer of the top 1% layer in each step will ensure that once we reach below a certain concentration i.e. well within a monolayer, the entire start- ing material continues to go from one dilution to the next, resulting in an asymptote beyond 6c. Conclusion Using state-of-the-art techniques (TEM, SAED, and ICP-AES) we have demonstrated the presence of nanopar- ticles of the starting materials and their aggregates even at extremely high dilutions. The confirmed presence of nano- particles challenges current thinking about the role of dilu- tion in homeopathic medicines. We have found that the concentrations reach a plateau at the 6c potency and be- yond. Further, we have shown that despite large differences in the degree of dilution from 6c to 200c (1012 to 10400), there were no major differences in the nature of the parti- cles (shape and size) of the starting material and their abso- lute concentrations (in pg/ml). How this translates into change in biological activity with increasing potency needs further study. Concrete evi- dence of the presence of particles as found by us could help take the research in homeopathy a step forward in under- standing these potentised medicines and also help to posi- tively change the perception of the scientific community towards this mode of treatment. Conflict of interest There are neither any financial nor any personal conflicts of interest with respect to the work carried out for this article. Acknowledgements We thank the Department of Earth Sciences and the Cryo-TEM central facility at IIT Bombay for ICP-AES and TEM analyses respectively. We also gratefully acknowledge funding by Shridhar Shukla, S G Kane and Industrial Research and Consultancy Center (IRCC), IIT Bombay. We also thank P N Varma for valuable insights. Supplementary data Supplementary data associated with this article can be found in the online version at doi:10.1016/j.homp.2010. 05.006. References 1 Khuda-Bukhsh AR. Laboratory research in homeopathy: Pro. 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